scholarly journals Risk of Proximal Femoral Nail Antirotation Implant Failure Upon Different Lateral Femoral Wall Thickness in Intertrochanteric Fracture :A Finite Element Analysis.

2020 ◽  
Author(s):  
Liqin Zheng ◽  
Duo Wai-Chi Wong ◽  
Xinming Chen ◽  
Yuanzhuang Chen ◽  
Pengfei Li
Keyword(s):  
Wall Thickness ◽  
Intertrochanteric Fracture ◽  
Element Model ◽  
Implant Failure ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Fracture Models ◽  
The Stability ◽  
Von Mises ◽  
Stability Type

Abstract PurposePFNA has been commonly used to treat intertrochanteric fractures, despite the risk of implant failure. The integrity of the femur could influence the risk of implant failure. This study aims to evaluate the influence of lateral femoral wall thickness on potential implant failure using a computational modeling approach. MethodsFinite element model of the hip was reconstructed from the Computed Tomography of a female patient. Five intertrochanteric fracture models at different lateral femoral wall thickness (T1 = 27.6 mm, T2 = 25.4 mm, T3 = 23.4 mm, T4 = 21.4 mm, and T5 = 19.3 mm) were created and fixed with PFNA. A critical loading condition was simulated that mimicked a high loading scenario during walking. The implant failure condition, stress and displacement of the PFNA implant and fracture femur were predicted for analysis. ResultsImplant failure of PNFA occurred at the sides of the proximal nail canal especially for the thinner wall models (T4 and T5).The maximum von Mises stress of the nail for T4 changed abruptly to 298.1 MPa. However, thinner wall decreased the displacement of the PFNA implant. There was approximately opponent trend of stress and displacement on proximal and distal fragments with decreasing thickness possibly due to the adaptation after failure.ConclusionA thinner wall increased the risk of PFNA implant failure. Our prediction showed that complete failure occurred when the thickness was 21.4 mm which was close to the value suggested to determine the stability type.

scholarly journals Effect of Ring Material and Diameter on Orthopedic Implant Stability: External Fixation in Femur Bone

2018 ◽  
Vol 7 (4.26) ◽  
pp. 190 ◽  
Author(s):  
Nur Fatin Izzati Ibrahim ◽  
Ruslizam Daud ◽  
Muhammad Khairul Ali Hassan ◽  
Noor Ali Hassan ◽  
Noor Alia Md Zain ◽  
...  
Keyword(s):  
External Fixation ◽  
Von Mises Stress ◽  
Axial Stiffness ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Ring Diameter ◽  
The Stability ◽  
Von Mises ◽  
Fixation Frame ◽  
Ring Material

Axial stiffness is the most important factor in stability. It is known that any changes in the diameter of any components of the frame will either increase or decrease the axial stiffness of the fixation. The model of implant and bone will be variety as the variables changes. Current studies states that ring stability are one of the most important factors in ensuring fractured bones to have a successful re-union. In circular external fixation, the stability of the pin-bone interaction is influenced by the stability of the fixation frame where the major component is the rings. The objective is to study the finite element analysis (FEA) of the external fixator assembled in human diaphysis under compression force with different materials of the exoskeleton which are stainless steel, titanium alloy, magnesium alloy and carbon fiber. The results obtained show the mechanical strength of each material where it will be used to compare the value of von-Mises stress, stiffness and total deformation to acquire the best suitable ring diameter and material. Based on the result, as the diameter of the ring increases, the stiffness of the ring will be decreased. 

An Improved Control Arm Design for a Commercial Vehicle

2021 ◽  
Author(s):  
Sinan Yıldırım ◽  
Ufuk Çoban ◽  
Mehmet Çevik
Keyword(s):  
Finite Element ◽  
Cost Effective ◽  
Element Model ◽  
Tensile Tests ◽  
The Body ◽  
Von Mises Stress ◽  
Driving Safety ◽  
Design Development ◽  
Element Analysis ◽  
Von Mises

Suspension linkages are one of the fundamental structural elements in each vehicle since they connect the wheel carriers i.e. axles to the body of the vehicle. Moreover, the characteristics of suspension linkages within a suspension system can directly affect driving safety, comfort and economics. Beyond these, all these design criteria are bounded to the package space of the vehicle. In last decades, suspension linkages have been focused on in terms of design development and cost reduction. In this study, a control arm of a diesel public bus was taken into account in order to get the most cost-effective design while improving the strength within specified boundary conditions. Due to the change of the supplier, the control arm of a rigid axle was redesigned to find an economical and more durable solution. The new design was analyzed first by the finite element analysis software Ansys and the finite element model of the control arm was validated by physical tensile tests. The outputs of the study demonstrate that the new design geometry reduces the maximum Von Mises stress 15% while being within the elastic region of the material in use and having found an economical solution in terms of supplier’s criteria.

scholarly journals Effects of placement angle and direction of orthopedic force application on the stability of orthodontic miniscrews

