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Journal of Magnesium and Alloys 2022年第5期10卷 1381-1400页

作者： S.Suresh M.Navaneetha Krishnan S.C.Vettivel Department of mechanical engineering University College of EngineeringNagercoilTamilnaduIndiaPin:629004 Department of mechanical engineering Universal College of Engineering and TechnologyVallioorTamilnaduIndiaPin:627117 Department of mechanical engineering Chandigarh College of Engineering and TechnologyChandiagarh 160019India

The emphasis of this exploration was to examine the workability and work hardening performance of Mg(Magnesium)specimen and Mg-B_(4)C composites created via the powder metallurgy technique.The pure Mg and Mg-B_(4)C composites are made with distinct weight percentages(Mg-5%B_(4)C,Mg-10%B_(4)C,and Mg-15%B_(4)C)at the unit aspect ratio.The powders and composites characterization are executed by SEM(Scanning Electron Microscope),EDS(Energy Dispersive Spectrum)with an elemental map,and XRD(X-ray Diffraction)examination.It displays that,the B_(4)C particles were dispersed consistently with the Mg matrix.The workability and work hardening examination was conducted in triaxial stress conditions using the cold deformation process.The consequence of workability stress exponent factor(β_(σ)),distinct stress proportion factors(σ_(m)/σ_(eff)and σ_(θ)/σ_(eff)),instantaneous work hardening exponent(n_(1)),work hardening exponent(n),coefficient of strength(k)and instantaneous coefficient of strength(k_(1))are recognized.The outcome displays that Mg-15%B_(4)C specimen has greater workability and work hardening parameter,initial relative density,and triaxial stresses compared with the Mg specimen and Mg-(5–10%)B_(4)C composites.

关键词： Powder metallurgy Cold deformation Workability Instantaneous work hardening exponent Workability stress exponent Triaxial stress

Transient swelling-induced finite bending of hydrogel-based bilayers:analytical and FEM approaches

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Applied Mathematics and Mechanics(English Edition) 2023年第2期44卷 273-288页

作者： A.AMIRI M.BANIASSADI M.BAGHANI School of mechanical engineering College of EngineeringUniversity of TehranTehran ***Iran

Hydrogels with their time-dependent intrinsic behaviors have recently been used widely in soft structures as sensors/actuators.One of the most interesting structures is the bilayer made up of hydrogels which may undergo swelling-induced bending.In this work,by proposing a semi-analytical method,the transient bending of hydrogel-based bilayers is investigated.Utilizing nonlinear solid mechanics,a robust semi-analytical solution is developed which captures the transient finite bending of hydrogel-based bilayers.Moreover,the multiphysics model of the hydrogels is implemented in the finite element method(FEM) framework to verify the developed semi-analytical procedure results.The effects of different material properties are investigated to illustrate the nonlinear behavior of these structures.The von-Mises stress contour extracted from FEM shows that the critical area of these soft structures is at the interface of the layers which experiences the maximum stress,and this area is most likely to rupture in large deformations.

关键词： hydrogel transient swelling bilayer multiphysics finite bending

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基于磁流变弹性体的磁致电感特性

Journal of Central South University 2022年第4期29卷 1075-1084页

作者：居本祥王小龙 College of Mechanical Engineering Chongqing University of TechnologyChongqing 400054China College of Mechanical Engineering North University of ChinaTaiyuan 030051China

磁流变(MR)材料是一类智能材料,通常为流体、胶泥或弹性体状,其特性可以利用磁场进行控制。在本研究中,利用硅橡胶基体与羰基铁粉填充颗粒制备各向同性与各向异性磁流变弹性体,为研究磁流变弹性体的磁致电感特性设计了试验电感器。采用... 详细信息

