Now showing 1 - 10 of 24
  • Publication
    Finite-volume stress analysis in multi-material linear elastic body
    (Wiley Blackwell (John Wiley & Sons), 2012-07-05) ; ;
    Correct calculation of stresses at the interface of bonded or otherwise joined materials plays a significant role in many applications. It is therefore important that traction at the material interface is calculated as accurately as possible. This paper describes procedures that can be employed to achieve this goal by using centre-based finite-volume method. Total traction at the interface is calculated by decomposing it into normal and tangential components, both being calculated at each side of the interface, and applying the continuity assumption. The way in which the traction approximation is achieved depends on calculation of tangential gradient of displacement at the interface. To this end, three different methods are proposed and validated against problems with known solutions. It was shown that all methods can be successfully used to simulate problems with multi-material domains, with the procedure based on finite area method being most accurate.
    Scopus© Citations 46  1227
  • Publication
    Development of a Hip Joint Model for Finite Volume Simulations
    This paper establishes a procedure for numerical analysis of a hip joint using the finite volume method. Patient-specific hip joint geometry is segmented directly from computed tomography and magnetic resonance imaging datasets and the resulting bone surfaces are processed into a form suitable for volume meshing. A high resolution continuum tetrahedral mesh has been generated, where a sandwich model approach is adopted; the bones are represented as a stiffer cortical shells surrounding more flexible cancellous cores. Cartilage is included as a uniform thickness extruded layer and the effect of layer thickness is investigated. To realistically position the bones, gait analysis has been performed giving the 3D positions of the bones for the full gait cycle. Three phases of the gait cycle are examined using a finite volume based custom structural contact solver implemented in open-source software OpenFOAM.
    Scopus© Citations 13  951
  • Publication
    A large strain finite volume method for orthotropic bodies with general material orientations
    This paper describes a finite volume method for orthotropic bodies with general principal material directions undergoing large strains and large rotations. The governing and constitutive relations are presented and the employed updated Lagrangian mathematical model is outlined. In order to maintain equivalence with large strain total Lagrangian methods, the constitutive stiffness tensor is updated transforming the principal material directions to the deformed configuration. Discretisation is performed using the cell-centred finite volume method for unstructured convex polyhedral meshes. The current methodology is successfully verified by numerically examining two separate test cases: a circular hole in an orthotropic plate subjected to a traction and a rotating orthotropic plate containing a hole subjected to a pressure. The numerical predictions have been shown to agree closely with the available analytical solutions. In addition, a 3-D composite component is examined to demonstrate the capabilities of the developed methodology in terms of a variable material orientation and parallel processing.
      984Scopus© Citations 42
  • Publication
    Investigating the behaviour of fluid-filled polyethylene containers under base drop impact: A combined experimental/numerical approach
    In this work, the behaviour of fluid-filled plastic containers under base drop impact is investigated using a combined experimental/numerical approach. In addition, theoretical predictions from two approaches, waterhammer theory and a mass-spring model, are also given. Experimental tests are conducted using a specially designed rig for testing plastic containers (bottles). Tested containers are fully instrumented with pressure transducers and strain gauges. The experiments are simulated using a two-system fluid-structure interaction procedure based on the Finite Volume Method. Good agreement is found between measured and predicted pressure and strain histories. Results obtained are in favour of waterhammer theory.
    Scopus© Citations 20  683
  • Publication
    Validation of a fluid–structure interaction numerical model for predicting flow transients in arteries
    The interaction between the flowing blood and deforming arterial wall is critical in understanding the role of hemodynamic forces such as wall shear stress (WSS) in atherosclerosis. Numerical methods have been extensively used to understand the nature of flow around atherosclerosis susceptible regions of the vascular tree in order to establish the exact role of WSS in atherosclerosis. Unfortunately, most of the numerical studies have been performed on rigid arterial geometries, which do not take into account the effect of the interaction between the flowing blood and the dynamics of the flexible arterial wall. In vivo , blood vessels are continuously deforming with every contraction and relaxation of the heart during the cardiac cycle. This paper forms the first of the two-part paper series discussing the need for fluid-structure interaction (FSI) in hemodynamic WSS analysis. The paper presents a well validated FSI based numerical model, capable of accurately predicting flow transients in arteries. The numerical model is validated using analytical solutions and experiments conducted on polyurethane mock artery, with the numerical predictions, analytical solutions and experimental data comparing very well. Numerical studies are performed using OpenFOAM, a 3D Finite Volume Method(FVM) based C++ library.
