µCT/HR-pQCT Image Based Plate-Rod Microstructural Finite Element Model Efficiently Predicts the Elastic Moduli and Yield Strength of Human Trabecular Bone

2010 ◽  
Author(s):  
X. Sherry Liu ◽  
Aaron J. Fields ◽  
Tony M. Keaveny ◽  
Elizabeth Shane ◽  
X. Edward Guo
Keyword(s):  
Finite Element ◽  
Trabecular Bone ◽  
Shell Element ◽  
Element Model ◽  
Fe Model ◽  
Human Trabecular Bone ◽  
Age Related ◽  
The Individual ◽  
3D Volume

Osteoporosis is an age-related disease characterized by low bone mass and architectural deterioration, which affects primarily the trabecular sites and causes millions of fractures. High-resolution image voxel-based finite element (FE) models with the detailed 3D microstructure have been widely utilized to assess the mechanical properties of trabecular bone [1, 2]. However, the very large size of the voxel-based FE model, in general, limits its application to linear elastic cases. Despite the great potential it has shown in studying trabecular bone failure, iterative nonlinear analysis is still hard to be performed efficiently. Therefore, there is an apparent need for an alternative approach, which maintains the advantages of the voxel-based FE models in capturing details of trabecular microstructure, while allowing faster computation. Based on the individual trabeculae segmentation (ITS) technique [3], a specimen-specific plate-rod (P-R) microstructural FE model was developed by substituting the individual beam/shell element for 3D volume of trabecular plate/rod of μCT images of trabecular bone (21 μm resolution) (Fig. 1). The first goal of this study is to validate both linear and nonlinear predictions based on the P-R models for in vitro μCT images of human trabecular bone samples. The prediction accuracy and computational speed of the P-R model were examined by comparing with those of the voxel-based FE model.

Individual Trabecula Segmentation (ITS)-Based Plate-Rod Microstructural Finite Element Model Predicts Nonlinear Mechanical Properties of Human Trabecular Bone

2012 ◽  
Author(s):  
Bin Zhou ◽  
Ji Wang ◽  
Arnav Sanyal ◽  
Aaron J. Fields ◽  
Hong Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
High Resolution ◽  
Trabecular Bone ◽  
Element Model ◽  
Bone Fragility ◽  
Fe Model ◽  
Computationally Efficient ◽  
Human Trabecular Bone ◽  
Voxel Model

Osteoporosis is a major bone disease characterized by low bone mass and microarchitecture deterioration, which affects primarily trabecular sites and leads to increased bone fragility. Trabecular bone mechanical properties have direct relations with bone fragility. High-resolution image based-finite element (FE) models with the detailed 3D microstructure have been widely utilized to assess the mechanical properties of trabecular bone. Voxel-based FE model can be generated by converting individual voxels of high resolution bone images into 8-node brick elements. A number of studies have compared mechanical properties predicted by the voxel model with those by mechanical testing and have demonstrated that the voxel FE model can accurately predict the Young’s modulus and yield strength of human trabecular bone (1). However, the computational expense of the voxel-based technique, in general, limits its clinical applications, especially the nonlinear analysis for whole bone strength. Thus, it is not applicable to apply this technique to clinical use with the respect of current computer capability. There is apparent need for an alternative modeling approach that is more computationally efficient while preserving the accuracy of the predictions.

Finite Element Model for Investigation of Disc Degeneration Under Dynamic Loads

2008 ◽  
Author(s):  
Taek Hyun Jang ◽  
Stephen Ekwaro-Osire ◽  
J. Brian Gill ◽  
Javad Hashemi
Keyword(s):  
Finite Element ◽  
Cervical Spine ◽  
Disc Degeneration ◽  
Element Model ◽  
Fe Analysis ◽  
Dynamic Loads ◽  
Fe Model ◽  
Age Related ◽  
Biological Structures ◽  
Injury Analysis

Complex biological structures involve uncertain parameters that may produce unexpected responses in the structures. The cervical spine is one of the most complex structures in human body. It is essential to consider the uncertainties contained in the cervical spine for accurate injury analysis. For this research, a finite element (FE) model of cervical spine column is created based on medical images. The FE model involves the skull, the vertebral body (C1-T1), the disc between adjacent vertebral bodies, and the ligaments. The disc consists of the annulus, nucleus, and fiber. The material property and disc height are adjusted for the disc degeneration levels in FE analysis. The FE model is validated with the experimental data. Probabilistic FE analysis is used to account for uncertainties of cervical spine components. Material properties of the disc are considered as random variables, which are defined by means, standard deviations, and distributions. In this study, the probability of injury of the disc, under dynamic loading, is investigated at various disc degeneration levels under dynamic loads. The result shows that the probability of injury was drastically increased with the disc degeneration levels. Even if the disc fracture was not reported and the magnitude of stress was small in whiplash loading, the possibility of disc injuries is increased when a degenerated disc was exposed to whiplash loading. The results presented in this research make a contribution to the understanding of age-related whiplash injuries. The results also provide evidence that the reliability of biomechanical injury analysis is also increased by accounting for uncertain factors contained in biological structures.

