A finite element model of the human lower thorax to pelvis spinal segment: Validation and modal analysis

2021 ◽  
pp. 1-13
Author(s):  
Wei Fan ◽  
Dan Zhao ◽  
Li-Xin Guo
Keyword(s):  
Computed Tomography ◽  
Finite Element ◽  
Lumbar Spine ◽  
Resonant Frequency ◽  
Modal Analysis ◽  
Dynamic Characteristics ◽  
Upper Body ◽  
Fe Model ◽  
Spinal Segment ◽  
First Order

BACKGROUND: Several finite element (FE) models have been developed to study the effects of vibration on human lumbar spine. However, the authors know of no published results so far that have proposed computed tomography-based FE models of whole lumbar spine including the pelvis to conduct dynamic analysis. OBJECTIVE: To create and validate a three-dimensional ligamentous FE model of the human lower thorax to pelvis spinal segment (T12–Pelvis) and provide a detailed simulation environment to investigate the dynamic characteristics of the lumbar spine under whole body vibration (WBV). METHODS: The T12–Pelvis model was generated based on volume reconstruction from computed tomography scans and validated against the published experimental data. FE modal analysis was implemented to predict dynamic characteristics associated with the first-order vertical resonant frequency and vibration mode of the model with upper body mass of 40 kg under WBV. RESULTS: It was found that the current FE model was validated and corresponded closely with the published data. The obtained results from the modal analysis indicated that the first-order vertical resonant frequency of the T12–Pelvis model was 6.702 Hz, and the lumbar spine mainly performed vertical motion with a small anteroposterior motion. It was also found that shifting the upper body mass centroid onwards or rearwards from the normal upright sitting posture reduced the vertical resonant frequency. CONCLUSIONS: These findings may be helpful to better understand vibration response of the human spine, and provide important information to minimize injury and discomfort for these WBV-exposed occupational groups.

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.

The Effect of Trabecular Bone on the Mechanical Response of Human Mandible with Implant

2014 ◽  
Vol 695 ◽  
pp. 588-591
Author(s):  
Khairul Salleh Basaruddin ◽  
Ruslizam Daud
Keyword(s):  
Computed Tomography ◽  
Finite Element ◽  
Trabecular Bone ◽  
Static Analysis ◽  
Load Distribution ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Fe Model ◽  
Micro Computed Tomography ◽  
Bone Specimen

This study aims to investigate the influence of trabecular bone in human mandible bone on the mechanical response under implant load. Three dimensional voxel finite element (FE) model of mandible bone was reconstructed from micro-computed tomography (CT) images that were captured from bone specimen. Two FE models were developed where the first consists of cortical bone, trabecular bone and implants, and trabecular bone part was excluded in the second model. A static analysis was conducted on both models using commercial software Voxelcon. The results suggest that trabecular bone contributed to the strength of human mandible bone and to the effectiveness of load distribution under implant load.

scholarly journals Analysis and Testing of the Dynamic Characteristics of Rotor Worktable

2021 ◽  
Vol 2113 (1) ◽  
pp. 012061
Author(s):  
Jianmin Wang ◽  
Dong Liu ◽  
Yi Bian
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Dynamic Characteristics ◽  
Mesh Generation ◽  
Finite Element Modelling ◽  
Experimental Results ◽  
Element Modelling ◽  
Software Analysis ◽  
Finite Element Software ◽  
Research And Teaching

Abstract The finite element modelling, mesh generation and modal analysis of the rotor worktable are carried out by combining the analysis technology of finite element software in this paper. Then, the software analysis results and the actual experimental results are compared and analyzed, so as to get the causes of error, which can provide good basic data for the use of the rotor table in the future that could better meet the needs of scientific research and teaching.

A Biomechanical Model of Lumbar Spine

2000 ◽  
Author(s):  
Subramanya Uppala ◽  
Robert X. Gao ◽  
Scott Cowan ◽  
K. Francis Lee
Keyword(s):  
Finite Element ◽  
Lumbar Spine ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Biomechanical Model ◽  
Element Model ◽  
Fe Model ◽  
Flexion Extension ◽  
Cortical Shell ◽  
Three Dimensional Finite Element

Abstract The strength and stability of the lumbar spine are determined not only by the bone and muscles, but also by the visco-elastic structures and the interplay between the different components of the spine, such as ligaments, capsules, annulus fibrosis, and articular cartilage. In this paper we present a non-linear three-dimensional Finite Element model of the lumbar spine. Specifically, a three-dimensional FE model of the L4-5 one-motion segment/2 vertebrae was developed. The cortical shell and the cancellous bone of the vertebral body were modeled as 3D isoparametric eight-nodal elements. Finite element models of spinal injuries with fixation devices are also developed. The deformations across the different sections of the spine are observed under the application of axial compression, flexion/extension, and lateral bending. The developed FE models provided input to both the fixture design and experimental studies.

