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Friction 2023年第1期11卷 76-92页

作者： Yuting LI Yuan LI Hao LI Xiaoqiang FAN Han YAN Meng CAI Xiaojun XU Minhao ZHU Key Laboratory of Advanced Technologies of Materials(Ministry of Education) School of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China Tribology Research Institute School of Mechanical EngineeringSouthwest Jiaotong UniversityChengdu 610031China

Deep eutectic solvents(DESs)have been considered as novel and economic alternatives to traditional lubricants because of their similar physicochemical performance.In this study,choline chloride(ChCl)DESs were successfully synthesized via hydrogen-bonding networks of urea and thiourea as the hydrogen bond donors(HBDs).The as-synthesized ChCl-urea and ChCl-thiourea DESs had excellent thermal stability and displayed good lubrication between steel/steel tribo-pairs.The friction coefficient and wear rate of ChCl-thiourea DES were 50.1%and 80.6%,respectively,lower than those of ChCl-urea DES for GCr15/45 steel tribo-pairs.However,for GCr15/Q45 steel,ChCl-urea DES decreased the wear rate by 85.0%in comparison to ChCl-thiourea DES.Under ChCl-thiourea DES lubrication,the tribo-chemical reaction film composed of FeS formed at the interfaces and contributed to low friction and wear.However,under high von mises stress,the film could not be stably retained and serious wear was obtained through direct contact of friction pairs.This illustrated that the evolution of the tribo-chemical reaction film was responsible for the anti-friction and anti-wearproperties of the DESs.

关键词： deep eutectic solvents(DESs) tribo-chemical film von mises stress lubrication mechanism

Application of the finite element method for evaluating the stress distribution in buried damaged polyethylene gas pipes

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Underground Space 2019年第1期4卷 59-71页

作者： R.Khademi-Zahedi Shahid Chamran University of Ahvaz AhvazIran

During the loading process,buried gas pipes can experience severe stresses due to soil-structure interaction,the presence of traffic load,the soil’s column weight,daily and/or seasonal temperature changes and uniform internal pressure.In this research,the finite element method is employed to evaluate the behavior of buried Medium Density Polyethylene(MDPE)pipes which have been subjected to damage at the pipe crown.The modeled pipe damage ranges from a very small circular hole to a large circular hole and elliptic holes with various minor to major diameter ratios,a/b,to simulate circular to crack-shaped defects.The computer simulation and stress analyses were performed using the ANSYS software finite element package.The stress distribution around the defect was determined under the aforementioned mechanical and thermal loading conditions.Then,the maximum values of von mises stresses in the damaged buried PE pipes,which were evaluated by finite element solution,were compared with their corresponding reduced strength for safe operation with a life expectancy of fifty years.Based on the results,the maximum von mises stress values in the defective buried polyethylene gas pipeline are significantly above the pipe strength limit at 35℃.The previously mentioned stress values increase with the following factors:temperature increase,increase in circular hole diameter and decrease in elliptic hole diameter ratio(a/b).The maximum stress in the damaged PE pipe is due to the simultaneous loading effects of soil column weight,internal pressure,vehicle wheel load and pipe temperature increase.Additionally,the novel finite element models and stress plots for the buried damaged pipe and the pipe material allowable strength will be used to investigate the correct repair method for the damaged gas pipeline and to choose the best patch arrangement which will assure a safe repair.

关键词： Buried gas distribution pipes Circular and elliptical defects Medium Density Polyethylene(MDPE) von mises stress Finite element method Temperature variation

Hip Fracture Risk Assessment Based on Different Failure Criteria Using QCT-Based Finite Element Modeling

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Computers, Materials & Continua 2020年第5期63卷 567-591页

作者： Hossein Bisheh Yunhua Luo Timon Rabczuk Department of Mechanical Engineering University of ManitobaWinnipegR3T 5V6Canada Institute of Structural Mechanics Bauhaus-Universität WeimarWeimar99423Germany Department of Biomedical Engineering University of ManitobaWinnipegR3T 5V6Canada Institute of Research and Development Duy Tan UniversityDa NangViet Nam

