Combining Freehand Ultrasound-Based Indentation and Inverse Finite Element Modeling for the Identification of Hyperelastic Material Properties of Thigh Soft Tissues

Abstract Finite element analysis (FEA) is a numerical modeling tool vastly employed in research facilities to analyze and predict load transmission between the human body and a medical device, such as a prosthesis or an exoskeleton. Yet, the use of finite element modeling (FEM) in a framework compatible with clinical constraints is hindered by, among others, heavy and time-consuming assessments of material properties. Ultrasound (U.S.) imaging opens new and unique opportunities for the assessment of in vivo material properties of soft tissues. Confident of these advances, a method combining a freehand U.S. probe and a force sensor was developed in order to compute the hyperelastic constitutive parameters of the soft tissues of the thigh in both relaxed (R) and contracted (C) muscles' configurations. Seven asymptomatic subjects were included for the experiment. Two operators in each configuration performed the acquisitions. Inverse FEM allowed for the optimization of an Ogden's hyperelastic constitutive model of soft tissues of the thigh in large displacement. The mean shear modulus identified for configurations R and C was, respectively, 3.2 ± 1.3 kPa and 13.7 ± 6.5 kPa. The mean alpha parameter identified for configurations R and C was, respectively, 10 ± 1 and 9 ± 4. An analysis of variance showed that the configuration had an effect on constitutive parameters but not on the operator.

Download Full-text

Hybrid neural network and finite element modeling of sub-base layer material properties in flexible pavements

Materials & Design (1980-2015) ◽

10.1016/j.matdes.2006.02.017 ◽

2007 ◽

Vol 28 (5) ◽

pp. 1725-1730 ◽

Cited By ~ 15

Author(s):

Mehmet Saltan ◽

Hüseyin Sezgin

Keyword(s):

Neural Network ◽

Finite Element ◽

Finite Element Modeling ◽

Material Properties ◽

Flexible Pavements ◽

Base Layer ◽

Hybrid Neural Network ◽

Element Modeling ◽

Layer Material

Download Full-text

Developing an Extended IFC Data Schema and Mesh Generation Framework for Finite Element Modeling

Advances in Civil Engineering ◽

10.1155/2019/1434093 ◽

2019 ◽

Vol 2019 ◽

pp. 1-19

Author(s):

Zhao Xu ◽

Zezhi Rao ◽

Vincent J. L. Gan ◽

Youliang Ding ◽

Chunfeng Wan ◽

...

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Finite Element Modeling ◽

Mesh Generation ◽

Geometric Model ◽

Information Modeling ◽

Element Analysis ◽

Element Modeling ◽

The Finite Element Analysis ◽

Ifc Standard

Mesh generation plays an important role in determining the result quality of finite element modeling and structural analysis. Building information modeling provides the geometry and semantic information of a building, which can be utilized to support an efficient mesh generation. In this paper, a method based on BRep entity transformation is proposed to realize the finite element analysis using the geometric model in the IFC standard. The h-p version of the finite element analysis method can effectively deal with the refined expression of the model of bending complex components. By meshing the connection model, it is suggested to adopt the method of scanning to generate hexahedron, which improves the geometric adaptability of the mesh model and the quality and efficiency of mesh generation. Based on the extension and expression of IFC information, the effective finite element structure information is extracted and extended into the IFC standard mode. The information is analyzed, and finally the visualization of finite element analysis in the building model can be realized.

Download Full-text

A Meta-Object Based Approach to Finite Element Modeling

Volume 2A: 27th Design Automation Conference ◽

10.1115/detc2001/dac-21062 ◽

2001 ◽

Author(s):

Santosh Shanbhag ◽

Ian R. Grosse ◽

Jack C. Wileden ◽

Alan Kaplan

Keyword(s):

Finite Element ◽

Finite Element Modeling ◽

Production Model ◽

Engineering Analysis ◽

Demand Model ◽

Element Analysis ◽

Modeling And Analysis ◽

Element Modeling ◽

Molded Part ◽

Analysis Models

Abstract With the integration of CAD and FEA software packages, design engineers who are not skilled in finite element analysis are performing finite element modeling and analysis. Furthermore, in the analysis of a system, engineers often make numerous modeling simplifications and analysis assumptions depending on the trade-off between cost, accuracy, precision or other engineering analysis objectives. Thus, reusability or interoperability of engineering analysis models is difficult and often impractical due to the wealth of knowledge involved in the creation of such models and the lack of formal methods to codify and explicitly represent this critical modeling knowledge. Most institutions and organizations have started documenting these simplifications and assumptions, making them understandable for the other engineers within the organization. However, this does not allow a seamless exchange of data or interoperability with other analysis models of similar or dissimilar nature. This plays a very important role in today’s market, which is moving away from the traditional make-to-stock production model to a build-to-demand model. We address these issues in this paper by adopting and extending the computer science concept of meta-object, and applying it in novel ways to the domain of FEA and the representation of finite element modeling knowledge. We present a taxonomy for engineering models that aids in the definition of the various object analysis classes. A simple beam analysis example, followed by a more realistic injection-molded part example. The latter example involves injection-mold filling simulation, thermal cooling, and part ejection analyses which are subclasses for a generic manufacturing analysis meta-object class. Prototype implementations of automated support for this meta-object approach to finite element modeling is in progress.

