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

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.

Study on Remeshing Technique for Three-Dimensional Rigid-plastic Finite Element Simulation

A new method of three-dimensional remeshing is proposed for rigid-plastic finiteelement analysis of a complicated forging process.The forging process of a cylindricalhousing has been simulated to show the effectiveness of the scheme.The result ofsimulation shows that the computation can be effectively carried out by using the des-cribed remeshing scheme.

Simulation of bulk metal forming processes using one-step finite element approach based on deformation theory of plasticity

The bulk metal forming processes were simulated by using a one-step finite element(FE)approach based on deformation theory of plasticity,which enables rapid prediction of final workpiece configurations and stress/strain distributions.This approach was implemented to minimize the approximated plastic potential energy derived from the total plastic work and the equivalent external work in static equilibrium,for incompressibly rigid-plastic materials,by FE calculation based on the extremum work principle.The one-step forward simulations of compression and rolling processes were presented as examples,and the results were compared with those obtained by classical incremental FE simulation to verify the feasibility and validity of the proposed method.

Identification of processing window for extrusion of large thick-walled Inconel 625 alloy pipes using response surface methodology

Identifying suitable processing window is necessary but difficult for achieving favorable microstructure and performance in extrusion of large thick-walled pipe with difficult-to-deform Inconel 625 alloy. In this work, a method was established for identifying the extrusion process window considering temperature control using response surface methodology. Firstly, the response surface models, which correlate temperature rise and peak temperature to key extrusion parameters, have been developed by orthogonal regression based on finite element calculated data. Secondly, the coupled effects of the key extrusion parameters on the temperature rise and peak temperature have been disclosed based on the regression models. Lastly, suitable extrusion processing windows, which are described by contour map of peak temperature in the space of extrusion speed and initial billet temperature, have been established for different extrusion ratios. Using the identified process window, a suitable combination of the key extrusion parameters can be determined conveniently and quickly.

FINITE ELEMENT ANALYSIS AND EXPERIMENTAL STUDY OF THE METAL MULTIDIE IRONING PROCESS

Taking double-die ironing for example, the plastic deformation behavior of theworkpiece in multidie ironing process is analysed by the rigid-plastic finite element method(RPFEM).Considering the strain hardening of the material, the distrbutions of the effective strainrate and hydrostatic stress are obtained. Calculated results and the effect of die argles on thedeformation and ironing force are discussed. The companrson of calculated results with thcoe of ex-poriment shows a good agreement.

A Numerical Method for Rigid-plastic FEM Analysis Basing on Mathematical Programming

The rigid-plastic analysis of mental forming simulation is formulated as a discrete nonlinear mathematical programming problem with equality and inequality constraints by means of the finite element technique. An iteration algorithm is used to solve this formulation, which distinguishes the integration points of the rigid zones and the plastic zones and solves a series of the quadratic programming to overcome the difficulties caused by the nonsmoothness and the nonlinearity of the objective function. This method has been used to carry out the rigid-plastic FEM analysis. An example is given to demonstrate the effectiveness of this method.

Simulation optimal design of a compliant mechanism with circular notch flexure hinges based on the equivalent beam methodology

This paper presents an in-depth study of Equivalent beam model (EBM).Firstly three-dimensional (3D) finite element analysis (FEA) model for circular flexure hinge developed by Zettl et al.was verified by the comparison with Smith's experimental results and the 3D FEA model was feasible within 5.5% error.Then the accuracy of Timoshenko short-beam due to shear force was verified based on finite element method.The results showed that the EBM has good accuracy within 5% error for 1≤r/t≤3.Finally the EBM methodology was applied for the simulation optimal design of a bridge-type compliant mechanism.The results showed that the EBM methodology has very high numerical efficiency and satisfactory accuracy for simulation optimal design of planar compliant mechanism with flexure hinges.

DEEP-DRAWING PROCESS ANALYSIS OF ELLIPTIC CUPS BY RIGID-PLASTIC FEM

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Development of an Accurate Numerical Methodology for Predicting the First Three Modes of Vibration of an Electric Motor Fixed on a Rigid Base

This paper proposes a numerical methodology for the prediction of the first three modes of vibration of an electric motor fixed on a rigid base. A deep literature review supported the production of four ad hoc prototypes that aided the development of the proposed approach. Tests carried out with the prototypes led to the procurement of the modal parameters be used to calibrate the numerical models, as well as the FRF （frequency response function） curves be used to validate the numerical solution. The validated model allowed structural changes to be then promoted on the prototypes, in order to make them more robust to variations in manufacturing and assembling processes. The mentioned adjustments and structural changes were accomplished by means of a process of structural optimization using Genetic Algorithm. The solution was developed based on the commercial finite element code ANSYS. The practical results obtained in this study show that a numerical model for modal analysis of an electric motor fixed on a rigid base with errors less than 3% for the first three modes of vibration can be achieved, allowing positive structural changes to be performed in the machine design that result in the minimization of manufacturing reworks associated with the dynamic behavior of the studied motor.