Precise evaluation of hip fracture risk leads to reduce hip fracture occurrence in individuals and assist to check the effect of a treatment.A subject-specific QCT-based finite element model is introduced to evaluate hip fracture risk using the strain energy,von-mises stress,and von-mises strain criteria during the single-leg stance and the sideways fall configurations.Choosing a proper failure criterion in hip fracture risk assessment is very important.The aim of this study is to define hip fracture risk index using the strain energy,von mises stress,and von mises strain criteria and compare the calculated fracture risk indices using these criteria at the critical regions of the femur.It is found that based on these criteria,the hip fracture risk at the femoral neck and the intertrochanteric region is higher than other parts of the femur,probably due to the larger amount of cancellous bone in these regions.The study results also show that the strain energy criterion gives more reasonable assessment of hip fracture risk based on the bone failure mechanism and the von-mises strain criterion is more conservative than two other criteria and leads to higher estimate of hip fracture risk indices.

关键词： Hip fracture risk finite element model strain energy von mises stress von mises strain

Simulation of Lumbar Spinal Stenosis Using the Finite Element Method

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Computers, Materials & Continua 2021年第12期69卷 3645-3657页

作者： Din Prathumwan Inthira Chaiya Kamonchat Trachoo Department of Mathematics Faculty of ScienceKhon Kaen UniversityKhon Kaen40002Thailand Department of Mathematics Faculty of ScienceMahasarakham UniversityMahasarakham44150Thailand

Lumbar spine stenosis(LSS)is a narrowing of the spinal canal that results in pressure on the spinal nerves.This orthopedic disorder can cause severe pain and dysfunction.LSS is a common disabling problem amongst elderly people.In this paper,we developed a finite element model(FEM)to study the forces and the von mises stress acting on the spine when people bend down.An artificial lumbar spine(L3)was generated from CT data by using the FEM,which is a powerful tool to study biomechanics.The proposed model is able to predict the effect of forces which apply to the lumbar spine.In addition,FEM allows us to investigate the tests into the lumbar spine instead of applying the tests to the real spine in humans.The proposed model is highly accurate and provides precise information about the lumbar spine(L3).We investigate the behavior of humans in daily life which effects to the lumbar spine in a normal person and a patient with LSS.The computational results revealed high displacement levels around the spinal canal and lower displacement levels in the spinal body when bending down.The total displacement of the axial load in a normal person was higher when compared with patients with LSS.Higher degree bends resulted in a lower total displacement when compared with lower degree bends,while the von mises stress decreased as the bending degree increased.

关键词： Lumbar spinal stenosis finite element method mathematical model von mises stress

The Topology Optimization Under the Static Loads

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International Journal of Plant Engineering and Management 2023年第4期28卷 249-254页

作者： LI Zhibin Zhangjiakou Xuanhua Huatai Mining&Metallurgical Machinery Co. Ltd.Zhangjiakou 075100China

The method of the structural topology optimization is often used to design machine in the early stage of the mechanical design.And one mechanical structure use the topology design to produce a new still and lightweigh... 详细信息

关键词： mechanical design FEA von mises stress comparison topology optimization

Analytical Research of Temperature Distribution and Thermal stresses within Circular Micro-hotplates

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Journal of Donghua University(English Edition) 2016年第6期33卷 997-1006页

作者：于慧俐李绪泉胡松涛 School of Environmental and Municipal Engineering Qingdao Technological University

