A multi-objective approach to optimize the weight and stress of the locking plates using finite element modeling

This paper aims to identify an optimum bone fracture stabilizer. For this purpose, three design variables including the ratio of the screw diameter to the plate width at three levels, the ratio of the plate thickness to the plate width at three levels, and the diameter of the bone at two levels were selected for analysis. Eighteen 3D verified finite element models were developed to examine the effects of these parameters on the weight, maximum displacement and maximum von Mises stress of the fixation structure. Considering the relations between the inputs and outputs using multivariate regression, a genetic algorithm was used to find the optimal choices. Results showed that the diameter of the bone and the amount of load applied on it did not have a significant effect on the normalized stresses on the structures. Furthermore, in all ratio of the plate thickness to the plate width, as the ratio of the screw diameter to the plate width increased, the amount of stress on the structure decreased. But, by further increasing the ratio of the screw diameter to the plate width, the amount of stress on the structure increased. On the other hand, by increasing the value of the ratio of the plate thickness to the plate width, the maximum amount of stress on the structure decreased. Finally, optimal solutions in terms of the weight and the maximum amount of stress on the structure were presented.

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Initial Crack Propagation and the Influence Factors of Aircraft Pipe Pressure

Materials ◽

10.3390/ma12193098 ◽

2019 ◽

Vol 12 (19) ◽

pp. 3098

Author(s):

Fusheng Wang ◽

Zheng Wei ◽

Pu Li ◽

Lingjun Yu ◽

Weichao Huang

Keyword(s):

Finite Element ◽

Crack Propagation ◽

Influence Factors ◽

Initial Crack ◽

Von Mises Stress ◽

Finite Element Models ◽

Opening Displacement ◽

Propagation Length ◽

Factors Affecting ◽

Von Mises

In aircraft engineering, an increase of internal pressure in a hydraulic pipe increases the probability of pipe damage, leading to crack propagation becoming a serious issue. In this study, the extended finite element method (XFEM) is applied to simulate initial crack propagation in hydraulic pipes and to investigate the influence factors. Stress intensity factors are extracted to verify the mesh independence of XFEM, which is based on the level set method and unit decomposition method. A total of 30 finite element models of hydraulic pipes with cracks are established. The distribution of von Mises stress under different initial crack lengths and internal pressures is obtained to analyze the change of load-carrying capacity in different conditions. Then, a total of 300 finite element models of hydraulic pipes with different initial crack sizes and locations are simulated under different working conditions. The relationship between the maximum opening displacement and crack length is analyzed by extracting the opening displacement under different initial crack lengths. The length and depth of the initial crack are changed to analyze the factors affecting crack propagation. The opening size and crack propagation length are obtained in different directions. The results show that radial propagation is more destructive than longitudinal propagation for hydraulic pipes in the initial stage of crack propagation.

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Stress Analysis of Osteoporotic Lumbar Vertebra Using Finite Element Model with Microscaled Beam-Shell Trabecular-Cortical Structure

Journal of Applied Mathematics ◽

10.1155/2013/285165 ◽

2013 ◽

Vol 2013 ◽

pp. 1-6 ◽

Cited By ~ 4

Author(s):

Yoon Hyuk Kim ◽

Mengying Wu ◽

Kyungsoo Kim

Keyword(s):

Finite Element ◽

Vertebral Body ◽

Burst Fracture ◽

Lumbar Vertebra ◽

Von Mises Stress ◽

Finite Element Models ◽

Age Related ◽

Complex Anatomy ◽

Von Mises

Osteoporosis is a disease in which low bone mass and microarchitectural deterioration of bone tissue lead to enhanced bone fragility and susceptibility to fracture. Due to the complex anatomy of the vertebral body, the difficulties associated with obtaining bones for in vitro experiments, and the limitations on the control of the experimental parameters, finite element models have been developed to analyze the biomechanical properties of the vertebral body. We developed finite element models of the L2 vertebra, which consisted of the endplates, the trabecular lattice, and the cortical shell, for three age-related grades (young, middle, and old) of osteoporosis. The compressive strength and stiffness results revealed that we had developed a valid model that was consistent with the results of previous experimental and computational studies. The von-Mises stress, which was assumed to predict the risk of a burst fracture, was also determined for the three age groups. The results showed that the von-Mises stress was substantially higher under relatively high levels of compressive loading, which suggests that patients with osteoporosis should be cautious of fracture risk even during daily activities.