      1753Scopus© Citations 42
  • Publication
    Modelling the Fracture Behaviour of Adhesively-Bonded Joints as a Function of Test Rate - A Rate Dependent CZM is Required to Predict the Full Range of Behaviour
    Adhesive bonding of lightweight, high-performance materials is regarded as a key enabling technology for the development of vehicles with increased crashworthiness, better fuel economy and reduced exhaust emissions. However, as automotive structures can be exposed to impact events during service, it is necessary to gain a sound understanding of the performance of adhesive joints under different rates of loading. Therefore, characterising the behaviour of adhesive joints as a function of loading rate is critical for assessing and predicting their performance and structural integrity over a wide range of conditions. The present work investigates the rate-dependent behaviour of adhesive joints under mode I loading conditions. A series of fracture tests were conducted using tapered double-cantilever beam (TDCB) specimens at various loading rates [1-2]. The experiments were analysed analytically and numerically. The full details of the analysis strategy employing analytical approaches for different types of fracture are presented in [1]. The numerical modelling of the TDCB experiments was performed using the finite-volume based package ‘OpenFOAM’ [3].
      306
  • Publication
    Effects of bond gap thickness on the fracture of nano-toughened epoxy adhesive joints
    The current work is a combined experimental-numerical study of the fracture behaviour of a nano-toughened, structural epoxy adhesive. The mode I fracture toughness of the adhesive is measured using tapered double-cantilever beam (TDCB) tests with various bond gap thicknesses ranging from 0.25 mm to 2.5 mm. Circumferentially deep-notched tensile specimens are independently employed to measure the cohesive strength of the adhesive as a function of constraint. The experimental TDCB test results are predicted numerically for each bond gap thickness using the Finite Volume method and a Dugdale cohesive zone model. A unique relationship between the fracture energy and the constraint level is established. The effect of bond gap thickness on the fracture behaviour of TDCB joints is hence directly attributed to the variation of the intrinsic fracture energy with constraint and not to the variation of the ‘far field’ plastic zone size with bond gap thickness. Using the well known Rice and Tracey void growth model, a link is established between the voids observed in the fracture process zone, the constraint imposed by the thickness of the adhesive and the resulting fracture energy.
    Scopus© Citations 57  686
  • Publication
    Development of a finite volume contact solver based on the penalty method
    This paper describes the development and application of a frictionless contact stress solver based on the cell-centred finite volume method. The contact methodology, implemented in the open-source software OpenFOAM, is derived from the penalty method commonly used in finite element contact algorithms. The solver is verified on two benchmark tests using the available Hertzian analytical solutions.
    Scopus© Citations 35  928
  • Publication
    Development of mapped stress-field boundary conditions based on a Hill-type muscle model
    (Wiley Blackwell (John Wiley & Sons), 2014-04-07) ; ; ;
    Forces generated in the muscles and tendons actuate the movement of the skeleton. Accurate estimation and application of these musculotendon forces in a continuum model is not a trivial matter. Frequently, musculotendon attachments are approximated as point forces; however, accurate estimation of local mechanics requires a more realistic application of musculotendon forces. This paper describes the development of mapped Hill-type muscle models as boundary conditions for a finite volume model of the hip joint, where the calculated muscle fibres map continuously between attachment sites. The applied muscle forces are calculated using active Hill-type models, where input electromyography signals are determined from gait analysis. Realistic muscle attachment sites are determined directly from tomography images. The mapped muscle boundary conditions, implemented in a finite volume structural OpenFOAM (ESI-OpenCFD, Bracknell, UK) solver, are employed to simulate the mid-stance phase of gait using a patient-specific natural hip joint, and a comparison is performed with the standard point load muscle approach. It is concluded that physiological joint loading is not accurately represented by simplistic muscle point loading conditions; however, when contact pressures are of sole interest, simplifying assumptions with regard to muscular forces may be valid.
      647Scopus© Citations 4