scholarly journals What makes an accurate and reliable subject-specific finite element model? A case study of an elephant femur

2011 ◽  
Vol 9 (67) ◽  
pp. 351-361 ◽  
Author(s):  
O. Panagiotopoulou ◽  
S. D. Wilshin ◽  
E. J. Rayfield ◽  
S. J. Shefelbine ◽  
J. R. Hutchinson
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Material Properties ◽  
Experimental Validation ◽  
Heterogeneous Material ◽  
Element Model ◽  
Heterogeneous Model ◽  
Element Size ◽  
Subject Specific ◽  
Size Type

Finite element modelling is well entrenched in comparative vertebrate biomechanics as a tool to assess the mechanical design of skeletal structures and to better comprehend the complex interaction of their form–function relationships. But what makes a reliable subject-specific finite element model? To approach this question, we here present a set of convergence and sensitivity analyses and a validation study as an example, for finite element analysis (FEA) in general, of ways to ensure a reliable model. We detail how choices of element size, type and material properties in FEA influence the results of simulations. We also present an empirical model for estimating heterogeneous material properties throughout an elephant femur (but of broad applicability to FEA). We then use an ex vivo experimental validation test of a cadaveric femur to check our FEA results and find that the heterogeneous model matches the experimental results extremely well, and far better than the homogeneous model. We emphasize how considering heterogeneous material properties in FEA may be critical, so this should become standard practice in comparative FEA studies along with convergence analyses, consideration of element size, type and experimental validation. These steps may be required to obtain accurate models and derive reliable conclusions from them.

A subject-specific integrative biomechanical framework of the pelvis for gait analysis

2018 ◽  
Vol 232 (11) ◽  
pp. 1083-1097
Author(s):  
Emiliano P Ravera ◽  
Marcos J Crespo ◽  
Paola A Catalfamo Formento
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Gait Analysis ◽  
Material Properties ◽  
Element Model ◽  
Musculoskeletal Model ◽  
Pelvic Bone ◽  
Subject Specific ◽  
Specific Material ◽  
The Finite Element Model

Analysis of the human locomotor system using rigid-body musculoskeletal models has increased in the biomechanical community with the objective of studying muscle activations of different movements. Simultaneously, the finite element method has emerged as a complementary approach for analyzing the mechanical behavior of tissues. This study presents an integrative biomechanical framework for gait analysis by linking a musculoskeletal model and a subject-specific finite element model of the pelvis. To investigate its performance, a convergence study was performed and its sensitivity to the use of non-subject-specific material properties was studied. The total hip joint force estimated by the rigid musculoskeletal model and by the finite element model showed good agreement, suggesting that the integrative approach estimates adequately (in shape and magnitude) the hip total contact force. Previous studies found movements of up to 1.4 mm in the anterior–posterior direction, for single leg stance. These results are comparable with the displacement values found in this study: 0–0.5 mm in the sagittal axis. Maximum von Mises stress values of approximately 17 MPa were found in the pelvic bone. Comparing this results with a previous study of our group, the new findings show that the introduction of muscular boundary conditions and the flexion–extension movement of the hip reduce the regions of high stress and distributes more uniformly the stress across the pelvic bone. Thus, it is thought that muscle force has a relevant impact in reducing stresses in pelvic bone during walking of the finite element model proposed in this study. Future work will focus on including other deformable structures, such as the femur and the tibia, and subject-specific material properties.

