scholarly journals Comparison of Displacement-Based and Force-Based Mapped Meshing

2008 ◽  
Author(s):  
Vincent Magnotta ◽  
Wen Li ◽  
Nicole Grosland
Keyword(s):  
Finite Element ◽  
Distal Phalanx ◽  
Limiting Factors ◽  
Human Hand ◽  
Mesh Quality ◽  
Fe Method ◽  
Template Mesh ◽  
Subject Specific ◽  
Displacement Based ◽  
Time Required

The finite element (FE) method is a powerful tool for the study of biomechanics. One of the limiting factors in transitioning this tool into the clinic is the time required to generate high quality meshes for analysis. Previously, we developed a mapped meshing technique that utilized force control and a finite element solver to warp a template mesh onto subject specific surfaces. This paper describes a displacement based method that directly warps the template mesh onto subject specific surfaces using distance as the driving measure for the deformable registration. The resulting meshes were evaluated for mesh quality and compared to the force based method. An initial evaluation was performed using a mathematical phantom. The algorithm was then applied to generate meshes for the phalanx bones of the human hand. The algorithm successfully mapped the template bone to all of the bony surfaces, with the exception of the distal phalanx bone. In this one case, significant differences existed between the geometries of the template mesh and the distal phalanx. Further refinement of the algorithm may allow the algorithm to successfully generate meshes even in the presence of large geometric shape differences.

scholarly journals Smoothed finite element method for two-dimensional elasto-plasticity

2009 ◽  
Vol 31 (3-4) ◽  
Author(s):  
Stéphane Pierre Alain Bordascorres ◽  
Hung Nguyen-Dang ◽  
Quyen Phan-Phuong ◽  
Hung Nguyen-Xuan ◽  
Sundararajan Natarajan ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Two Dimensional ◽  
Fe Method ◽  
Mesh Distortion ◽  
Elasto Plasticity ◽  
Smoothed Finite Element Method ◽  
Displacement Based ◽  
Theoretical Developments ◽  
Element Method

This communication shows how the smoothed finite element method (SFEM) very recently proposed by G. R. Liu [14] can be extended to elasto-plasticity. The SFEM results are in excellent agreement with the finite element (FEM) and analytical results. For the examples treated, the method is quite insensitive to mesh distortion and volumetric locking. Moreover, the SFEM yields more compliant load-displacement curves compared to the standard, displacement based FE method, as expected from the theoretical developments recently published in [4], [3] and [6].

Comparison of Different Radial Basis Functions in Developing Subject-Specific Infant Head Finite Element Models for Injury Biomechanics Study

2012 ◽  
Author(s):  
Zhigang Li ◽  
Jingwen Hu ◽  
Jinhuan Zhang
Keyword(s):  
Finite Element ◽  
Interpolation Method ◽  
Fe Model ◽  
Mesh Quality ◽  
Injury Biomechanics ◽  
Shell Elements ◽  
Mesh Morphing ◽  
Subject Specific ◽  
Radial Basis ◽  
Spatial Interpolation Method

Developing a subject-specific finite element (FE) model, especially with only high quality hexahedral solid elements and quadrilateral shell elements, is very time-consuming. Recently, template-based mesh morphing method has become popular to construct subject-specific FE models, in which a baseline FE mesh can be morphed into a FE model with subject-specific geometry. Because the mesh morphing algorithm could be programmed and run automatically, it is a very promising method for future applications of subject-specific FE models in injury biomechanics studies. Radial Basis Function (RBF) as a powerful spatial interpolation method has already been used as a mesh morphing method (1). The types of RBFs can affect the morphed mesh quality and geometry accuracy in the RBF method. However, to date, no previous study has tried to compare the differences generated by different RBFs. Therefore, in this study, different RBFs were used to morph a baseline infant head FE model into 10 different subject-specific infant head FE models based on CT images from 10 children aged from 0 to 3 months. The mesh quality and geometry accuracy of the subject-specific models generated by different RBFs were compared using statistic analysis.

scholarly journals Subject-Specific Finite Element Modelling of the Human Hand Complex: Muscle-Driven Simulations and Experimental Validation

2019 ◽  
Vol 48 (4) ◽  
pp. 1181-1195 ◽  
Author(s):  
Yuyang Wei ◽  
Zhenmin Zou ◽  
Guowu Wei ◽  
Lei Ren ◽  
Zhihui Qian
Keyword(s):  
Finite Element ◽  
Contact Pressure ◽  
Material Properties ◽  
Finite Element Modelling ◽  
Human Hand ◽  
Fe Model ◽  
Muscle Forces ◽  
Element Modelling ◽  
Subject Specific

