School of Mechanical and Materials Engineering

Control strategies for building energy systems to unlock demand side flexibility – A review

2017-10-26T14:44:47Z

Control strategies for building energy systems to unlock demand side flexibility – A review Clauß, John; Finck, Christian; Vogler-Finck, Pierre; Beagon, Paul Conventional key performance indicators (KPI) assessed in building simulation lack specific measures of how the building interacts with the grid and its energy flexibility. This paper aims to provide an overview of specific energy flexibility performance indicators, together with supporting control strategies. If applied correctly, the indicators help improving the building performance in terms of energy flexibility and can enable minimization of operational energy costs. Price-based load shifting, self-generation and self-consumption are among the most commonly used performance indicators that quantify energy flexibility and grid interaction. It has been found that the majority of performance indicators, specific to energy flexibility, are combined with rule-based control. Only a limited amount of specific energy flexibility KPIs are used in combination with optimal control or model predictive control. Both of these advanced control approaches often have a couple of economic or comfort objectives that do not take into account an energy flexibility KPI. There is evidence that recent model predictive control approaches incorporate some aspects of building energy flexibility to minimize operational cost in conjunction with time varying pricing. IPBSA Building Simulation 2017, San Francisco, 7-9 August 2017

Regression analysis of temperature-dependent mechanical and thermal properties of dielectric technical ceramics

2017-08-23T12:24:50Z

Regression analysis of temperature-dependent mechanical and thermal properties of dielectric technical ceramics de Faoite, Daithí; Browne, David J.; Stanton, Kenneth T. Regression analysis is performed on a dataset of temperature-dependent material properties of several ceramic materials. The materials considered are alumina, aluminium nitride, beryllia, fused quartz, sialon and silicon nitride. The properties considered are density, Young's, bulk and shear moduli, Poisson's ratio, tensile, flexural and compressive strength, thermal conductivity, specific heat capacity, and thermal expansion coefficient. The dataset, previously reported by de Faoite et al. (J Mater Sci 47(10):4211, 2012), was compiled to facilitate the materials selection and design of a ceramic component for the Variable Specific-Impulse Magnetoplasma Rocket (VASIMR®). Temperature-dependent material property data are required for accurate thermo-structural modelling of such ceramic components which operate over a wide temperature range. The goal of this paper is to calculate a set of regression coefficients to reduce this dataset to a tractable format for use in the materials selection and design of such components. Regression analysis could not be performed for all material properties for all of these materials, due to a lack of data in the literature, and these gaps in the available data are highlighted.

Inverse estimate of heat flux on a plasma discharge tube to steady-state conditions using thermocouple data and a radiation boundary condition

2017-08-23T11:54:51Z

Inverse estimate of heat flux on a plasma discharge tube to steady-state conditions using thermocouple data and a radiation boundary condition de Faoite, Daithí; Browne, David J.; Del Valle Gamboa, J. I.; Stanton, Kenneth T. The heat flux incident upon the inner surface of a plasma discharge tube during a helicon plasma discharge was estimated using an inverse method. Temperature readings were taken from the outer surface of the tube using thermocouples, and the temperature data were interpolated over the tube surface. A numerical inverse procedure based on the Alifanov iterative regularisation method was used to reconstruct the heat flux on the tube inner surface as a function of space and time. In contrast to previously-used inverse models for this application, the current model implements a thermal radiation boundary condition to realistically model the energy exchange in the device. Additionally in these experiments, steady-state operation was reached, and the accurate modelling of the steady-state condition was facilitated by the thermal radiation boundary condition. The variation of heat flux with helicon discharge power, propellant flowrate, and electromagnet current was studied, and it was found that the waste heat flux increased with applied RF power and propellant flowrate, and decreased with current supplied to the electromagnets, over the range of parameter variation tested.

Prediction of tool-wear in turning of medical grade cobalt chromium molybdenum alloy (ASTM F75) using non-parametric Bayesian models

2017-08-18T10:42:31Z

Prediction of tool-wear in turning of medical grade cobalt chromium molybdenum alloy (ASTM F75) using non-parametric Bayesian models McParland, Damien; Baron, Szymon; O'Rourke, Sarah; Dowling, Denis P.; Ahearne, Eamonn; Parnell, Andrew C. We present a novel approach to estimating the effect of control parameters on tool wear rates and related changes in the three force components in turning of medical grade Co-Cr-Mo (ASTM F75) alloy. Co-Cr-Mo is known to be a difficult to cut material which, due to a combination of mechanical and physical properties,is used for the critical structural components of implantable medical prosthetics. We run a designed experiment which enables us to estimate tool wear from feed rate and cutting speed, and constrain them using a Bayesian hierarchical Gaussian Process model which enables prediction of tool wear rates for untried experimental settings. The predicted tool wear rates are non-linear and, using our models,we can identify experimental settings which optimise the life of the tool. This approach has potential in the future for real time application of data analytics to machining processes.

Development of glass-ceramic scintillators for gamma-ray astronomy

2017-08-14T15:34:46Z

Development of glass-ceramic scintillators for gamma-ray astronomy de Faoite, Daithí; Hanlon, Lorraine; Roberts, O.; Ulyanov, A.; McBreen, S.; Tobin, I.; Stanton, Kenneth T. Scintillators synthesised as glass-ceramics have several potential benefits compared to the currently-used halide scintillators, including non-hygroscopicity, mechanical ruggedness, ease of producing customisable shapes, and the potential for low-cost synthesis. The use of these scintillators is considered for a gamma-ray telescope operating in the 0.2 MeV¿50 MeV photon range. Inorganic scintillator compounds suitable for incorporation into glass-ceramics are assessed. In addition, several families of glass suitable for use as hosts for scintillating compounds are also reviewed. Applications of Novel Scintillators for Research and Industry (ANSRI 2015), Dublin, Ireland, 12–14 January 2015

Thermo-structural modelling of a plasma discharge tube for electric propulsion

2017-08-14T15:31:31Z

Thermo-structural modelling of a plasma discharge tube for electric propulsion de Faoite, Daithí; Browne, David J.; Del Valle Gamboa, J. I.; Stanton, Kenneth T. Potential thermal management strategies for the plasma generation section of a VASIMR® high-power electric propulsion space thruster are assessed. The plasma is generated in a discharge tube using helicon waves. The plasma generation process causes a significant thermal load on the plasma discharge tube and on neighbouring components, caused by cross-field particle diffusion and UV radiation. Four potential cooling system design strategies are assessed to deal with this thermal load. Four polycrystalline ceramics are evaluated for use as the plasma discharge tube material: alumina, aluminium nitride, beryllia, and silicon nitride. A finite element analysis (FEA) method was used to model the steady-state temperature and stress fields resulting from the plasma heat flux. Of the four materials assessed, aluminium nitride would result in the lowest plasma discharge tube temperatures and stresses. It was found that a design consisting of a monolithic ceramic plasma containment tube fabricated from aluminium nitride would be capable of operating up to a power level of at least 250 kW.

Elimination of porosity in bulk metallic glass castings using hot isostatic pressing

2017-07-28T14:48:37Z

Elimination of porosity in bulk metallic glass castings using hot isostatic pressing Srivastava, Amit P.; Tong, Mingming; Ștefanov, Tatiana; Browne, David J. This study presents design and implementation of a systematic method to remove the pores in as-cast bulk metallic glass using hot isostatic pressing, without changing the amorphous structure of the samples. The supercooled liquid region of Zr44Cu40Al8Ag8 was characterized using differential scanning calorimetry and dynamic mechanical analysis. This enabled informed choice of the range of hot isostatic pressing process variables likely to result in successful reduction of the porosity in the glassy alloy. The operating pressure in hot isostatic press processing was relatively less influential than either the temperature or the dwell time in controlling the porosity. It was shown that the dwell time should be longer than the average relaxation time in the glass transition range. With the specific bulk amorphous alloy under study, the optimized temperature, pressure and dwell time are 475 °C, 50 MPa and 3 min, respectively. Excess dwell times will result in crystallization.

