scholarly journals FEM Modeling of Delamination in AS4/PEEK Thermoplastic Composites under Mixed – Mode Bending Test

Mechanika ◽  
2020 ◽  
Vol 26 (2) ◽  
pp. 120-125
Author(s):  
IONESCU VIOREL
Keyword(s):  
Mixed Mode ◽  
Strain Energy ◽  
Laminated Composite ◽  
Bending Test ◽  
Von Mises Stress ◽  
Thermoplastic Composites ◽  
Displacement Curve ◽  
Fem Modeling ◽  
Energy Rate ◽  
Von Mises

Interfacial failure by delamination in the unidirectional AS4/PEEK laminated composite was simulated through this paper with a finite element method (FEM) based model developed with Comsol Multiphysics software. The mixed – mode bending (MMB) test was investigated numerically here after a successful validation of the model by comparing with experimental measurements of the load –displacement curve provided in the literature. The maximum delamination length of the specimens modeled, the corresponding von Mises stress distributions and the damage evolution function have been evaluated for different ratios between mode II strain energy rate and total strain energy rate GII/GT = 20%, 50% and 80%.

Design improvement and fatigue analysis for a bicycle handlebar stem system using uniform design method and genetic algorithm

2020 ◽  
Vol 234 (11) ◽  
pp. 2266-2278
Author(s):  
Cho-Pei Jiang ◽  
Ching-Wei Wu ◽  
Yung-Chang Cheng
Keyword(s):  
Genetic Algorithm ◽  
Objective Function ◽  
Safety Factor ◽  
Uniform Design ◽  
Optimization Procedure ◽  
Bending Test ◽  
Von Mises Stress ◽  
Kriging Interpolation ◽  
Optimized Design ◽  
Von Mises

An integrating optimization procedure is presented to improve the von Mises stress and fatigue safety factor for a handlebar stem system in a bicycle system. The optimization procedure involves uniform design of experiment, Kriging interpolation, genetic algorithm, and nonlinear programming method. Using ANSYS/Workbench software and the ISO 4210 bicycle handlebar stem testing standard, the von Mises stress for the lateral bending test simulation and the fatigue safety factor for the fatigue test simulation is calculated. The von Mises stress and fatigue safety factor are combined into a single and integrated objective function, and Kriging interpolation is then used to create the surrogate model of the integrated objective function. When the integrating optimization procedure is used, the integrated objective function demonstrates that the von Mises stress for the optimized handlebar stem is reduced to 225 MPa and the fatigue safety factor increases to 1.796. This shows that the optimized design increases the strength of the handlebar stem. The proposed technique yields a handlebar stem with an optimized shape.

scholarly journals Biomechanical Dynamics of Cranial Sutures during Simulated Impulsive Loading

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Z. Q. Zhang ◽  
J. L. Yang
Keyword(s):  
Strain Energy ◽  
Element Model ◽  
Impulsive Loading ◽  
Dynamic Responses ◽  
Von Mises Stress ◽  
Cranial Sutures ◽  
Collagen Fibres ◽  
Biomechanical Behavior ◽  
Von Mises ◽  
Surrounding Bone

Background. Cranial sutures are deformable joints between the bones of the skull, bridged by collagen fibres. They function to hold the bones of the skull together while allowing for mechanical stress transmission and deformation.Objective. The aim of this study is to investigate how cranial suture morphology, suture material property, and the arrangement of sutural collagen fibres influence the dynamic responses of the suture and surrounding bone under impulsive loads.Methods. An idealized bone-suture-bone complex was analyzed using a two-dimensional finite element model. A uniform impulsive loading was applied to the complex. Outcome variables of von Mises stress and strain energy were evaluated to characterize the sutures’ biomechanical behavior.Results. Parametric studies revealed that the suture strain energy and the patterns of Mises stress in both the suture and surrounding bone were strongly dependent on the suture morphologies.Conclusions. It was concluded that the higher order hierarchical suture morphology, lower suture elastic modulus, and the better collagen fiber orientation must benefit the stress attenuation and energy absorption.

An Innovative Yield Criterion Considering Strain Rates Based on Von Mises Stress

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Jingwei Yu ◽  
Qingguo Fei ◽  
Peiwei Zhang ◽  
Yanbin Li ◽  
Dahai Zhang ◽  
...  
Keyword(s):  
Energy Density ◽  
Yield Strength ◽  
Constitutive Model ◽  
Strain Rate ◽  
Dynamic Load ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Yield Criterion ◽  
Von Mises Stress ◽  
Von Mises

Abstract An innovative yield criterion based on von Mises stress is proposed to represent the strain rate-dependent behavior under dynamic load. Considering the strain rate in the constitutive model, the distortional strain energy density is derived and the yield criterion is established. A plot of yield strength for a range of strain rate reveals that despite the differences in material properties and test methods, the yield strength rise can be represented by a unified criterion. The overall yield behavior of the material under dynamic load can be explained by introducing the strain rate into the constitutive model and threshold distortional strain energy density. This criterion is in a simple form that may be widely applied.