Micro-hotplate(MHP) technology is one key part in the manufacturing of gas sensors.The pursuit of analytical solutions for the temperature distribution and also thermal stresses within the MHP is of intrinsic scientific interest.In this study,analytical solutions for the temperature field,and both radial and tangential stresses and von mises stress for circular MHP were obtained.Two geometries were considered:one had a circular heater at the center and the other had a circular heater at the center and an annular heater within the membrane part.Internal heat generation was incorporated in the energy equation for the MHP and different values of convection heat transfer coefficient were used at the upper and lower surfaces of the MHP.It has been shown that the MHP with two heaters can provide more uniform temperature field compared with the MHP with one heater.The main objective of this work is to provide an exact analytical solution for thermal stresses within the circular micro-heater with a simple geometry as a benchmark,from mathematical point of view,against which the accuracy of new numerical schemes can be checked.To make sure that the analytical procedure is correct,the analytical results are checked against numerical solutions derived from finite element simulation.Since the analytical models for the temperature field and especially for the thermal stresses of MHP are seldom investigated in the literature,the obtained results are believed to facilitate the design and performance evaluation of MHPs as well.

关键词： micro-hotplate(MHP) temperature distribution thermal analysis von mises stress analytical solutions numerical solution

3D Model Simulating the Hydro-mechanical State of Unsaturated and Deformable Material during Hot air Drying

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Hydro Science & Marine Engineering 2020年第1期2卷 27-32页

作者： Lamine Hassini Sadoth Sandoval Torres University of Tunis El Manar Facultédes Sciences de TunisLaboratoire d’Energétique et des Transferts Thermique et Massique(LETTM)Tunisia Instituto Politécnico Nacional CIIDIR unidad OaxacaHornos No.1003Col.Noche BuenaSanta Cruz XoxocotlánOaxacaMexico Department of Physics College of Science and Humanities in AlGuayah-Shaqra UniversitySaudi Arabia

A three dimensional model to predict the hydro-mechanical state of unsaturated and deformable material during hot air drying has been proposed.The material viscoelastic behaviour was formulated using Bishop’s effective stress theory for partially saturated material using the liquid saturation as the Bishop parameter.The hydro-thermal and mechanical equations were coupled by the fluid pressure and the solid matter velocity.The model was applied to a deformable material(innovative clay-cellulose fibers composite)subjected to convective drying.A generalized Maxwell model with five elements,whose parameters were measured experimentally and correlated to water content was used to describe the material’s viscoelastic behavior.The hydro-thermal part of the proposed model was validated on the basis of a comparison of experimental and simulated drying rate curves.The von mises stress was simulated and compared to the experimental tensile strength in order to predict the time and the region of material failure.For a drying process at 95°C,the region of failure risk was identified.The failure may occur on the lateral surface of the slab in contact with air at a drying time of 2.5h.

关键词： Modeling and simulation Cellulosic-clay composite Convective drying von mises stress Material failure

Comparative Study of Different Materials with Al-Sic for Engine Valve Guide by Using FEM

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World Journal of Engineering and Technology 2016年第2期4卷 238-251页

作者： Hemendra Kumar Srivastva Arurendra Singh Chauhan Manmohan Kushwaha Amaan Raza Prashantkr Bhardwaj Vaibhav Raj Department of Mechanical Engineering Naraina Group of Institutions Kanpur India Department of Mechanical Engineering Maharana Pratap Engineering College Kanpur India

In this work, an effort has been designed to raise the reliability of engine using Al-Sic composites with other alternatively materials for the engine valve guides. Aluminum matrix composites have found the most suitable inside automotive, aerospace and aircraft industries and contain the greatest promise for future year’s growth. The finite element analysis of the Al-Sic composite with Titanium alloy (Ti-834), Copper Nickel Silicon alloys (CuNi3Si), and aluminum bronze alloy as an alternative material for engine valve guide was done using Ansys 13.0 software. The stress analysis of engine valve guide under the different pressure and temperature is considered, the pressure is taken as from 10 MPa to 100 MPa with different temperatures varying from 600℃ to 650℃. The temperature, principal stress and principal strain distribution on the entire surface area of the engine valve guide were obtained. The stresses were observed to be well below the permitted stress for all the materials but the Al-Sic composites found the most suitable one. Valve guide is modeled in pro-engineer software and analysis is carried out in Ansys 13.0. The deformations and stresses induced due to structural and thermal loading is illustrated and discussed.

关键词： Valve Guide Composite Materials FEM Deformation von mises stress