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Three Dimensional Finite Element Interference Contact Analysis about Cone Screw and Bush of Opposed Biconinal Cone Screw High-Pressure Seawater Hydraulic Pump

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.197.174 ◽

2012 ◽

Vol 197 ◽

pp. 174-178 ◽

Cited By ~ 1

Author(s):

Xin Hua Wang ◽

Xiu Xia Cao ◽

Shu Wen Sun ◽

Yan Gao

Keyword(s):

Finite Element ◽

High Pressure ◽

Displacement Vector ◽

Three Dimensional ◽

Von Mises Stress ◽

Hydraulic Pump ◽

Maximum Displacement ◽

Element Analysis ◽

Factors Affecting ◽

Von Mises

The main components of the opposed biconinal cone screw high-pressure seawater hydraulic pump is the rubber bush and metal cone screw, and the interaction of the bush and cone screw is one of the main factors affecting the novel pump performance. The deformation and stress of the bush and cone screw under the initial interference is analyzed by the nonlinear finite element analysis. The analysis shows that: under the effect of the initial interference, large displacement is present to the radial surface of the cone screw, and the displacement of the radial surface mainly affects the displacement vector sum of the cone screw, and the deformation decreases gradually from the middle to the ends of the cone screw, while the cone screw is bending; the deformation in three direction of the bush is close to each other, but the location of the maximum displacement in each direction is different; with the shrink range increasing, the deformation of the cone screw and bush increases, but the deformation of the cone screw is much smaller than that of bush, so the deformation of the bush mainly affects the seal between the cone screw and bush, and the shrink range between the cone screw and bush decreases because of the deformation of the bush. Over the role of the interference force, the maximum von mises stress of the cone screw is an order larger than that of bush, and the maximum von mises stress both increases with the shrink range increasing; although shrink range is different, the location of the maximum von mises about the cone screw and bush is the same.

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INFLUENCE OF THREE DIFFERENT CURVATURES FLEX-FOOT PROSTHESIS WHILE SINGLE-LEG STANDING OR RUNNING: A FINITE ELEMENT ANALYSIS STUDY

Journal of Mechanics in Medicine and Biology ◽

10.1142/s0219519417500555 ◽

2017 ◽

Vol 17 (03) ◽

pp. 1750055 ◽

Cited By ~ 1

Author(s):

MING-JEN KE ◽

KUI-CHOU HUANG ◽

CHENG-HUNG LEE ◽

HENG-YI CHU ◽

YUNG-TSAN WU ◽

...

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Potential Energy ◽

Von Mises Stress ◽

Finite Element Models ◽

Element Analysis ◽

Analysis Study ◽

Considerable Impact ◽

Von Mises ◽

Beneficial Property

Flex foot device was one of the most common prosthesis for the athletes with the transtibial amputation on the recent market. Thus, the results of investigation with biomechanics on the flex foot would be a considerable impact on the performance of disabled athletes wearing the flex foots. This study was designed to investigate the biomechanical condition of the flex foot prosthesis with different curvatures while standing and running by finite element analysis. This study demonstrated finite element models of flex foot established with three different curvatures 20[Formula: see text] (small bending), 35[Formula: see text] (medium bending) and 50[Formula: see text] (big bending). Besides, it simulates and investigates the condition of flex foot while a person is wearing it with single-leg standing or running. The evaluation indices were selected as von Mises stress and displacements at top of socket surface. The results show that the big-bending flex foot generated the higher stress and the larger deformed displacement. Without exceeding the material tolerance of the flex foot, the larger displacement of big-bending flex foot could generate more energy, which possessed larger resilient potential energy and enabled the athletes to have better performance after using the flex foot. As a result, due to its beneficial property of energy storage and return, the large-bending flex foot user could have better effect. In the future, more innovative designs of the flex foot prosthesis can be laid out with the reference of the result in this study.