谐波减速器集成式扭矩传感器的设计与测试

为实现协作机器人关节力控和提高集成度,提出一种集成于谐波减速器内部的扭矩传感器,以精确获取关节输出扭矩值,推动智能化控制的实现。采用有限元计算方法分析了谐波减速器柔轮底面应变与加载扭矩之间的规律;然后根据有限元分析的结果,考虑柔轮底面敏感栅在不同栅丝长度、栅丝间距和栅丝位置情况下,建立底面应变与扭矩变化皮尔逊相关系数的响应面模型,求解模型获得最优的敏感栅结构参数,确保该结构下集成式传感器具有最佳线性响应,结合惠斯通电桥原理设计扭矩传感器结构;最后,对集成式扭矩传感器进行标定和测试。结果表明:集成式扭矩传感器的灵敏度为0.249 mV/N·m,线性度为0.99974,迟滞误差为2.19%。施加0~70 N·m之间阶梯变化的负载扭矩并进行重复实验,集成式扭矩传感器相对于标准扭矩传感器均方根误差为0.89~0.98 N·m。施加在±70 N·m之间正弦变化的负载扭矩,均方根误差为0.96~1.05 N·m。该集成式扭矩传感器能够较为精准地感应负载扭矩,有助于实现协作机器人关节力控制,提升机器人系统的集成度。

成组立模成型机模板结构优化设计研究

混凝土预制构件成组立模成型机(简称成组立模)是一种新型的生产混凝土预制构件的设备。为了提高成组立模台面的振动效果和承载能力,本研究以成组立模模板结构为研究对象,提出了一种拓扑优化新兴设计与响应面法结合的优化设计理论。首先,基于变密度法对成组立模模板结构加强筋布局进行拓扑优化设计,得到了加强筋最佳的材料分布形式,以此对成组立模模板结构进行了结构优化设计。为得到最佳的加强筋设计参数,采用中心组合试验设计,建立模板结构最大位移、最大等效应力的响应面模型。利用多目标遗传算法对响应面模型进行优化求解,得出加强筋各参数最优的组合方案。有限元分析结果表明:与初始方案相比,优化设计方案提高了台面的刚度和强度,同时改善了模板结构的振动特性,并提高了混凝土预制构件的成型质量。该研究为进一步推进成组立模的研究提供了理论指导。

基于响应面法的绞磨机辅助拉尾绳装置优化设计

针对绞磨机辅助拉尾绳装置的轻量化问题,结合装置的刚度和强度要求,提出了一种基于响应面法的优化设计方法。通过对绞磨机辅助拉尾绳装置进行参数化建模和静力学分析,将辅助拉尾绳装置的关键结构尺寸作为设计参数,以整体质量最小为目标函数、最大等效应力和最大变形量为约束条件,采用中心复合设计法建立响应面模型,并对响应面的拟合程度和设计参数的灵敏度进行分析。基于响应面模型迭代寻求最优解集,以获得辅助拉尾绳装置的最优设计参数。经优化设计后,辅助拉尾绳装置的质量减小了29%,且工程验证表明,辅助拉尾绳装置整体轻便高效且工作可靠,达到了预期的应用效果,由此验证了所提出的优化设计方法的可行性和有效性。研究结果可为同类型工程装备的结构优化设计与实际应用提供理论支撑和技术指导。

基于有限元分析的大口径曲面棱镜胶接优化设计

针对大口径曲面棱镜高面形精度的需求,提出了一种考虑胶固化收缩应力的胶结优化设计路线,得到了胶接优化方案。首先,根据胶体非自由固化模型,推导了胶固化应力的有限元微分方程。其次,设计了圆弧形胶斑式柔性粘结环及其框架结构。基于温度载荷法搭建了胶固化对镜面面形影响的仿真模型,并建立了等效胶收缩力关于胶体参数的响应面模型,研究了胶粘剂种类、胶体参数、粘结数量对面形的影响规律,结果表明:选用3 m-2216环氧胶、圆弧形胶斑及其柔性粘结环、在侧面6胶点胶接工况下,曲面棱镜前镜面面形PV值从0.66λ降到0.005λ、RMS值从0.15λ降到0.001λ;后镜面面形PV值从0.61λ降到0.003λ、RMS值从0.14λ降到0.001λ,曲面棱镜面形精度得到显著改善。最后,采用有限元法进行了结构力热特性分析,验证了结构设计的合理性。

