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Applied Mathematics and Mechanics(English Edition) 2000年第2期21卷 185-192页

作者：马景槐 Xinjiang Petroleum Institute Ulumuqi P R China

The virtual displacement principle of elasto-plastic damage mechanics is presented. A linear complementary method for elasto-plastic damage problem is proposed by using FEM technique. This method is applicable to solv... 详细信息

关键词： elasto-plastic damage mechanics virtual work principle FEM technique linear complementary method

Plastic deformation analysis and forming quality prediction of tube N C bending

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Chinese Journal of Aeronautics 2016年第5期29卷 1436-1444页

作者： Lu Shiqiang Fang Jun Wang Kelu National Defense Key Disciplines Laboratory of Light Alloy Processing Science and Technology School of Aeronautical Manufacturing Engineering Nanchang Hangkong University Nanchang 330063 China Jiangxi Key Laboratory of Surface Engineering Jiangxi Science and Technology Normal University Nanchang 330013 China

Plane strain assumption and exponent hardening law are used to investigate the plastic deformation in tube bending. Some theoretical formulae including stress, curvature radius of neutral layer, angle of neutral layer deviation, bending moment, wall thickness variation and crosssection distortion, are developed to explain the phenomena in tube bending and their magnitudes are also determined. During unloading process, the springback angle is deduced using the virtual work principle, and springback radius is also given according to the length of the neutral layer which remains unchanged before and after springback. The theoretical formulae are validated by the experimental results or the validated simulation results in literature, which can be used to auicklv predict the forming aualitv of tube numerical control （NC） bending.

关键词： Forming quality Plane strain Tube NC bending Theoretical analysis virtual work principle

Third-order polynomial model for analyzing stickup state laminated structure in flexible electronics

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Acta Mechanica Sinica 2018年第1期34卷 48-61页

作者： Xianhong Meng Zihao Wang Boya Liu Shuodao Wang School of Aeronautic Science and Engineering Beihang University Beijing 100191 China School of Mechanical and Aerospace Engineering Oklahoma State University Stillwater OK 74078 USA

Laminated hard-soft integrated structures play a significant role in the fabrication and development of flexible electronics devices. Flexible electronics have advantageous characteristics such as soft and light-weight, can be folded,twisted, flipped inside-out, or be pasted onto other surfaces of arbitrary shapes. In this paper, an analytical model is presented to study the mechanics of laminated hard-soft structures in flexible electronics under a stickup state. Thirdorder polynomials are used to describe the displacement field,and the principle of virtual work is adopted to derive the governing equations and boundary conditions. The normal strain and the shear stress along the thickness direction in the bimaterial region are obtained analytically, which agree well with the results from finite element analysis. The analytical model can be used to analyze stickup state laminated structures, and can serve as a valuable reference for the failure prediction and optimal design of flexible electronics in the future.

关键词： Flexible electronics Stickup state Third-order polynomials virtual work principle

Bioinspired Spiral Soft Pneumatic Actuator and Its Characterization

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Journal of Bionic Engineering 2021年第5期18卷 1101-1116页

作者： Zhiyuan Zhang Xueqian Wang Deshan Meng Bin Liang Shenzhen Key Laboratory of Intelligent Robotics Tsinghua Shenzhen International Graduate SchoolShenzhen 518055China Institute of Robotics and Intelligent Systems ETH Zurich8801 ZurichSwitzerland Research Institute of Tsinghua University at Shenzhen Shenzhen 518057China School of Aeronautics and Astronautics Sun Yat-Sen UniversityShenzhen 518107China

