scholarly journals A Finite Element Study of the Dynamic Response of Brain Based on Two Parasagittal Slice Models

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
Xuewei Song ◽  
Cong Wang ◽  
Hao Hu ◽  
Tianlun Huang ◽  
Jingxu Jin
Keyword(s):  
Finite Element ◽  
Relevant Literature ◽  
Equivalent Stress ◽  
Human Head ◽  
Stress And Strain ◽  
The Maximum Principle ◽  
Simulation Results ◽  
Gray Matters ◽  
Evident Difference ◽  
Different Parts

The objective of this study is to investigate the influence of gyri and sulci on the response of human head under transient loading. To this end, two detailed parasagittal slice models with and without gyri and sulci have been developed. The models comprised not only cerebrum and skull but also cerebellum, brain stem, CSF, and corpus callosum. In addition, white and gray matters were separated. The material properties were adopted from the literature and assigned to different parts of the models. Nahum’s and Trosseille’s experiments reported in relevant literature were simulated and the simulation results were compared with the test data. The results show that there is no evident difference in terms of intracranial pressure between the models with and without gyri and sulci under simulated conditions. The equivalent stress below gyri and sulci in the model with gyri and sulci is slightly higher than that in the counterpart model without gyri and sulci. The maximum principle strain in brain tissue is lower in the model with gyri and sulci. The stress and strain distributions are changed due to the existence of gyri and sulci. These findings highlight the necessity to include gyri and sulci in the finite element head modeling.

scholarly journals A Three-Dimensional Finite-Element Model of a Human Dry Skull for Bone-Conduction Hearing

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Namkeun Kim ◽  
You Chang ◽  
Stefan Stenfelt
Keyword(s):  
Finite Element ◽  
Bone Conduction ◽  
Three Dimensional ◽  
Human Head ◽  
Element Model ◽  
Fe Model ◽  
Lateral Direction ◽  
Dimensional Finite Element ◽  
Simulation Results ◽  
Three Dimensional Finite Element

A three-dimensional finite-element (FE) model of a human dry skull was devised for simulation of human bone-conduction (BC) hearing. Although a dry skull is a simplification of the real complex human skull, such model is valuable for understanding basic BC hearing processes. For validation of the model, the mechanical point impedance of the skull as well as the acceleration of the ipsilateral and contralateral cochlear bone was computed and compared to experimental results. Simulation results showed reasonable consistency between the mechanical point impedance and the experimental measurements when Young’s modulus for skull and polyurethane was set to be 7.3 GPa and 1 MPa with 0.01 and 0.1 loss factors at 1 kHz, respectively. Moreover, the acceleration in the medial-lateral direction showed the best correspondence with the published experimental data, whereas the acceleration in the inferior-superior direction showed the largest discrepancy. However, the results were reasonable considering that different geometries were used for the 3D FE skull and the skull used in the published experimental study. The dry skull model is a first step for understanding BC hearing mechanism in a human head and simulation results can be used to predict vibration pattern of the bone surrounding the middle and inner ear during BC stimulation.

Three-Dimensional Nonlinear Contact Finite Element Analysis of Mandibular All-on-4 Design

2015 ◽  
Vol 41 (2) ◽  
pp. e12-e18 ◽  
Author(s):  
Mostafa Omran Hussein ◽  
Mahmoud Elsayed Rabie
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Equivalent Stress ◽  
Stress And Strain ◽  
Element Analysis ◽  
Implant Position ◽  
Finite Element Software ◽  
Edentulous Mandible ◽  
Nonlinear Contact ◽  
Position And Orientation

The All-on-4 design was used successfully for restoring edentulous mandible. This design avoids anatomic cripples such as inferior alveolar nerve by tilting posterior implants. Moreover, tilting posterior implants of All-on-4 design had a mechanical preference than the conventional design. On the other hand, the anterior implants are parallel at the lateral incisor region. Several researches showed favorable results for tilting posterior implants. However, research did not study the influence of the anterior implant position or orientation on the mechanical aspects of this design. This study analyzes the influence of varying anterior implant position and orientation of the All-on-4 design using nonlinear contact 3D finite-element analysis. Three copied 3-dimensional models of the All-on-4 design were classified according to anterior implant position and orientation. The frictional contact between fixtures and bone was the contact type in this finite element analysis. Finally, von Mises stress and strain at implant and bone levels were recorded and analyzed using finite element software. Stress concentrations were detected mainly around the posterior implant at the loaded side. Values of the maximum equivalent stress and strain were around tilted implants of design III followed by design II, then design I. Changing the position or orientation of the anterior implants in All-on-4 design influences stress-strain distribution of the whole design.