Determining the relationship between linear and rotational acceleration and MPS for different magnitudes of classified brain injury risk in ice hockey

2017-07-26T14:25:52Z

Determining the relationship between linear and rotational acceleration and MPS for different magnitudes of classified brain injury risk in ice hockey Clark, J. Michio; Post, Andrew; Hoshizaki, Thomas Blaine; Gilchrist, M. D. Helmets have successfully decreased the incidence of traumatic brain injuries (TBI) in ice hockey, yet the incidence of concussions has essentially remained unchanged. Current ice hockey helmet certification standards use peak linear acceleration as the principal measuring helmet performance, however peak linear acceleration may not be an appropriate variable to evaluate risk at all magnitudes of brain injury. The purpose of this study is to determine the relationship between linear acceleration, rotational acceleration and maximum principal strain (MPS) for different magnitudes of classified brain injury risk in ice hockey. A helmeted and unhelmeted Hybrid III headform were impacted to the side of the head at two sites and at three velocities under conditions representing three common mechanisms of injury. Resulting linear and rotational accelerations were used as input for the University College Dublin Brain Trauma Model (UCDBTM), to calculate MPS in the brain. The resulting MPS magnitudes were used to separate the data into three groups: low risk; concussion; and TBI. The results demonstrate that the relationship between injury metrics in ice hockey impacts is dependent on the magnitude of classified injury risk and the mechanism of injury. International Research Council on Biomechanics of Injury Conference, Lyon, France, 9-11 September 2015

The effect of acceleration signal processing for head impact numeric simulations

2017-10-18T01:00:09Z

The effect of acceleration signal processing for head impact numeric simulations Post, Andrew; Clark, J. Michio; Robertson, D.G.E.; Hoshizaki, Thomas Blaine; Gilchrist, M. D. Brain injury research in sport employs a variety of physical models equipped with accelerometers. These acceleration signals are commonly processed using filters. The purpose of this research was to determine the effect of applying filters with different cutoff frequencies to the acceleration signals used as input for finite element modelling of the brain. Signals were generated from reconstructions of concussion events from American football and ice hockey in the laboratory using a Hybrid III headform. The resulting acceleration signals were used as input for the University College Dublin Brain Trauma Model after being processed with filters. The results indicated that using a filter with a cutoff of 300 Hz or higher had little effect on the resulting strain measures. In some cases there was some effect of the filters on the peak linear (8¿30g) and rotational measures (1000¿4000 rad/s2), but little effect on the finite element strain result (approximately 2¿6 %). The short duration and high magnitude accelerations, such as the puck impact, were most affected by the cutoff frequency of different filters.

Protective Capacity of Ice Hockey Helmets against Different Impact Events

2017-07-26T12:19:02Z

Protective Capacity of Ice Hockey Helmets against Different Impact Events Clark, J. Michio; Post, Andrew; Hoshizaki, Thomas Blaine; Gilchrist, M. D. In ice hockey, concussions can occur as a result of many different types of impact events, however hockey helmets are certified using a single injury scenario, involving drop tests to a rigid surface. The purpose of this study is to measure the protective capacity of ice hockey helmets for different impact events in ice hockey. A helmeted and unhelmeted Hybrid III headform were impacted simulating falls, elbow, shoulder and puck impacts in ice hockey. Linear and rotational acceleration and maximum principal strain (MPS) were measured. A comparison of helmeted and unhelmeted impacts found significant differences existed in most conditions (p < 0.05), however some shoulder and puck impacts showed no significant difference (p > 0.05). Impacts to the ice hockey helmet tested resulted in acceleration levels below reported ranges of concussion and TBI for falls up to 5 m/s, elbow collisions, and low velocity puck impacts but not for shoulder collisions or high velocity puck impacts and falls. The helmet tested reduced MPS below reported ranges of concussion and TBI for falls up to 5 m/s but not for the other impact events across all velocities and locations. This suggests that the ice hockey helmet tested is unable to reduce engineering parameters below reported ranges of concussion and TBI for impact conditions which do not represent a drop against a rigid surface.

The Association among Injury Metrics for Different Events in Ice Hockey Goaltender Impact

2017-05-11T10:23:03Z

The Association among Injury Metrics for Different Events in Ice Hockey Goaltender Impact Clark, J. Michio; Post, Andrew; Hoshizaki, Thomas Blaine; Gilchrist, M. D. Current ice hockey goaltender helmet standards use a drop test and peak linear acceleration to evaluate performance. However, ice hockey goaltenders are exposed to impacts from collisions, falls and pucks which each create unique loading conditions. As a result, the use of peak linear acceleration as a predictor for brain trauma in current ice hockey standards may not be most appropriate. The purpose of this study was to determine how kinematic response measures correlate to maximum principal strain and von Mises stress for different impact events. A NOCSAE headform was fitted with three ice hockey goaltender helmet models and impacted under conditions representing these three different impact events (fall, puck, collision). Peak resultant linear acceleration, rotational acceleration and rotational velocity of the headform were measured. Resulting accelerations were input into the University College Dublin Brain Trauma Model, which calculated maximum principal strain and von Mises stress in the cerebrum. The results demonstrated that the relationship between injury metrics in ice hockey goaltender impacts is dependent on the impact event and velocity. As a result of these changing relationships, the inclusion of finite element analysis in test protocols may provide a more practical representation of brain loading in evaluating the performance of ice hockey goaltender helmets. 2016 International Research Council on Biomechanics of Injury Conference, Malaga, Spain, 14-16 September 2016

A review of the processing, composition and temperature-dependent mechanical and thermal properties of dielectric technical ceramics

2017-08-14T15:30:55Z

A review of the processing, composition and temperature-dependent mechanical and thermal properties of dielectric technical ceramics de Faoite, Daithí; Browne, David J.; Chang-Díaz, Franklin R.; Stanton, Kenneth T. The current review uses the material requirements of a new space propulsion device, the Variable Specific Impulse Magnetoplasma Rocket (VASIMR®) as a basis for presenting the temperature dependent properties of a range of dielectric ceramics, but data presented could be used in the engineering design of any ceramic component with complementary material requirements. A material is required for the gas containment tube (GCT) of VASIMR® to allow it to operate at higher power levels. The GCT's operating conditions place severe constraints on the choice of material. A dielectric is required with a high thermal conductivity, low dielectric loss factor, and high thermal shock resistance. There is a lack of a representative set of temperature-dependent material property data for materials considered for this application and these are required for accurate thermo-structural modelling. This modelling would facilitate the selection of an optimum material for this component. The goal of this paper is to determine the best material property data values for use in the materials selection and design of such components. A review of both experimentally and theoretically-determined temperature-dependent & room temperature properties of several materials has been undertaken. Data extracted are presented by property. Properties reviewed are density, Young's, bulk and shear moduli, Poisson's ratio, tensile, flexural and compressive strength, thermal conductivity, specific heat capacity, thermal expansion coefficient and the factors affecting maximum service temperature. Materials reviewed are alumina, aluminium nitride, beryllia, fused quartz, sialon and silicon nitride.