Soft robots have unique advantages over traditional rigid robots and have broad application prospects in many fields.To expand their bioinspired applications,we propose a novel Soft Pneumatic Actuator(SPA)associated with spiral configuration inspired by the structure and unwinding motion of the seahorse tail.Diff erent from bending motion of common soft actuators,the spiral SPA can generate unwinding motion as input air pressure increases.First,to explore the eff ect of diff erent initial spiral types on unwinding performance,three typical spiral SPAs are designed and simulated while keeping the outside arc of actuator body constant.Second,a static model of the spiral SPA is established by combining the hyperelastic material model,geometric relationships,and virtual work principle.To improve model accuracy,two geometric correction parameters are employed and their physical significance is analyzed by finite element simulations.Third,a prototype of the logarithmic spiral SPA(Log_spiral SPA)is fabricated and a Fiber Bragg Grating(FBG)sensor array is designed to detect and reconstruct unwinding shapes of the prototype.Finally,the unwinding performance,static model and output force capability of the prototype are tested and verified.Furthermore,we discuss prospects for this novel spiral SPA and test its practical applications in inchworm-like motion,assisting finger rehabilitation and object capture.

关键词： Soft robotics Spiral Soft actuator virtual work principle Fiber Bragg grating

Dynamic Modeling and Experiment of a New Type of Parallel Servo Press Considering Gravity Counterbalance

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Chinese Journal of Mechanical Engineering 2013年第6期26卷 1222-1233页

作者： HE Jun GAO Feng BAI Yongjun WU Shengfu State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University China First Heavy Industries

The large capacity servo press is traditionally realized by means of redundant actuation, however there exist the over-constraint problem and interference among actuators, which increases the control difficulty and the product cost. A new type of press mechanism with parallel topology is presented to develop the mechanical servo press with high stamping capacity. The dynamic model considering gravity counterbalance is proposed based on the virtual work principle, and then the effect of counterbalance cylinder on the dynamic performance of the servo press is studied. It is found that the motor torque required to operate the press is a lot less than the others when the ratio of the counterbalance force to the gravity of ram is in the vicinity of 1.0. The stamping force of the real press prototype can reach up to 25 MN on the position of 13 mm away from the bottom dead center. The typical deep-drawing process with 1 200 mm stroke at 8 strokes per minute is proposed by means of five order polynomial. On this process condition, the driving torques are calculated based on the above dynamic model and the torque measuring test is also carried out on the prototype. It is shown that the curve trend of calculation torque is consistent to the measured result and that the average error is less than 15%. The parallel mechanism is introduced into the development of large capacity servo press to avoid the over-constraint and interference of traditional redundant actuation, and its dynamic characteristics with gravity counterbalance are presented.

关键词： mechanical press parallel mechanism dynamic modeling virtual work principle

Analysis on Buckling Performance of Submarine Pipelines During Deepwater Pipe-Laying Operation

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China Ocean Engineering 2009年第2期23卷 303-316页

作者：袁林龚顺风金伟良李志刚赵冬岩 Institute of Structural Engineering Zhejiang University Offshore Oil Engineering Co. Ltd

Pipes inevitably encounter high ambient pressure and bending moment during the deepwater pipe-laying process,which can lead to elliptical buckling and even deterioration failure.For the safety of pipe-laying operation,available formulas for the pipe stability are established on the basis of the assumption of uniform deformation along the tube length and symmetrical buckling.This method can predict the nonlinear response of elliptical collapse of steel circular tubes for different ratios of diameter to thickness（D/t）under pure bending or combined bending and external pressure.In these formulas,the strain-displacement relationship is deduced from the nonlinear ring theory,and the Ramberg-Osgood constitutive model is applied to simulate the inelastic material behavior.Meanwhile,the principle of virtual work is adopted to derive the equilibrium equations.A set of equations is solved by the Newton-Raphson method,and the iterative scheme contains nested iteration for the constitutive relation.In order to check the effectiveness of this theoretical method,illustrative examples are presented in this paper.Besides,the numerical simulation is carried out by use of ANSYS.A comparison of the results shows that the theoretical method can provide reasonable prediction for engineering practice.

关键词： submarine pipeline buckling deep water pipe-laying nonlinear ring theory virtual work principle numerical simulation

STIFFNESS ANALYSIS OF THREE DEGREE OF FREEDOM PARALLEL MANIPULATOR

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STIFFNESS ANALYSIS OF THREE DEGREE OF FREEDOM PARALLEL MANIP...