Download Full-text

Finite Element Modeling of Repair Cartilage Beneath a Protective Layer

Advances in Bioengineering ◽

10.1115/imece2003-42923 ◽

2003 ◽

Author(s):

John R. Owen ◽

Jennifer S. Wayne

Keyword(s):

Finite Element ◽

Material Properties ◽

Critical Role ◽

Axial Deformation ◽

Element Analysis ◽

Direction Parallel ◽

Preferred Direction ◽

Articulating Surface ◽

Line Direction

Significant efforts are being devoted to the creation of replacement tissue for repair of defects in articular surfaces. Some success has been realized; yet, the normal zonal characterstics of articular cartilage throughout its thickness and normal material properties have not been reproduced in vitro in scaffolds nor in vivo in repairing defects. The fate of such transplanted scaffolds in vivo may be doomed mechanically from the outset if material properties of sufficient quality are not developed. The superficial tangential zone (STZ) has been shown to play a critical role in supporting axial loads and retaining fluids (Glazer and Putz, 2002, Torzilli, et al, 1983, Torzilli, 1993). Previous models have demonstrated excessive axial deformation of repair cartilage without the STZ (Smith, et al 2001, Wayne, et al, 1991) Additionally, modeling the STZ of normal cartilage as transversely isotropic has yielded better agreement with indentation experimental results than isotropic models (Korhonen, et al, 2002, Mow, et al, 2000, Cohen, et al, 1993). This study uses finite element analysis to model the STZ with a preferred direction parallel to the articulating surface, thereby simulating a “split-line” direction. The in-plane directions are modeled normal to the “split-line” direction and the articulating surface. Normal and repairing defects are modeled with the importance of the STZ emphasized.

Download Full-text

Contact Stiffness Parameters for Finite Element Modeling of Contact

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.799.211 ◽

2019 ◽

Vol 799 ◽

pp. 211-216

Author(s):

Alina Sivitski ◽

Priit Põdra

Keyword(s):

Finite Element ◽

Finite Element Modeling ◽

Contact Stiffness ◽

Influential Factors ◽

Element Analysis ◽

Normal Contact ◽

Element Modeling ◽

Contact Models ◽

Machine Elements ◽

Normal Contact Pressure

Contact modeling could be widely used for different machine elements normal contact pressure calculations and wear simulations. However, classical contact models as for example Hertz contact models have many assumptions (contact bodies are elastic, the contact between bodies is ellipse-shaped, contact is frictionless and non-conforming). In conditions, when analytical calculations cannot be performed and experimental research is economically inexpedient, numerical methods have been applied for solving such engineering tasks. Contact stiffness parameters appear to be one of the most influential factors during finite element modeling of contact. Contact stiffness factors are usually selected according to finite element analysis software recommendations. More precise analysis of contact stiffness parameters is often required for finite element modeling of contact.

Download Full-text

Breast Tumor Diagnosis Using Finite‐Element Modeling Based on Clinical in vivo Elastographic Data

Journal of Ultrasound in Medicine ◽

10.1002/jum.15344 ◽

2020 ◽

Vol 39 (12) ◽

pp. 2351-2363

Author(s):

Ahmed M. Sayed ◽

Mohamed A. Naser ◽

Ashraf A. Wahba ◽

Mohamed A. A. Eldosoky

Keyword(s):

Finite Element ◽

Finite Element Modeling ◽

Breast Tumor ◽

Tumor Diagnosis ◽

Element Modeling

Download Full-text

Characterization of Maple and Ash Material Properties for the Finite Element Modeling of Wood Baseball Bats

Applied Sciences ◽

10.3390/app8112256 ◽

2018 ◽

Vol 8 (11) ◽

pp. 2256 ◽

Cited By ~ 5

Author(s):

Joshua Fortin-Smith ◽

James Sherwood ◽

Patrick Drane ◽

David Kretschmann

Keyword(s):

Finite Element ◽

Finite Element Modeling ◽

Material Properties ◽

Charpy Impact ◽

Impact Testing ◽

Charpy Test ◽

Ball Impact ◽

Element Modeling ◽

The Impact ◽

Baseball Bats

To assist in developing a database of wood material properties for the finite element modeling of wood baseball bats, Charpy impact testing at strain rates comparable to those that a wood bat experiences during a bat/ball collision is completed to characterize the failure energy and strain-to-failure as a function of density and slope-of-grain (SoG) for northern white ash (Fraxinus americana) and sugar maple (Acer saccharum). Un-notched Charpy test specimens made from billets of ash and maple that span the range of densities and SoGs that are approved for making professional baseball bats are impacted on either the edge grain or face grain. High-speed video is used to capture each test event and image analysis techniques are used to determine the strain-to-failure for each test. Strain-to-failure as a function of density relations are derived and these relations are used to calculate inputs to the *MAT_WOOD (Material Model 143) and *MAT_EROSION material options in LS-DYNA for the subsequent finite element modeling of the ash and maple Charpy Impact tests and for a maple bat/ball impact. The Charpy test data show that the strain-to-failure increases with increasing density for maple but the strain-to-failure remains essentially constant over the range of densities considered in this study for ash. The flat response of the ash data suggests that ash-bat durability is less sensitive to wood density than maple-bat durability. The available SoG results suggest that density has a greater effect on the impact failure properties of the wood than SoG. However, once the wood begins to fracture, SoG plays a large role in the direction of crack propagation of the wood, thereby determining if the shape of the pieces breaking away from the bat are fairly blunt or spear-like. The finite element modeling results for the Charpy and bat/ball impacts show good correlation with the experimental data.

Download Full-text