Identification of key liquid metal flow features in the physical conditioning of molten aluminium alloy with high shear processing

2017-05-03T10:09:57Z

Identification of key liquid metal flow features in the physical conditioning of molten aluminium alloy with high shear processing Tong, Mingming; Patel, Jayesh B.; Stone, Ian; Fan, Zhongyun; Browne, David J. Although treating molten alloy with high shear processing (HSP) can dramatically refine the microstructure of solidified aluminium alloys, it was also recently employed as part of an effective route to purification of contaminated aluminium alloy scrap. The key mechanisms of HSP include the dispersion of large aluminium oxide films and clusters into very fine oxide particles by the high shear rate, and the redistribution of bulk melt by the agitation. These fine oxides act as nucleation sites for iron-based intermetallic phases, the formation of which is a pre-cursor to purification of the alloy. Macroscopic flow features of HSP, such as flow rate and shear rate, influence its performance significantly. Simulation based on Computational Fluid Dynamics was used to predict key features of fluid flow during HSP in a static direct chill (DC) caster. It was found that the distribution of shear rate and mass flow rate is highly nonuniform in the caster, and only in the close vicinity of the mixing head is there a relatively high level of shear rate and effective melt agitation. Therefore, effective dispersion of oxide films and clusters, and resulting significant nucleation of the intermetallics and/or primary aluminium phase, can only occur near the mixing head, and not throughout the whole crucible. Confidence in the model validity was built, by comparison with post-solidification microstructures in a previous experiment with similar process parameters and geometry.

A comparison of the movement patterns of specific rugby union movements on both natural turf and artificial turf

2017-04-25T14:54:25Z

A comparison of the movement patterns of specific rugby union movements on both natural turf and artificial turf O'Keeffe, Seamus; Fullam, Karl; Feeley, Marc O.; Caulfield, Brian; Delahunt, Eamonn; Coughlan, Garrett; Gilchrist, M. D. A limitation of sports kinematic studies is that they cannot fully represent in-situ play conditions for fast dynamic sports. This paper describes the use of new inertial sensor measurement technology (ODonovan et al., 2009) to analyse player motions in the field under game-like conditions in order to quantify the impact of different playing surfaces on movement patterns. The wireless sensor system used in this study (Shimmer 3, Shimmer Research, Ireland) is a lightweight (50x25x12.5mm3), wearable, low-power consumption inertial measurement unit that contains a tri-axial accelerometer, gyroscope, and magnetometer. Sensor data can be used to derive a range of spatiotemporal and kinematic variables to quantify performance during gait and other functional activities. In our research we are using these sensors as a means to characterise movement during a running activity. The motivation for this study has been to compare movement profiles and strategies of rugby players performing game related tasks on natural turf surfaces and on synthetic surfaces, to enable a better understanding of the impact of different playing surfaces on movement and associated forces and stresses exerted on the body. This is important as there is a growing trend towards use of synthetic surfaces in rugby union and there have been anecdotal reports of injuries that are perceived to be related to the playing surface. In this paper we present preliminary movement data acquired from players performing a 10m sprint test on natural and synthetic surfaces and describe our methods of data extraction and subsequent data processing. 2nd International Congress on Sport Sciences Research and Technology Support (IcSPORTS 2014), Rome, Italy, 24-26 October 2014

Effect of impact surface in equestrian falls

2017-02-27T15:05:55Z

Effect of impact surface in equestrian falls Clark, J. Michio; Post, Andrew; Connor, Thomas A.; Hoshizaki, Thomas Blaine; Gilchrist, M. D. This study examines the effect of impact surface on head kinematic response and maximum principal strain (MPS) for equestrian falls. A helmeted Hybrid III headform was dropped unrestrained onto three impact surfaces of different stiffness (steel, turf and sand) and three locations. Peak resultant linear acceleration, rotational acceleration and duration of the impact events were measured. A finite element brain model was used to calculate MPS. The results revealed that drops onto steel produced higher peak linear acceleration, rotational acceleration and MPS but lower impact durations than drops to turf and sand. However, despite lower MPS values, turf and sand impacts compared to steel impacts still represented a risk of concussion. This suggests that certification standards for equestrian helmets do not properly account for the loading conditions experienced in equestrian accidents. 34th International Conference on Biomechanics in Sports, Tsukuba, Japan, 18-22 July 2016

Plasmon enhanced fluorescence studies from aligned gold nanorod arrays modified with SiO2 spacer layers

2017-02-06T13:12:40Z

Plasmon enhanced fluorescence studies from aligned gold nanorod arrays modified with SiO2 spacer layers Damm, Signe; Fedele, Stefano; Murphy, Antony; Barry, James N.; Dowling, Denis P.; Rice, James H.; et al. Here we demonstrate that quasi self-standing Au nanorod arrays prepared with plasma polymerisation deposited SiO2 dielectric spacers support surface enhanced fluorescence (SEF) while maintaining high signal reproducibility. We show that it is possible to find a balance between enhanced radiative and non-radiative decay rates at which the fluorescent intensity is maximized. The SEF signal optimised with a 30 nm spacer layer thickness, showed a 3.5-fold enhancement with a signal variance of <15% thereby keeping the integrity of the nanorod array. We also demonstrate the decreased importance of obtaining resonance conditions when LSPR is positioned within the spectral region of Au interband transitions. Procedures for further increasing the SEF enhancement factor are also discussed.

Direct observation of spatially isothermal equiaxed solidification of an Al-Cu alloy in microgravity on board the MASER 13 sounding rocket

2016-12-21T13:39:46Z

Direct observation of spatially isothermal equiaxed solidification of an Al-Cu alloy in microgravity on board the MASER 13 sounding rocket Murphy, A. G.; Mathiesen, Ragnvald H.; Browne, David J.; et al. For the first time, isothermal equiaxed solidification of a metallic alloy has been observed in situ in space, providing unique benchmark experimental data. The experiment was completed on board the MASER 13 sounding rocket, launched in December 2015, using a newly developed isothermal solidification furnace. A grain-refined Al–20 wt%Cu sample was fully melted and solidified during 360 s of microgravity and the solidification sequence was recorded using time-resolved X-radiography. Equiaxed nucleation, dendritic growth, solutal impingement, and eutectic transformation were thus observed in a gravity-free environment. Equiaxed nucleation was promoted through application of a controlled cooling rate of −0.05 K/s producing a 1D grain density of ~6.5 mm−1, uniformly distributed throughout the field of view (FOV). Primary growth slowed to a visually imperceptible level at an estimated undercooling of 7 K, after which the cooling rate was increased to −1.0 K/s for the remainder of solidification and eutectic transformation, ensuring the sample was fully solidified inside the microgravity time window. The eutectic transformation commenced at the centre of the FOV proceeding radially outwards covering the entire FOV in ~3 s. Microgravity-based solidification is compared to an identical pre-flight ground-based experiment using the same sample and experiment timeline. The ground experiment was designed to minimise gravity effects, by choice of a horizontal orientation for the sample, so that any differences would be subtle. The first equiaxed nucleation occurred at an apparent undercooling of 0.6 K less than the equivalent event during microgravity. During primary equiaxed solidification, as expected, no buoyant grain motion was observed during microgravity, compared to modest grain rotation and reorientation observed during terrestrial-based solidification. However, when the cooling rate was increased from −0.05 K/s to −1.0 K/s during the latter stages of solidification, in both 1g and micro-g environments, some grain movement was apparent due to liquid feeding and mechanical impingement of neighbouring grains.

