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Optimal design of butterfly-shaped linear ultrasonic motor using finite element method and response surface methodology

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Journal of Central South University 2013年第2期20卷 393-404页

作者：时运来陈超赵淳生 state key laboratory of mechanics and control of Mechanical structures(Nanjing University of Aeronautics and Astronautics)

A new method for optimizing a butterfly-shaped linear ultrasonic motor was proposed to maximize its mechanical output. The finite element analysis technology and response surface methodology were combined together to realize the optimal design of the butterfly-shaped linear ultrasonic motor. First, the operation principle of the motor was introduced. Second, the finite element parameterized model of the stator of the motor was built using ANSYS parametric design language and some structure parameters of the stator were selected as design variables. Third, the sample points were selected in design variable space using latin hypercube Design. Through modal analysis and harmonic response analysis of the stator based on these sample points, the target responses were obtained. These sample points and response values were combined together to build a response surface model. Finally, the simplex method was used to find the optimal solution. The experimental results showed that many aspects of the design requirements of the butterfly-shaped linear ultrasonic motor have been fulfilled. The prototype motor fabricated based on the optimal design result exhibited considerably high dynamic performance, such as no-load speed of 873 ram/s, maximal thrust of 27.5 N, maximal efficiency of 43%, and thrust-weight ratio of 45.8.

关键词： linear ultrasonic motor piezoelectric optimal design response surface methodology finite element method

Effect of Interconnect Linewidth on Evolution of Intragranular Microcracks Due to Electromigration Analyzed by Finite Element Method

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Transactions of Nanjing University of Aeronautics and Astronautics 2019年第2期36卷 290-297页

作者： HE Dingni HUANG Peizhen state key laboratory of mechanics and control of Mechanical structures Nanjing University of Aeronautics and Astronautics

The effect of interconnect linewidth on the evolution of intragranular microcracks due to surface diffusion induced by electromigration is analyzed by finite element *** numerical results indicate that there exists critical values of the linewidth hc,the electric fieldχc and the aspect ratioβ*** h>hc,χ<χc orβ<βc,the microcrack will evolve into a stable shape as it migrates along the interconnect *** h≤hc,χ≥χc orβ≥βc,the microcrack will split into two smaller *** critical electric field,the critical aspect ratio and the splitting time have a stronger dependence on the linewidth when h≤*** addition,the decrease of the linewidth,the increase of the electric field or the aspect ratio is beneficial to accelerate microcrack splitting,which may delay the open failure of the interconnect line.

关键词： finite element method surface diffusion electromigration linewidth microcrack evolution

Model Study of IPMC Beam Electroactive Response Based on Root Deformation

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Journal of Wuhan University of Technology(Materials Science) 2013年第1期28卷 31-39页

作者：彭瀚旻 LI Huafeng ZHAO Chunsheng state key laboratory of mechanics and control of Mechanical structures Nanjing University of Aeronautics and Astronautics

Ionic polymer-metal composite （IPMC） is a type of electroactive polymer （EAP）. In this paper, based on Nemat-Nasser model, an improved model is developed to explain the initial nonlinear response of electric actuation on the fixed end deformation. Three IPMC strip samples with different surface resistance are chosen for analysis. Further, from simulation and experiment results, it is found that the root deformation made the tip movement of the IPMC strip with little surface resistance, but this effect was less and less when the surface resistance reduced. The calculation results of this model for the fixed end show a more accurate simulation for the actual deformation of IPMC strips.

