scholarly journals Simulation of nonlinear transient elastography: finite element model for the propagation of shear waves in homogeneous soft tissues

2017 ◽  
Vol 34 (1) ◽  
pp. e2901 ◽  
Author(s):  
W. Ye ◽  
A. Bel-Brunon ◽  
S. Catheline ◽  
A. Combescure ◽  
M. Rochette
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Soft Tissues ◽  
Transient Elastography ◽  
Shear Waves ◽  
Element Model ◽  
Nonlinear Transient

Finite Element Model of the Human Knee Joint to Study Tibio-Femoral Contact Mechanics

2000 ◽  
Author(s):  
Tammy Haut Donahue ◽  
Maury L. Hull ◽  
Mark M. Rashid ◽  
Christopher R. Jacobs
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Degrees Of Freedom ◽  
Soft Tissues ◽  
Element Model ◽  
Human Knee ◽  
Human Knee Joint ◽  
Solid Models ◽  
Flexion Extension ◽  
A New Technique

Abstract A finite element model of the tibio-femoral joint in the human knee was created using a new technique for developing accurate solid models of soft tissues (i.e. cartilage and menisci). The model was used to demonstrate that constraining rotational degrees of freedom other than flexion/extension when the joint is loaded in compression markedly affects the load distribution between the medial and lateral sides of the joint. The model also was used to validate the assumption that the bones can be treated as rigid.

A 3D Biphasic Finite Element Model of the Human Knee Joint for the Study of Tibiofemoral Contact and Fluid Pressurization

2013 ◽  
Author(s):  
Hongqiang Guo ◽  
Suzanne A. Maher ◽  
Robert L. Spilker
Keyword(s):  
Finite Element ◽  
Fluid Flow ◽  
Knee Joint ◽  
Contact Problem ◽  
Finite Element Model ◽  
Soft Tissues ◽  
Fluid Pressure ◽  
Element Model ◽  
Human Knee Joint ◽  
Biphasic Finite Element

Biphasic theory which considers soft tissue, such as articular cartilage and meniscus, as a combination of a solid and a fluid phase has been widely used to model their biomechanical behavior [1]. Though fluid flow plays an important role in the load-carrying ability of soft tissues, most finite element models of the knee joint consider cartilage and the meniscus as solid. This simplification is due to the fact that biphasic contact is complicated to model. Beside the continuity conditions for displacement and traction that a single-phase contact problem consists of, there are two additional continuity conditions in the biphasic contact problem for relative fluid flow and fluid pressure [2]. The problem becomes even more complex when a joint is being modeled. The knee joint, for example, has multiple contact pairs which make the biphasic finite element model of this joint far more complex. Several biphasic models of the knee have been developed [3–9], yet simplifications were included in these models: (1) the 3D geometry of the knee was represented by a 2D axisymmetric geometry [3, 5, 6, 9]; (2) no fluid flow was allowed between contact surfaces of the soft tissues [4, 8] which is inconsistent with the equation of mass conservation across the contact interface [10]; (3) zero fluid pressure boundary conditions were inaccurately applied around the contact area [7].

scholarly journals BIOMECHANICAL ANALYSES OF STRESS DISTRIBUTION WITHIN THE SEATED BUTTOCK AND CUSHION

2002 ◽  
Vol 14 (06) ◽  
pp. 269-272 ◽  
Author(s):  
PEI-HSI CHOU ◽  
YOU-LI CHOU ◽  
CHOE-JAN CHIANG ◽  
TING-SHENG LIN ◽  
SHU-ZON LOU
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Finite Element Model ◽  
Soft Tissues ◽  
Element Model ◽  
The Elderly ◽  
Pressure Sore ◽  
Measuring System ◽  
Internal Stresses ◽  
Simplified Finite Element Model

The elderly wheelchair users frequently encountered the prevalence of pressure sore, also known as decubitus, since they have to be seated in the wheelchair for daily activities. The major cause induced the formation of pressure sore was that the soft tissues were over-stressed. The purpose of this study was to provide the information about internal stresses of soft tissues and establish a simplified finite element model to simulate the behavior of the interface between human buttock and cushion. Computational stresses were verified by comparing the buttock-cushion interface pressures, which was measured with Q.A. pressure pads. The displacement of the cushion was also validated with the experimental results of buttock measuring system. Two cushion geometries, fat and contoured, were adopted in this study to explore the effects on stress distributions. The results showed that the simplified finite element model was consistent with the experimental data. Contoured cushions had better stress distribution and lower interface stress.

Seismo-Acoustic Benchmark Problems Involving Sloping Fluid–Solid Interfaces

2016 ◽  
Vol 24 (04) ◽  
pp. 1650022 ◽  
Author(s):  
Katherine Woolfe ◽  
Michael D. Collins ◽  
David C. Calvo ◽  
William L. Siegmann
Keyword(s):  
Finite Element ◽  
Wave Equation ◽  
Parabolic Equation ◽  
Finite Element Model ◽  
Shear Waves ◽  
Element Model ◽  
Single Scattering ◽  
Benchmark Problems ◽  
Sediment Layer ◽  
Compressional Waves

The accuracy of the seismo-acoustic parabolic equation is tested for problems involving sloping fluid–solid interfaces. The fluid may correspond to the ocean or a sediment layer that only supports compressional waves. The solid may correspond to ice cover or a sediment layer that supports compressional and shear waves. The approach involves approximating the medium in terms of a series of range-independent regions, using a parabolic wave equation to propagate the field through each region, and applying single-scattering approximations to obtain transmitted fields across the vertical interfaces between regions. The accuracy of the parabolic equation method for range-dependent problems in seismo-acoustics was previously tested in the small slope limit. It is tested here for problems involving larger slopes using a finite-element model to generate reference solutions.

scholarly journals Numerical Assessment of the Structural Effects of Relative Sliding between Tissues in a Finite Element Model of the Foot

Mathematics ◽  
2021 ◽  
Vol 9 (15) ◽  
pp. 1719
Author(s):  
Marco A. Martínez Bocanegra ◽  
Javier Bayod López ◽  
Agustín Vidal-Lesso ◽  
Andrés Mena Tobar ◽  
Ricardo Becerro de Bengoa Vallejo
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Soft Tissues ◽  
Element Model ◽  
Structural Behavior ◽  
Sliding Contacts ◽  
Plantar Aponeurosis ◽  
Motion Constraints ◽  
Numerical Assessment ◽  
Foot Model

Penetration and shared nodes between muscles, tendons and the plantar aponeurosis mesh elements in finite element models of the foot may cause inappropriate structural behavior of the tissues. Penetration between tissues caused using separate mesh without motion constraints or contacts can change the loading direction because of an inadequate mesh displacement. Shared nodes between mesh elements create bonded areas in the model, causing progressive or complete loss of load transmitted by tissue. This paper compares by the finite element method the structural behavior of the foot model in cases where a shared mesh has been used versus a separated mesh with sliding contacts between some important tissues. A very detailed finite element model of the foot and ankle that simulates the muscles, tendons and plantar aponeurosis with real geometry has been used for the research. The analysis showed that the use of a separate mesh with sliding contacts and a better characterization of the mechanical behavior of the soft tissues increased the mean of the absolute values of stress by 83.3% and displacement by 17.4% compared with a shared mesh. These increases mean an improvement of muscle and tendon behavior in the foot model. Additionally, a better quantitative and qualitative distribution of plantar pressure was also observed.

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