scholarly journals Integrating Finite Element Death Technique and Bone Remodeling Theory to Predict Screw Loosening Affected by Radiation Treatment after Mandibular Reconstruction Surgery

Diagnostics ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 844
Author(s):  
Le-Jung Wu ◽  
Kai-Hung Hsieh ◽  
Chun-Li Lin
Keyword(s):  
Finite Element ◽  
Crack Propagation ◽  
Bone Remodeling ◽  
Fe Simulation ◽  
Radiation Treatment ◽  
Fe Model ◽  
Screw Loosening ◽  
Predictive Diagnosis ◽  
Fixation Screw ◽  
Distal Fixation

This study developed a numerical simulation to understand bone mechanical behavior and micro-crack propagation around a fixation screw with severe mandibular defects. A mandible finite element (FE) model was constructed in a rabbit with a right unilateral body defect. The reconstruction implant was designed to be fixed using six screws distributed on the distal and mesial sides. The element death technique provided in FE analysis was combined with bone remodeling theory to simulate bone necrosis around the fixation screw in which the strain value reached the overload threshold. A total of 20 iterations were performed to observe the micro-crack propagation pattern for each screw according to the high strain locations occurring in each result from consecutive iterations. A parallel in vivo animal study was performed to validate the FE simulation by placing specific metal 3D printing reconstruction implants in rabbits to compare the differences in bone remodeling caused by radiation treatment after surgery. The results showed that strain values of the surrounding distal bone fixation screws were much larger than those at the mesial side. With the increase in the number of iteration analyses, the micro-crack prorogation trend for the distal fixation screws can be represented by the number and element death locations during the iteration analysis process. The corresponding micro-movement began to increase gradually and induced screw loosening after iteration calculation. The strained bone results showed that relatively high bone loss (damage) existed around the distal fixation screws under radiation treatment. This study concluded that the FE simulation developed in this study can provide a better predictive diagnosis method for understanding fixation screw loosening and advanced implant development before surgery.

MODELING OF FAILURE FEATURES FOR TiN COATINGS WITH DIFFERENT SUBSTRATE MATERIALS

2011 ◽  
Vol 03 (01n02) ◽  
pp. 49-64 ◽  
Author(s):  
S. WANG ◽  
J. LIN ◽  
D. BALINT
Keyword(s):  
Finite Element ◽  
Tool Steel ◽  
Coating Thickness ◽  
Constitutive Equations ◽  
Fe Simulation ◽  
Pure Copper ◽  
Fe Model ◽  
Tin Coating ◽  
Tin Coatings ◽  
Gear Steel

A set of continuum viscoplastic damage constitutive equations is presented in this paper. The equations are calibrated for a TiN coating material, and a number of substrate materials, and are implemented into the commercial finite element (FE) solver, ABAQUS, through the user-defined material subroutine, VUMAT, for FE simulation. An FE model has been created to simulate a load-bearing test. Studies are carried out to investigate failure features of the coating with variations in coating thickness for three different substrate materials: pure copper, a gear steel and a tool steel. It has been demonstrated that the proposed damage equations can be used to predict failure features of coatings, which are affected by the thickness of the coating and the stiffness of the substrate.

scholarly journals Prediction of Cross-Tension Strength of Self-Piercing Riveted Joints Using Finite Element Simulation and XGBoost Algorithm

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Jianping Lin ◽  
Chengwei Qi ◽  
Hailang Wan ◽  
Junying Min ◽  
Jiajie Chen ◽  
...  
Keyword(s):  
Finite Element ◽  
Regression Model ◽  
Fe Simulation ◽  
Gradient Boosting ◽  
Fe Model ◽  
Cross Sectional ◽  
Extreme Gradient Boosting ◽  
The Cross ◽  
Cross Tension ◽  
Tension Strength

AbstractSelf-piercing riveting (SPR) has been widely used in automobile industry, and the strength prediction of SPR joints always attracts the attention of researchers. In this work, a prediction method of the cross-tension strength of SPR joints was proposed on the basis of finite element (FE) simulation and extreme gradient boosting decision tree (XGBoost) algorithm. An FE model of SPR process was established to simulate the plastic deformations of rivet and substrate materials and verified in terms of cross-sectional dimensions of SPR joints. The residual mechanical field from SPR process simulation was imported into a 2D FE model for the cross-tension testing simulation of SPR joints, and cross-tension strengths from FE simulation show a good consistence with the experiment result. Based on the verified FE model, the mechanical properties and thickness of substrate materials were varied and then used for FE simulation to obtain cross-tension strengths of a number of SPR joints, which were used to train the regression model based on the XGBoost algorithm in order to achieve prediction for cross-tension strength of SPR joints. Results show that the cross-tension strengths of SPR steel/aluminum joints could be successfully predicted by the XGBoost regression model with a respective error less than 7.6% compared to experimental values.