THE INFLUENCE OF BRAIN TISSUE MATERIAL PARAMETERS ON THE RESPONSE OF DYNAMIC CHARACTERISTICS BASED ON FINITE ELEMENT MODEL

2019 ◽  
Vol 19 (08) ◽  
pp. 1940058
Author(s):  
BIN YANG ◽  
HAO SUN ◽  
AIYUAN WANG ◽  
QUN WANG
Keyword(s):  
Finite Element ◽  
Head And Neck ◽  
Brain Tissue ◽  
Dynamic Characteristics ◽  
Human Head ◽  
Initial Parameter ◽  
Fe Model ◽  
Nasal Cartilage ◽  
Material Parameters ◽  
Tissue Material

Aiming at the uncertainty of material parameters of human brain tissue, the influence of tissue material performance sensitivity on frequency and mode shape under free vibration is studied. In this paper, the 50th percentile finite element (FE) model of human head and neck with detailed anatomical characteristics has been chosen as the research object, the parameters of skull, cerebrospinal fluid (CSF) and brain tissue materials with high sensitivity are analyzed by orthogonal test design and variance analysis. The results show that the natural frequencies of Group 7, Group 8 and Group 9 are all around 230[Formula: see text]Hz, which are basically consistent with the initial parameter of 229.18[Formula: see text]Hz, and the intracranial displacements of the three groups are also concentrated on the lateral nasal cartilage. The main reason is that the Young’s modulus of the skull used in three groups of experiments is 9780[Formula: see text]Mpa, which is close to the initial parameter of 8000[Formula: see text]Mpa. It indicates that the material parameter of the skull has the greatest influence on the dynamic characteristics of human head and neck, followed by the CSF and brain tissue. This study provides an effective method for vehicle safety and head and neck injury protection, and supplies a reference for FE analysis of head collision damage.

Development and Preliminary Validation of a 50th Percentile Pedestrian Finite Element Model

2015 ◽  
Author(s):  
Costin D. Untaroiu ◽  
Jacob B. Putnam ◽  
Jeremy Schap ◽  
Matt L. Davis ◽  
F. Scott Gayzik
Keyword(s):  
Finite Element ◽  
Lumbar Spine ◽  
Test Data ◽  
Element Model ◽  
Human Model ◽  
Whole Body ◽  
Fe Model ◽  
Pedestrian Protection ◽  
Bending Tests ◽  
Impact Tests

Pedestrians represent one of the most vulnerable road users and comprise nearly 22% of the road crash related fatalities in the world. Therefore, protection of pedestrians in the car-to-pedestrian collisions (CPC) has recently generated increased attention with regulations which involve three subsystem tests for adult pedestrian protection (leg, thigh and head impact tests). The development of a finite element (FE) pedestrian model could be a better alternative that characterizes the whole-body response of vehicle–pedestrian interactions and assesses the pedestrian injuries. The main goal of this study was to develop and to preliminarily validate a FE model corresponding to a 50th male pedestrian in standing posture. The FE model mesh and defined material properties are based on the Global Human Body Modeling (GHBMC) 50th percentile male occupant model. The lower limb-pelvis and lumbar spine regions of the human model were preliminarily validated against the post mortem human surrogate (PMHS) test data recorded in four-point lateral knee bending tests, pelvic impact tests, and lumbar spine bending tests. Then, pedestrian-to-vehicle impact simulations were performed using the whole pedestrian model and the results were compared to corresponding pedestrian PMHS tests. Overall, the preliminary simulation results showed that lower leg response is close to the upper boundaries of PMHS corridors. The pedestrian kinematics predicted by the model was also in the overall range of test data obtained with PMHS with various anthropometries. In addition, the model shows capability to predict the most common injuries observed in pedestrian accidents. Generally, the validated pedestrian model may be used by safety researchers in the design of front ends of new vehicles in order to increase pedestrian protection.

Simulation of Bus Ride Comfort under the Excitation of Road Irregularity

2012 ◽  
Vol 510 ◽  
pp. 249-254 ◽  
Author(s):  
Jin Feng ◽  
Yuan Hua Chen
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Ride Comfort ◽  
Temporal Frequency ◽  
Vertical Vibration ◽  
Fe Model ◽  
Analysis Method ◽  
The Road ◽  
Power Spectral ◽  
Bus Structure

Bus vibration is studied by the finite element method (FEM) base on bus structure model. The bus mathematical model of vertical vibration is established and the vibration response variables were deduced with the modal analysis method. The finite element (FE) model is established and decoupled. The transformational relation between spatial frequency displacement power spectral density (PSD) and temporal frequency displacement PSD and the sampling characteristics of the road irregularity PSD in numerical computation are discussed. Road irregularity load is modeled in software. The FE model is solved using modal analysis method and the acceleration PSD of each keypoint can be gained. Finally, a road test experiment is carried on to verify the simulation results. The example indicated that study on vehicle ride comford by FEM has instructive meaning.