Modelling of a Multi-purpose Commercial Building for Demand Response Analysis

2016-11-30T16:04:33Z

Modelling of a Multi-purpose Commercial Building for Demand Response Analysis Christantoni, Despoina; Flynn, Damian; Finn, Donal This paper examines the implementation of demand response measures, using an EnergyPlus simulation model, in a multipurpose commercial building. The simulation model, which has been developed specifically for demand response analysis, is used to assess the effectiveness of different demand response strategies, which were considered for the building. The strategies were examined for a representative zone within the building and evaluate the contribution of the building capacitance and HVAC equipment operation, as mechanisms for shifting the building electrical demand. Associated zone temperature responses and load shifts are also quantified. 6th International Building Physics Conference (IBPC), Turin, Italy, 14-17 June 2015

Investigation of demand response strategies in a mixed use building

2016-11-21T17:32:27Z

Investigation of demand response strategies in a mixed use building Christantoni, Despoina; Oxizidis, Simeon; Flynn, Damian; Finn, Donal This paper investigates demand response measures, using an EnergyPlus simulation model, developed specifically for demand response analysis, in a mixed-used commercial building. The effectiveness of various building pre-conditioning strategies, which were considered for different durations, immediacy and activation time were assessed using the simulation model. Assessment was carried out for a representative summer day and the contribution of the building capacitance as a mechanism for shifting the building electric power demand was evaluated, recording a maximum load reduction of 6.6% of the baseload. CLIMA 2016: 12th REHVA conference, Aalborg, Denmark, 22-25 May 2016

Calibration of a commercial building energy simulation model for demand response analysis

2016-11-21T17:30:06Z

Calibration of a commercial building energy simulation model for demand response analysis Christantoni, Despoina; Oxizidis, Simeon; Flynn, Damian; Finn, Donal This paper describes the calibration process of an EnergyPlus simulation model, for a multi-purpose commercial building, which has been developed specifically for demand response analysis. Power, gas and air temperature data are collected in fifteen minute intervals as part of the calibration process. Real occupancy data are implemented as well. The results indicate a mean bias error of -1.6% for the annual electricity consumption. Calibration under the scope of demand response at zone and equipment level is also described. 14th International Conference of the International Building Performance Simulation Association: Building Simulation, Hyderabad, India, 07-09 December 2015

Developing building archetypes for electrical load shifting assessment: Analysis of Irish residential stock

2016-11-21T15:45:25Z

Developing building archetypes for electrical load shifting assessment: Analysis of Irish residential stock Neu, Olivier; Sherlock, Brónagh; Oxizidis, Simeon; Flynn, Damian; Finn, Donal Appropriate use of demand side management (DSM) strategies in residential buildings, when placed in a smart grid environment, can help reduce power supplydemand mismatches by shifting electrical loads, thus leading to better integration of renewable energy sources, particularly wind and solar generation. In the current paper, detailed building energy simulation models of residential stock are developed, using an occupant focused approach. Five archetypes are considered over three construction periods, representative of about 82% of the Irish building stock. The archetype models were found to be accurate to within 10% of the Irish standards, as exemplified using the Dwelling Energy Assessment Procedure (DEAP), for space and water heating energy requirements. The proposed approach was found to be more accurate than DEAP to estimate the electricity consumption. By integrating high resolution models for occupancy and electrical equipment use, it can generate more accurate models of the housing stock and expands previous investigations to include occupant behaviour, electrical load shifting and thermal comfort issues. Chartered Institution of Building Services Engineers (CIBSE) and American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) Technical Symposium: Moving to a New World of Building Systems Performance, Dublin, Ireland, 3-4 April 2014

Natural ventilation in residential building archetypes: a stochastic approach based on occupant behaviour and thermal comfort

2016-11-21T15:36:52Z

Natural ventilation in residential building archetypes: a stochastic approach based on occupant behaviour and thermal comfort Neu, Olivier; Evon, Valentin; Oxizidis, Simeon; Flynn, Damian; Finn, Donal As houses become more energy efficient due to highly thermal resistant fabrics, the impact of natural ventilation on indoor comfort and on transient heating and cooling loads increases. These two constraints must be integrated within building performance simulation models when assessing the potential for electrical load shifting strategies in residential buildings placed in a smart grid environment. A natural ventilation model is developed and implemented for five residential building archetypes. A bottom-up methodology based on occupant behaviour, through the use of time-of-use data, is implemented at room level within EnergyPlus. A stochastic approach determines whether to open or close windows, depending on the occupancy state, the activity type and level, and the thermal comfort experienced. The algorithms proposed consider the main drivers governing window operation within a residential context. Focus is placed on the modelling challenges, and the impacts of the model are assessed using energy performance and thermal comfort. IBPSA-Canada eSim Conference: Removing barriers to application of Building Performance Simulation in design practice, Ottawa, Canada, 07-10 May 2014

High Resolution Space - Time Data: Methodology for Residential Building Simulation Modelling

2016-11-21T15:17:52Z

High Resolution Space - Time Data: Methodology for Residential Building Simulation Modelling Neu, Olivier; Oxizidis, Simeon; Flynn, Damian; Pallonetto, Fabiano; Finn, Donal A bottom-up approach is developed for the specification of operational data with a high spacetime resolution, to be used as inputs in multi-zone residential building models. These archetype models will be used to analyse demand modulation of total domestic electricity consumption, thus requiring a detailed knowledge of domestic loads. The approach is based on national Time-Use Survey (TUS) resident activity data. To illustrate the approach, the EnergyPlus simulation platform is used to model a multi-zone case study building. Occupancy profiles, lighting load and disaggregated electrical appliance load profiles, as well as their associated heat gains, are generated and spatially mapped within the building. A good match is seen between synthesised and measured profiles. A greater sharing of electrical appliances, as the household size increases, is also seen. Fifteen-minute resolution of the model outputs is found to be sensible in the context of the current project, due to aggregation. 13th International Building Performance Simulation Association (Building Simulation 2013), Chambéry, France, 25-28 August 2013

Implementation of demand response strategies in a multi-purpose commercial building using a whole-building simulation model approach

2016-10-24T17:50:22Z

Implementation of demand response strategies in a multi-purpose commercial building using a whole-building simulation model approach Christantoni, Despoina; Oxizidis, Simeon; Flynn, Damian; Finn, Donal This paper exploits a whole-building energy simulation approach to develop and evaluate demand response strategies for commercial buildings. The research is motivated by the increasing penetration of renewable energy sources such as wind and solar, which owing to their stochastic nature, means that enhanced integration of demand response measures in buildings is becoming more challenging and complex. Using EnergyPlus, a simulation model of a multi-purpose commercial building was developed and calibrated. Demand response strategies are evaluated for a number of building zones, which utilise different heating, cooling and ventilation equipment. The results show that for events of varying demand response durations, different strategies should be selected for each zone based on their thermal and usage profiles. Overall, a maximum reduction of 14.7% in electrical power demand was recorded when targeting a centralised chiller load, with smaller reductions for other decentralised building loads.

Utilising time of use surveys to predict water demand profiles of residential building stocks: Irish case study for domestic hot water

2016-10-03T15:37:15Z

Utilising time of use surveys to predict water demand profiles of residential building stocks: Irish case study for domestic hot water Neu, Olivier; Oxizidis, Simeon; Flynn, Damian; Finn, Donal The prediction of water consumption patterns is a challenge, especially when water metering is not available at scale. The paper focuses on the prediction of analytical domestic hot water (DHW) demand profiles for detailed building archetype models, using an occupant focused approach based on time-of-use survey (TUS) data. Five dwelling types are considered over different construction periods, representative of the majority of the Irish residential stock, which is used here as a case study. They are modelled at room level using EnergyPlus and converted into archetype models. A bottom-up approach is utilised to develop the required operational data at high space and time resolution. That methodology applies Markov Chain Monte Carlo techniques to TUS activity data to develop activity-specific profiles for occupancy and domestic equipment electricity use. It is extended to DHW demand profiles by combining the probability distributions for particular TUS activities with average daily DHW consumptions, depending on the household size, day type and season. The archetype models are found to be 90% accurate with the Irish standard dwelling energy assessment procedure in estimating the annual energy requirements for DHW heating. Moreover, they capture variations in DHW consumption, heat demand and energy usage for DHW heating, on a national scale and a fifteen-minute basis. Water Efficiency Conference, Brighton, UK, 9-11 September 2014

Utilising time of use surveys to predict domestic hot water consumption and heat demand profiles of residential building stocks