The Stress Laws of H-Beam Rolling Deformation during Rectangular Billet Cogging-Down

2013 ◽  
Vol 631-632 ◽  
pp. 632-636
Author(s):  
Lin Chen ◽  
Guo Chang ◽  
Shu Qin Liu ◽  
Ke Xin Bi
Keyword(s):  
Finite Element ◽  
Compression Ratio ◽  
Equivalent Stress ◽  
Stress Variation ◽  
Finite Element Software ◽  
Performance Requirements ◽  
Simulation Results ◽  
H Beam ◽  
And Performance ◽  
Rolling Deformation

In order to ensure H-beam’s organization and performance requirements, there is a certain compression ratio from the rolling of the billet to the finished product. This paper select rectangular billets and use DEFORM finite element software to simulate and analyze the rules of stress variation when rectangular billet is cogged down. The simulation results show that: from rectangular billet to finished product, the compression ratio is 17.4 and after cogging, billet size meet the requirements of the CCS rolling. The equivalent stress of breakdown rolling is mainly concentrated in the waist or in the junction of waist and legs. In the first few pass，equivalent stress is mainly concentrated in Sharp-angled position of both top and bottom, however the next few pass’s equivalent stress is mainly concentrated in the junction of web Plate and flange.

scholarly journals Deformation Investigations on the Flexspline with the Conic Curve Combined Cam Wave Generator

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Shuyan Wang ◽  
Dongxiang Guo ◽  
Shiteng Mao
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Equivalent Stress ◽  
Mathematic Model ◽  
Transmission Efficiency ◽  
Experimental Results ◽  
Stress And Strain ◽  
Element Analysis ◽  
Wave Generator ◽  
Maximum Equivalent Stress

The deformation of the flexspline and the meshing quality are largely determined by the profile of a wave generator. The wave generator with a combined profile can effectively reduce or improve the deformation stress and strain of the flexspline for improving the transmission efficiency and reducing wear or noise. In this paper, in view of the facts that conic is originally cut out of the cone and different conic curves are easy to transform, a design concept of the curve cam wave generator based on the conic curve is proposed. Firstly, the combined principle, constraint conditions, and mathematic model of the curve cam generator based on the conic curve are established. Secondly, the deformation theory of the flexspline acted by the curve cam wave generator with conic curves has been developed, and finite element analysis on stress and strain of the flexspline compared with a standard elliptic wave generator has been carried out. Finally, a cam wave generator combined with the circle and ellipse as a sample has been developed and manufactured. Circumferential strain test has been further carried out by a static strain gauge to verify the strain characteristics of the flexspline acted with the circle and ellipse combined cam wave generator. The FEM results show that, in the meshing area of the flexspline, the maximum equivalent stress of the flexspline under the action of the arc and the ellipse wave generator is about 93 MPa, which is 36.3% lower than the maximum equivalent stress of the flexspline under the action of the standard ellipse which is 143 MPa. The experimental results show that the fitting curve of the experimental results fits well with the finite element analysis curve.

scholarly journals Influence of Trabecular Bone on Peri-Implant Stress and Strain Based on Micro-CT Finite Element Modeling of Beagle Dog

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Sheng-hui Liao ◽  
Xing-hao Zhu ◽  
Jing Xie ◽  
Vikesh Kumar Sohodeb ◽  
Xi Ding
Keyword(s):  
Finite Element ◽  
Trabecular Bone ◽  
Equivalent Stress ◽  
Three Dimensional ◽  
Simplified Model ◽  
Stress And Strain ◽  
Refined Model ◽  
Bone Interface ◽  
Trabecular Microstructure ◽  
Trabecular Bone Microstructure

The objective of this investigation is to analyze the influence of trabecular microstructure modeling on the biomechanical distribution of the implant-bone interface. Two three-dimensional finite element mandible models, one with trabecular microstructure (a refined model) and one with macrostructure (a simplified model), were built. The values of equivalent stress at the implant-bone interface in the refined model increased compared with those of the simplified model and strain on the contrary. The distributions of stress and strain were more uniform in the refined model of trabecular microstructure, in which stress and strain were mainly concentrated in trabecular bone. It was concluded that simulation of trabecular bone microstructure had a significant effect on the distribution of stress and strain at the implant-bone interface. These results suggest that trabecular structures could disperse stress and strain and serve as load buffers.

Lightweight Design of the Truck Side Framework

2012 ◽  
Vol 236-237 ◽  
pp. 209-212
Author(s):  
Jun Li ◽  
Ying Xiang Teng
Keyword(s):  
Finite Element ◽  
Lightweight Design ◽  
Equivalent Stress ◽  
Side Wall ◽  
Stress And Strain ◽  
State Variables ◽  
The Finite Element Method ◽  
Analysis Software ◽  
Element Analysis ◽  
Design Variables

For the vehicle, lightweight means low fuel consumption. and small quantity of exhausted gas. In this paper by using the finite element method, the author established the model of the truck side framework. After meshing, exerting constraint, loading and calculating through finite element analysis software,the author obtained the deformation of the component. By researching changes of the stress and strain in X, Y, Z three directions of the component,the author obtained chart of the stress and strain. By using the method of arithmetic, the author defined the internal dimension as design variables, the equivalent stress and the deformation as the state variables, and quality as the objective function to get the lightest side wall frame of the vehicle on the premise of warranty of the intensity and stiffness.From the result, we can see the framework after optimal design is still very strong to resist the stress and the deformation.