Stepwise Validated Finite Element Model of the Human Lumbar Spine

2013 ◽  
Author(s):  
Dana Coombs ◽  
Michael Bushelow ◽  
Peter Laz ◽  
Milind Rao ◽  
Paul Rullkoetter
Keyword(s):  
Soft Tissues ◽  
Element Model ◽  
Intervertebral Discs ◽  
Lumbosacral Spine ◽  
Fe Model ◽  
Human Lumbar Spine ◽  
Spine Mechanics ◽  
Structural Configurations ◽  
The Individual

Understanding the kinematics of the lumbosacral spine and the individual functional spinal units (FSU) is essential in assessing spine mechanics and implant performance. The lumbosacral spine and the FSU are comprised of bones and complex soft tissues such as intervertebral discs (IVD) and ligaments. Prior studies have focused on the behavior of isolated structures, but the contribution of each structure to the overall kinematics of the spine needs to be further understood. In this study, the behavior of various structural conditions was determined by experimentally dissecting each ligament in a stepwise fasion until only the IVD remained, and applying loading conditions to the FSU. The FE model was validated through optimization to match the in vitro load-deflection characteristics and contact mechanics for the various structural configurations.

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

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.

Age-related changes in resorption cavity characteristics in human trabecular bone

1991 ◽  
Vol 1 (4) ◽  
pp. 257-261 ◽  
Author(s):  
P. I. Croucher ◽  
N. J. Garrahan ◽  
R. W. E. Mellish ◽  
Juliette E. Compston
Keyword(s):  
Trabecular Bone ◽  
Human Trabecular Bone ◽  
Age Related ◽  
Cavity Characteristics ◽  
Age Related Changes

Finite Element Model of Human Cochlea Considering of the Helicotrema Size

2013 ◽  
Vol 456 ◽  
pp. 576-581 ◽  
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.

Contrastive Study on Finite Element Models of High-Strength Pipelines Crossing Active Faults

2016 ◽  
Vol 850 ◽  
pp. 957-964
Author(s):  
Wei Zheng ◽  
Hong Zhang ◽  
Xiao Ben Liu ◽  
Le Cai Liang ◽  
Yin Shan Han
Keyword(s):  
Finite Element ◽  
Design Method ◽  
Active Faults ◽  
Shell Element ◽  
High Strength ◽  
Element Model ◽  
Beam Element ◽  
Finite Element Models ◽  
Fixed Boundary ◽  
Equivalent Boundary

There is a potential for major damage to the pipelines crossing faults, therefore the strain-based design method is essential for the design of buried pipelines. Finite element models based on soil springs which are able to accurately predict pipelines’ responses to such faulting are recommended by some international guidelines. In this paper, a comparative analysis was carried out among four widely used models (beam element model; shell element model with fixed boundary; shell element model with beam coupled; shell element model with equivalent boundary) in two aspects: differences of results and the efficiency of calculation. The results show that the maximum and minimum strains of models coincided with each other under allowable strain and the calculation efficiency of beam element model was the highest. Besides, the shell element model with beam coupled or equivalent boundary provided the reasonable results and the calculation efficiency of them were higher than the one with fixed boundary. In addition, shell element model with beam coupled had a broader applicability.

Finite Element Mesh Generator Applying Constraints’ Propagation and Isoparametric Mapping

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.

Biomechanical in Vitro and Finite Element Study On Different Sagittal Alignment Postures of the Lumbar Spine During Multiaxial Daily Motion

2021 ◽  
Author(s):  
Nadja Wilmanns ◽  
Agnes Beckmann ◽  
Luis Fernando Nicolini ◽  
Christian Herren ◽  
Rolf Sobottke ◽  
...  
Keyword(s):  
Finite Element ◽  
Lumbar Spine ◽  
Planning Process ◽  
Axial Rotation ◽  
Intervertebral Discs ◽  
Fe Model ◽  
Bending Moments ◽  
Sagittal Spinal Alignment ◽  
Biomechanical Response

Abstract Lumbar Lordotic correction (LLC), the gold standard treatment for Sagittal Spinal malalignment (SMA), and its effect on sagittal balance have been critically discussed in recent studies. This paper assesses the biomechanical response of the spinal components to LLC as an additional factor for the evaluation of LLC. Human lumbar spines (L2L5) were loaded with combined bending moments in Flexion (Flex)/Extension (Ex) or Lateral Bending (LatBend) and Axial Rotation (AxRot) in a physiological environment. We examined the dependency of AxRot range of motion (RoM) on the applied bending moment. The results were used to validate a Finite Element (FE) model of the lumbar spine. With this model, the biomechanical response of the intervertebral discs (IVD) and facet joints under daily motion was studied for different sagittal spinal alignment (SA) postures, simulated by a motion in Flex/Ex direction. Applied bending moments decreased AxRot RoM significantly (all P<0.001). A stronger decline of AxRot RoM for Ex than for Flex direction was observed (all P<0.0001). Our simulated results largely agreed with the experimental data (all R2>0.79). During daily motion, the IVD was loaded higher with increasing lumbar lordosis (LL) for all evaluated values at L2L3 and L3L4 and posterior Annulus Stress (AS) at L4L5 (all P<0.0476). The results of this study indicate that LLC with large extensions of LL may not always be advantageous regarding the biomechanical loading of the IVD. This finding may be used to improve the planning process of LLC treatments.

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