AbstractThis paper aims to develop and validate a subject-specific framework for modelling the human hand. This was achieved by combining medical image-based finite element modelling, individualized muscle force and kinematic measurements. Firstly, a subject-specific human hand finite element (FE) model was developed. The geometries of the phalanges, carpal bones, wrist bones, ligaments, tendons, subcutaneous tissue and skin were all included. The material properties were derived from in-vivo and in-vitro experiment results available in the literature. The boundary and loading conditions were defined based on the kinematic data and muscle forces of a specific subject captured from the in-vivo grasping tests. The predicted contact pressure and contact area were in good agreement with the in-vivo test results of the same subject, with the relative errors for the contact pressures all being below 20%. Finally, sensitivity analysis was performed to investigate the effects of important modelling parameters on the predictions. The results showed that contact pressure and area were sensitive to the material properties and muscle forces. This FE human hand model can be used to make a detailed and quantitative evaluation into biomechanical and neurophysiological aspects of human hand contact during daily perception and manipulation. The findings can be applied to the design of the bionic hands or neuro-prosthetics in the future.

Subject-specific finite element models can accurately predict strain levels in long bones

2007 ◽  
Vol 40 (13) ◽  
pp. 2982-2989 ◽  
Author(s):  
Enrico Schileo ◽  
Fulvia Taddei ◽  
Andrea Malandrino ◽  
Luca Cristofolini ◽  
Marco Viceconti
Keyword(s):  
Finite Element ◽  
Finite Element Models ◽  
Long Bones ◽  
Subject Specific

Development of a Finite Element Model of the Inferior Glenohumeral Ligament of the Glenohumeral Joint

2003 ◽  
Author(s):  
William J. Newman ◽  
Richard E. Debski ◽  
Susan M. Moore ◽  
Jeffrey A. Weiss
Keyword(s):  
Finite Element ◽  
Glenohumeral Joint ◽  
External Rotation ◽  
Element Model ◽  
Fe Modeling ◽  
Glenohumeral Ligament ◽  
Subject Specific ◽  
Inferior Glenohumeral Ligament ◽  
Glenohumeral Capsule ◽  
Shoulder Stability

The shoulder is one of the most complex and often injured joints in the human body. The inferior glenohumeral ligament (IGHL), composed of the anterior band (AB), posterior band (PB) and the axillary pouch, has been shown to be an important contributor to anterior shoulder stability (Turkel, 1981). Injuries to the IGHL of the glenohumeral capsule are especially difficult to diagnose and treat effectively. The objective of this research was to develop a methodology for subject-specific finite element (FE) modeling of the ligamentous structures of the glenohumeral joint, specifically the IGHL, and to determine how changes in material properties affect predicted strains in the IGHL at 60° of external rotation. Using the techniques developed in this research, an improved understanding of the contribution of the IGHL to shoulder stability can be acquired.

Assessing the Local Mechanical Environment in Medial Opening Wedge High Tibial Osteotomy Using Finite Element Analysis

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Yves Pauchard ◽  
Todor G. Ivanov ◽  
David D. McErlain ◽  
Jaques S. Milner ◽  
J. Robert Giffin ◽  
...  
Keyword(s):  
Finite Element ◽  
High Tibial Osteotomy ◽  
Volume Fraction ◽  
Compressive Strain ◽  
Tibial Osteotomy ◽  
Fe Modeling ◽  
Knee Alignment ◽  
Mechanical Environment ◽  
Significant Difference ◽  
Subject Specific

