Automated Segmentation of Swine Skulls for Finite Element Model Creation Using High Resolution μ-CT Images

Finite element (FE) analysis has been widely used to investigate bone responses to mechanical loading. Research in long bones has been straight forward because modeling of these bones requires only two material properties. Such an FE model may provide an adequate approximation of the anatomy for many cases. However, a more detailed model of skull bones is needed to accurately capture its complex structure of multiple bone pieces and the various mineral densities distributed throughout these bone pieces. Unfortunately, FE model development incorporating both complex geometries and anatomically accurate material properties is both computationally and labor intensive. In this study, a method is proposed to automatically segment micro-computed tomography ([Formula: see text]-CT) scan images of bone pieces to build an FE model of a full swine hemi-skull. Using the Digital Imaging and Communications in Medicine (DICOM) files from scanned bones, the complete geometry of each bone piece is recreated through seven customized processing algorithms. After assembling the bone pieces to form the skull, experimentally derived Young’s modulus values are correlated to grayscale values to produce a detailed FE model for accurate simulation. This detailed skull model can be used to predict strain/stress patterns in response to various loading regimes to facilitate research questions in fracture healing and growth, as well as bone tissue engineering and bone mineral density loss (e.g., osteoporosis).

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The Biomechanics of Human Femurs in Axial and Torsional Loading: Comparison of Finite Element Analysis, Human Cadaveric Femurs, and Synthetic Femurs

Journal of Biomechanical Engineering ◽

10.1115/1.2401178 ◽

2006 ◽

Vol 129 (1) ◽

pp. 12-19 ◽

Cited By ~ 114

Author(s):

M. Papini ◽

R. Zdero ◽

E. H. Schemitsch ◽

P. Zalzal

Keyword(s):

Finite Element ◽

Bone Quality ◽

Material Properties ◽

Element Model ◽

Torsional Stiffness ◽

Fe Model ◽

Bone Stock ◽

Torsional Loading ◽

Input Material ◽

Geometric Size

To assess the performance of femoral orthopedic implants, they are often attached to cadaveric femurs, and biomechanical testing is performed. To identify areas of high stress, stress shielding, and to facilitate implant redesign, these tests are often accompanied by finite element (FE) models of the bone/implant system. However, cadaveric bone suffers from wide specimen to specimen variability both in terms of bone geometry and mechanical properties, making it virtually impossible for experimental results to be reproduced. An alternative approach is to utilize synthetic femurs of standardized geometry, having material behavior approximating that of human bone, but with very small specimen to specimen variability. This approach allows for repeatable experimental results and a standard geometry for use in accompanying FE models. While the synthetic bones appear to be of appropriate geometry to simulate bone mechanical behavior, it has not, however, been established what bone quality they most resemble, i.e., osteoporotic or osteopenic versus healthy bone. Furthermore, it is also of interest to determine whether FE models of synthetic bones, with appropriate adjustments in input material properties or geometric size, could be used to simulate the mechanical behavior of a wider range of bone quality and size. To shed light on these questions, the axial and torsional stiffness of cadaveric femurs were compared to those measured on synthetic femurs. A FE model, previously validated by the authors to represent the geometry of a synthetic femur, was then used with a range of input material properties and change in geometric size, to establish whether cadaveric results could be simulated. Axial and torsional stiffnesses and rigidities were measured for 25 human cadaveric femurs (simulating poor bone stock) and three synthetic “third generation composite” femurs (3GCF) (simulating normal healthy bone stock) in the midstance orientation. The measured results were compared, under identical loading conditions, to those predicted by a previously validated three-dimensional finite element model of the 3GCF at a variety of Young’s modulus values. A smaller FE model of the 3GCF was also created to examine the effects of a simple change in bone size. The 3GCF was found to be significantly stiffer (2.3 times in torsional loading, 1.7 times in axial loading) than the presently utilized cadaveric samples. Nevertheless, the FE model was able to successfully simulate both the behavior of the 3GCF, and a wide range of cadaveric bone data scatter by an appropriate adjustment of Young’s modulus or geometric size. The synthetic femur had a significantly higher stiffness than the cadaveric bone samples. The finite element model provided a good estimate of upper and lower bounds for the axial and torsional stiffness of human femurs because it was effective at reproducing the geometric properties of a femur. Cadaveric bone experiments can be used to calibrate FE models’ input material properties so that bones of varying quality can be simulated.

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A detailed finite element model of a mid-sized male for the investigation of traffic pedestrian accidents

Proceedings of the Institution of Mechanical Engineers Part H Journal of Engineering in Medicine ◽

10.1177/0954411920976223 ◽

2020 ◽

pp. 095441192097622

Author(s):

Daniel Grindle ◽

Wansoo Pak ◽

Berkan Guleyupoglu ◽

Bharath Koya ◽

F Scott Gayzik ◽

...