关键词： IPMC EAP polymer coupling model fixed end root deformation

Structural Design and control of Variable Camber Wing Driven by Ultrasonic Motors

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Transactions of Nanjing University of Aeronautics and Astronautics 2015年第2期32卷 180-186页

作者：刘卫东朱华周盛强白亚磊赵淳生 state key laboratory of mechanics and control of Mechanical structures Nanjing University of Aeronautics and Astronautics

A novel variable camber wing driven by ultrasonic motors is *** techniques of distributed layout of drive mechanisms,coordination control of distributed ultrasonic motors as well as novel flexible skin undergoing one-dimensional morphing are *** system integration of small variable camber wing is *** layout of parallelogram linkages driven by geared ultrasonic motors is adopted for morphing,aimed at reducing the load for each motor and producing various aerodynamic configurations suitable for different flying *** system-on-chip(PSoC)is used to realize the coordination control of the distributed ultrasonic *** the morphing driving systems are assembled in the interior of the *** wing surface is covered with a novel smooth flexible skin in order to maintain wing shape and decrease the aerodynamic drag during *** tunnel test shows that the variable camber wing can realize morphing under low speed flight *** and drag characteristics and aerodynamic efficiency of the wing are *** configurations can be selected to satisfy aerodynamic requirements of different flight *** study provides a practical application of piezoelectric precision driving technology in flow control.

关键词： variable camber wing ultrasonic motors(USMs) morphing skin control system wind tunnel test

Mechanical Behavior of Bistable Bump Surface for Morphing Inlet

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Transactions of Nanjing University of Aeronautics and Astronautics 2015年第6期32卷 610-622页

作者：张平周丽程文杰 state key laboratory of mechanics and control of Mechanical structures Nanjing University of Aeronautics and Astronautics

There exists inlet-engine match conflict between high and low speeds for a non-adjustable bump inlet.A scheme of using a bistable bump surface at the throat region of the inlet is proposed to adjust the throat *** FEM model of the bistable surface is established with hinged constraint,and the bistability condition and structural transition process are investigated in ***,the effects of loading method,loading position and structural parameters on critical driving force,input energy and structural strain are ***,the influences of an elastic boundary condition on the structural bistability are *** results show that the bistability of the adjustable bump surface requires a certain boundary constraint and geometric parameter combination,and that there are local and overall snap-through phenomena during transition which are related to the loading position and structural ***,suitable loading position and structural material could reduce input energy and meet the demand of structural strain.

关键词： bistable structure inlet-engine match bump surface morphing inlet transition process

Crack Propagation Path in Two-Directionally Graded Composites Subjected to Mixed-Mode Ⅰ+Ⅱ Loading

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Transactions of Nanjing University of Aeronautics and Astronautics 2017年第3期34卷 272-285页

作者： Zhao Zhenbo Xu Xiwu Guo Shuxiang state key laboratory of mechanics and control of Mechanical structures Nanjing University of Aeronautics and Astronautics

Crack propagation path in two-directionally graded composites was investigated by the finite element method.A graded extended finite element method(XFEM)was employed to calculate displacement and stress fields in cracked graded *** a post-processing subroutine of interaction energy integral was implemented to extract the mixed-mode stress intensity factors(SIFs).The maximum hoop stress(MHS)criterion was adopted to predict crack growth direction based on the assumption of local homogenization of asymptotic crack-tip fields in graded *** of material nonhomogeneous parameters on crack propagation paths were also discussed in *** is shown that the present method can provide relatively accurate predictions of crack paths in two-directionally graded *** propagates in the decreasing direction of effective Young′s *** shape and steepness of property gradient perpendicular to the crack surface have great influences on crack *** redesigning material property reasonably,crack growth in graded material can be changed to improve mechanical behaviours of cracked structures.

