scholarly journals Effectiveness of Selected Fitness Exercises on Stress of Femoral Neck using Musculoskeletal Dynamics Simulations and Finite Element Model

2014 ◽  
Vol 41 (1) ◽  
pp. 59-70 ◽  
Author(s):  
Jing-Guang Qian ◽  
Zhaoxia Li ◽  
Hong Zhang ◽  
Rong Bian ◽  
Songning Zhang
Keyword(s):  
Finite Element ◽  
Femoral Neck ◽  
Finite Element Model ◽  
High Stress ◽  
Gluteus Maximus ◽  
Neck Region ◽  
Peak Stress ◽  
Element Model ◽  
Dynamics Model ◽  
Simple Method

AbstractThe purpose of the study was to establish a dynamics model and a three-dimensional (3D) finite element model to analyze loading characteristics of femoral neck during walking, squat, single-leg standing, and forward and lateral lunges. One male volunteer performed three trials of the five movements. The 3D kinematic data were captured and imported into the LifeMOD to establish a musculoskeletal dynamics model to obtain joint reaction and muscle forces of iliacus, gluteus medius, gluteus maximus, psoas major and adductor magnus. The loading data LfeMOD were imported and transformed into a hip finite-element model. The results of the finite element femur model showed that stress was localized along the compression arc and the tension arc. In addition, the trabecular bone and tension lines of the Ward's triangle also demonstrated high stress. The compact bone received the greatest peak stress in the forward lunge and the least stress in the squat. However, the spongy bone in the femoral neck region had the greatest stress during the walk and the least stress in the squat. The results from this study indicate that the forward lunge may be an effective method to prevent femoral neck fractures. Walking is another effective and simple method that may improve bone mass of the Ward's triangle and prevent osteoporosis and femoral neck fracture.

Research of the Connecting Form about the Spherical Shell and the Nozzle

2011 ◽  
Vol 413 ◽  
pp. 520-523
Author(s):  
Cai Xia Luo
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Finite Element Model ◽  
Spherical Shell ◽  
Maximum Stress ◽  
Peak Stress ◽  
Element Model ◽  
Small Opening ◽  
Large Opening ◽  
Reducing Stress

The Stress Distribution in the Connection of the Spherical Shell and the Opening Nozzle Is Very Complex. Sharp-Angled Transition and Round Transition Are Used Respectively in the Connection in the Light of the Spherical Shell with the Small Opening and the Large One. the Influence of the Two Connecting Forms on Stress Distribution Is Analyzed by Establishing Finite Element Model and Solving it. the Result Shows there Is Obvious Stress Concentration in the Connection. Round Transition Can Reduce the Maximum Stress in Comparison with Sharp-Angled Transition in both Cases of the Small Opening and the Large Opening, Mainly Reducing the Bending Stress and the Peak Stress, but Not the Membrane Stress. the Effect of Round Transition on Reducing Stress Was Not Significant. so Sharp-Angled Transition Should Be Adopted in the Connection when a Finite Element Model Is Built for Simplification in the Future.

scholarly journals Investigation on aerodynamic characteristics of bionic membrane nano rotor

2021 ◽  
Vol 18 ◽  
pp. 175682932110433
Author(s):  
Shanyong Zhao ◽  
Zhen Liu ◽  
Ke Lu ◽  
Dacheng Su ◽  
Shangjing Wu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Structural Parameters ◽  
Element Model ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Performance ◽  
Dynamics Model ◽  
Interaction Method ◽  
Calculation Results ◽  
The Finite Element Model

In this paper, the bionic membrane structure is introduced to improve the aerodynamic performance of nano rotor at the low Reynolds number. The aerodynamic characteristics of nano rotor made of hyperelastic material as membrane blades are studied. Firstly, based on the hyperelastic constitutive model, a finite element model of the rotor is established and compared with the results of the modal test to verify the accuracy of the model. Then the computational fluid dynamics model of membrane nano rotor is established which combined with the finite element model. The aerodynamic characteristics of the membrane rotor under hovering conditions are studied using fluid–structure interaction method. It is found that the calculation results matched well with the experiment results. The design of the structural parameters such as the membrane proportion, shape, and position of the membrane rotor is optimized. The influence of each parameter on the aerodynamic performance of the rotor is obtained. Under certain structural conditions, the performance can be effectively improved, which provides a new idea for the design of the nano rotor.