Investigation of Vibration Characteristics of the Ligamentous Lumbar Spine Using the Finite Element Approach

1994 ◽  
Vol 116 (4) ◽  
pp. 377-383 ◽  
Author(s):  
Vijay K. Goel ◽  
Hosang Park ◽  
Weizeng Kong
Keyword(s):  
Finite Element ◽  
Resonant Frequency ◽  
Cyclic Load ◽  
Static Load ◽  
Three Dimensional ◽  
Element Model ◽  
Upper Body ◽  
Experimental Investigations ◽  
Flexion Extension

A nonlinear, three-dimensional finite element model of the ligamentous L4-SI segment was developed to analyze the dynamic response of the spine in the absence of damping. The effects of the upper body mass were simulated by including a mass of 40 kg on the L4 vertebral body. The modal analyses of the model indicated a resonant frequency of 17.5 Hz in axial mode and 3.8 Hz in flexion-extension mode. Accordingly, the predicted responses for the cyclic load of −400 ± 40 N applied at four different frequencies (5, 11, 16.5, and 25 Hz) were compared with the corresponding results for axial compressive static loads (−360, and −440 N). As compared to the static load cases, the predicted responses were higher for the cyclic loading. For example, the effect of cyclic load at 11 Hz was to produce significant changes (9.7 – 19.0 percent) in stresses, loads transmitted through the facets, intradiscal pressure (IDP), disk bulge, as compared to the static load predictions. The responses were found to be frequency dependent as well; supporting the in vivo observations of other investigators that the human spine has a resonant frequency. For example, the 11 Hz model (DYN11) compared to the DYN5 model showed an increase in majority of the predicted parameters. The parameters showed an increase with frequency until 17.5 Hz (resonant frequency of the model); thereafter a decrease at 25 Hz. A chronic change in these parameters, especially at the resonant frequency, beyond the “base” values may trigger the bone remodeling process leading to spinal degeneration/disorders associated with chronic vibration exposure. Future directions for extending the present model as a complement to the experimental investigations are also discussed.

A three-dimensional finite element model from computed tomography data: A semi-automated method

2001 ◽  
Vol 215 (2) ◽  
pp. 203-212 ◽  
Author(s):  
P M Cattaneo ◽  
M Dalstra ◽  
L H Frich
Keyword(s):  
Computed Tomography ◽  
Finite Element ◽  
Three Dimensional ◽  
Patient Specific ◽  
Fe Model ◽  
Element Analysis ◽  
Automated Method ◽  
Bone Properties ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Three-dimensional finite element analysis is one of the best ways to assess stress and strain distributions in complex bone structures. However, accuracy in the results may be achieved only when accurate input information is given. A semi-automated method to generate a finite element (FE) model using data retrieved from computed tomography (CT) was developed. Due to its complex and irregular shape, the glenoid part of a left embalmed scapula bone was chosen as working material. CT data were retrieved using a standard clinical CT scanner (Siemens Somatom Plus 2, Siemens AG, Germany). This was done to produce a method that could later be utilized to generate a patient-specific FE model. Different methods of converting Hounsfield unit (HU) values to apparent densities and subsequently to Young's moduli were tested. All the models obtained were loaded using three-dimensional loading conditions taken from literature, corresponding to an arm abduction of 90°. Additional models with different amounts of elements were generated to verify convergence. Direct comparison between the models showed that the best method to convert HU values directly to apparent densities was to use different equations for cancellous and cortical bone. In this study, a reliable method of determining both geometrical data and bone properties from patient CT scans for the semi-automated generation of an FE model is presented.

Output-Only Modal Analysis of an Internal Unreachable Module Embedded in a Space Electronic Equipment

2012 ◽  
Author(s):  
Lassaad Ben Fekih ◽  
Georges Kouroussis ◽  
David Wattiaux ◽  
Olivier Verlinden ◽  
Christophe De Fruytier
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Degrees Of Freedom ◽  
Transverse Direction ◽  
Mode Shapes ◽  
Fe Model ◽  
Fe Method ◽  
Numeric Model ◽  
Stiffness Matrices ◽  
Output Only

An approach is proposed to identify the modal properties of a subsystem made up of an arbitrary chosen inner module of embedded space equipment. An experimental modal analysis was carried out along the equipment transverse direction with references taken onto its outer housing. In parallel, a numerical model using the finite element (FE) method was developed to correlate with the measured results. A static Guyan reduction has led to a set of master degrees of freedom in which the experimental mode shapes were expanded. An updating technique consisting in minimizing the dynamic residual induced by the FE model and the measurements has been investigated. A last verification has consisted in solving the numeric model composed of the new mass and stiffness matrices obtained by means of a minimization of the error in the constitutive equation method.

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