Subject-Specific Experimental Validation of a C27 Cervical Spine Finite Element Model

2009 ◽  
Author(s):  
Nicole A. Kallemeyn ◽  
Kiran H. Shivanna ◽  
Anup A. Gandhi ◽  
Swathi Kode ◽  
Nicole M. Grosland
Keyword(s):  
Finite Element ◽  
Cervical Spine ◽  
Finite Element Model ◽  
Experimental Validation ◽  
Element Model ◽  
Fe Analysis ◽  
External Loading ◽  
Computational Simulations ◽  
Angular Rotation ◽  
Subject Specific

Computational simulations of the spine have the ability to quantify both the external (i.e. angular rotation) and internal (i.e. stresses and strains) responses to external loading. This is an advantage over cadaveric bench top studies, which are limited to studying mostly external responses. Finite element (FE) analysis has been used extensively to investigate the behavior of the normal cervical spine in addition to its diseased and degenerated states [1,2].

scholarly journals Probing time-dependent afterslip and viscoelastic relaxation following the 2015 Mw 7.8 Gorkha earthquake based on the 3-D Finite Element Model

2020 ◽  
Author(s):  
Lina Su ◽  
Fuqiang Shi ◽  
Weijun Gan ◽  
Xiaoning Su ◽  
Junyi Yan
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Material Properties ◽  
Heterogeneous Material ◽  
Element Model ◽  
Postseismic Deformation ◽  
Viscoelastic Relaxation ◽  
Gorkha Earthquake ◽  
2015 Gorkha Earthquake ◽  
Continuous Gps

Abstract We analyzed daily displacement time series from 34 continuous GPS stations in Nepal and 5 continuous GPS stations in South Tibet, China, and extracted the first 4.8 years of postseismic motion after the 2015 Mw7.8 Gorkha earthquake. With the longer duration GPS observations, we find that postseismic displacements mainly exhibit southward and uplift motion. To study the postseismic afterslip and viscoelastic relaxation, we built a 3-D spherical finite element model (FEM) with heterogeneous material properties and surface topography across the Himalayan range, accounting for the strong variations in material properties and surface elevation along central Himalayan arc. On the basis of the FEM, we reveal that the predicted viscoelastic relaxation of cm level moves southward to the north of the Gorkha earthquake rupture, but in an opposite direction to the observed postseismic deformation in the south; the postseismic deformation excluding viscoelastic relaxation is well explained by afterslip downdip of the coseismic rupture. The afterslip is dominant during 4.8 years after the 2015 Mw7.8 Gorkha earthquake; the contribution by the viscoelastic relaxation gradually increases slightly. The lack of slip on a shallow portion and western segment of the MHT during and after the 2015 Gorkha earthquake implies continued seismic hazard in the future.

scholarly journals Probing afterslip and viscoelastic relaxation following the 2015 Mw 7.8 Gorkha earthquake based on the 3-D Finite Element Model

2020 ◽  
Author(s):  
Lina Su ◽  
Fuqiang Shi ◽  
Weijun Gan ◽  
Xiaoning Su ◽  
Junyi Yan
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Material Properties ◽  
Heterogeneous Material ◽  
Element Model ◽  
Postseismic Deformation ◽  
Viscoelastic Relaxation ◽  
Gorkha Earthquake ◽  
2015 Gorkha Earthquake ◽  
Continuous Gps

Abstract We analyzed daily displacement time series from 34 continuous GPS stations in Nepal and 5 continuous GPS stations in South Tibet, China, and extracted the first 4.8 years of postseismic motion after the 2015 Mw7.8 Gorkha earthquake. With the longer duration GPS observations, we find that postseismic displacements mainly exhibit southward and uplift motion. To study the postseismic afterslip and viscoelastic relaxation, we built a 3-D spherical finite element model (FEM) with heterogeneous material properties and surface topography across the Himalayan range, accounting for the strong variations in material properties and surface elevation along central Himalayan arc. On the basis of the FEM, we reveal that the predicted viscoelastic relaxation of cm level moves southward to the north of the Gorkha earthquake rupture, but in an opposite direction to the observed postseismic deformation in the south; the postseismic deformation with viscoelastic relaxation is well explained by afterslip downdip of the coseismic rupture, which is still dominant 4.8 years after the 2015 Mw7.8 Gorkha earthquake. The lack of slip on a shallow portion and western segment of the MHT during and after the 2015 Gorkha earthquake implies continued seismic hazard in the future.

scholarly journals Probing time-dependent afterslip and viscoelastic relaxation following the 2015 Mw7.8 Gorkha earthquake based on the 3-D finite-element model