Complicated Super High-Rise Structural Model Conversion Technology

2014 ◽  
Vol 681 ◽  
pp. 187-194
Author(s):  
Xing Zhang ◽  
Qun Cheng
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Structural Design ◽  
Large Scale ◽  
Element Model ◽  
Simple Method ◽  
High Rise ◽  
Finite Element Technology ◽  
Design And Construction ◽  
Conversion Technology

Abstract. With the development of building science and technology, there are more and more super high-rise buildings. Meanwhile, difficulties in structural design and construction are also on the rise. As the finite element technology field develops, there are numerous types of structural design software, with different mutual functional characteristics. In order to satisfy the design and construction calculation of large-scale engineering, formats of different structural models shall be converted frequently, so as to satisfy the demand of design and construction calculation. In this paper, a simple method will be sought for converting the finite element model of SAP2000 structural design into ANSYS finite element model based on super high-rise structural design model by combining the practical engineering. After conversion, simple APDL [1] programming can be applied for realizing the conversion technology of model.

scholarly journals Finite Element Model Optimization Using Diagonal Mass Matrix

1997 ◽  
Vol 4 (3) ◽  
pp. 163-168
Author(s):  
B.P. Wang ◽  
F.H. Chu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Mass Matrix ◽  
Element Model ◽  
Model Optimization ◽  
Simple Method ◽  
Numerical Examples ◽  
Modal Data

By adjusting the analytic mass matrix or stiffness parameters, the correlation between measured and computed modal data can be improved. This article proposes a simple method for model optimization. Numerical examples will be included to illustrate the proposed approach.

scholarly journals Mechanical stress analysis of a rigid inclusion in distensible material: a model of atherosclerotic calcification and plaque vulnerability

2009 ◽  
Vol 297 (2) ◽  
pp. H802-H810 ◽  
Author(s):  
Tetsuya Hoshino ◽  
Lori A. Chow ◽  
Jeffrey J. Hsu ◽  
Alice A. Perlowski ◽  
Moeen Abedin ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Rigid Inclusion ◽  
Biaxial Loading ◽  
Circumferential Stress ◽  
Peak Stress ◽  
Element Model ◽  
Mechanical Failure ◽  
Calcium Deposit ◽  
Soft Inclusion

The role of atherosclerotic calcification in plaque rupture remains controversial. In previous analyses using finite element model analysis, circumferential stress was reduced by the inclusion of a calcium deposit in a representative human anatomical configuration. However, a recent report, also using finite element analysis, suggests that microscopic calcium deposits increase plaque stress. We used mathematical models to predict the effects of rigid and liquid inclusions (modeling a calcium deposit and a lipid necrotic core, respectively) in a distensible material (artery wall) on mechanical failure under uniaxial and biaxial loading in a range of configurations. Without inclusions, stress levels were low and uniform. In the analytical model, peak stresses were elevated at the edges of a rigid inclusion. In the finite element model, peak stresses were elevated at the edges of both inclusions, with minimal sensitivity to the wall distensibility and the size and shape of the inclusion. Presence of both a rigid and a soft inclusion enlarged the region of increased wall stress compared with either alone. In some configurations, the rigid inclusion reduced peak stress at the edge of the soft inclusion but simultaneously increased peak stress at the edge of the rigid inclusion and increased the size of the region affected. These findings suggest that the presence of a calcium deposit creates local increases in failure stress, and, depending on relative position to any neighboring lipid pools, it may increase peak stress and the plaque area at risk of mechanical failure.

scholarly journals Finite Element Model for Analysis of the Spatial Interfacial Debonding of FRP from Concrete

2017 ◽  
Vol 26 (3) ◽  
pp. 096369351702600
Author(s):  
Feng Zhang ◽  
Lei Gao
Keyword(s):  
Finite Element ◽  
Crack Propagation ◽  
Finite Element Model ◽  
Plate Thickness ◽  
High Stress ◽  
Element Model ◽  
Horizontal Stress ◽  
Interfacial Debonding ◽  
Plate Edge ◽  
Free Region

The debonding of the FRP plate from concrete and crack-propagation processes are complex and the current research studies regarding this debonding mechanism are insufficient and not comprehensive. This work proposes a plane stress model along with equal width and different width FRP to concrete models to simulate the debonding and crack-propagation processes are presented. The longitudinal and horizontal stress distributions were analysed and the FRP to concrete width effect and FRP thickness parameters were also studied by means of the proposed three-dimensional finite element model. The results show that the different width 3D model is optimal for analysing the spatial interfacial debonding of FRP from concrete. The concrete surface horizontal stress distribution along the length of the concrete substrate could judge the effective bond length. Both the normal stress and shear stress are mainly divided into the following two small central stress regions under the PRP plate: a high stress gradient region near the FRP plate edge and a stress-free region near the concrete edge. The debonding strength and the stiffness of the bonding interface increase with the width of the FRP plate and the FRP plate thickness. The stress range and magnitude are strongly dependent on the width of the FRP plate. Debonding begins at the FRP plate edge; the thicker FRP plate more easily exhibits debonding.

