A Multilevel Hierarchical Finite Element Model for Capillary Failure in Soft Tissue

2014 ◽  
Vol 136 (8) ◽  
Author(s):  
Ian R. Grosse ◽  
Lu Huang ◽  
Julian L. Davis ◽  
Dennis Cullinane
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Volume Fraction ◽  
Element Model ◽  
Capillary Wall ◽  
Failure Stress ◽  
The Third ◽  
Human Arm ◽  
Hoop Stresses ◽  
Hierarchical Finite Element

Bruising, the result of capillary failure due to trauma, is a common indication of abuse. However, the etiology of capillary failure has yet to be determined as the scale change from tissue to capillary represents several orders of magnitude. As a first step toward determining bruise etiology, we have developed a multilevel hierarchical finite element model (FEM) of a portion of the upper human arm using a commercial finite element tool and a series of three interconnected hierarchical submodels. The third and final submodel contains a portion of the muscle tissue in which a single capillary is embedded. Nonlinear, hyperelastic material properties were applied to skin, adipose, muscle, and capillary wall materials. A pseudostrain energy method was implemented to subtract rigid-body-like motion of the submodel volume experienced in the global model, and was critical for convergence and successful analyses in the submodels. The deformation and hoop stresses in the capillary wall were determined and compared with published capillary failure stress. For the dynamic load applied to the skin of the arm (physiologically simulating a punch), the model predicted that approximately 8% volume fraction of the capillary wall was above the reference capillary failure stress, indicating bruising would likely occur.

A SPECTRAL/hp NONLINEAR FINITE ELEMENT ANALYSIS OF HIGHER-ORDER BEAM THEORY WITH VISCOELASTICITY

2012 ◽  
Vol 04 (01) ◽  
pp. 1250010 ◽  
Author(s):  
V. P. VALLALA ◽  
G. S. PAYETTE ◽  
J. N. REDDY
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Virtual Work ◽  
Constitutive Relations ◽  
Beam Theory ◽  
Element Model ◽  
Higher Order ◽  
Time Step ◽  
Third Order ◽  
The Third

In this paper, a finite element model for efficient nonlinear analysis of the mechanical response of viscoelastic beams is presented. The principle of virtual work is utilized in conjunction with the third-order beam theory to develop displacement-based, weak-form Galerkin finite element model for both quasi-static and fully-transient analysis. The displacement field is assumed such that the third-order beam theory admits C0 Lagrange interpolation of all dependent variables and the constitutive equation can be that of an isotropic material. Also, higher-order interpolation functions of spectral/hp type are employed to efficiently eliminate numerical locking. The mechanical properties are considered to be linear viscoelastic while the beam may undergo von Kármán nonlinear geometric deformations. The constitutive equations are modeled using Prony exponential series with general n-parameter Kelvin chain as its mechanical analogy for quasi-static cases and a simple two-element Maxwell model for dynamic cases. The fully discretized finite element equations are obtained by approximating the convolution integrals from the viscous part of the constitutive relations using a trapezoidal rule. A two-point recurrence scheme is developed that uses the approximation of relaxation moduli with Prony series. This necessitates the data storage for only the last time step and not for the entire deformation history.

Finite-Element Simulations and Probabilistic Fracture Assessments of the Response of Alternate Rifling Geometries

2007 ◽  
Author(s):  
A. E. Segall ◽  
R. Carter
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Thermal Stresses ◽  
Rotational Symmetry ◽  
Element Model ◽  
Time Dependent ◽  
Uniform Heating ◽  
Thermal Pressure ◽  
Single Firing ◽  
Hoop Stresses

A 3-D finite-element model was used to simulate the severe and localized thermal/pressure transients and the resulting stresses experienced by a rifled ceramic-barrel with a steel outer-liner; the focus of the simulations was on the influence of non-traditional rifling geometries on the thermoelastic- and pressure-stresses generated during a single firing event. In order to minimize computational requirements, a twisted segment of the barrel length based on rotational symmetry was used. Using this simplification, the model utilized uniform heating and pressure across the ID surface via a time-dependent convective coefficient and pressure generated by the propellant gasses. Results indicated that the unique rifling geometries had only a limited influence on the maximum circumferential (hoop) stresses and temperatures when compared with more traditional rifling configurations because of the compressive thermal stresses developed at the heated (and rifled) surface.