Keyword(s):

Finite Element ◽

Test Data ◽

Element Model ◽

Upper Body ◽

Whole Body ◽

Fe Model ◽

Automotive Safety ◽

Detailed Model ◽

Body Regions ◽

Safety Research

The pedestrian is one of the most vulnerable road users and comprises approximately 23% of the road crash-related fatalities in the world. To protect pedestrians during Car-to-Pedestrian Collisions (CPC), subsystem impact tests are used in regulations. These tests provide insight but cannot characterize the complex vehicle-pedestrian interaction. The main purpose of this study was to develop and validate a detailed pedestrian Finite Element (FE) model corresponding to a 50th percentile male to predict CPC induced injuries. The model geometry was reconstructed using a multi-modality protocol from medical images and exterior scan data corresponding to a mid-sized male volunteer. To investigate injury response, this model included internal organs, muscles and vessels. The lower extremity, shoulder and upper body of the model were validated against Post Mortem Human Surrogate (PMHS) test data in valgus bending, and lateral/anterior-lateral blunt impacts, respectively. The whole-body pedestrian model was validated in CPC simulations using a mid-sized sedan and simplified generic vehicles bucks and previously unpublished PMHS coronal knee angle data. In the component validations, the responses of the FE model were mostly within PMHS test corridors and in whole body validations the kinematic and injury responses predicted by the model showed similar trends to PMHS test data. Overall, the detailed model showed higher biofidelity, especially in the upper body regions, compared to a previously reported simplified pedestrian model, which recommends using it in future pedestrian automotive safety research.

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Representation of bolted joints in a structure using finite element modelling and model updating

JOURNAL OF MECHANICAL ENGINEERING AND SCIENCES ◽

10.15282/jmes.14.3.2020.15.0560 ◽

2020 ◽

Vol 14 (3) ◽

pp. 7141-7151 ◽

Cited By ~ 1

Author(s):

R. Omar ◽

M. N. Abdul Rani ◽

M. A. Yunus

Keyword(s):

Finite Element ◽

Dynamic Behaviour ◽

Model Updating ◽

Complex Structure ◽

Bolted Joints ◽

Model Parameters ◽

Fe Model ◽

Bolted Joint ◽

Fe Modelling ◽

Joint Structure

Efficient and accurate finite element (FE) modelling of bolted joints is essential for increasing confidence in the investigation of structural vibrations. However, modelling of bolted joints for the investigation is often found to be very challenging. This paper proposes an appropriate FE representation of bolted joints for the prediction of the dynamic behaviour of a bolted joint structure. Two different FE models of the bolted joint structure with two different FE element connectors, which are CBEAM and CBUSH, representing the bolted joints are developed. Modal updating is used to correlate the two FE models with the experimental model. The dynamic behaviour of the two FE models is compared with experimental modal analysis to evaluate and determine the most appropriate FE model of the bolted joint structure. The comparison reveals that the CBUSH element connectors based FE model has a greater capability in representing the bolted joints with 86 percent accuracy and greater efficiency in updating the model parameters. The proposed modelling technique will be useful in the modelling of a complex structure with a large number of bolted joints.

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Finite Element Analysis of the Distributed Vibration Absorbers for Structural Noise Control

Noise Control and Acoustics ◽

10.1115/imece2005-82798 ◽

2005 ◽

Author(s):

Ashwini Gautam ◽

Chris Fuller ◽

James Carneal

Keyword(s):

Finite Element ◽

Numerical Model ◽

Base Plate ◽

Element Model ◽

Fe Model ◽

Vibration Absorbers ◽

Element Analysis ◽

Poroelastic Media ◽

Hexahedral Elements ◽

Component Models

This work presents an extensive analysis of the properties of distributed vibration absorbers (DVAs) and their effectiveness in controlling the sound radiation from the base structure. The DVA acts as a distributed mass absorber consisting of a thin metal sheet covering a layer of acoustic foam (porous media) that behaves like a distributed spring-mass-damper system. To assess the effectiveness of these DVAs in controlling the vibration of the base structures (plate) a detailed finite elements model has been developed for the DVA and base plate structure. The foam was modeled as a poroelastic media using 8 node hexahedral elements. The structural (plate) domain was modeled using 16 degree of freedom plate elements. Each of the finite element models have been validated by comparing the numerical results with the available analytical and experimental results. These component models were combined to model the DVA. Preliminary experiments conducted on the DVAs have shown an excellent agreement between the results obtained from the numerical model of the DVA and from the experiments. The component models and the DVA model were then combined into a larger FE model comprised of a base plate with the DVA treatment on its surface. The results from the simulation of this numerical model have shown that there has been a significant reduction in the vibration levels of the base plate due to DVA treatment on it. It has been shown from this work that the inclusion of the DVAs on the base plate reduces their vibration response and therefore the radiated noise. Moreover, the detailed development of the finite element model for the foam has provided us with the capability to analyze the physics behind the behavior of the distributed vibration absorbers (DVAs) and to develop more optimized designs for the same.