Crack Propagation Calculation for Axial Cracks in Hollow Cylinders Subjected to Thermal Shock

2021 ◽  
Author(s):  
Diego F. Mora M. ◽  
Markus Niffenegger
Keyword(s):  
Fracture Toughness ◽  
Finite Element ◽  
Crack Propagation ◽  
Weight Function ◽  
Thermal Shock ◽  
Initial Crack ◽  
Fe Model ◽  
Simple Method ◽  
Hollow Cylinders ◽  
Fracture Arrest

Abstract The core region of the RPV can be considered a hollow circular cylinder disregarding the geometrical details due to nozzles. This contribution investigates the prediction capabilities for crack initiation, crack growth and arrest by means of a rather simple method based on the closed-weight function formula for the stress intensity factor (SIF) for axial cracks in hollow cylinders subjected to thermal shock. The method is explained together with some illustrative examples for real low allow steel used in nuclear applications. In order to obtain the temperature and stress distribution in the cylinder during the thermal shock, a finite element (FE) model is defined to obtain the uncoupled solution of these two fields needed for the closed-weight function. Since the material exhibits a ductile-brittle transition fracture behavior, the temperature-dependent fracture toughness for initiation and for arrest are described using the ASME model. The solution for the SIF is based on linear elastic fracture mechanics (LEFM) and therefore only elastic material is assumed and the crack can propagate in brittle manner. The crack initiates propagation if the SIF value at the crack tip reaches the fracture toughness (for initiation) and propagates unstably in mode I unless the fracture arrest toughness is reached. The quality of the solution is checked by comparing the obtained solution for a “stationary” crack with the calculated extended finite element method (XFEM) solution for the same loading transient. The results show that for some geometries of the cylinder, the crack stops and in some other cases the crack propagates until the cylinder fails. The combined closed-weight function-initiation-growth-arrest (WFF-IGA) algorithm does not require expensive computational resources and gives fast reliable results. The WFF-IGA method provides a powerful and economical way to predict the crack propagation and arrest of the initial crack. This is an advantage when an optimization of the structure is needed.

scholarly journals The Effects of Shot Distance and Impact Sequence on the Residual Stress Field in Shot Peening Finite Element Model

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 462
Author(s):  
Zhou Wang ◽  
Ming Shi ◽  
Jin Gan ◽  
Xiaoli Wang ◽  
Ying Yang ◽  
...  
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stress Distribution ◽  
Shot Peening ◽  
Dynamic Models ◽  
Fe Simulation ◽  
Residual Stress Distribution ◽  
Fe Model ◽  
Residual Stress Field ◽  
The Impact

In order to investigate the effect of shot distance and impact sequence on the residual stress distribution of 42CrMo steel in shot peening (SP) finite element (FE) simulation, 3D dynamic models with order dimple pattern and stochastic dimple pattern were established via ABAQUS/Explicit 6.14, and the simulation results were compared with experiments. The results show that shot overlap has a significant effect on the residual stress distribution of peened parts. Meanwhile, there is a threshold (related to SP parameter) for shot distance in the vertical and horizontal directions. When the shot distance is greater than the threshold in this direction, the residual stress distribution after SP tends to be stable. The impact sequence has almost no effect on the impact of a small number of shots, but this effect will appear when the number of shots increases. It is necessary to avoid shot overlap and continuous impact of adjacent dimples when the FE model is established; on this basis, the distance between shots and the number of layers of the shots can be reduced as much as possible without affecting the residual stress distribution. In addition, the comparison of simulation and experimental results shows that the residual stress evaluation area consistent with the experimental measurement is essential to obtain accurate residual stress distribution in the FE simulation process.

scholarly journals Prediction of cross-tension strength of self-piercing riveted joints using finite element simulation and XGBoost algorithm

2020 ◽  
Author(s):  
Jianping Lin ◽  
Chengwei Qi ◽  
Hailang Wan ◽  
Junying Min ◽  
Jiajie Chen ◽  
...  
Keyword(s):  
Finite Element ◽  
Regression Model ◽  
Fe Simulation ◽  
Gradient Boosting ◽  
Fe Model ◽  
Cross Sectional ◽  
Extreme Gradient Boosting ◽  
The Cross ◽  
Cross Tension ◽  
Tension Strength

