scholarly journals Quantifying Cartilage Contact Modulus, Tension Modulus, and Permeability With Hertzian Biphasic Creep

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
A. C. Moore ◽  
J. F. DeLucca ◽  
D. M. Elliott ◽  
D. L. Burris
Keyword(s):  
Finite Element ◽  
Tibial Plateau ◽  
Femoral Condyle ◽  
Tissue Mechanics ◽  
Ease Of Use ◽  
Soft Tissue Mechanics ◽  
The Finite Element Method ◽  
Finite Element Package ◽  
Creep Measurements ◽  
Time Required

This paper describes a new method, based on a recent analytical model (Hertzian biphasic theory (HBT)), to simultaneously quantify cartilage contact modulus, tension modulus, and permeability. Standard Hertzian creep measurements were performed on 13 osteochondral samples from three mature bovine stifles. Each creep dataset was fit for material properties using HBT. A subset of the dataset (N = 4) was also fit using Oyen's method and FEBio, an open-source finite element package designed for soft tissue mechanics. The HBT method demonstrated statistically significant sensitivity to differences between cartilage from the tibial plateau and cartilage from the femoral condyle. Based on the four samples used for comparison, no statistically significant differences were detected between properties from the HBT and FEBio methods. While the finite element method is considered the gold standard for analyzing this type of contact, the expertise and time required to setup and solve can be prohibitive, especially for large datasets. The HBT method agreed quantitatively with FEBio but also offers ease of use by nonexperts, rapid solutions, and exceptional fit quality (R2 = 0.999 ± 0.001, N = 13).

Engineering Analysis of Shoulder Dystocia in the Human Birth Process by the Finite Element Method

1992 ◽  
Vol 206 (4) ◽  
pp. 243-250 ◽  
Author(s):  
A Meghdari ◽  
R Davoodi ◽  
F Mesbah
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Shoulder Dystocia ◽  
Point Of View ◽  
Engineering Analysis ◽  
The Finite Element Method ◽  
Birth Process ◽  
Beam Elements ◽  
Finite Element Package ◽  
Human Birth

This paper presents an engineering analysis of shoulder dystocia (SD) in the human birth process which usually results in damaging the brachial plexus nerves and the humerus and/or clavicle bones of the baby. The goal is to study these injuries from the mechanical engineering point of view. Two separate finite element models of the neonatal neck and the clavicle bone have been simulated using eight-node three-dimensional elements and beam elements respectively. Simulated models have been analysed under suitable boundary conditions using the ‘SAP80’ finite element package. Finally, results obtained have been verified by comparing them with published clinical and experimental observations.

scholarly journals On the Finite Element Implementation of Functionally Graded Materials

Materials ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 287 ◽  
Author(s):  
Emilio Martínez-Pañeda
Keyword(s):  
Finite Element ◽  
Functionally Graded Materials ◽  
Functionally Graded ◽  
The Finite Element Method ◽  
Element Level ◽  
Graded Materials ◽  
Property Variation ◽  
User Subroutine ◽  
Finite Element Package ◽  
Fracture Assessment

We investigate the numerical implementation of functionally graded properties in the context of the finite element method. The macroscopic variation of elastic properties inherent to functionally graded materials (FGMs) is introduced at the element level by means of the two most commonly used schemes: (i) nodal based gradation, often via an auxiliary (non-physical) temperature-dependence, and (ii) Gauss integration point based gradation. These formulations are extensively compared by solving a number of paradigmatic boundary value problems for which analytical solutions can be obtained. The nature of the notable differences revealed by the results is investigated in detail. We provide a user subroutine for the finite element package ABAQUS to overcome the limitations of the most popular approach for implementing FGMs in commercial software. The use of reliable, element-based formulations to define the material property variation could be key in fracture assessment of FGMs and other non-homogeneous materials.