2016-09-30T12:09:33Z

Utilising time of use surveys to predict domestic hot water consumption and heat demand profiles of residential building stocks Neu, Olivier; Oxizidis, Simeon; Flynn, Damian; Finn, Donal Aims: The prediction of water consumption patterns is a challenge, especially when water metering is not available at scale. The use of time-of-use survey (TUS) data offers an alternative to metering in order to track the general patterns of water consumption across large and representative groups of end-users. The paper focuses on the prediction of analytical domestic hot water (DHW) demand profiles for detailed building archetype models, using an occupant focused approach based on TUS data. The paper illustrates and discusses the resulting capability of dwelling archetypes to capture variations in heat demand and energy usage for water heating on a national scale and at high time resolution. Methodology: Five dwelling types are considered over different construction periods, representative of the majority of the Irish residential stock, which is used here as a case study. They are modelled at room level using EnergyPlus and converted into archetype models. A bottom-up approach is utilised to develop the required operational data at high space and time resolution. That methodology applies Markov Chain Monte Carlo techniques to TUS activity data to develop activity-specific profiles for occupancy and domestic equipment electricity use. It is extended to DHW demand profiles by combining the probability distributions for particular TUS activities with average daily DHW consumptions, depending on the household size, day type and season. Results: The archetype models capture variations in DHW consumption, heat demand and energy usage for DHW heating, on a national scale and a fifteen-minute basis. Moreover, they are found to be 90% accurate with the Irish standard dwelling energy assessment procedure in estimating the annual energy requirements for DHW heating. Conclusion: This study demonstrates the potential for utilising time of use surveys to predict domestic water demand profiles on a national scale and at high time resolution.

Evaluation of the protective capacity of baseball helmets for concussive impacts

2016-09-30T12:03:20Z

Evaluation of the protective capacity of baseball helmets for concussive impacts Post, Andrew; Karton, Clara M.; Hoshizaki, Thomas Blaine; Gilchrist, M. D.; Bailes, Julian The purpose of this research was to examine how four different types of baseball helmets perform for baseball impacts when performance was measured using variables associated with concussion. A helmeted Hybrid III headform was impacted by a baseball, and linear and rotational acceleration as well as maximum principal strain were measured for each impact condition. The method was successful in distinguishing differences in design characteristics between the baseball helmets. The results indicated that there is a high risk of concussive injury from being hit by a ball regardless of helmet worn.

Wave-Based Attitude Control of Spacecraft with Fuel Sloshing Dynamics

2016-09-30T11:58:44Z

Wave-Based Attitude Control of Spacecraft with Fuel Sloshing Dynamics Thompson, Joseph W.; O'Connor, William Wave-Based Control has been previously applied successfully to simple underactuated flexible mechanical systems. Spacecraft and rockets with structural flexibility and sloshing are examples of such systems but have added difficulties due to non-uniform structure, external disturbing forces and non-ideal actuators and sensors. The aim of this paper is to extend the application of WBC to spacecraft systems, to compare the performance of WBC to other popular controllers and to carry out experimental validation of the designed control laws. A mathematical model is developed for an upper stage accelerating rocket moving in a single plane. Fuel sloshing is represented by an equivalent mechanical pendulum model. A wave-based controller is designed for the upper stage AVUM of the European launcher Vega. In numerical simulations the controller successfully suppresses the sloshing motion. A major advantage of the strategy is that no measurement of the pendulum states (sloshing motion) is required. 2015 ECCOMAS Thematic Conference on Multibody Dynamics, Barcelona, Spain, 29 June - 2 July 2015

Tool Wear in Milling of Medical Grade Cobalt Chromium Alloy - Requirements for Advanced Process Monitoring and Data Analytics

2016-09-30T11:50:33Z

Tool Wear in Milling of Medical Grade Cobalt Chromium Alloy - Requirements for Advanced Process Monitoring and Data Analytics Ahearne, Eamonn; Baron, Szymon; Keaveney, Shane; Dowling, Denis P.; Byrne, Gerald Computer Aided Design (CAD), Computer Aided Manufacturing (CAM) and Computer Numerical Control (CNC) are platform technologies in high end manufacturing. However, the machining process on the CNC Machine Tool is generally the main source of loss of component accuracy, precision and extraneous effects on surface finish and integrity. Moreover these 'losses', and therefore costs, only increase in cutting processes due to the inherent modes and mechanisms of progressive and catastrophic tool wear. In high end manufacturing sectors, these losses are also exacerbated by the use of 'difficult-to-cut (DTC)' materials while more stringent specifications apply and higher levels of process capability are demanded. The use of Cobalt Chromium (Co-Cr-Mo) alloys in the Medical Device sector is indicative of the many challenges. However, notwithstanding the importance of the application, there are few publications on the fundamental mechanisms in cutting this alloy, other than by the present authors. This paper builds on our research to date by reporting some preliminary results on tool wear progression in CNC milling of the Co-Cr-Mo alloy conforming to ASTM F75. It also assesses the feasibility of real time tool wear monitoring on a Mori Seiki NMV1500 CNC Machining Centre using the MTConnect communication standard. The results obtained through MTConnect are provided by embedded sensors within the machine tool and are correlated with a laboratory piezoelectric dynamometer. The results from both methods, obtained at two cutting speeds, are also related to observed tool wear progression and the cumulative volume of material removed. The results are discussed in terms of the potential and limitations of using of MTConnect and the machine tools embedded sensors, for monitoring of the process and the onset of tool wear. The Machine Tool Technologies Research Foundation (MTTRF) and iAM-CNC Annual Meeting 2016, San Fransisco, California, USA, 5-7 July 2016

Analysis and optimization of sandwich tubes energy absorbers under lateral loading

2017-08-01T01:00:17Z

Analysis and optimization of sandwich tubes energy absorbers under lateral loading Baroutaji, A.; Gilchrist, M. D.; Smyth, D.; Olabi, A. G. In this paper, the sandwich tubes, which consist of thin-walled circular tubes with aluminium foam core, were proposed as energy absorption devices. The sandwich tubes were laterally crushed under quasi-static loading conditions. Detailed finite element model, validated against existing experimental results, was developed using the explicit code (ANSYS-LSDYNA) to assess the energy absorption responses and deformation modes. Response surface methodology (RSM) was employed in parallel with the finite element models to perform both parametric studies and multi-objective optimization in order to establish the optimal configuration of the sandwich tube. Sampling designs of the sandwich tubes were constructed based on a D - optimal design of experiment (DOE) method. Factorial analysis was performed using the DOE results to investigate the influences of the geometric parameters on the responses of sandwich tubes. In addition, multi-objective optimization design (MOD) of the sandwich tubes is carried out by adopting a desirability approach. It was found that the tube with a minimum diameter of the inner layer and a maximum foam thickness are more suitable for use as energy absorbing components.

Crush analysis and multi-objective optimization design for circular tube under quasi-static lateral loading

2016-09-29T15:58:59Z

Crush analysis and multi-objective optimization design for circular tube under quasi-static lateral loading Baroutaji, A.; Gilchrist, M. D.; Smyth, D.; Olabi, A. G. This paper addresses the energy absorption behaviour and crash worthiness optimisation of short length circular tubes under quasi-static lateral loading. Finite element (FE) models were developed using implicit FE code ANSYS to simulate the deformation behaviour and energy absorption of circular tube under lateral loading. These FE models were validated using experimental techniques to ensure that they can predict the responses of circular tube with sufficient accuracy. Response surface methodology (RSM) for design of experiments (DOE) was used in conjunction with finite element modelling to evaluate systematically the effects of geometrical parameters on the energy absorption responses of laterally crushed circular tubes. Statistical software package, design-expert, was used to apply the response surface methodology (RSM). The energy absorbing responses (specific energy absorbing capacity (SEA) and collapse load (F)) were modelled as functions of geometrical factors (tube diameter, tube thickness, and tube width). These developed functions allow predictions of the energy absorption response of laterally crushed tubes, based on their geometry parameters. Based on DOE results, parametric studies were conducted to generate design information on using the laterally crushed tubes in energy absorbing systems. Finally, the approach of multi-objective optimization design (MOD) was employed to find the optimal configuration of the proposed energy absorption structures. Design-expert software, which employs the desirability approach as optimization algorithm, was used for solving the MOD problem.