Abstract Self-piercing riveting (SPR) has been widely used in automobile industry, and the strength prediction of SPR joints always attracts the attention of researchers. In this work, a prediction method of the cross-tension strength of SPR joints was proposed on the basis of finite element (FE) simulation and extreme gradient boosting decision tree (XGBoost) algorithm. An FE model of SPR process was established to simulate the plastic deformations of rivet and substrate materials and verified in terms of cross-sectional dimensions of SPR joints. The residual mechanical field from SPR process simulation was imported into a 2D FE model for the cross-tension testing simulation of SPR joints, and cross-tension strengths from FE simulation show a good consistence with the experiment result. Based on the verified FE model, the mechanical properties and thickness of substrate materials were varied and then used for FE simulation to obtain cross-tension strengths of a number of SPR joints, which were used to train the regression model based on the XGBoost algorithm in order to achieve prediction for cross-tension strength of SPR joints. Results show that the cross-tension strengths of SPR steel/aluminum joints could be successfully predicted by the XGBoost regression model with a respective error less than 7.6% compared to experimental values.

scholarly journals Finite Element based Transient Elastohydrodynamic Simulation of Translational Hydraulic Seals

2019 ◽  
pp. 1-26
Author(s):  
Julian Angerhausen ◽  
Hubertus Murrenhoff ◽  
Bo N. J. Persson ◽  
Leonid Dorogin ◽  
Michele Scaraggi
Keyword(s):  
Finite Element ◽  
Fe Simulation ◽  
Fe Model ◽  
Butadiene Rubber ◽  
Rubber Friction ◽  
Physically Based ◽  
Solid Friction ◽  
Machine Elements ◽  
Sealing Mechanism ◽  
Hydraulic Devices

Seals are crucial machine elements in hydraulic devices. However, especially with regard to dynamic seals – for example in cylinder applications – the physical understanding of the sealing mechanism is still insufficient. In this paper a physically based, transient elastohydrodynamic simulation for translational hydraulic seals is presented. The deformation of the seal is calculated in a dynamic finite element (FE) simulation, hyper- and viscoelastic material properties are taken into account. For the numerical calculation of the fluid film and its influences on the seal deformation the FE simulation is coupled with an implementation of the transient Reynold’s equation. For a physically based calculation of the solid contact, the FE-model is coupled with Persson’s theory of rubber friction and contact mechanics. Both, normal force and solid friction are implemented. In a simulation study the influence of the relative velocity in the contact between the elastic, highly deformable seal and a hard cylinder is investigated. The initial phase of motion is investigated in detail. The simulation results are compared to experimental data of a lubricated sliding contact between an nitrile butadiene rubber (NBR) O-ring and a rough steel surface.

Laser Transmission Joining of PC and POM Process: A Finite Element Simulation

2013 ◽  
Vol 579-580 ◽  
pp. 856-861
Author(s):  
Hao Chen ◽  
Yang Yang Gao ◽  
Xiao Wang ◽  
Pin Li ◽  
Chuang Huang ◽  
...  
Keyword(s):  
Finite Element ◽  
Process Parameters ◽  
Parametric Design ◽  
Fe Simulation ◽  
Scanning Speed ◽  
Fe Model ◽  
Element Simulation ◽  
Joint Width ◽  
Ansys Parametric Design Language ◽  
Good Agreement

In this paper, the process of laser transmission joining (LTJ) of polycarbonate (PC) and polyformaldehyde (POM) which are thermoplastic plastics is investigated through a finite element (FE) simulation. Firstly, a 3D thermal model is developed with a moving Super-Gaussian heat source based on the ANSYS parametric design language APDL and the distribution of the temperature field is obtained. Then the effect of process parameters namely laser power, scanning speed and spot diameter on the joint width is analyzed. At the same time, the calculated joint width is achieved. Finally, the curves of calculated results are compared with the curves of experimental results. The comparison shows a good agreement between them which shows that the FE model is reliable. This lays the foundation for reducing experimental times, designing of experiments based on FE simulation and optimizing process parameters.