基于响应曲面中心组合设计的介质阻挡负载特征参数分析与优化

为了充分发挥介质阻挡放电(DBD)负载的性能,以高频脉冲激励作为介质阻挡负载的激励波形,以第一次放电时的负载电流幅值作为优化目标。基于响应曲面法中心组合设计建立数学模型,分析介质阻挡层厚度、脉冲电压幅值、脉冲升降沿时间和相对介电常数4个因素对高频脉冲激励下DBD负载第一次放电时负载电流幅值的影响,优化介质阻挡负载特征参数。结果表明,对DBD负载电流的影响强度从大到小依次为介质阻挡层厚度、脉冲电压幅值、脉冲升降沿时间、相对介电常数。在本文设定条件下,负载电流幅值的最大值8.692A在脉冲升降沿时间为200ns、脉冲电压幅值为4kV、介质阻挡层厚度为1mm、相对介电常数为8时获得。

基于响应面法的双悬臂搬运桁架结构优化设计

为进行双悬臂搬运桁架结构优化设计,基于三维参数化建模、有限元分析及数值分析建立了克里金(Kriging)响应面法与多目标遗传算法(MOGA)相结合的优化方法,实现了以桁架的强度和刚度作为约束条件,以桁架质量为优化目标的全局优化方法。根据实际桁架的作业情况,对2种特殊工况进行结构分析,表明原始的桁架结构存在较大的安全裕量。采用4种不同方法对桁架静力学分析进行响应面建模,结果表明Kriging方法构建的响应面模型决定系数R2最高。将MOGA算法与Kriging响应面相结合对桁架进行迭代优化,结果表明优化后的桁架在满足强度和刚度的前提下,实现了质量减小20.00%。

关于转体混凝土球铰的重要参数分析

当前对于影响混凝土球铰正常使用的设计参数取值缺乏理论分析依据,本文依托湖北某县在建的转体拱桥,利用有限元软件ABAQUS,创建多个包含球铰结构的有限元模型,其中定义下球铰露出高度、曲率半径、支承半径数据为模型的可变参数,利用控制变量法对比分析数十个有限元模型,研究并归纳三个球铰重要设计参数对混凝土球铰界面接触应力的影响方式,并基于曲面响应法量化上述变化参数的影响性,进而得出相应的结论,通过本文分析可知,曲率半径越大、支承半径越小,球铰接触应力大小分布产生越不利,最后观察Design-Expert软件的ANOVA结果可知,对于球铰最大接触应力的影响最至关重要的设计参数是球铰支承半径。

基于响应面法的立式加工中心动静态多目标优化

为了满足在保证加工中心初始动静态刚度的条件下达到整机轻量化的要求,提出基于质量和第一阶固有频率为目标函数的整机多目标优化设计方法。将有限元分析和模态试验相结合,测试和分析整机动态特性,确保有限元模型精度。通过中心复合设计的试验方法选取合适的结构有限元分析样本点,在ANSYS仿真软件中对样本点处的整机动静态特性进行计算和分析,根据获取的响应值建立反映结构设计输入与响应输出关系的二次多项式响应面模型。利用转移哈默斯利抽样技术,抽取均匀分布于设计空间中的样本点,并对其进行权衡排序,获得较优的初始种群。运用多目标遗传算法对加工中心整机质量和第一阶固有频率进行多目标优化,得到Pareto优化解集,在保证加工中心整机动静态性能不降的前提下,质量减轻6.58%。结果表明,该方法具有较高的精度和较强的工程实用性。

电容式角位移传感器电场有限元仿真研究

对电容式角位移传感器二维及三维的电场进行了有限元法分析 ,同时对不同结构参数的敏感元件进行仿真研究 。

应用ANSYS Workbench对大断面集成材压机机架的优化设计

利用ANSYS Workbench有限元分析软件对大断面集成材压机机架的单个框架进行了静力学分析,以其质量与强度指标为目标,采用ANSYS Gold Driven Optimization模块进行优化设计,旨在研究框架工作过程中的应力、应变分布状态,降低框架生产成本。研究结果表明:优化前,框架存在局部应力集中现象,但最大应力为156.2 MPa,明显小于框架的许用应力196 MPa,强度富余,有进一步优化的空间;水平和垂直方向的最大位移值分别为0.31、0.08mm,刚度可靠。优化后,框架的最大等效应力与最大位移分别为179.8 MPa与0.44 mm,保证框架强度与刚度的前提下,框架的质量降低了26.3%,可显著降低生产成本。

排水性沥青表面层半刚性基层路面温度场分析

为了分析具有排水性沥青面层的半刚性基层路面的温度场,建立了二维有限元模型来对半刚性基层路面的温度场进行预估,并对沪宁高速镇江支线两种结构形式的沥青路面的温度场进行了长时间的监测。发现排水性沥青上面层底面的夏季日最高温度较普通密级配沥青路面低2℃左右,冬季最低温度高1℃左右;排水性沥青路面的半刚性基层顶面日温度变幅较普通密级配沥青混凝土路面低3～4℃;建立的温度预估模型计算结果与实测温度相差较小。结果表明,排水性沥青面层有很好的温度调节作用,能有效改善半刚性基层的温度状况;建立的温度模型可以对半刚性基层路面的温度场进行可靠的预估。