Fully Coupled Three-Scale Finite Element Model for the Mechanical Response of a New Bio-Inspired Composite

2011 ◽  
Author(s):  
Erick I. Saavedra Flores ◽  
Senthil Murugan ◽  
Michael I. Friswell ◽  
Eduardo A. de Souza Neto
Keyword(s):  
Finite Element ◽  
Magnesium Alloy ◽  
Finite Element Model ◽  
Large Scale ◽  
Mechanical Response ◽  
Volume Fraction ◽  
Element Model ◽  
Crystalline Cellulose ◽  
Gauss Point ◽  
Fully Coupled

This paper proposes a fully coupled three-scale finite element model for the mechanical description of an alumina/magnesium alloy/epoxy composite inspired in the mechanics and architecture of wood cellulose fibres. The constitutive response of the composite (the large scale continuum) is described by means of a representative volume element (RVE, corresponding to the intermediate scale) in which the fibre is represented as a periodic alternation of alumina and magnesium alloy fractions. Furthermore, at a lower scale the overall constitutive behavior of the alumina/magnesium alloy fibre is modelled as a single material defined by a large number of RVEs (the smallest material scale) at the Gauss point (intermediate) level. Numerical material tests show that the choice of the volume fraction of alumina based on those volume fractions of crystalline cellulose found in wood cells results in a maximisation of toughness in the present bio-inspired composite.

The Method of Modal Parameters to Determine the Boundary Condition of Finite Element Model

1991 ◽  
Author(s):  
Chen Shiyu ◽  
Wang Fengquan
Keyword(s):  
Boundary Condition ◽  
Finite Element ◽  
Finite Element Model ◽  
Interpolation Method ◽  
Element Model ◽  
Accurate Method ◽  
Modal Parameters ◽  
Computation Method ◽  
Modal Parameter ◽  
The Third

Abstract In this paper, a method used to determine the boundary condition of Finite Element Model with structure modal parameters is presented. On deriving the method, the theory of Finite Element Model for dynamic calculating is used. Combined with the modal parameters got from experiment, a FEM-Modal Parameter equation to determine the boundary condition is put forward. For solving the equation, three methods are given. The first is the accurate method. The second is the full mode computation method by means of generlized inverse matrix. The third is the interpolation method of frequency. An applied example is given and the results of calculation fully verify the effectiveness of the method offered.

scholarly journals Finite Element Analysis and Experimental Characterisation of SMC Composite Car Hood Specimens under Complex Loadings

2018 ◽  
Vol 2 (3) ◽  
pp. 53
Author(s):  
Josh Kelly ◽  
Edward Cyr ◽  
Mohsen Mohammadi
Keyword(s):  
Finite Element ◽  
Composite Materials ◽  
Finite Element Model ◽  
Volume Fraction ◽  
Failure Strain ◽  
Fibre Volume Fraction ◽  
Element Model ◽  
Experimental Results ◽  
Uniaxial Tensile ◽  
Structural Applications

Composite materials have recently been of particular interest to the automotive industry due to their high strength-to-weight ratio and versatility. Among the different composite materials used in mass-produced vehicles are sheet moulded compound (SMC) composites, which consist of random fibres, making them inexpensive candidates for non-structural applications in future vehicles. In this work, SMC composite materials were prepared with varying fibre orientations and volume fractions (25% and 45%) and subjected to a series of uniaxial tensile and flexural bending tests at a strain rate of 3 × 10−3 s−1. Tensile strength as well as failure strain increased with the increasing fibre volume fraction for the uniaxial tests. Flexural strength was found to also increase with increasing fibre percentage; however, failure displacement was found to decrease. The two material directions studied—longitudinal and transverse—showed superior strength and failure strain/displacement in the transverse direction. The experimental results were then used to create a finite element model to describe the deformation behaviour of SMC composites. Tensile results were first used to create and calibrate the model; then, the model was validated with flexural experimental results. The finite element model closely predicted both SMC volume fraction samples, predicting the failure force and displacement with less than 3.5% error in the lower volume fraction tests, and 6.6% error in the higher volume fraction tests.