磁流变(MR)材料是一类智能材料,通常为流体、胶泥或弹性体状,其特性可以利用磁场进行控制。在本研究中,利用硅橡胶基体与羰基铁粉填充颗粒制备各向同性与各向异性磁流变弹性体,为研究磁流变弹性体的磁致电感特性设计了试验电感器。采用自建的可产生恒定与瞬态激励磁场的试验系统表征磁流变弹性体的填充颗粒含量、制备条件等因素对磁致电感特性的影响。研究结果表明:上述影响因素对磁流变弹性体电感器在外加磁场下的电感特性有明显影响,各向同性磁流变弹性体电感器的电感变化比各向异性磁流变弹性体电感器的更为显著。此外,在恒定磁场作用下,磁流变弹性体电感器的电感值随着外加磁场激励的增强而衰减,并深入分析了磁致影响机理。本研究成果可以促进磁流变弹性体用于检测外磁场或磁流变材料内部填充颗粒含量。

关键词：磁流变弹性体磁流变弹性体电感装置电感恒定磁场瞬态

An investigation on multilayer shape memory polymers under finite bending through nonlinear thermo-visco-hyperelasticity

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Applied Mathematics and Mechanics(English Edition) 2023年第1期44卷 73-88页

作者： A.BAKHTIYARI M.BAGHANI S.SOHRABPOUR School of mechanical engineering College of EngineeringUniversity of TehranTehran ***Iran Department of mechanical engineering Sharif University of TechnologyTehran ***Iran

This study presents a semi-analytical solution to describe the behavior of shape memory polymers(SMPs) based on the nonlinear thermo-visco-hyperelasticity which originates from the concepts of internal state variables and rational thermodynamics.This method is developed for the finite bending of multilayers in a dual-shape memory effect(SME) cycle.The layer number and layering order are investigated for two different SMPs and a hyperelastic material.In addition to the semi-analytical solution,the finite element simulation is performed to verify the predicted results,where the outcomes demonstrate the excellent accuracy of the proposed solution for predicting the behavior of the multilayer SMPs.Since this method has a much lower computational cost than the finite element method(FEM),it can be used as an effective tool to analyze the SMP behavior under different conditions,including different materials,different geometries,different layer numbers,and different layer arrangements.

关键词： smart material shape memory polymer(SMP) semi-analytical solution thermo-visco-hyperelasticity finite strain bending

Rail Internal Defect Detection Method Based on Enhanced Network Structure and Module Design Using Ultrasonic Images

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Chinese Journal of mechanical engineering 2023年第6期36卷 277-288页

作者： Fupei Wu Xiaoyang Xie Weilin Ye Department of mechanical engineering College of EngineeringShantou UniversityShantou 515063China

Improving the detection accuracy of rail internal defects and the generalization ability of detection models are not only the main problems in the field of defect detection but also the key to ensuring the safe operation of high-speed trains.For this reason,a rail internal defect detection method based on an enhanced network structure and module design using ultrasonic images is proposed in this paper.First,a data augmentation method was used to extend the existing image dataset to obtain appropriate image samples.Second,an enhanced network structure was designed to make full use of the high-level and low-level feature information in the image,which improved the accuracy of defect detection.Subsequently,to optimize the detection performance of the proposed model,the Mish activation function was used to design the block module of the feature extraction network.Finally,the pro-posed rail defect detection model was trained.The experimental results showed that the precision rate and F1score of the proposed method were as high as 98%,while the model’s recall rate reached 99%.Specifically,good detec-tion results were achieved for different types of defects,which provides a reference for the engineering application of internal defect detection.Experimental results verified the effectiveness of the proposed method.

关键词： Ultrasonic detection Rail defects detection Deep learning Enhanced network structure Module design

Motion Planning for a Cable-Driven Lower Limb Rehabilitation Robot with Movable Distal Anchor Points

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Journal of Bionic engineering 2023年第4期20卷 1585-1596页

作者： Jinghang Li Keyi Wang Yanzhuo Wang Chao Wang college of mechanical and Electrical engineering Harbin Engineering UniversityHarbin150001China