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.

The Biomechanical Consequence of Insufficient Femoral Component Lateralization and Exposed Cancellous Bone in Hip Resurfacing Arthroplasty

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Michael Olsen ◽  
Edward T. Davis ◽  
Cari M. Whyne ◽  
Rad Zdero ◽  
Emil H. Schemitsch
Keyword(s):  
Finite Element ◽  
Femoral Neck ◽  
Finite Element Model ◽  
Femoral Neck Fracture ◽  
Femoral Component ◽  
Cancellous Bone ◽  
Proximal Femur ◽  
Element Model ◽  
Cement Mantle ◽  
Neck Fracture

Insufficient lateralization of the femoral component coupled with exposed reamed cancellous bone has been speculated to predispose to femoral neck fracture. The current study examined the effect of mediolateral implant position and exposed cancellous bone on the strength of the resurfaced proximal femur. Composite femurs were prepared in three configurations: (1) partial, with the implant placed at the native femoral head offset of the femur, partially exposing reamed cancellous bone; (2) proud, with a medialized implant exposing a circumferential ring of cancellous bone; and (3) complete, with a lateralized implant covering all reamed cancellous bone. Specimens were loaded to failure in axial compression. A finite element model was used to further explore the effect of exposed cancellous bone, cement mantle thickness, and relative valgus orientation on the strain distributions in the resurfaced femur. The proud group (2063 N) was significantly weaker than both the partial (2974 N, p=0.004) and complete groups (5899 N, p=0.001) when tested to failure. The partial group was also significantly weaker than the complete group when tested to failure (p=0.001). The finite element model demonstrated increasing levels of strain in the superior reamed cortical-cancellous bone interface with increasing degree of exposed cancellous bone. The condition of the femoral component medialized as the result of a thick cement mantle had the greatest detrimental impact on strain level in the superior reamed cancellous bone while a valgus oriented implant provided a protective effect. This study provides biomechanical evidence that exposed reamed cancellous bone significantly reduces the load-to-failure and increases maximum strains in the resurfaced proximal femur. The perceived benefit of reconstructing the femur to its native geometry may inherently weaken the proximal femur and increase femoral neck fracture risk if the femoral component is not sufficiently lateralized to cover all unsupported reamed cancellous bone. Relative valgus orientation of the implant may help to minimize the risk of neck fracture if reamed cancellous bone remains exposed following implant impaction.

The Penn State Safety Floor: Part II—Reduction of Fall-Related Peak Impact Forces on the Femur

1998 ◽  
Vol 120 (4) ◽  
pp. 527-532 ◽  
Author(s):  
J. A. Casalena ◽  
A. Badre-Alam ◽  
T. C. Ovaert ◽  
P. R. Cavanagh ◽  
D. A. Streit
Keyword(s):  
Finite Element ◽  
Femoral Neck ◽  
Finite Element Model ◽  
Deformable Body ◽  
Element Model ◽  
Experimental Models ◽  
Peak Force ◽  
Design Parameters ◽  
Penn State ◽  
The Finite Element Model

The goal of this study was to develop and validate a finite element model (FEM) for use in the design of a flooring system that would provide a stable walking surface during normal locomotion but would also deform elastically under higher loads, such as those resulting from falls. The new flooring system is designed to reduce the peak force on the femoral neck during a lateral fall onto the hip. The new flooring system is passive in nature and exhibits two distinct stiffnesses. During normal activities, the floor remains essentially rigid. Upon impact, the floor collapses and becomes significantly softer. The flooring system consists of a multitude of columns supporting a continuous walking surface. The columns were designed to remain stiff up to a specific load and, after exceeding this load, to deform elastically. The flooring returns to its original shape after impact. Part I of this study presented finite element and experimental results demonstrating that the floor deflection during normal walking remained less than 2 mm. To facilitate the floor’s development further, a nonlinear finite element model simulating the transient-impact response of a human hip against various floor configurations was developed. Nonlinearities included in the finite element models were: changing topology of deformable-body-to-deformable-body contact, snap-through buckling, soft tissue stiffness and damping, and large deformations. Experimental models developed for validating the finite element model included an anthropomorphic hip, an impact delivery mechanism, a data collection system, and four hand-fabricated floor tiles. The finite element model discussed in this study is shown to capture experimentally observed trends in peak femoral neck force reduction as a function of flooring design parameters. This study also indicates that a floor can be designed that deflects minimally during walking and reduces the peak force on the femoral neck during a fall-related impact by 15.2 percent.

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