Characterization of persistent concussive syndrome using injury reconstruction and finite element modelling

2016-09-29T15:52:26Z

Characterization of persistent concussive syndrome using injury reconstruction and finite element modelling Post, Andrew; Kendall, Marshall; Koncan, David; Cournoyer, Janie; Gilchrist, M. D.; et al. Concussions occur 1.7 million times a year in North America, and account for approximately 75% of all traumatic brain injuries (TBI). Concussions usually cause transient symptoms but 10 to 20% of patients can have symptoms that persist longer than a month. The purpose of this research was to use reconstructions and finite element modeling to determine the brain tissue stresses and strains that occur in impacts that led to persistent post concussive symptoms (PCS) in hospitalized patients. A total of 21 PCS patients had their head impacts reconstructed using computational, physical and finite element methods. The dependent variables measured were maximum principal strain, von Mises stress (VMS), strain rate, and product of strain and strain rate. For maximum principal strain alone there were large regions of brain tissue incurring 30 to 40% strain. This large field of strain was also evident when using strain rate, product of strain and strain rate. In addition, VMS also showed large magnitudes of stress throughout the cerebrum tissues. The distribution of strains throughout the brain tissues indicated peak responses were always present in the grey matter (0.481), with the white matter showing significantly lower strains (0.380) (p<0.05). The impact conditions of the PCS cases were severe in nature, with impacts against non-compliant surfaces (concrete, steel, ice) resulting in higher brain deformation. PCS biomechanical parameters were shown to fit between those that have been shown to cause transient post concussive symptoms and those that lead to actual pathologic damage like contusion, however, values of all metrics were characterized by large variance and high average responses. This data supports the theory that there exists a progressive continuum of impacts that lead to a progressive continuum of related severity of injury from transient symptoms to pathological damage.

Functionalising Polymer Surfaces with Cold Spray for Applications in Bioenvironments

2016-09-27T12:32:32Z

Functionalising Polymer Surfaces with Cold Spray for Applications in Bioenvironments Lupoia, R.; Stensona, C.; McDonnell, K. A.; Dowling, Denis P.; Ahearne, Eamonn Cold Spray (CS) of copper particles onto polymers has been validated as an effective tool for maintaining surface integrity in bioenvironments. CS requires limited heat input, can be applied locally or in large areas. The key parameters are particle penetration depth and copper surface coverage. However, the process parameters that can optimize the coating performance with deposition have not been comprehensively explored. In this paper, copper particles were deposited onto two polymers used in marine applications. A detailed analysis was carried out to correlate the key surface properties to the process so as to determine the optimum conditions.

The characteristics of traumatic brain injury

2016-09-27T11:53:59Z

The characteristics of traumatic brain injury Post, Andrew; Hoshizaki, Thomas Blaine; Gilchrist, M. D.; et al. Traumatic brain injury (TBI) is a common injury and is a leading cause of morbidity and mortality throughout the world. Research has been undertaken in order to better understand the characteristics of the injury event and measure the risk of injury to develop more effective environmental, technological, and clinical management strategies. This research used methods that have limited applications to predicting human responses. This limits the current understanding of the mechanisms of TBI in humans. As a result, the purpose of this research was to examine the characteristics of impact and dynamic response that leads to a high risk of incurring a TBI in a human population. Twenty TBI events collected from hospital reports and eyewitness accounts were reconstructed in the laboratory using a combination of computational mechanics models and Hybrid III anthropometric dummy systems. All cases were falls, with an average impact velocity of approximately 4.0 m/s onto hard impact surfaces. The results of the methodology were consistent with current TBI research, describing TBI to occur in the range of 335 to 445 g linear accelerations and 23.7 to 51.2 krad/s2 53 angular accelerations. More significantly, this research demonstrated that lower responses in the antero-posterior direction can cause TBI, with lateral impact responses requiring larger magnitudes for the same types of brain lesions. This suggests an increased likelihood of incurring TBI for impacts to the front or back of the head, a result that has implications affecting current understanding of themechanisms of TBI and associated threshold parameters.

The use of variotherm systems for microinjection molding

2016-11-14T02:00:11Z

The use of variotherm systems for microinjection molding Su, Quanliang; Zhang, Nan; Gilchrist, M. D. Microinjection molding (μIM) is a fast-developing technology which is used to produce polymeric microcomponents or components with micro/nanoscale features, such as are used in many fields including microfluidic diagnostics, microneedle drug delivery devices, microgears, and microswitches. The capabilities and performance of the microinjection molding process can be improved by incorporating a variotherm system. This leads to improved component quality, especially for high aspect ratio features. It can also help to increase the polymer flow path, improve feature replication, reduce residual stresses and molecular orientations, and also can eliminate weld lines. This article reviews the use of different variotherm systems in μIM, and describes how simulation of its use can provide insight when designing a mold cavity or a component with challenging microfeatures. The article highlights important problems, challenges and areas for further research. An increased understanding of these issues will provide opportunities to enhance further developments in the μIM process.

The effects of miniaturization and processing on microinjection moldings

2016-09-27T11:39:59Z

The effects of miniaturization and processing on microinjection moldings Zhang, Nan; Gilchrist, M. D. Product miniaturization and high shear/cooling rates during microinjection molding increase the volume of the highly oriented skin layer, thereby modifying the mechanical properties of the fabricated product.

Vacuum venting enhances the replication of nano/micro-features in microinjection molding process

2017-03-24T02:00:13Z

Vacuum venting enhances the replication of nano/micro-features in microinjection molding process Choi, Seong Ying; Zhang, Nan; Toner, J. P.; Gilchrist, M. D. Vacuum venting is a method proposed to improve feature replication in microparts that are fabricated using micro injection molding (MIM). A qualitative and quantitative study has been carried out to investigate the effect of vacuum venting on nano/micro feature replication in MIM. Anodized aluminium oxide containing nanofeatures and a bulk metallic glass tool mold containing micro features were used as mold inserts. The effect of vacuum pressure at constant vacuum time, and of vacuum time at constant vacuum pressure on the replication of these features is investigated. It is found that vacuum venting qualitatively enhances the nano-scale feature definition as well as increases the area of feature replication. In the quantitative study, higher aspect ratio features can be replicated more effectively using vacuum venting. Increasing both vacuum pressure and vacuum time are found to improve the depth of replication, with the vacuum pressure having more influence. Feature orientation and final sample shape could affect the absolute depth of replication of a particular feature within the sample.

Miniaturization/process dependent mechanical properties of microinjection moldings

2016-09-27T11:01:27Z

Miniaturization/process dependent mechanical properties of microinjection moldings Zhang, Nan; Gilchrist, M. D. Product miniaturization and high shear/cooling rates in microinjection molding increase the volume of highly oriented skin layer, which modifies a product’s mechanical properties and needs careful consideration for product design.

Manufacturing microstructured tool inserts for the production of polymeric microfluidic devices

2016-09-26T17:23:58Z

Manufacturing microstructured tool inserts for the production of polymeric microfluidic devices Zhang, Nan; Srivastava, Amit P.; Kirwan, Brendan; Byrne, Richard; Fang, Fengzhou; Browne, David J.; Gilchrist, M. D. Tooling is critical in defining multi-scale patterns for mass production of polymeric microfluidic devices using the microinjection molding process. In the present work, fabrication of various microstructured tool inserts using stainless steel, nickel and bulk metallic glasses (BMGs) is discussed based on die-sinking EDM (electrical discharge machining), electroforming, focused ion beam milling and thermoplastic forming processes. Tool performance is evaluated in terms of surface roughness, hardness and tool life. Compared to stainless steel, nickel and BMGs are capable of integrating length scales from 100 to 10−8 m and are good candidates for producing polymeric microfluidics. Selection of tool materials and manufacturing technologies should consider the end-user requirements of actual applications.