This article introduces a cable-driven lower limb rehabilitation robot with movable distal anchor points(M-CDLR).The traditional cable-driven parallel robots(CDPRs)control the moving platform by changing the length of cables,M-CDLR can also adjust the position of the distal anchor point when the moving platform moves.The M-CDLR this article proposed has gait and single-leg training modes,which correspond to the plane and space motion of the moving platform,respectively.After introducing the system structure configuration,the generalized kinematics and dynamics of M-CDLR are established.The fully constrained CDPRs can provide more stable rehabilitation training than the under-constrained one but requires more cables.Therefore,a motion planning method for the movable distal anchor point of M-CDLR is proposed to realize the theoretically fully constrained with fewer cables.Then the expected trajectory of the moving platform is obtained from the motion capture experiment,and the motion planning of M-CDLR under two training modes is simulated.The simulation results verify the effectiveness of the proposed motion planning method.This study serves as a basic theoretical study of the structure optimization and control strategy of M-CDLR.

关键词： Bionic robot Cable-driven parallel robot(CDPR) Lower limb rehabilitation robot Movable anchor point Motion planning Simulation

Prediction of pressure gradient and hold-up in horizontal liquid-liquid pipe flow

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Petroleum Science 2023年第6期20卷 3766-3782页

作者： Syed Amjad Ahmed Bibin John School of mechanical engineering Vellore Institute of TechnologyIndia Department of mechanical engineering C Abdul Hakeem College of Engineering&TechnologyIndia

This paper aims to propose correlations to predict pressure gradient,friction factor and fluid phase hold-up in liquid-liquid horizontal pipe flow.To develop the correlations,experiments are conducted using high viscous oils(202 and 630 mPa⋅s)in a steel pipe of length 11.25 m and length-to-diameter ratio of 708.In addition,the experimental data from the literature comprising wide range of flow and fluid properties is analyzed.For the analysis,the liquid-liquid pipe flow data is categorized into two as:stratified and dispersed.The existing friction factor correlations are modified to incorporate the effects of viscosity of the oil phase,interfacial curvature(contact/wetting angle-in lieu of material of the pipe)and fluid phase fraction.In the two-fluid model of stratified flow,the wall stress and interfacial stress correlations are substituted with superficial velocities of fluids and superficial Reynolds numbers of fluid phases replacing fluid phase velocities and fluid Reynolds numbers.Similarly,for dispersed flow,an effective Reynolds number is described as the sum of superficial Reynolds number of oil and water phases.Substituting the generally employed mean or mixture Reynolds number with the effective Reynolds number into the existing single-phase turbulent flow friction factor correlation,an effective friction factor for oil-water flow is proposed.Employing the proposed correlations,the pressure gradient across the oil-water flow and hold-up volume fraction are predicted with significant reduction in error compared with that of conventionally employed correlations.The average error and standard deviation values of−7.06%,20.72%and 0.31%,18.79%are found for stratified flow and dispersed flow respectively.

关键词： oil-water flow two-fluid model pressure gradient stratified flow dispersed flow

Data-driven fault diagnosis of control valve with missing data based on modeling and deep residual shrinkage network

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Journal of Zhejiang University-Science A(Applied Physics & engineering) 2022年第4期23卷 303-313页

作者： Feng SUN He XU Yu-han ZHAO Yu-dong ZHANG college of mechanical and Electrical engineering Harbin Engineering UniversityHarbin150001China

A control valve is one of the most widely used machines in hydraulic systems.However,it often works in harsh environments and failure occurs from time to time.An intelligent and robust control valve fault diagnosis is therefore important for operation of the system.In this study,a fault diagnosis based on the mathematical model(MM)imputation and the modified deep residual shrinkage network(MDRSN)is proposed to solve the problem that data-driven models for control valves are susceptible to changing operating conditions and missing data.The multiple fault time-series samples of the control valve at different openings are collected for fault diagnosis to verify the effectiveness of the proposed method.The effects of the proposed method in missing data imputation and fault diagnosis are analyzed.Compared with random and k-nearest neighbor(KNN)imputation,the accuracies of MM-based imputation are improved by 17.87%and 21.18%,in the circumstances of a20.00%data missing rate at valve opening from 10%to 28%.Furthermore,the results show that the proposed MDRSN can maintain high fault diagnosis accuracy with missing data.