Modeling of Fatigue Crack Closure by Finite Element Method

2012 ◽  
Vol 544 ◽  
pp. 145-150
Author(s):  
Zhen Yu Ding ◽  
Xiao Gui Wang ◽  
Zeng Liang Gao
Keyword(s):  
Finite Element ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Crack Closure ◽  
Fe Simulation ◽  
Crack Tip ◽  
Cyclic Plasticity ◽  
Stress And Strain

Crack closure concept is often used to explain the crack propagation behavior in cracked components. The effective stress intensity factor range is considered as a driving force of fatigue crack growth based on the traditional crack closure concept. The crack closure process and the plastic deformation near the crack tip were discussed in this paper. The standard compact tension specimen with the plane-stress condition was used to study the crack closure. A dynamic crack propagation method was proposed to simulate the effect of previous fatigue crack growth on the successive crack growth behavior. To obtain the accurately numerical results of stress and strain components, the Jiang and Sehitoglu cyclic plasticity model was implemented into ABAQUS as UMAT. With the detailed stress and strain response taken from the finite element (FE) simulation, the whole process of crack closure was described by the load curve. The load corresponding to maximum crack closure length is firstly proposed to describe the effect of fatigue damage. According to the results of FE simulation, the cyclic plasticity of the material near the crack tip persists during the crack closure period and should not be ignored.

Combined Bone Ingrowth and Remodeling Around Uncemented Acetabular Component: A Multiscale Mechanobiology-Based Finite Element Analysis

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Kaushik Mukherjee ◽  
Sanjay Gupta
Keyword(s):  
Finite Element ◽  
Bone Remodeling ◽  
Acetabular Component ◽  
Bone Ingrowth ◽  
Relative Displacement ◽  
Bone Adaptation ◽  
Fe Model ◽  
Bone Apposition ◽  
Element Analysis ◽  
Acetabular Rim

Bone ingrowth and remodeling are two different evolutionary processes which might occur simultaneously. Both these processes are influenced by local mechanical stimulus. However, a combined study on bone ingrowth and remodeling has rarely been performed. This study is aimed at understanding the relationship between bone ingrowth and adaptation and their combined influence on fixation of the acetabular component. Based on three-dimensional (3D) macroscale finite element (FE) model of implanted pelvis and microscale FE model of implant–bone interface, a multiscale framework has been developed. The numerical prediction of peri-acetabular bone adaptation was based on a strain-energy density-based formulation. Bone ingrowth in the microscale models was simulated using the mechanoregulatory algorithm. An increase in bone strains near the acetabular rim was observed in the implanted pelvis model, whereas the central part of the acetabulum was observed to be stress shielded. Consequently, progressive bone apposition near the acetabular rim and resorption near the central region were observed. Bone remodeling caused a gradual increase in the implant–bone relative displacements. Evolutionary bone ingrowth was observed around the entire acetabular component. Poor bone ingrowth of 3–5% was predicted around the centro-inferio and inferio-posterio-superio-peripheral regions owing to higher implant–bone relative displacements, whereas the anterio-inferior and centro-superior regions exhibited improved bone ingrowth of 35–55% due to moderate implant–bone relative displacement. For an uncemented acetabular CoCrMo component, bone ingrowth had hardly any effect on bone remodeling; however, bone remodeling had considerable influence on bone ingrowth.

Finite Element Analysis of Brain Damage due to Impact Force with a Three Dimensional Head Model

2005 ◽  
Vol 297-300 ◽  
pp. 1333-1338
Author(s):  
Chang Min Suh ◽  
Sung Ho Kim ◽  
Byung Won Hwang
Keyword(s):  
Finite Element ◽  
Brain Damage ◽  
Fe Simulation ◽  
Impact Force ◽  
Three Dimensional ◽  
Head Impact ◽  
Head Model ◽  
Fe Model ◽  
The Impact ◽  
The Brain

Brain damage by the impact force was evaluated by the numerical analysis with a three dimensional Finite Element (FE) model. The FE model was constructed from the MRI data of a subject, and visco-elastic behavior for constitutive equation was applied to the brain tissue. From the FE simulation, brain damage and deformation of the frontal head impacted by a steel impactor were analyzed. The variations of head acceleration and Intra-Cranial Pressure (ICP) during the impact were analyzed in order to evaluate Traumatic Brain Injury (TBI). In addition, relative displacement between the skull and the brain due to head impact was investigated. And, pathological severity was evaluated according to Head Injury Criterion (HIC) from the FE simulation. The analytic results of brain damage showed a good agreement with those of the cadaver test performed by Nahum et al. (1977) and other medical reports. And then, the variation of the HIC value was evaluated according to various impact conditions. This study would provide useful data and methodology in the field of biomechanics for analyzing the brain damage by head impact.

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