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Gilchrist, M. D.
Preferred name
Gilchrist, M. D.
Official Name
Gilchrist, M. D.
Research Output
Now showing 1 - 10 of 133
- PublicationManufacturing & design with engineering polymers: Educational aspects of a specialist dissertation in a part-time elective postgraduate mechanical engineering degree course for industry-based studentsThe elective course on Manufacturing & Design with Engineering Polymers that is available to postgraduate students on the Master of Engineering Design degree programme at The National University of Ireland, Dublin uses active learning to teach students about processing and performance related issues pertinent to polymer engineering for Irish industry. A significant element of this course is undertaken by students preparing a Specialist Dissertation that is pertinent to their particular industry and employer and which simultaneously implements and illustrates many specific topics on the course syllabus (e.g., viscoelasticity, deformation & fracture, processing, design for manufacture, design for strength, etc.). The case of a recent student, employed as a full-time R&D engineer by a company manufacturing viscoelastic pressure relieving pressure pads, is used to illustrate the practical educational issues that arise when implementing such a teaching method. This method of education, i.e., by means of a Specialist Dissertation, proved to be an effective and popular teaching method in that specific concepts that were integral to the aims and objectives of the Manufacturing & Design with Engineering Polymers course were learned actively by the student. This method of teaching works well with relatively small class sizes but does require a tutorial style of involvement between course teacher and students. It is recommended that further uses of this method of teaching within the present context of the Master of Engineering Design degree programme be explored further.
290 - PublicationFatigue resistance of bituminous layers incorporating reclaimed asphalt pavement(2006-02)
; ; ; This paper presents the results of an investigation into the fatigue performance of a 20mm Binder Course Asphalt Pavement Mix incorporating Recycled Asphalt Pavement (RAP). For the study, a series of binder course mixes were designed containing varying percentages of RAP. A mix made only from virgin material, was selected as the control mix for the investigation. A Circular Wheel Tracker (CWT) was developed in order to simulate the dynamic loading conditions of a rolling wheel and to study the initiation and growth of fatigue cracks in an asphalt pavement mix. The CWT was commissioned within a temperature-controlled room with a customised data acquisition system. The test specimens were subjected to dynamic loading in the CWT and the dynamic strain on the underside of the slab was monitored throughout the test. A digital image processing technique was also used to measure the crack area and crack length at the underside of the test specimen. Parallel to this a separate testing programme was undertaken, whereby the fatigue resistance of bituminous mixtures incorporating same RAP contents was assessed using the indirect tensile fatigue test as described in BS DD ABF:1997. The results from these parallel strands are compared, and the performance of the various mixes incorporating RAP is assessed.2956 - PublicationMechanical Test Procedures for Bituminous MixturesIn recent years the increasing traffic volumes on the world’s highways have indicated shortcomings in the existing empirical procedures that are used to assess road building materials. As a result, new fundamental performance based test procedures have been developed that are currently being considered for acceptance in defining material specification codes of practise. In Ireland, to date, it has only been possible to observe and monitor these developments. The procedures will shortly be introduced by the Central European Standards Organisation (CEN) and will affect Irish material suppliers, design engineers in local authorities and consulting engineers.
160 - PublicationInnovations in Undergraduate Engineering Mechanics Education : Use of Team-Based Research-Led Project Methods for Large Student CohortsAs a cornerstone subject for all undergraduate engineering degree programmes, mechanics is best taught from fundamental principles and by reinforcing students’ learning through active learning strategies. This approach provides students with a solid understanding of basic concepts before they subsequently study more advanced topics such as dynamics, control, solid mechanics and fluid mechanics. MEEN10030, Mechanics for Engineers, is a compulsory module taught annually in Semester I to 260 First Year students at University College Dublin, Ireland’s largest university. The syllabus topics include forces, Newton’s laws of motion, statics in two and three dimensions, equilibrium, friction, trusses and cables, distributed forces, centres of mass and centroids, motion, and kinematics of a particle and of a rigid body. Traditional teaching of this subject relies solely on formal lectures and tutorials, without any laboratory sessions or student assignments, both of which are resource intensive. Five years ago, following a programme review in 2006, this module was completely revised and the subject material was rationalised with regard to what is taught in subsequent Second Year modules. Three entirely integrated laboratory sessions were developed so that groups of students would complete a variety of analytical and enquiry-led exercises in numerical, graphical and written form. A more recent additional major initiative, introduced three years ago in 2008, provides team-based assignments to the entire 260 students in which groups of up to five students are set a design challenge directly related to one specific topic from the course material. These changes have proven popular with students and have led to improved learning outcomes and student performance without compromising on academic standards. This paper describes these innovative developments in which Irish engineering students have opportunities for research-led active learning in this manner.