High-tibial osteotomy (HTO) is a surgical technique aimed at shifting load away from one tibiofemoral compartment, in order the reduce pain and progression of osteoarthritis (OA). Various implants have been designed to stabilize the osteotomy and previous studies have been focused on determining primary stability (a global measure) that these designs provide. It has been shown that the local mechanical environment, characterized by bone strains and segment micromotion, is important in understanding healing and these data are not currently available. Finite element (FE) modeling was utilized to assess the local mechanical environment provided by three different fixation plate designs: short plate with spacer, long plate with spacer and long plate without spacer. Image-based FE models of the knee were constructed from healthy individuals (N = 5) with normal knee alignment. An HTO gap was virtually added without changing the knee alignment and HTO implants were inserted. Subsequently, the local mechanical environment, defined by bone compressive strain and wedge micromotion, was assessed. Furthermore, implant stresses were calculated. Values were computed under vertical compression in zero-degree knee extension with loads set at 1 and 2 times the subject-specific body weight (1 BW, 2 BW). All studied HTO implant designs provide an environment for successful healing at 1 BW and 2 BW loading. Implant von Mises stresses (99th percentile) were below 60 MPa in all experiments, below the material yield strength and significantly lower in long spacer plates. Volume fraction of high compressive strain ( > 3000 microstrain) was below 5% in all experiments and no significant difference between implants was detected. Maximum vertical micromotion between bone segments was below 200 μm in all experiments and significantly larger in the implant without a tooth. Differences between plate designs generally became apparent only at 2 BW loading. Results suggest that with compressive loading of 2 BW, long spacer plates experience the lowest implant stresses, and spacer plates (long or short) result in smaller wedge micromotion, potentially beneficial for healing. Values are sensitive to subject bone geometry, highlighting the need for subject-specific modeling. This study demonstrates the benefits of using image-based FE modeling and bone theory to fine-tune HTO implant design.

Spreadsheet Tool for Quick-Turn 3D Numerical Modeling of Package Thermal Performance With Non-Uniform Die Heating

2001 ◽  
Author(s):  
Abhay A. Watwe ◽  
Ravi S. Prasher
Keyword(s):  
Finite Element ◽  
Numerical Modeling ◽  
Finite Volume ◽  
Thermal Performance ◽  
Three Dimensional ◽  
3D Numerical Modeling ◽  
Conventional Analysis ◽  
Time Required ◽  
The Impact ◽  
Fourier Equation

Abstract Traditional methods of estimating package thermal performance employ numerical modeling using commercially available finite-volume or finite-element tools. Use of these tools requires training and experience in thermal modeling. This methodology restricts the ability of die designers to quickly evaluate the thermal impact of their die architecture due to the added throughput time required to enlist the services of a thermal analyst. This paper describes the development of an easy to use spreadsheet tool, which performs quick-turn numerical evaluations of the impact of non-uniform die heating. The tool employs well-established finite-volume numerical techniques to solve the steady-state, three-dimensional Fourier equation of conduction in the package geometry. Minimal input data is required and the inputs are customized using visual basic pull-down menus to assist die designers who may not be thermal experts. Data showing comparison of the estimates from the spreadsheet tool with that obtained from a conventional analysis using the commercially available finite element code ANSYS™ is also presented.

Effect of Ramp Angle on the Anti-Loosening Ability of Wedge Self-Locking Nuts Under Vibration

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Jianhua Liu ◽  
Hao Gong ◽  
Xiaoyu Ding
Keyword(s):  
Finite Element ◽  
Numerical Simulations ◽  
Production Technology ◽  
Material Properties ◽  
Threshold Value ◽  
Commercial Production ◽  
Experimental Results ◽  
Fe Method ◽  
Transversal Vibration

Recently, the wedge self-locking nut, a special anti-loosening product, is receiving more attention because of its excellent reliability in preventing loosening failure under vibration conditions. The key characteristic of a wedge self-locking nut is the special wedge ramp at the root of the thread. In this work, the effect of ramp angle on the anti-loosening ability of wedge self-locking nuts was studied systematically based on numerical simulations and experiments. Wedge self-locking nuts with nine ramp angles (10 deg, 15 deg, 20 deg, 25 deg, 30 deg, 35 deg, 40 deg, 45 deg, and 50 deg) were modeled using a finite element (FE) method, and manufactured using commercial production technology. Their anti-loosening abilities under transversal vibration conditions were analyzed based on numerical and experimental results. It was found that there is a threshold value of the initial preload below which the wedge self-locking nuts would lose their anti-loosening ability. This threshold value of initial preload was then proposed for use as a criterion to evaluate the anti-loosening ability of wedge self-locking nuts quantitatively and to determine the optimal ramp angle. Based on this criterion, it was demonstrated, numerically and experimentally, that a 30 deg wedge ramp resulted in the best anti-loosening ability among nine ramp angles studied. The significance of this study is that it provides an effective method to evaluate the anti-loosening ability of wedge self-locking nuts quantitatively, and determined the optimal ramp angle in terms of anti-loosening ability. The proposed method can also be used to optimize other parameters, such as the material properties and other dimensions, to guarantee the best anti-loosening ability of wedge self-locking nuts.

Sign in / Sign up

Export Citation Format

Share Document