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Finite Element Model of Human Cochlea Considering of the Helicotrema Size

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.456.576 ◽

2013 ◽

Vol 456 ◽

pp. 576-581 ◽

Cited By ~ 1

Author(s):

Li Fu Xu ◽

Na Ta ◽

Zhu Shi Rao ◽

Jia Bin Tian

Keyword(s):

Finite Element ◽

Finite Element Model ◽

Basilar Membrane ◽

Round Window ◽

Element Model ◽

Oval Window ◽

Fe Model ◽

Cochlear Duct ◽

Human Cochlea ◽

Set Up

A 2-D finite element model of human cochlea is established in this paper. This model includes the structure of oval window, round window, basilar membrane and cochlear duct which is filled with fluid. The basilar membrane responses are calculated with sound input on the oval window membrane. In order to study the effects of helicotrema on basilar membrane response, three different helicotrema dimensions are set up in the FE model. A two-way fluid-structure interaction numerical method is used to compute the responses in the cochlea. The influence of the helicotrema is acquired and the frequency selectivity of the basilar membrane motion along the cochlear duct is predicted. These results agree with the experiments and indicate much better results are obtained with appropriate helicotrema size.

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Finite-element model development of a uniformly loaded simply supported beam using strain energy density criterion

Computers & Structures ◽

10.1016/0045-7949(86)90018-0 ◽

1986 ◽

Vol 22 (4) ◽

pp. 659-663

Author(s):

A.H. Patel ◽

R. Ali

Keyword(s):

Finite Element ◽

Energy Density ◽

Finite Element Model ◽

Strain Energy Density ◽

Strain Energy ◽

Model Development ◽

Element Model ◽

Simply Supported Beam ◽

Simply Supported

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Finite Element Mesh Generator Applying Constraints’ Propagation and Isoparametric Mapping

ASME 1991 Computers in Engineering Conference: Volume 2 — Finite Elements/Computational Geometry; Computers in Education; Robotics and Controls ◽

10.1115/cie1991-0122 ◽

1991 ◽

Author(s):

J. Rodriguez ◽

M. Him

Keyword(s):

Finite Element ◽

Mesh Generation ◽

Element Model ◽

Finite Element Mesh ◽

Fe Model ◽

Element Analysis ◽

Element Mesh ◽

Mesh Generator ◽

Generation Algorithm ◽

Essential Input

Abstract This paper presents a finite element mesh generation algorithm (PREPAT) designed to automatically discretize two-dimensional domains. The mesh generation algorithm is a mapping scheme which creates a uniform isoparametric FE model based on a pre-partitioned domain of the component. The proposed algorithm provides a faster and more accurate tool in the pre-processing phase of a Finite Element Analysis (FEA). A primary goal of the developed mesh generator is to create a finite element model requiring only essential input from the analyst. As a result, the generator code utilizes only a sketch, based on geometric primitives, and information relating to loading/boundary conditions. These conditions represents the constraints that are propagated throughout the model and the available finite elements are uniformly mapped in the resulting sub-domains. Relative advantages and limitations of the mesh generator are discussed. Examples are presented to illustrate the accuracy, efficiency and applicability of PREPAT.

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FEBio finite element model of a pediatric cervical spine

Journal of Neurosurgery Pediatrics ◽

10.3171/2021.7.peds21276 ◽

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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Age Dependent and Anisotropic Material Properties of Immature Porcine Sclera

Volume 1A: Abdominal Aortic Aneurysms; Active and Reactive Soft Matter; Atherosclerosis; BioFluid Mechanics; Education; Biotransport Phenomena; Bone, Joint and Spine Mechanics; Brain Injury; Cardiac Mechanics; Cardiovascular Devices, Fluids and Imaging; Cartilage and Disc Mechanics; Cell and Tissue Engineering; Cerebral Aneurysms; Computational Biofluid Dynamics; Device Design, Human Dynamics, and Rehabilitation; Drug Delivery and Disease Treatment; Engineered Cellular Environments ◽

10.1115/sbc2013-14679 ◽

2013 ◽

Cited By ~ 1

Author(s):

Jami M. Saffioti ◽

Brittany Coats

Keyword(s):

Finite Element ◽

Material Properties ◽

Anisotropic Material ◽

Computational Models ◽

Fe Model ◽

Ocular Tissues ◽

Load Bearing ◽

Anisotropic Properties ◽

Age Dependent ◽

Testing Protocols

Current finite element (FE) models of the pediatric eye are based on adult material properties [2,3]. To date, there are no data characterizing the age dependent material properties of ocular tissues. The sclera is a major load bearing tissue and an essential component to most computational models of the eye. In preparation for the development of a pediatric FE model, age-dependent and anisotropic properties of sclera were evaluated in newborn (3–5 days) and toddler (4 weeks) pigs. Data from this study will guide future testing protocols for human pediatric specimens.

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