关键词： Control valve Missing data Fault diagnosis Mathematical model(MM) Deep residual shrinkage network(DRSN)

Abnormal Twinning Behavior and Constitutive Modeling of a Fine-Grained Extruded Mg-8.0Al-0.1Mn-2.0Ca Alloy under High-Speed Impact along Various Directions

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Acta Metallurgica Sinica(English Letters) 2023年第2期36卷 281-294页

作者： Fei-Yang Chen Peng-Cheng Guo Zi-Han Jiang Xiao Liu Tie-Jun Song Chao Xie college of mechanical and Electrical engineering Central South University of Forestry and TechnologyChangsha410004China College of Mechanical Engineering and Mechanics Ningbo UniversityNingbo315211China College of Mechanical Engineering Xiangtan UniversityXiangtan411105China college of Material Science and engineering Hunan University of Science and TechnologyXiangtan411201China

To understand the mechanical and twinning behaviors of a fine-grained extruded Mg-8.0Al-0.1Mn-2.0Ca alloy under high-speed impact,impact tests were carried out using a split Hopkinson pressure bar,and microstructures at strains of 0.05,0.10 and 0.20 were obtained using a series of stop rings manufactured by high-strength steel.The stress response and twinning behavior are closely related to loading direction and applied strain rate.The true stress-true strain curves are s-shaped in extrusion direction(ED)and c-shaped in transverse direction(TD),showing apparent anisotropy,while the yield strength is insensitive to loading direction.Almost identical strain-rate sensitivity is demonstrated by the stress in ED and TD.Interestingly,de-twinning is apparent as the applied strain increases to 0.20,and it is enhanced with increasing the applied strain rate.In contrast,the twin density in ED samples is clearly higher than that in TD samples.By modifying the terms of strain hardening and strain rate hardening in the classical JC model,an optimized model is built,which can accurately predict the stress response behavior of the studied alloy under high-speed impact along ED and TD.The correlation coefficient(R)and average absolute relative error(AARE)are 98.63%and 0.0199 for ED,and 96.88%and 0.0202 for TD,respectively.

关键词： High-speed impact Magnesium alloy Twinning behavior Constitutive model Anisotropy

激光焊接铜与不锈钢接头之间焊缝区显微组织的非均匀性（英文）

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Transactions of Nonferrous Metals Society of China 2020年第3期30卷 727-745页

作者： Saranarayanan RAMACHANDRAN A.K.LAKSHMINARAYANAN Department of mechanical engineering SSN College of Engineering

研究激光焊接(LBW)工艺对铜(Cu)和不锈钢(SS)异种焊缝显微组织与力学性能关系的影响。采用背散射(BSE)扫描电子显微镜(SEM)成像来表征LBW (Cu-SS)焊缝的高度非均匀组织特征。BSE分析充分证明在异种焊接界面和熔合区产生复杂的显微组织... 详细信息

研究激光焊接(LBW)工艺对铜(Cu)和不锈钢(SS)异种焊缝显微组织与力学性能关系的影响。采用背散射(BSE)扫描电子显微镜(SEM)成像来表征LBW (Cu-SS)焊缝的高度非均匀组织特征。BSE分析充分证明在异种焊接界面和熔合区产生复杂的显微组织。沿铜/焊缝界面存在明显的晶粒生长差异:从粗柱状晶到等轴状超细晶。高分辨电子背散射衍射(EBSD)分析证实铜/焊缝界面存在晶粒细化机制。拉伸和冲击试验结果表明,异种焊缝的拉伸和冲击性能与铜基体的基本一致。在熔合区和铜/焊接界面区等非均匀材料成分区,存在明显的显微硬度梯度。为了全面了解局部焊缝亚区的组织与性能的关系,确定出焊缝亚区的异质形核点,并与显微硬度测试结果相互关联。

关键词：激光焊接铜不锈钢显微组织表征拉伸性能冲击韧性