Experimentally determined microcracking around a circular hole in a flat plate of bone: comparison with predicted stresses

1995 ◽  
Vol 347 (1322) ◽  
pp. 383-396 ◽  
Keyword(s):  
Energy Density ◽  
Circular Hole ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Bone Remodelling ◽  
Von Mises Stress ◽  
Analysis Model ◽  
Material Interfaces ◽  
Empirical Examination ◽  
Von Mises

We examined the microcracking (damage) in the vicinity of a circular hole in bovine femoral bone specimens. The stresses near the hole were derived by a finite element analysis model using the bone’s elastic constants and yield stresses, which were determined from a series of mechanical tests specifically for the type of bone under examination. The spatial occurrence and distribution of microcracking was compared to the patterns of the predicted maximum principal stress, the von Mises stress, and the strain energy density function (all implicated by various workers as stimuli for bone remodelling) and to the predictions derived by the use of two engineering criteria for anisotropic yield under mixed mode of stress. The predictions for stresses and the strain energy density were all very similar, making it impossible to claim that any of them is superior to the others. However, empirical examination of the results of the Hencky-von Mises and Tsai-Wu anisotropic yield criteria showed that the Tsai-Wu criterion approximated reasonably the pattern of microcracking around the hole. We suggest that, in the light of the considerable damage observed in the vicinity of stress concentrators, similar damage in irregular material interfaces (i.e. near orthopaedic implants) would require the re-examination of the theories concerning bone remodelling so as to account for the possibility of occurrence of damage and the quantification of its magnitude and likely effect. The presence of considerable microdamage in bone long before it fails suggests that damage-based criteria are more likely to be successful predictors of bone remodelling behaviour than would stress or strain-based criteria.

Microstructure Evolution and Analysis of a Single Crystal Nickel-Based Superalloy during Tensile Creep

2011 ◽  
Vol 689 ◽  
pp. 154-158 ◽  
Author(s):  
Shu Zhang ◽  
Su Gui Tian ◽  
Yong Su ◽  
Ben Jiang Qian
Keyword(s):  
Energy Density ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Lattice Misfit ◽  
Tensile Creep ◽  
Von Mises Stress ◽  
Stress Axis ◽  
Directional Growth ◽  
Misfit Stress ◽  
Von Mises

By means of the finite element method (FEM) for calculating the von Mises stress and strain energy density in the cubic γ/γ′ phases, the regularity of γ′ phase directional growth is investigated. Results show that the change of the strain energy density in the different planes of the cubical γ′ phase occurs during tensile creep of alloy, the cubical γ′ phase is directionally grown, along the crystal plane with bigger strain energy, to transform into the mesh-like rafted structure along the direction perpendicular to the applied stress axis. The change of the atomic potential energy, interfacial energy and lattice misfit stress is thought to be the driving force for promoting the elements diffusion and directional growth of γ′ phase.

scholarly journals THE ROLE OF PDL-CEMENTUM ENTHESIS IN PROTECTING PDL UNDER MASTICATORY LOADING: A FINITE ELEMENT INVESTIGATION

2021 ◽  
pp. 2150049
Author(s):  
HOSSEIN JOKAR ◽  
GHOLAMREZA ROUHI ◽  
NABIOLLAH ABOLFATHI
Keyword(s):  
Finite Element ◽  
Strain Energy ◽  
Alveolar Bone ◽  
Tooth Movement ◽  
Orthodontic Tooth Movement ◽  
Von Mises Stress ◽  
Mechanical Stimuli ◽  
The Finite Element Method ◽  
Von Mises