关键词： graded cracked asymptotic homogenization reasonably criterion Loading assumption traction modulus

An Efficient Method for Local Buckling Analysis of Stiffened Panels

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Transactions of Nanjing University of Aeronautics and Astronautics 2019年第1期36卷 17-25页

作者： WANG Xinwei YUAN Zhangxian state key laboratory of mechanics and control of Mechanical structures Nanjing University of Aeronautics and Astronautics School of aerospace Engineering Georgia Institute of Technology

The local buckling of stiffened panels is one of possible failure modes and concerned by engineers in the preliminary design of lightweight structures. In practice,a simplified model,i.e.,a rectangular plate with elastically restrained along its unloaded edges,is established and the Ritz method is usually employed for solutions. To use the Ritz method,however,the loaded edges of the plate are usually assumed to be simply supported. An empirical correction factor has to be used to account for clamped loaded edges. Here,a simple and efficient method,called the quadrature element method(QEM),is presented for obtaining accurate buckling behavior of rectangular plates with any combinations of boundary conditions, including the elastically restrained conditions. Different from the conventional high order finite element method(FEM),non-uniformly distributed nodes are used,and thus the method can achieve an exponential rate of convergence. Formulations are worked out in detail. A computer program is developed. Improvement of solution accuracy can be easily achieved by changing the number of element nodes in the computer program. Several numerical examples are given. Results are compared with either existing solutions or finite element data for verifications. It is shown that high solution accuracy is achieved. In addition,the proposed method and developed computer program can allow quick analysis of local buckling of stiffened panels and thus is suitable for optimization routines in the preliminary design stage.

关键词： local buckling quadrature element method elastically restrained stiffened panel

Design of a Non-cooperative Target Capture Mechanism

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Transactions of Nanjing University of Aeronautics and Astronautics 2019年第1期36卷 146-153页

作者： WANG Chen NIE Hong CHEN Jinbao PAN Zhengwei state key laboratory of mechanics and control of Mechanical structures Nanjing University of Aeronautics and Astronautics

A passive compliant non-cooperative target capture mechanism is designed to maintain the non-cooperative target on-orbit. When the relative position between capture mechanism and satellite is confirmed,a pair of four-bar linkages lock the docking ring,which is used for connecting the satellite and the rocket. The mathematical model of capture mechanism and capture space is built by the Denavit-Hartenberg(D-H)method,and the torque of each joint is analyzed by the Lagrange dynamic equation. Besides,the capture condition and the torque of every joint under different capture conditions are analyzed by simulation in MSC. Adams. The results indicate that the mechanism can capture the non-cooperative target satellite in a wide range. During the process of capture,the passive compliant mechanism at the bottom can increase capture space,thereby reducing the difficulty and enhance stability of the capture.

关键词： non-cooperative target passive compliance capture mechanism kinematics analysis dynamics analysis

Numerical Simulation on Intergranular Microcracks in Interconnect Lines Due to Surface Diffusion Induced by Stress-,Electro-and Thermo-migration

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Transactions of Nanjing University of Aeronautics and Astronautics 2019年第6期36卷 1004-1017页

作者： ZHOU Linyong HUANG Peizhen state key laboratory of mechanics and control of Mechanical structures Nanjing University of Aeronautics and Astronautics

Based on the weak formulation for combined surface diffusion and evaporation-condensation,a governing equation of the finite element is derived for simulating the evolution of intergranular microcracks in copper interconnects induced simultaneously by stressmigration,electromigration and *** previously published works,the effect of thermomigration is *** results show that thermomigration can contribute to the microcrack splitting and accelerate the drifting process along the direction of the electric *** evolution of the intergranular microcracks depends on the mechanical stress field,the temperature gradient field,the electric field,the initial aspect ratio and the *** there exists a critical electric fieldχ_c,a critical stress field■,a critical aspect ratioβ_c and a critical linewidth■.When■or■,the intergranular microcrack will split into two or three small intergranular ***,the microcrack will evolve into a stable shape as it migrates along the interconnect *** critical stress field,the critical electric field and the critical aspect ratio decrease with a decrease in the linewidth,and the critical linewidth increases with an increase in the electric field and the aspect *** increase of the stress field,the electric field or the aspect ratio and the decrease of the linewidth are not only beneficial for the intergranular microcrack to split but also accelerate the microcrack splitting process.

关键词： stressmigration electromigration thermomigration surface diffusion finite element method intergranular microcrack