Effect of gate design and cavity thickness on filling, morphology and mechanical properties of microinjection moldings

2017-10-15T01:00:15Z

Effect of gate design and cavity thickness on filling, morphology and mechanical properties of microinjection moldings Zhang, Nan; Su, Quanliang; Choi, Seong Ying; Gilchrist, M. D. Miniaturized parts weighing up to tens of milligrams represent a large category of microinjection moulded products. Both miniaturization and extreme processing under microinjection moulding cause material to experience high shear rates and high cooling rates, and to have different morphology and final properties from conventional injection moulding. It also makes mould design quite challenging. This study investigates micro gate design (opening and thickness) and cavity thickness (100–500 μm) on filling, morphology and mechanical properties of Poly(ether-block-amide) miniaturized dumbbell parts. It is found that a reduction of gate size has two conflicting effects: increased shear heating increases flow length; increased cooling rate reduces flow length. Filling increases significantly with an increase of cavity thickness. In addition, skin ratio reduces from ∼70% to ∼10%, when part thickness increases from 100 μm to 500 μm. Such oriented skin layer determines molecular orientation and broadly influences Young’s modulus, elongation and yield stress. Natural aging at room temperature induces an increase of modulus and yield stress, and a decrease of strain at break. Mechanical properties of microinjection mouldings are significantly different from conventional injection mouldings and measurement at the microscale is required for successful miniaturized product design.

Fundamental Mechanisms in Orthogonal Cutting of Medical Grade Cobalt Chromium Alloy (ASTM F75)

2016-09-21T09:38:35Z

Fundamental Mechanisms in Orthogonal Cutting of Medical Grade Cobalt Chromium Alloy (ASTM F75) Ahearne, Eamonn; Baron, Szymon Cobalt chromium (Co-Cr-Mo) alloys are sui generis materials for orthopaedic implants mainly due to the unique properties of biocompatibility and wear resistance in the demanding in vivo environments. Notwithstanding the importance of the machining processes, a review of literature in the public domain has identified a niche for research into the fundamental mechanisms in cutting of Co-Cr-Mo alloys. This paper reports on initial research into cutting of the biomedical grade cobalt chrome molybdenum (Co-Cr-Mo) alloy, ASTM F75. Following an initial review of the known micro-structural, physical and mechanical properties of the class of Co-Cr-Mo alloys, the results of a full factorial, orthogonal cutting experiment are presented. This involved measurement of force components (Ff and Ft) as a function of the undeformed chip thickness (h) and cutting speed (vc) which were varied over ranges from 20 to 140 µm and 20 to 60 m/min respectively. The results demonstrated an expected linear increase in force components with h at speeds of 20 and 60 m/min. However, at the intermediate speed of 40 m/min, there was a transition between about 60 and 80 µm indicating a discontinuous rather than continuous effect of speed. The results enabled determination of the cutting force coefficients Ktc, Kte, Kf c and Kf e, for the ranges examined as well as the coefficients, ki1.0.1 and mi0.1, of the Kienzle equations. These relations will enable macro-mechanic modelling of more complex cutting operations, such as milling, in the future.

Characterization of Chip Morphology in Orthogonal Cutting of Medical Grade Cobalt Chromium Alloy (ASTM F1537)

2016-09-21T09:34:06Z

Characterization of Chip Morphology in Orthogonal Cutting of Medical Grade Cobalt Chromium Alloy (ASTM F1537) Baron, Szymon; Ahearne, Eamonn Cobalt Chromium alloys (CoCr) are used in the manufacture of class 3 medical devices, notably knee and hip implants, due to singular mechanical properties such as wear resistance and biocompatibility. Notwithstanding the importance of the material, there has been limited research reported on the fundamental mechanism in machining of this alloy. This paper initially propounds on the properties that define a material as “difficult to cut” (DTC) in order to compare machining related properties of ASTM F1537 CoCr with other known DTC alloys. This is followed by a brief summary of literature specifically on the chip morphology produced in turning of ASTM F136 Ti-6Al-4V and Inconel 718. Orthogonal cutting tests are then undertaken to examine the chip morphology in cutting ASTM F1537 over a range of cutting speeds (Vc) and levels of undeformed chip thickness (hm). The findings of this research were compared with those found in literature. It is concluded that ASTM F1537 CoCr produced segmented chips under all tested conditions and chip segmentation frequency increases with the cutting speed but is independent of the undeformed chip thickness. Moreover, the ratio of the segment height to the maximum chip thickness was found to decrease with cutting speed. 32nd International Manufacturing Conference, Queen's University Belfast, Northern Ireland, 3-4 September 2016

Prediction of tool-wear in turning of medical grade cobalt chromium molybdenum alloy (ASTM F75) using non-parametric Bayesian models

2017-09-01T01:00:10Z

Prediction of tool-wear in turning of medical grade cobalt chromium molybdenum alloy (ASTM F75) using non-parametric Bayesian models McParland, Damien; Baron, Szymon; O'Rourke, Sarah; Dowling, Denis P.; Ahearne, Eamonn; Parnell, Andrew C. We present a novel approach to estimating the effect of control parameters on tool wear rates and related changes in the three force components in turning of medical grade Co-Cr-Mo (ASTM F75) alloy. Co-Cr-Mo is known to be a difficult to cut material which, due to a combination of mechanical and physical properties, is used for the critical structural components of implantable medical prosthetics. We run a designed experiment which enables us to estimate tool wear from feed rate and cutting speed, and constrain them using a Bayesian hierarchical Gaussian Process model which enables prediction of tool wear rates for untried experimental settings. However, the predicted tool wear rates are non-linear and, using our models, we can identify experimental settings which optimise the life of the tool. This approach has potential in the future for realtime application of data analytics to machining processes.

An Investigation of Force Components in Orthogonal Cutting of Medical Grade Cobalt Chromium Alloy (ASTM F1537)

2016-09-21T09:21:57Z

An Investigation of Force Components in Orthogonal Cutting of Medical Grade Cobalt Chromium Alloy (ASTM F1537) Baron, Szymon; Ahearne, Eamonn An aging population, increased physical activity and obesity, are identified as life style changes contributing to growth in the use of in-vivo prosthetics for total hip and knee arthroplasty. Cobalt chromium alloys, due to mechanical properties and excellent biocompatibility, uniquely qualify as a class of materials that meet the stringent functional requirements for these devices. To cost effectively assure the required dimensional and geometric tolerances, manufacturers invariably rely on high precision machining. However, a comprehensive literature review has shown that there has been limited research into mechanical cutting of these materials. This paper delineates the physical and mechanical properties that determine the machinability of a material, and compares medical grade cobalt chromium alloy ASTM F1537 with titanium alloy, Ti-6Al-4V ASTM F136. The results of a full factorial orthogonal cutting experiment are reported where cutting and thrust force components were measured over a range of cutting speeds (Vc) and levels of undeformed chip thickness (hm). It was found that the forces generated in cutting of ASTM F1537 are significantly higher than for ASTM F136, depending primarily on undeformed chip thickness, but with some influence of the cutting speed. The effect of chip segmentation on component force variations is also reported. 15th Computer-Aided Production Engineering (CAPE15) Conference, Edinburgh, UK, 3-4 November, 2015

A Comparison of the Head Dynamic Response and Brain Tissue Deformation from Impacts Resulting in Concussion, Concussion with Persistent Post-Concussive Symptoms, and Subdural Hematoma