Background: The function of periodontal ligament (PDL)-cementum enthesis (PCE) in transferring the mechanical stimuli within the tooth–periodontium (PDT)–bone complex was not made clear yet. This study aimed to evaluate the effects of PCE on the mechanical stimuli distribution within the PDL and alveolar bone in the tooth–PDT–bone complex under occlusal forces using the finite element method. Methods: A computed tomography-based model of alveolar bone and second premolar of mandible was constructed, in which the PDT was considered at the interface of alveolar bone and tooth. Under a 3 MPa distributed occluso-apical masticatory load, applied over the uppermost surface of crown, the von Mises strain (vMST) and strain energy density (SED) within PDL, and von Mises stress (vMSR) and SED within alveolar bone were calculated in two situations: 1. When the PCE was absent; and 2. When the PCE was present between the PDL and cementum. Results: PCE levels-off SED and vMST within PDL up to 59% and 27%, respectively, compared to the model with no PCE. Moreover, in the alveolar bone, SEDs and vMSR increased up to 28% and 30%, respectively, compared to the model without PCE. Conclusion: By including PCE in the tooth–PDT–bone model, the mechanical stimuli shifted from PDL to its surrounding alveolar bone. Thus, it can be speculated that the tooth–PDT–bone complex has the capability of reducing the risk of PDL damage, through shifting excess mechanical stimuli from PDL toward the alveolar bone, during prolonged cyclic masticatory loading, as well as while one applies nonphysiologic and therapeutic loads, such as in orthodontic tooth movement.

scholarly journals Performance Analysis of Gudgeon Pin of Various Cross Sections by FEM

2020 ◽  
Vol 8 (5) ◽  
pp. 4569-4573
Keyword(s):  
Performance Analysis ◽  
Cross Sections ◽  
Strain Energy ◽  
Maximum Principal Stress ◽  
Von Mises Stress ◽  
Outer Diameter ◽  
Connecting Rod ◽  
Automobile Engines ◽  
Von Mises ◽  
Stressed Component

Gudgeon pin are one of most heavily stressed component present in engine Gudgeon pin is used in automobile engines to connect piston and connecting rod. and its failure can cause seizure of the engine. Thus they are carefully designed. This project deals with gudgeon pin of different inner profiles keeping the outer diameter constant which is equal to piston boss to provide a more strengthen gudgeon pin. Profiles investigated are hollow, uniform stepped, tapered, step taper. The models with mentioned inner profiles keeping outer profile straight are made using CATIA and then analyzed for using ANSYS for parameters maximum principal stress, equivalent (von-mises) stress, strain energy and total deflection. Considering all these parameters most suitable design of gudgeon pin is decided. On investigation of the different profile it was found that step taper profile gave the best results .Thus providing a stronger gudgeon pin leading to decrease in chances of failure.

scholarly journals The role of PDL-cementum enthesis in protecting PDL under masticatory loading: A finite element investigation

2021 ◽  
Author(s):  
Hossein Jokar ◽  
Gholamreza Rouhi ◽  
Nabiollah Abolfathi
Keyword(s):  
Computed Tomography ◽  
Finite Element ◽  
Periodontal Ligament ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Alveolar Bone ◽  
Von Mises Stress ◽  
Mechanical Stimuli ◽  
Von Mises

Abstract PURPOSE. Function of periodontal ligament-cementum enthesis (PCE) in transferring mechanical stimuli within tooth-periodontium (PDT)-bone complex was not made clear yet. This study aimed to evaluate the effects of PCE on the mechanical stimuli distribution within the PDL and alveolar bone in the tooth-PDT-bone complex under occlusal forces using finite element method (FEM). METHODS. A computed tomography (CT) based model of alveolar bone and 2nd premolar of mandible was constructed, in which the PDT was considered at the interface of alveolar bone and tooth. Under a 3MPa distributed occluso-apical masticatory load, applied over the uppermost surface of crown, the von Mises strain (vMST) and strain energy density (SED) within PDL, and von Mises stress (vMSR) and SED within alveolar bone were calculated in two situations: 1. When the PCE was absent; and 2. When the PCE was present between the PDL and cementum. RESULTS. PCE levels-off the SED and vMST within PDL by maximum values of 92 kPa and 0.04 mm/mm, respectively, compared to the model without PCE. Moreover, it increased the alveolar bone SEDs and vMSR by maximum values of 0.36 kPa and 0.63 MPa, respectively, compared to the without PCE model.CONCLUSION. By including PCE in the tooth-PDT-bone model, the mechanical stimuli shift from PDL to its surrounding alveolar bone. Thus, it can be speculated that the tooth-PDT-bone complex has the capability of, through shifting excess mechanical stimuli from PDL toward the alveolar bone, reducing the risk of PDL damage.

scholarly journals Beneficial osseointegration effect of hydroxyapatite coating on cranial implant – FEM investigation

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0254837
Author(s):  
Jakub Chamrad ◽  
Petr Marcián ◽  
Jan Cizek
Keyword(s):  
Promising Result ◽  
Spray Deposition ◽  
Calcium Phosphates ◽  
Von Mises Stress ◽  
Fixation Method ◽  
Implant Fixation ◽  
Fem Modeling ◽  
Bioactive Materials ◽  
Bone Implant ◽  
Von Mises