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Lina Su ◽  
Fuqiang Shi ◽  
Weijun Gan ◽  
Xiaoning Su ◽  
Junyi Yan
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Material Properties ◽  
Heterogeneous Material ◽  
Element Model ◽  
Postseismic Deformation ◽  
Viscoelastic Relaxation ◽  
Gorkha Earthquake ◽  
2015 Gorkha Earthquake ◽  
Continuous Gps

Abstract We analyzed daily displacement time series from 34 continuous GPS stations in Nepal and 5 continuous GPS stations in South Tibet, China, and extracted the first 4.8 years of postseismic motion after the 2015 Mw7.8 Gorkha earthquake. With the longer duration GPS observations, we find that postseismic displacements mainly exhibit southward and uplift motion. To study the postseismic afterslip and viscoelastic relaxation, we built a 3-D spherical finite-element model (FEM) with heterogeneous material properties and surface topography across the Himalayan range, accounting for the strong variations in material properties and surface elevation along the central Himalayan arc. On the basis of the FEM, we reveal that the predicted viscoelastic relaxation of cm level moves southward to the north of the Gorkha earthquake rupture, but in an opposite direction to the observed postseismic deformation in the south; the postseismic deformation excluding viscoelastic relaxation is well explained by afterslip downdip of the coseismic rupture. The afterslip is dominant during 4.8 years after the 2015 Mw7.8 Gorkha earthquake; the contribution by the viscoelastic relaxation gradually increases slightly. The lack of slip on a shallow portion and western segment of the MHT during and after the 2015 Gorkha earthquake implies continued seismic hazard in the future.

FEBio finite element model of a pediatric cervical spine

2021 ◽  
pp. 1-7
Author(s):  
Sean M. Finley ◽  
J. Harley Astin ◽  
Evan Joyce ◽  
Andrew T. Dailey ◽  
Douglas L. Brockmeyer ◽  
...  
Keyword(s):  
Finite Element ◽  
Cervical Spine ◽  
Finite Element Model ◽  
Material Properties ◽  
Surgical Simulation ◽  
Element Model ◽  
Axial Stiffness ◽  
Published Data ◽  
Axial Tension ◽  
Flexion Extension

OBJECTIVE The underlying biomechanical differences between the pediatric and adult cervical spine are incompletely understood. Computational spine modeling can address that knowledge gap. Using a computational method known as finite element modeling, the authors describe the creation and evaluation of a complete pediatric cervical spine model. METHODS Using a thin-slice CT scan of the cervical spine from a 5-year-old boy, a 3D model was created for finite element analysis. The material properties and boundary and loading conditions were created and model analysis performed using open-source software. Because the precise material properties of the pediatric cervical spine are not known, a published parametric approach of scaling adult properties by 50%, 25%, and 10% was used. Each scaled finite element model (FEM) underwent two types of simulations for pediatric cadaver testing (axial tension and cardinal ranges of motion [ROMs]) to assess axial stiffness, ROM, and facet joint force (FJF). The authors evaluated the axial stiffness and flexion-extension ROM predicted by the model using previously published experimental measurements obtained from pediatric cadaveric tissues. RESULTS In the axial tension simulation, the model with 50% adult ligamentous and annulus material properties predicted an axial stiffness of 49 N/mm, which corresponded with previously published data from similarly aged cadavers (46.1 ± 9.6 N/mm). In the flexion-extension simulation, the same 50% model predicted an ROM that was within the range of the similarly aged cohort of cadavers. The subaxial FJFs predicted by the model in extension, lateral bending, and axial rotation were in the range of 1–4 N and, as expected, tended to increase as the ligament and disc material properties decreased. CONCLUSIONS A pediatric cervical spine FEM was created that accurately predicts axial tension and flexion-extension ROM when ligamentous and annulus material properties are reduced to 50% of published adult properties. This model shows promise for use in surgical simulation procedures and as a normal comparison for disease-specific FEMs.

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