2012 ◽  
Vol 83 (4) ◽  
pp. 667-673 ◽  
Author(s):  
Jihye Lee ◽  
Ji Young Kim ◽  
Yoon Jeong Choi ◽  
Kyung-Ho Kim ◽  
Chooryung J. Chung
Keyword(s):  
Cortical Bone ◽  
Lateral Force ◽  
Von Mises Stress ◽  
Biomechanical Stability ◽  
Element Analysis ◽  
Force Application ◽  
Pull Out ◽  
The Stability ◽  
Von Mises ◽  
Pull Out Strength

ABSTRACT Objectives: To evaluate the influence of placement angle and direction of orthopedic force application on the stability of miniscrews. Materials and Methods: Finite element analysis was performed using miniscrews inserted into supporting bone at angles of 90°, 60°, and 30° (P90°, P60°, and P30°). An orthopedic heavy force of 800 gf was applied to the heads of the miniscrews in four upward (U0°, U30°, U60°, U90°) or lateral (L0°, L30°, L60°, L90°) directions. In addition, pull-out strength of the miniscrews was measured with various force directions and cortical bone thicknesses. Results: Miniscrews with a placement angle of 30° (P30°) and 60° (P60°) showed a significant increase in maximum von Mises stress following the increase in lateral force vectors (U30°, U60°, U90°) compared to those with a placement angle of 90° (P90°). In accordance, the pull-out strength was higher with the axial upward force when compared to the upward force with lateral vectors. Maximum von Mises stress and displacement of the miniscrew increased as the angle of lateral force increased (L30°, L60°, L90°). However, a more dramatic increase in maximum von Mises stress was noted in P30° than in P60° and P90°. Conclusion: Placement of the miniscrew perpendicular to the cortical bone is advantageous in terms of biomechanical stability. Placement angles of less than 60° can reduce the stability of miniscrews when orthopedic forces are applied in various directions.

Finite Element Analysis of Gold Bonding under Different Loading Conditions

2014 ◽  
Vol 607 ◽  
pp. 713-716
Author(s):  
Wen Liang Tang ◽  
Chun Yue Huang ◽  
Tian Ming Li ◽  
Ying Liang ◽  
Guo Ji Xiong ◽  
...  
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Element Model ◽  
Simulation Software ◽  
Bonding Time ◽  
Von Mises Stress ◽  
Bonding Pressure ◽  
Element Analysis ◽  
Von Mises ◽  
Three Dimensional Finite Element

In this paper, ANSYS-LSDYNA simulation software is used to build the three-dimensional finite element model of the ball bond and to get the Von Mises stress. The change of stress about the bump is researched which base on the model in different bonding pressure, bonding power and bonding time. The result show that: The stress increase with bonding pressure increase within a certain bonding pressure range, and then the stress will maintain a table number, however, the stress will continue to increase when the bonding pressure reach a certain value; increasing the bonding power, the area of lager stress will grow; prolonging the bonding time, the stress of the pad will increase with time, but when time increase to a certain value, the stress of the pad will not increase over time.

Finite Element Analysis of Screw-Plate Systems for Fixation of Parasymphyseal Fractures of the Mandible

2007 ◽  
Vol 23 (1) ◽  
pp. 69-77 ◽  
Author(s):  
Scott T. Lovald ◽  
Tariq Khraishi ◽  
John Wood ◽  
Jon Wagner ◽  
Bret Baack ◽  
...  
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Point Of View ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Fracture Region ◽  
Modeling Practices ◽  
Orthotropic Properties ◽  
Von Mises ◽  
Early Healing

AbstractFinite Element Modeling was used to compare the efficacy of common screw-plate configurations used for fixation of parasymphyseal fractures of the mandible. Measures of Von Mises stress on the screw bone interface, as well as principal strain in the reduced fracture region, were used in this comparison. This study also explored differences between orthotropic and isotropic modeling practices and compared the effect of mastication forces on both the fractured and intact halves of the mandible. The results of this analysis showed no major differences between configurations from a mechanistic point of view. This suggests that the use of any of the studied screw-plate configurations will not increase chances for post-operative complications. Furthermore, little difference is seen between analyses with either orthotropic or isotropic material properties. The inclusion of orthotropic properties can thus be avoided in future studies with similar boundary and plating conditions. Mastication ipsilateral to the fracture increases Von Mises stress 2 to 4 times, and should be avoided during early healing periods. These recommendations only apply to patients whose fractures mimic the finite-element model.

Three-Dimensional Modeling and Finite Element Analysis of an Ankle External Fixator

2020 ◽  
Vol 899 ◽  
pp. 94-102
Author(s):  
Nur Faiqa Ismail ◽  
Muhammmad Aiman Firdaus Bin Adnan ◽  
Solehuddin Shuib ◽  
Nik Ahmad Hambali Nik Abd Rashid
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
External Fixator ◽  
Three Dimensional ◽  
Von Mises Stress ◽  
External Fixators ◽  
Element Analysis ◽  
Stress And Deformation ◽  
The Stability ◽  
Von Mises

External fixator has played an important role in repairing fractured ankle bone. This surgery is done due to the several factors which are the bone is not normal position or has broken into several pieces. The external fixator will help the broken bone to grow and remodel back to the original appearance. However, there are some issues regarding to the stability of this fixation. Improper design and material are the major factor that decreased the stability since it is related to the deformation of the external fixator to hold the bone fracture area. This study aims to design a stable structure for constructing delta frame ankle external fixator to increase the stability of the fixation. There are two designs of external fixator with two types of material used in this present study. Both external fixators with different materials are analyzed in terms of von Mises stress and deformation by using a conventional Finite Element Analysis software; ANSYS Workbench V15. The result obtained shows the Model 1 with stainless steel has less stress and deformation distributions compared to the Model 2. Hence, by using Model 1 as the external fixator, the stability of the fixation can be increased.