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DYNAMIC BEHAVIOUR OF SANDWICH PLATE WITH DIFFERENT CORE CONFIGURATION UNDER ACTION OF IMPULSIVE LOADING

THE IRAQI JOURNAL FOR MECHANICAL AND MATERIALS ENGINEERING ◽

10.32852/iqjfmme.v18i4.226 ◽

2019 ◽

Vol 18 (4) ◽

pp. 506-526

Author(s):

Ammar M Nemah ◽

Hatem H Obied

Keyword(s):

Finite Element ◽

Sandwich Plate ◽

Dynamic Properties ◽

Time History ◽

Impulsive Loading ◽

Von Mises Stress ◽

Finite Element Models ◽

Out Of Plane ◽

Bending Loads ◽

Von Mises

Steel sandwich structures with honeycomb and corrugated cellular cores have demonstrated the capability of supporting significant static bending loads while also enabling effective mitigation of impulse loads, the main objectives to use these structures is weight reduction and isolate or reduce the deflection and stress. This research aims to study the effect of dynamic load on the dynamic properties of various types of sandwich cores then find the best model that withstand high stresses and dissipate loads with less mass was possible. The studied model of sandwich is of dimensions (500x500x100) mm with five cells. Four types of steel sandwich plate (SSP) finite element models of various core types have been created: (1) triangle corrugated core, (2) trapezoid corrugated core, (3) square honeycomb and (4) out-of plane hexagonal honeycomb, the mass of various types was constant with value of 13.75 kg. The SSP types were compared by using ANSYS (15.0) APDL software.The finite element models are examined under the effect of transient concentrated stepped load of (350N) during 10ms. The time history response showed that the minimum von-Mises stress and minimum deflection occur at triangle corrugated SSP with values of stress (12.5Mpa) and deflection (3.8 ), but in energy absorption the square honeycomb is the best type with reduction of stress (99.65%) and reduction of deflection of (98.95%).

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Finite Element Analysis of Orthodontic Relapse in Different Maxillary Arch Form

BIO Integration ◽

10.15212/bioi-2021-0012 ◽

2021 ◽

Author(s):

Yuanyuan Li, MD ◽

Yiting Shao, MD ◽

Yansong Yu, MD ◽

Yushan Ye, MD ◽

Yingjuan Lu, PhD ◽

...

Keyword(s):

Finite Element ◽

Von Mises Stress ◽

Dental Arch ◽

Finite Element Models ◽

Element Analysis ◽

3D Finite Element ◽

Arch Form ◽

Arch Forms ◽

Von Mises ◽

Maxillary Arch

Background: Orthodontic relapse is fairly common; however, the mechanisms between relapse and the dental arch form remain unclear. The purpose of our study was to establish three-dimensional (3D) finite element models of different dental arch forms after orthodontic treatment and to analyze the states of different arches applied with various sagittal forces.Methods: By calculating the equations of different dental arch forms and combining them with a full maxillary arch (14 teeth), 3D finite element models of square, oval, and tapered dental arches were established; they were designed to be subjected to anterior lingual, posterior mesial, and combined forces, respectively.Results: The von Mises stress and displacement of teeth under different forces were calculated for each loading scenario. Under the different forcing scenarios, all incisors had irregularity trends, and the inclination and intrusion of the canines were increased, and the premolars had a tendency to buccal or lingual crown tipping or even intrusion in our study. The tapered arch was the most stable and had the smallest displacement and von Mises stress, followed by the ovoid arch; the most unstable arch was the square arch.Conclusions: To achieve a stable orthodontic effect, a tapered or ovoid arch, rather than a square arch, should be chosen as the final outcome of treatment.