Accumulator Roll Analysis Using the Finite Element Method

1999 ◽  
Author(s):  
Hazel M. Pierson ◽  
Daniel H. Suchora ◽  
Anthony V. Viviano
Keyword(s):  
Finite Element ◽  
Sheet Metal ◽  
Comparative Approach ◽  
The Finite Element Method ◽  
Roll Design ◽  
Roll Body ◽  
Finite Element Software ◽  
Fea Model ◽  
Finite Element Package ◽  
The Impact

Abstract The purpose of this study was to develop a method to analyze various designs of non-driven accumulator rolls using a static finite element software package. This would allow the engineer to determine how the various components of the roll design contribute to or lessen the deflection of and stresses in the roll body when it is loaded by sheet metal passing over o under it. The method outlined is intended mainly for use when an advanced dynamic finite element package that incorporates contact elements is not available and when a comparison of various roll designs is desired. First, an approximation of the pressure on the roll body caused by the force of the sheet metal as it wrapped over or under the roll was determined. Then using the finite element package ALGOR, an FEA model of a standard accumulator roll design was loaded with this pressure and the stresses and deflections were calculated. Next, components of this basic roll design were varied in the FEA model. These were the location of the stiffeners and the thickness of the roll body, the end plates, and the stiffeners. A comparative approach was then used to assess the impact each of these variations in roll design had oh the deflection of and the stresses in the roll.

Modelling of continuous crushing of ice in front of offshore structures

1995 ◽  
Vol 22 (3) ◽  
pp. 544-550 ◽  
Author(s):  
T. G. Brown ◽  
U. A. Morsy
Keyword(s):  
Finite Element ◽  
Plastic Material ◽  
Crack Density ◽  
Offshore Structures ◽  
Rate Theory ◽  
Theory Approach ◽  
The Finite Element Method ◽  
Dimensional Finite Element ◽  
Finite Element Package ◽  
Component Models

A one-dimensional finite element is developed to represent the continuous crushing and extrusion of ice in interactions with offshore structures. The element is developed with the objective of providing a model for the analysis of dynamic ice–structure interactions in which both nonsimultaneous and phase-locked behaviours occur. The element has two components: one to model the damage accumulation in intact ice and one to model the extrusion of pulverized ice between the intact ice and the structure. The intact but damaging ice behaviour is based on a rate theory approach to crack density and damaged material compliance which is a function of stress and damage. The extrusion component models a viscous-plastic material which is modelled using a Tresca failure criterion and viscous flow. The element is developed as part of an existing finite element package (Abaqus) through its user material and user element capabilities. The paper describes in detail the development and implementation of the element and presents sample results of its performance in continuous crushing interactions with a rigid structure. The results show that the element can be used as the interface between moving intact ice sheets and offshore structures modelled using the finite element method. Key words: ice, structures, dynamics, finite elements, rheology.

scholarly journals Finite Element Evaluation of Effective Thermal Conductivity of Short Carbon Nano Tubes: A Comparative Study

2017 ◽  
Vol 372 ◽  
pp. 208-214 ◽  
Author(s):  
Zia Javanbakht ◽  
Wayne Hall ◽  
Andreas Öchsner
Keyword(s):  
Thermal Conductivity ◽  
Finite Element ◽  
Random Distribution ◽  
Resin Matrix ◽  
The Finite Element Method ◽  
Effective Parameters ◽  
The Matrix ◽  
Finite Element Package ◽  
Carbon Nano Tubes ◽  
Short Carbon

In the current study, two extreme cases are considered for the dispersion of carbon nanotubes(CNTs) in a polymeric matrix: randomly-oriented and randomly-aligned. The representative volume element (RVE) is used to represent the composite material consisting of epoxy resin matrix and CNT-reinforcement. The finite element method acts as the computational tool to conduct the simulations and investigate the effective parameters, i.e., the influence of the aspect ratio and the orientation, on the thermal conductivity of the matrix. A Fortran subroutine was used for both generation and analysis of the models by means of the MSC Marc finite element package and a Python script was used for the sensitivity analysis. The results indicate that optimum performance of the CNTs in terms of thermal conductivity can be reached by orienting them along the temperature gradient whereas a random distribution improves the conductivity by a smaller magnitude.

Stress Concentration Factors of Cross-Bores in Thick Walled Cylinders and Blocks

2004 ◽  
Vol 126 (2) ◽  
pp. 184-187 ◽  
Author(s):  
Ricky D. Dixon ◽  
Daniel T. Peters ◽  
Jan G. M. Keltjens
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress Concentration ◽  
Cylindrical Shells ◽  
Ease Of Use ◽  
Stress Fields ◽  
The Finite Element Method ◽  
Internal Radius ◽  
Concentration Factors ◽  
Stress Concentration Factors