452 - PublicationThe Association among Injury Metrics for Different Events in Ice Hockey Goaltender Impact(International Research Council on Biomechanics of Injury (IRCOBI), 2016-09-16)
; ; ; 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.529 - PublicationRayleigh-Lamb wave detection of two-dimensional defects in metal platesNondestructive testing of engineering structures is essential to ensure safety. Ultrasonic C-scanning uses waves ropagating normal to a plane surface. This is accurate, but slow for planar structures. Longitudinal waves would allow quicker testing of such structtwes. This paper considers the reflection of low to moderate frequency Rayleigh Lamb waves by a through width lozenge-shaped defect in an isotropic plate. A numerical method is used. It is shown that such longitudinal ultrasonic waves can be used with success to detect and locate structural defects if care is exercies in frequency selection.
97 - PublicationExperimental Facility for Simulating the Initiation and Propagation of Fatigue Damage in Bituminous Road Paving MaterialsAn exoerimental simulation facility was designed and constructed for the purpose of investigating the initiation and development of fatigue damage in bituminour road paving material. The design of the test facility was based upon a cicular wheel track which incorporated four pavement monitoring stations. Hot Rollede Asphalt specimens were manufactured and prepared for testing in order to verify the operation of this experimental facility. The variation of strains, deformations, and the distribution of pavement damage, in the form of cracking, were monitored digitally with increasing cycles of fatigue loading. Failure of pavement specimen due to local tensile strains, propogated through the complete thickness of the specimen and became apparent on the top surface.
320 - PublicationThe influence of recycled asphalt pavement on 20mm binder course mix performance(2006-10)
; ; ; This paper presents the results of ongoing research on the mechanical performance of a 20mm binder course asphalt pavement mix incorporating recycled asphalt pavement (RAP). A series of binder course mixes were designed containing varying percentages of RAP. A mix made only from virgin material was selected as the control mix for the investigation. The effect of introducing RAP into the binder course mix was evaluated through a series of laboratory tests including the Marshall Test, Indirect Tensile Stiffness Modulus Test, Indirect Tensile Fatigue Test and Water Sensitivity Test. A Circular Wheel Track (CWT) was developed in order to study the dynamic effects of a rolling wheel travelling over an asphalt pavement. The CWT was commissioned within a temperature controlled room along with a customised Data Acquisition (DAQ) system. The system involves the testing of rectangular slabs and allows for the investigation of the dynamic tensile strain. The dynamic tensile strain is digitally recorded and the loading effect assessed. The laboratory tests have shown that the introduction of RAP to the binder course mix resulted in an improvement in all mechanical properties. This was also observed in the dynamic tensile strain test.5791 - PublicationModelling and Accident Reconstruction of Head Impact InjuriesThis paper describes a computational mechanics framework within which the physiological consequences of an accidental head impact injury can be simulated. This method relies on a combined use of multibody dynamics and finite element analyses. Such a procedure could ultimately be used to assist in the clinical diagnosis of neurotrauma and in the design of optimised safety helmets.
600 - PublicationA comparison of the movement patterns of specific rugby union movements on both natural turf and artificial turf(SCITEPRESS – Science and Technology Publications, 2014-10-26)
; ; ; ; ; ; 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.206