2016-09-20T12:21:40Z

A Comparison of the Head Dynamic Response and Brain Tissue Deformation from Impacts Resulting in Concussion, Concussion with Persistent Post-Concussive Symptoms, and Subdural Hematoma Oeur, Anna; Karton, Clara M.; Post, Andrew; Gilchrist, M. D.; et al. Objective: Concussions typically resolve within a few days however in a few cases the symptoms last for a month or longer and are termed persistent post-concussive symptoms (PPCS) with more serious brain trauma resulting in bleeds, such as subdural hematoma (SDH). Dynamic response and brain tissue deformation characteristics may provide a means of distinguishing between these three types of injuries. Methods: Reconstruction cases were recruited from sports medicine clinics and hospitals along with medical reports, video footage, and medical imaging. All subjects received a direct blow to the head resulting in head trauma symptoms, those that resolved in 9 days were termed concussions, those with symptoms longer than 18 months were PPCS and those presenting with subdural hematoma (SDH). An anthropometric dummy headform was dropped onto various impact surfaces using a monorail drop rig. Headform dynamic response data was collected and used as input into the University College Dublin Brain Trauma Model to obtain maximum principal strain and von Mises stress. Results: Both linear and rotational acceleration of the head increased in magnitude with an increase in injury severity (from concussion, to PPCS, and SDH). The PPCS group had peak resultant rotational accelerations similar to SDH and significantly higher than concussions. There were no significant differences for peak resultant linear accelerations between the two concussion groups however they were both significantly lower than the SDH group. Brain tissue deformation measures however, did not follow the same trend as dynamic response and resulted with SDH having the lowest values of stress and strain. PPCS had significantly higher values of strain than the SDH group, where both the concussion and PPCS groups had significantly higher stress values than the SDH group. Conclusion: This study supports the notion that there is a positive relationship between an increase in the dynamic response and the risk for more serious brain injury. Peak resultant linear acceleration may be more related to SDH meanwhile rotational acceleration may be more relatedto severity of concussion. Despite SDH being the more severe brain injury, on average this group had the lowest values for stress and strain as compared to concussion and PPCS. Finite element analysis of the SDH injuries examined brain tissue values for the group of elements in the model than corresponded to the location of the bleed which may not be reflective of the highest values if the entire cerebrum was considered. More importantly, SDH injuries are vascular injuries and may not necessarily result in damage to the brain. In summary, this study found that the dynamic response of an impact is reflective of injury severity. Understanding the relationship between the dynamic response and the nature of the injury provides important information for developing strategies for injury prevention.

Performance of nickel and bulk metallic glass as tool inserts for the microinjection molding of polymeric microfluidic devices

2016-09-20T12:13:31Z

Performance of nickel and bulk metallic glass as tool inserts for the microinjection molding of polymeric microfluidic devices Zhang, Nan; Srivastava, Amit P.; Browne, David J.; Gilchrist, M. D. Electroformed nickel and bulk metallic glasses (BMGs) can be designed to incorporate features withlength scales ranging from millimeters to nanometers. This, combined with their good mechanical prop-erties relative to other materials, makes them competitive candidates for manufacturing multi-scalemolds to produce high volumes of polymeric microfluidics components and other micro/nano devices.Despite this attractiveness, BMGs are newly developed engineering materials and their capabilities asa mold material have not been evaluated. This paper compares the performance of nickel tools madeby an electroforming process and BMG tools made by a thermoplastic forming process, specifically withregard to typical microfluidics patterns and features. Ni shows excellent capabilities for good featurereplication. BMG thermoplastic forming is highly dependent on the choice of alloy composition, whichrestricts the achievable feature size and aspect ratio. Compared to Ni, BMG has hardness values that areclose to those of stainless steel and shows the superior mechanical strength that is required for massproduction applications. However, oxidation in BMG tool manufacturing process affects the tool surfacefinish significantly and reduces the tool¿s corrosion resistance. Future development of BMG tools includepreventing the formation of oxidation layers or developing BMGs with an anti-oxidation composition,and further reducing their overall cost and widening its processing window parameters. Despite thesechallenges, however, BMGs are shown to combine excellent mechanical properties and capabilities formulti-scale forming; this makes them significantly more attractive than relatively soft Ni tools.

The influence of built-up layer formation on cutting performance of GG25 grey cast iron

2016-09-20T11:36:26Z

The influence of built-up layer formation on cutting performance of GG25 grey cast iron Fiorini, Paolo; Byrne, Gerald The success of high speed machining of grey cast iron relates to the protective built-up layer (BUL) that forms on the tool. The present work investigates BUL formation on pcBN tools for dry, high speed machining of GG25 grey cast iron (up to vc = 750 m/min). This work suggests that the BUL distribution on the tool at high cutting speed (vc = 750 m/min) is key to tool protection. Protection in the area of maximum cutting temperature is critical in preventing thermally driven wear modes, such as crater wear, found at low cutting speeds (vc = 250 m/min).

A Block-Coupled Finite Volume Methodology for Linear Elasticity and Unstructured Meshes

2016-09-15T15:39:05Z

A Block-Coupled Finite Volume Methodology for Linear Elasticity and Unstructured Meshes Cardiff, Philip; Tuković, Željko; Jasak, Hrvoje; Ivankovic, Alojz The current article presents a new implicit cell-centred Finite Volume solution methodology for linear elasticity and unstructured meshes. Details are given of the implicit discretisation, including use of a Finite Area method for face tangential gradients and implicit non-orthogonal correction. A number of 2-D and 3-D linear-elastic benchmark test cases are examined using hexahedral, tetrahedral and general polyhedral meshes; solution accuracy and efficiency are compared with that of a segregated procedure and a commercial Finite Element software, where the new method is shown to be faster in all cases.

A Lagrangian Cell-Centred Finite Volume Method for Metal Forming Simulation

2017-08-06T01:00:12Z

A Lagrangian Cell-Centred Finite Volume Method for Metal Forming Simulation Cardiff, Philip; Tuković, Željko; Jaeger, Peter De; Clancy, M.; Ivankovic, Alojz The current article presents a Lagrangian cell-centred finite volume solution methodology for simulation of metal forming processes. Details are given of the mathematical model in updated Lagrangian form, where a hyperelastoplastic J2 constitutive relation has been employed. The cell-centred finite volume discretisation is described, where a modified discretised is proposed to alleviate erroneous hydrostatic pressure oscillations; an outline of the memory efficient segregated solution procedure is given. The accuracy and order of accuracy of the method is examined on a number of 2-D and 3-D elastoplastic benchmark test cases, where good agreement with available analytical and finite element solutions is achieved.

High Performance Cutting in the New Era of Digital Manufacturing - A Roadmap

2016-09-07T16:02:15Z

High Performance Cutting in the New Era of Digital Manufacturing - A Roadmap Byrne, Gerald; Ahearne, Eamonn; Cotterell, M.; et al. We are rapidly moving into the new era of digitisation, into an era of the Massive Internet of Things - towards the Gigabit Society and towards 5G Technology. The implications are truly far reaching. Rapid transformation through the implementation of INDUSTRY 4.0 is becoming visible in industries all over the world. Disruption to the more traditional industrial practices and processes is inevitable. High Performance Cutting is no exception. Developments in the Internet of Things (IoT) opens up new and extremely powerful capabilities to help us gain a significantly deeper understanding of the fundamentals of cutting processes and offers entirely new connectivity possibilities at all interfaces, some old and some new, 'between the Chip Root and the Cloud'. This supports us in our attempts since the foundation of CIRP in 1951 to remove technological roadblocks and can lead on a new journey towards new and unprecedented scientific/technological developments as well as new business models for companies involved in the various elements of the supply chain for cutting processes (DIN 8580). 'Performance' will take on a new and unanticipated meaning over what was originally meant when we established this CIRP-HPC Conference back in the early 2000’s. In this paper a critical review of a previous roadmap is undertaken for cutting processes presented in a CIRP Keynote Paper in 2003 by Byrne, Dornfeld and Denkena [1] and new thoughts and ideas are presented on a vision for a 2020 skeleton Roadmap for High Performance Cutting in the new age of Digitisation. 7th CIRP Conference on High Performance Cutting HPC2016, Chemnitz, Germany, 31 May - 2 June, 2016