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A Hybrid Uniplanar Pedicle Screw System with a New Intermediate Screw for Minimally Invasive Spinal Fixation: A Finite Element Analysis

BioMed Research International ◽

10.1155/2020/5497030 ◽

2020 ◽

Vol 2020 ◽

pp. 1-9

Author(s):

Jia Li ◽

Li-Cheng Zhang ◽

Jiantao Li ◽

Hao Zhang ◽

Jing-Xin Zhao ◽

...

Keyword(s):

Finite Element ◽

Minimally Invasive ◽

Range Of Motion ◽

Pedicle Screw ◽

Axial Rotation ◽

Von Mises Stress ◽

Spinal Fixation ◽

Lateral Bending ◽

Maximum Displacement ◽

Von Mises

Purpose. A hybrid pedicle screw system for minimally invasive spinal fixation was developed based on the uniplanar pedicle screw construct and a new intermediate screw. Its biomechanical performance was evaluated using finite element (FE) analysis. Methods. A T12-L2 FE model was established to simulate the L1 vertebral compression fracture with Magerl classification A1.2. Six fixation models were developed to simulate the posterior pedicle screw fracture fixation, which were divided into two subgroups with different construct configurations: (1) six-monoaxial/uniplanar/polyaxial pedicle screw constructs and (2) four-monoaxial/uniplanar/polyaxial pedicle screw constructs with the new intermediate screw. After model validation, flexion, extension, lateral bending, and axial rotation with 7.5 Nm moments and preloading of 500 N vertical compression were applied to the FE models to compare the biomechanical performances of the six fixation models with maximum von Mises stress, range of motion, and maximum displacement of the vertebra. Results. Under four loading scenarios, the maximum von Mises stresses were found to be at the roots of the upper or lower pedicle screws. In the cases of flexion, lateral bending, and axial rotation, the maximum von Mises stress of the uniplanar screw construct lay in between the monoaxial and polyaxial screw constructs in each subgroup. Considering lateral bending, the uniplanar screw construct enabled to lower the maximum von Mises stress than monoaxial and polyaxial pedicle screw constructs in each subgroup. Two subgroups showed comparable results of the maximum von Mises stress on the endplates, range of motion of T12-L1, and maximum displacement of T12 between the corresponding constructs with the new intermediate screw or not. Conclusions. The observations shown in this study verified that the hybrid uniplanar pedicle screw system exhibited comparable biomechanical performance as compared with other posterior short-segment constructs. The potential advantage of this new fixation system may provide researchers and clinical practitioners an alternative for minimally invasive spinal fixation with vertebral augmentation.

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Optimizing Cement Distribution in the Fractured Area for Osteoporotic Vertebral Compression Fractures Through Biomechanical Effects Analysis Based on a Three Dimentional Lumbar Finite Element Modeling

10.21203/rs.3.rs-100325/v1 ◽

2020 ◽

Author(s):

Lin-qiang Ye ◽

De Liang ◽

Zhen Li ◽

Rui Weng ◽

Xue-cheng Huang ◽

...

Keyword(s):

Finite Element ◽

Cortical Bone ◽

Cancellous Bone ◽

Von Mises Stress ◽

Vertebral Compression Fractures ◽

Osteoporotic Vertebral Compression Fractures ◽

Maximum Displacement ◽

Compression Fractures ◽

Cement Distribution ◽

Von Mises

Abstract Background: While cement distributes sufficiently in the fractured area and relatively symmetrically around the fractured area, three types of cement mass location in the vertebral body are commonly seen when performing bipedicular percutaneous vertebral augmentation (PVA) for osteoporotic vertebral compression fractures (OVCFs), including anterolateral (AL), anteromedial (AM) and posterolateral (PL). However, little is known about differences of biomechanical behaviors among these three types of cement distribution so far. The present study aimed to investigate biomechanical effects of AL, AM and PL in the fractured area on OVCFs.Methods: Three dimentional finite element methods were utilized to construct OVCF model and simulate AL, AM and PL in the fractured area for OVCFs treated with PVA. Distributions and magnitudes of von Mises stress in cortical and cancellous bone and maximum displacement of the four models were compared.Results: Compared with the OVCF model, Distribution of von Mises stress in cortical bone was unchanged while that in cancellous bone was transferred to be concentrated symmetrically at cancellous bone surrounding cement after PVA. Maximum displacement and maximum von Mises stress in cortical bone in AL decreased the most significantly, while AM created the lowest maximum von Mises stress in cancellous bone.Conclusions: Cement distribution between AL and AM may balance stress in cortical and cancellous bone, better restoring vertebral strength, meanwhile, providing sufficient vertebral stability.