Finite Element Analysis of Laminating Press Frame

2011 ◽  
Vol 201-203 ◽  
pp. 44-48
Author(s):  
Xin Zhou Zhang ◽  
Shang Bin Wang ◽  
Kai Wu ◽  
Yu Sun
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Boundary Conditions ◽  
Structural Characteristics ◽  
Complex Structure ◽  
Element Model ◽  
Stress And Strain ◽  
Element Analysis ◽  
Frame Design ◽  
Different Parts

The structural characteristics of a laminating press were analyzed, and the corresponding finite element model was built with some essential simplification. By structural analysis, the distributions of stress and strain were obtained, based on which the rationality of the frame design can be verified. According to the complex structure and loading conditions of the laminating press, four analytical schemes with different models and boundary conditions were adopted, then the results of different analytical schemes were compared, and the causes resulting in the calculation differences were analyzed. The result shows that in analyzing different parts of the laminating press frame, different models and boundary conditions were required.

Effect of Stress State on Mode II Stable Crack Extension

2005 ◽  
Vol 297-300 ◽  
pp. 1604-1610 ◽  
Author(s):  
Abdel-Hamid I. Mourad
Keyword(s):  
Finite Element ◽  
Fracture Surface ◽  
Crack Extension ◽  
Equivalent Stress ◽  
Experimental Results ◽  
Mode Ii ◽  
Stress And Strain ◽  
Resistance Curve ◽  
Plane State ◽  
State Of Stress

The effect of assumption of plane state of stress on the predictability of experimental results observed during the mode II stable crack growth (SCG) through 8 mm thick compact tension specimens (CTS) of a workhardening aluminum alloy (D16AT) has been studied. Experimental results include load-sliding displacement diagram, extent of SCG, crack front geometry and fracture surface fractographs. The experimental results show that the crack extends in its own plane, the fracture surface is flat, smooth and free of any shear lip. The crack front geometry, which is straight initially, remains mostly so throughout the SCG. Theoretical investigations have been done using an elastic-plastic finite element scheme and the COA/COD criterion as the criterion governing the growth. Finite element results, assuming plane stress and plane strain conditions separately, on the load-sliding displacement diagrams, J-resistance curve, plastic zones and variation of equivalent stress and strain along the crack-line ahead of the crack tip are also presented. The resistance curve is a straight-line and the magnitudes of equivalent stress and strain increases as the crack extension proceeds. In general, the predictions based on the assumption of plane state of stress are closer to the experimental results.

A Biomechanical and Finite Element Analysis of Femoral Neck Notching During Hip Resurfacing

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Edward T. Davis ◽  
Michael Olsen ◽  
Rad Zdero ◽  
Marcello Papini ◽  
James P. Waddell ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Femoral Neck ◽  
Finite Element Model ◽  
Proximal Femur ◽  
Equivalent Stress ◽  
Element Model ◽  
Hip Resurfacing ◽  
Stress And Strain ◽  
Element Analysis

Hip resurfacing is an alternative to total hip arthroplasty in which the femoral head surface is replaced with a metallic shell, thus preserving most of the proximal femoral bone stock. Accidental notching of the femoral neck during the procedure may predispose it to fracture. We examined the effect of neck notching on the strength of the proximal femur. Six composite femurs were prepared without a superior femoral neck notch, six were prepared in an inferiorly translated position to create a 2 mm notch, and six were prepared with a 5 mm notch. Six intact synthetic femurs were also tested. The samples were loaded to failure axially. A finite element model of a composite femur with increasing superior notch depths computed maximum equivalent stress and strain distributions. Experimental results showed that resurfaced synthetic femurs were significantly weaker than intact femurs (mean failure of 7034 N, p<0.001). The 2 mm notched group (mean failure of 4034 N) was significantly weaker than the un-notched group (mean failure of 5302 N, p=0.018). The 5 mm notched group (mean failure of 2808 N) was also significantly weaker than both the un-notched and the 2 mm notched groups (p<0.001, p=0.023, respectively). The finite element model showed the maximum equivalent strain in the superior reamed cancellous bone increasing with corresponding notch size. Fracture patterns inferred from equivalent stress distributions were consistent with those obtained from mechanical testing. A superior notch of 2 mm weakened the proximal femur by 24%, and a 5 mm notch weakened it by 47%. The finite element analysis substantiates this showing increasing stress and strain distributions within the prepared femoral neck with increasing notch depth.

A Study on Application of the Honeycomb Structure in the Large-Scaled Parts

2010 ◽  
Vol 426-427 ◽  
pp. 525-528
Author(s):  
F.H. Yin ◽  
H. Guo
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Strain Distribution ◽  
Large Scale ◽  
Honeycomb Structure ◽  
Theoretical Research ◽  
Stress And Strain ◽  
The Finite Element Method ◽  
Simulation Results ◽  
Stress And Strain Distribution

The Application of honeycomb structure was studied for the large-scaled structures in the paper. Stress and strain distribution of different nephogram structure is gained by the finite element method (FEM), the simulation results are discussed. Based on above-mentioned analysis, the evaluation of distortion is accomplished. The research provides a useful reference for the design of large-scale structure; it has had a certain project practical value and theoretical research value academically.

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