Evaluation of Biomechanical Health Degree of Peri-Implant Bone Through Finite Element Analysis: A First Approach

2018 ◽  
Vol 10 (09) ◽  
pp. 1850097 ◽  
Author(s):  
Junxiong Lin ◽  
Ge Zhang ◽  
Zhenyu Jiang ◽  
Liqun Tang ◽  
Keqian Lian
Keyword(s):  
Finite Element ◽  
Stress State ◽  
Critical Role ◽  
Control Sample ◽  
Stress Shielding ◽  
Element Model ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Computer Tomography Scan ◽  
Von Mises

The biomechanical health degree of peri-implant bone plays a critical role during the service of implants. This paper presents a preliminary exploration of the quantitative evaluation of the biomechanical health degree for the bone tissues around dental implant through finite element method. The finite element model of a part of mandible with three molars is constructed based on computer tomography scan image as a control sample, which is supposed to represent a healthy state. The model of treated mandible is made by replacing the middle tooth in the healthy model with a commercial implant. A regional average strain energy density (RASED) is proposed as a more accurate index to describe the stress state of peri-implant bone tissues, compared with the widely used maximum equivalent von Mises stress. The simulation shows that the stress state in peri-implant bone, i.e., the distribution and level of stress, is highly dependent on the modulus of implant material. Among the implants made of materials with various moduli, including Ti, stainless steel, zirconia, porous Ti, dentin material and polyether-ether-ketone (PEEK), the ones with medium modulus (15–40[Formula: see text]GPa) are found to achieve relatively healthy stress states. This study provides an effective tool to assess the risk of overloading or stress shielding in peri-implant bone tissues. It demonstrates a great potential in the optimization of design, production and usage of implants.

scholarly journals Effect of the screw tightening sequence on the stress distribution of a dynamic compression plate: A pilot finite element study

2019 ◽  
Vol 27 (3) ◽  
pp. 230949901987607
Author(s):  
Xiaoreng Feng ◽  
Weichen Qi ◽  
Chengyong Wang ◽  
Frankie Leung ◽  
Bin Chen
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Dynamic Compression ◽  
Von Mises Stress ◽  
Femoral Diaphysis ◽  
Element Analysis ◽  
Dynamic Compression Plate ◽  
Compression Plate ◽  
The Stability ◽  
Von Mises

Objective: Although the optimal screw tightening sequence is a common question orthopaedists encounter during fractures fixation with a dynamic compression plate (DCP), the effect of the screw tightening sequence on the stability of the plate has never been explored. This study explores the effect of the screw tightening sequence on the stress distribution of a DCP using a finite element method. Methods: Idealized finite element analysis models of the femoral diaphysis with six-hole or eight-hole DCPs were constructed. The screw tightening preload was simulated using ‘bolt load’ in ABAQUS. Two screw tightening sequences were studied for the six-hole plate and six sequences were studied for the eight-hole plate. U magnitude and Von Mises stress were used to evaluate the deformation and stress distribution of the plate, respectively. Deformation and stress distribution plots from different sequences were compared. Results: The different screw tightening sequences showed different deformation processes, while all had the same final deformation after all the screws were tightened. Each screw tightening step of different tightening sequences showed different stress distributions in the plate, while all had the same stress distribution after all the screws were tightened. Conclusion: Using different screw tightening sequences to fix the same DCP can produce the same stability, which means in terms of fixation stability, after the two screws nearest to the fracture line are tightened, surgeons do not need to hesitate about the order in which the rest screws should be inserted during the surgery.

Coupled Thermal Analysis on Carbide Anvil of Cubic Press

2014 ◽  
Vol 852 ◽  
pp. 629-633
Author(s):  
Xian Jun Zhou ◽  
Zhong Wen Xu ◽  
Ren Quan Chen ◽  
Shao Ping Li
Keyword(s):  
Thermal Analysis ◽  
Finite Element ◽  
Shear Stress ◽  
Element Model ◽  
Heat Transfer Analysis ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Material Defects ◽  
Indirect Coupling ◽  
Von Mises

Based on finite element analysis software ANSYS, the 3D contact finite element model of carbide anvil, steel ring and cushion block were built to make heat transfer analysis, and the temperature field distribution was obtained. The indirect coupling thermal analysis of carbide anvil, steel ring and cushion block were made regarding as a whole, the Von Mises stress nephogram of them and the shear stress nephogram of carbide anvil were displayed. The stress nephogram revealed that it was liable to fracture on the edge of top surface under high pressure status, and it was also proven that the main reason of fracture was the yield of internal material defects under the action of shear stress.

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