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Dynamic Characteristics and Time-History Analysis of Hydraulic Climbing Formwork for Seismic Motions

Advances in Civil Engineering ◽

10.1155/2021/2139153 ◽

2021 ◽

Vol 2021 ◽

pp. 1-17

Author(s):

Gang Yao ◽

Haoting Guo ◽

Yang Yang ◽

Chengming Xiang ◽

Soltys Robert

Keyword(s):

Finite Element ◽

Time History ◽

Element Model ◽

Von Mises Stress ◽

Guide Rail ◽

Maximum Displacement ◽

High Rise ◽

History Analysis ◽

Von Mises ◽

The Finite Element Model

With the widespread use and increasing cycle life of climbing formwork to construct high-rise buildings in earthquake-prone areas, the risk of earthquakes during the construction period increases. Hence, it is necessary to analyze the seismic response of climbing formwork. According to actual climbing formwork in the super high-rise office building of Wanda Plaza in Kunming, China, the finite element model of the climbing formwork is established on the Ansys platform. The correctness of the model is verified by comparing the natural frequencies of the actual climbing formwork and the finite element model. The time-history analysis of the climbing formwork subjected to earthquakes of varying strong magnitudes is carried out. The maximum displacement position and maximum von Mises stress position of the climbing formwork under different working conditions are determined, and the seismic response of the climbing formwork is analyzed. It has been found that when the formwork is under construction, the maximum displacement position of the climbing formwork is at the center of the long beam of the upper platform, and the maximum von Mises stress position is the joint of the outer pole of the main platform and tripod. Under the climbing condition, the maximum displacement position of the climbing formwork is at the top of the outer pole of the upper platform, and the maximum von Mises stress position is the joint of the beam of the tripod and guide rail. The climbing formwork is partially damaged under the simulated earthquake. However, the displacement is large, and some components have reached the yield state. It is recommended to strengthen the connection between the upper platform and the guide rail and enhance the strength and rigidity of the outer pole and tripod. Climbing formwork is more sensitive to horizontal earthquakes and has minimal sensitivity to vertical earthquakes. The structure attached to the climbing formwork will reduce its sensitivity to earthquakes. The research results are of practical significance for seismic design and improvement of climbing formwork.

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THE INFLUENCE OF MEDIAL-LATERAL CONTACT PAIR CONFORMITY ON CONTACT STRESSES IN TOTAL KNEE REPLACEMENT

Transactions of the Canadian Society for Mechanical Engineering ◽

10.1139/tcsme-2017-1021 ◽

2017 ◽

Vol 41 (2) ◽

pp. 301-312

Author(s):

Usman ◽

Shyh-Chour Huang

Keyword(s):

Finite Element ◽

Stress Sensitivity ◽

Contact Stresses ◽

Von Mises Stress ◽

Finite Element Models ◽

Knee Joint Replacement ◽

Lateral Contact ◽

Total Knee ◽

Von Mises ◽

Flat Contact

Eleven finite element models representing the medial-lateral conformity level and shape have been analyzed. From the result, we concluded that the flat-on-flat contact model of knee joint replacement was the most vulnerable to damage. Moreover, in the flat-on-flat model, the highest von Mises stress occurred at two points in a model, namely at the medial and lateral edge of the contact area. With respect to the sensitivity of the contact stresses to the conformity (frontal clearance) in the curved-on-curved model, the larger radius of the femoral indenter showed more contact stress sensitivity to the change in conformity. The von Mises stress dropped to almost half of its previous value when the frontal clearance decreased from 10 to 2 mm.

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