A firm connection of the bone-implant-fixation system is of utmost importance for patients with cranial defects. In order to improve the connection reliability, the current research focuses on finding the optimal fixation method, as well as selection of the implant manufacturing methods and the used materials. For the latter, implementation of bioactive materials such as hydroxyapatite or other calcium phosphates has also been considered in the literature. The aim of this study was to investigate the effect of gradual osseointegration on the biomechanical performance of cranial Ti6Al4V implants with a deposited HA coating as the osseointegration agent. This effect was assessed by two different computational approaches using finite element method (FEM) modeling. The values of key input parameters necessary for FEM were obtained from experimental plasma spray deposition of HA layers onto Ti6Al4V samples. Immediately upon implantation, the HA layer at the bone-implant contact area brought only a slight decrease in the values of von Mises stress in the implant and the micro-screws when compared to a non-coated counterpart; importantly, this was without any negative trade-off in other important characteristics. The major benefit of the HA coatings was manifested upon the modeled osseointegration: the results of both approaches confirmed a significant reduction of investigated parameters such as the total implant displacements (reduced from 0.050 mm to 0.012 mm and 0.002 mm while using Approach I and II, respectively) and stresses (reduced from 52 MPa to 10 MPa and 1 MPa) in the implanted components in comparison to non-coated variant. This is a very promising result for potential use of thermally sprayed HA coatings for cranial implants.

scholarly journals Biomechanical feasibility of semi-rigid stabilization and semi-rigid lumbar interbody fusion: a finite element study

2022 ◽  
Vol 23 (1) ◽  
Author(s):  
Chia-En Wong ◽  
Hsuan-Teh Hu ◽  
Li-Hsing Kao ◽  
Che-Jung Liu ◽  
Ke-Chuan Chen ◽  
...  
Keyword(s):  
Finite Element ◽  
Strain Energy ◽  
Lumbar Fusion ◽  
Axial Rotation ◽  
Von Mises Stress ◽  
Peek Cage ◽  
Lateral Bending ◽  
Interspinous Spacer ◽  
Flexion Extension ◽  
Von Mises

Abstract Background Semi-rigid lumbar fusion offers a compromise between pedicle screw-based rigid fixation and non-instrumented lumbar fusion. However, the use of semi-rigid interspinous stabilization (SIS) with interspinous spacer and ligamentoplasty and semi-rigid posterior instrumentation (SPI) to assist interbody cage as fusion constructs remained controversial. The purpose of this study is to investigate the biomechanical properties of semi-rigidly stabilized lumbar fusion using SIS or SPI and their effect on adjacent levels using finite element (FE) method. Method Eight FE models were constructed to simulate the lumbosacral spine. In the non-fusion constructs, semi-rigid stabilization with (i) semi-rigid interspinous spacer and artificial ligaments (PD-SIS), and (ii) PI with semi-rigid rods were simulated (PD + SPI). For fusion constructs, the spinal models were implanted with (iii) PEEK cage only (Cage), (iv) PEEK cage and SIS (Cage+SIS), (v) PEEK cage and SPI (Cage+SPI), (vi) PEEK cage and rigid PI (Cage+PI). Result The comparison of flexion-extension range of motion (ROM) in the operated level showed the difference between Cage+SIS, Cage+SPI, and Cage+PI was less than 0.05 degree. In axial rotation, ROM of Cage+SIS were greater than Cage+PI by 0.81 degree. In the infrajacent level, while Cage+PI increased the ROM by 24.1, 27,7, 25.9, and 10.3% and Cage+SPI increased the ROM by 26.1, 30.0, 27.1, and 10.8% in flexion, extension, lateral bending and axial rotation respectively, Cage+SIS only increased the ROM by 3.6, 2.8, and 11.2% in flexion, extension, and lateral bending and reduced the ROM by 1.5% in axial rotation. The comparison of the von Mises stress showed that SIS reduced the adjacent IVD stress by 9.0%. The simulation of the strain energy showed a difference between constructs less than 7.9%, but all constructs increased the strain energy in the infradjacent level. Conclusion FE simulation showed semi-rigid fusion constructs including Cage+SIS and Cage+SPI can provide sufficient stabilization and flexion-extension ROM reduction at the fusion level. In addition, SIS-assisted fusion resulted in less hypermobility and less von Mises stress in the adjacent levels. However, SIS-assisted fusion had a disadvantage of less ROM reduction in lateral bending and axial rotation. Further clinical studies are warranted to investigate the clinical efficacy and safety of semi-rigid fusions.

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