Finite Element Analysis of Six Transcortical Pin Parameters and Their Effect on Bone–Pin Interface Stresses in the Equine Third Metacarpal Bone

2019 ◽  
Vol 33 (02) ◽  
pp. 121-129
Author(s):  
Timothy B. Lescun ◽  
Stephen B. Adams ◽  
Russell P. Main ◽  
Eric A. Nauman ◽  
Gert J. Breur
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Axial Loading ◽  
Element Model ◽  
Metacarpal Bone ◽  
Distal Limb ◽  
Element Analysis ◽  
Minimal Impact ◽  
The Third ◽  
Tomography Scan

Abstract Objective The objectives of this study were to validate a finite element model of the equine distal limb transfixation cast and to determine the effect of six transcortical pin parameters on bone–pin interface (BPI) stresses in the third metacarpal bone. Study Design A transfixation cast finite element model was developed from a computed tomography scan of the third metacarpal bone and modelled pin elements. The model was validated by comparing strain measured around a 6.3-mm transfixation pin in the third metacarpal bone with the finite element model. The pin parameters of diameter, number, location, spacing, orientation and material were evaluated by comparing a variety of pin configurations within the model. Results Pin diameter and number had the greatest impact on BPI stress. Increasing the diameter and number of pins resulted in lower BPI stresses. Diaphyseal pin location and stainless-steel pins had lower BPI stresses than metaphyseal location and titanium alloy pins, respectively. Offset pin orientation and pin spacing had minimal impact on BPI stresses during axial loading. Conclusion The results provide evidence that diameter and number are the main pin parameters affecting BPI stress in an equine distal limb transfixation cast. Configurations of various pin size and number may be proposed to reduce BPI stresses and minimize the risk of pin related complications. Further refinement of these models will be required to optimize pin configurations to account for pin hole size and its impact on overall bone strength.

Modified Quartet Structure Generation Set Reconstruction of Finite Element Model for Co-Continuous Ceramic Composites

2015 ◽  
Vol 782 ◽  
pp. 278-290 ◽  
Author(s):  
Qing Xiang Wang ◽  
Hong Mei Zhang ◽  
Hong Nian Cai ◽  
Qun Bo Fan
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Volume Fraction ◽  
Element Model ◽  
Ceramic Composites ◽  
Structure Generation ◽  
Sem Image

Co-continuous ceramic composites have a complicated topology structure which makes it much more difficult for finite element model reconstruction. In this paper, the two-dimensional co-continuous ceramic composites finite element model is reconstructed by a modified quartet structure generation set method which modified the generation parameters based on quartet structure generation set (QSGS) method, and a numerical simulation at high strain rate is accomplished. The content mainly contains: (1) The distribution features of metal phase and ceramic phase of real co-continuous ceramic composites SEM image is calculated by mathematical statistics to determine the parameters that control the reconstruction such as volume fraction, core distribution probability and directional growth probability; (2) Two phase volume fraction and 2-point correlation function of the reconstructed finite element model is calculated as the quality assessment parameters, which verify the reconstructed finite element model are in allowable error range compared with the real SEM image; (3) Numerical simulation at high strain rate is carried out using the reconstructed finite element model. The failure behavior of co-continuous ceramic composites at high strain rate is analyzed, validates the reconstructed finite element model meets the requirements of numerical calculation.

A Three-Dimensional Finite Element Model of the Human Arm

1999 ◽  
Author(s):  
Pal Palaniappan, Jr. ◽  
Paul Wipasuramonton ◽  
Anand S. Tanavde ◽  
Fuchun Zhu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Three Dimensional ◽  
Element Model ◽  
Human Arm ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element
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