The purpose of this paper is to investigate the stress concentration in stress fields around crossbores for closed-end thick-walled square blocks and cylindrical shells using the finite element method. These stress concentration factors are presented and discussed as a function of the ratio of crossbore radius to the cylinder internal radius (HR/Ri=0.01 to 0.7) for a range of wall ratios (Y=1.5 to 5). Charts and simple expressions are provided for ease of use.

scholarly journals Effect of Weaving Type on Damage Behaviour of Carbon/Epoxy Laminate under Low Velocity Impact Loading

2017 ◽  
Vol 61 (2) ◽  
pp. 140 ◽  
Author(s):  
Djilali Beida Maamar ◽  
Ramdane Zenasni
Keyword(s):  
Finite Element ◽  
Composite Material ◽  
Impact Load ◽  
Low Velocity Impact ◽  
The Finite Element Method ◽  
Low Velocity ◽  
Velocity Impact ◽  
Rigid Body Model ◽  
The Matrix ◽  
Finite Element Package

The main purpose of the present investigation was to determine the damages generated by the low velocity impact by mean of the finite element method. The commercial transient finite element package LS-dyna used to model the effect of slug impactor induced damage in composite material subjected to low velocity impact. Four types of weaving were considered; serge (2/2), serge (0/30/-30/0), serge (0/45-45/0) and taffeta. The Texgen package was used to build the laminate pattern weaves. The composite material was subjected to stainless steel slug impactor in the transverse direction dropping the composite laminate at the center with a velocity about of 15m/s. The analysis was carried out using the model 001-ELASTIC for matrix, 002-ORTHOTROPIC_ELASTIC for fibersand a rigid body model MAT20 for the slug impactor. The contact automatic single surface has been used between the yarns and the automatic_surface_to_surface between the matrix and the impactor and the contact automatic_surface_to_surface_tiebreak between the matrix and yarns and the contact automatic_surface_to_surface_tiebreak between layers.The impact load, energy, displacements were reported as function of impact time. The delamination area was represented at the layer interfaces for each material.

Computational and Experimental Investigation on Thermal Conductivity of SiС Particle Reinforced Al-Matrix Composite Containing Pores

2013 ◽  
Vol 762 ◽  
pp. 769-776 ◽  
Author(s):  
Ai Hua Zou ◽  
Xian Liang Zhou ◽  
Yu Long Que ◽  
Xiao Zhen Hua ◽  
Duo Sheng Li
Keyword(s):  
Thermal Conductivity ◽  
Finite Element ◽  
The Finite Element Method ◽  
Distribution Models ◽  
Element Analysis ◽  
Finite Element Package ◽  
Experimental Values ◽  
Infiltration Method ◽  
Al Matrix Composite ◽  
Al Matrix

In this paper, the finite element method (FEM) was implemented to determine the effective thermal conductivity of SiC particle reinforced Al matrix (SiCp/Al) composites containing various pores and that method was validated by experimentation. A commercially available finite-element package ANSYS is used to for this numerical analysis. Multi-particle and pores random distribution models based on the effective medium approximation (EMA) scheme are constructed to simulate the microstructure of composite materials for various porosities ranging from 0.96 to 10.58%. The SiCp/Al composites were fabricated by the pressureless infiltration method. This study shows that the smaller pores contained in the composite results in sharp reduction of thermal conductivity, when the porosity is up to 2.66 vol.%, the thermal conductivity of composite is found to decrease by about 9.02%. The experimentally measured thermal conductivity values are compared with the numerically calculated ones and also with the existing theoretical and empirical models. The values obtained from finite-element analysis (FEA) are found to be in reasonable agreement with the experimental values.

The Indentation Behavior of Closed-Cell Al Foam under the Flat-End Cylindrical Indenter

2011 ◽  
Vol 704-705 ◽  
pp. 960-966
Author(s):  
Xin Zhu Wang ◽  
Guang Tao Zhou
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Plastic Material ◽  
Indentation Test ◽  
The Finite Element Method ◽  
Spherical Cap ◽  
Closed Cell ◽  
Finite Element Package ◽  
Al Foam ◽  
Indentation Response

The indentation response of the closed-cell Al foam under the flat-end cylindrical indenter is examined by use the finite element method. The MSC/Marc finite element package is used to model the indentation response of the foam panels, and the Al foam was defined in MSC/Marc as the homogeneous, elasto-plastic material. The simulation result reveals that the deformation was found to be almost totally restricted to a spherical cap-shape compacted zone under the indenter, and the shape of the deformation zone is similar to the observed phenomenon from the indentation test.

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