基于UG的焊缝建模和有限元分析技术

利用UG的焊接助理模块和高级仿真模块实现了焊缝的实体建模和有限元分析过程。考虑到焊缝结构尺寸对焊缝强度的影响,提出了从结构角度出发建立焊缝的有限元模型,利用UG NX4的刚性杆单元模拟焊缝的焊接,并比较了3种尺寸类型的焊缝在两种工况下的应力情况。结果表明,UG NX4的刚性杆单元可以真实地模拟焊缝的焊接;坡口夹角对焊缝强度影响较大,有无钝边对焊缝强度影响较小。     

蜂窝夹芯板参数化建模与优化设计

在蜂窝夹芯板的有限元分析过程中,为提高结构的建模和分析效率,基于有限元软件开发参数化建模与分析模块,可以完整地进行蜂窝结构的建模、分析、校核与后处理,使蜂窝结构的有限元分析过程流程化、高效化.在此基础上,以质量轻量化为目标,以结构强度为约束条件,基于MATLAB使用遗传算法、罚函数法、模式搜索法对蜂窝结构进行尺寸参数优...     

基于Deform 3D的金属车削过程仿真

基于材料变形的弹塑性理论、热力耦合理论以及Usui磨损模型,采用有限元仿真技术,利用三维仿真软件Deform对车削过程进行仿真,得出了在不同切削用量下切削力的变化规律、切削过程中刀具中切削应力的分布情况以及刀具表面切削热的分布情况。仿真结果为生产实践中切削用量的优化选择提供理论依据。     

瑞风商务车托架拉延成形数值模拟及工艺参数优化

基于逆向工程建立瑞风商务车托架零件的几何模型,并基于Dynaform软件平台对不同工艺参数下该零件的拉延成形过程进行数值模拟。在此基础上,以压边力、拉延筋高度和拉延筋圆角半径作为设计变量,以零件不发生破裂为优化目标,以有限元数值模拟结果作为虚拟样本,建立目标函数的人工神经网络预测模型;将人工神经网络预测模型作为优化算法的知识源,采用遗传算法对压边力、拉深筋几何参数等工艺参数进行了优化设计。试验结果表明,数值模拟、神经网络预测和工艺优化是可靠的,从而可为制定金属板料最佳的冲压成形工艺提供一条先进、合理的途径。     

超声振动车削的有限元仿真及参数优化

基于超声振动切削中的关键参数振幅、振动频率和切削速度,针对如何确定其最优值的问题,以典型的难加工材料不锈钢作为研究对象,利用ABAQUS建立有限元模型,通过数学模型和试验数据验证有限元模型的准确性,并结合优化软件ISIGHT进行联合优化,采用全局优化中的Evol进化优化算法得到超声加工中的最优刀具参数和最优切削参数。     

Semi-analytical formulation for the guided waves-based reconstruction of elastic moduli

In this study an inverse procedure based on the propagation of guided ultrasonic waves is proposed for the characterization of the elastic material constants of plates. The procedure consists of an optimization problem in which the discrepancy between the dispersion curves obtained through a semi analytical finite element (SAFE) formulation and numerical or experimental dispersion curves is minimized. The numerical dispersion curves were obtained from the application of the commercial finite element analysis software ANSYS. Finally experimental data were obtained by adopting a hybrid broadband laser/PZT ultrasonic set-up in a pitch-catch configuration. For both numerical and experimental data, the joint time-frequency analysis of the continuous wavelet transform was used.The optimization scheme proposed in this study is based on an improved version of the simplex search method. The scheme inputs an initial guess of the material parameters in the SAFE formulation. The values of these parameters are iteratively updated until the discrepancy between the SAFE-based group velocity dispersion curves and the numerical or experimental curves is minimized. The scheme is designed to minimize the discrepancy associated with the lowest symmetric and anti-symmetric order mode simultaneously.The validity of the SAFE method coupled to the inverse procedure scheme is tested to characterize the elastic material properties of a 2.54 mm thick aluminum plate. As the SAFE formulation is valid for waveguides of arbitrary cross-section the paper represents the first step toward the integration of an inversion scheme applicable into the SAFE algorithm to characterize the material properties of waveguides of complex geometries and various boundary conditions.     

Optimization of the forging of aerofoil blade using the finite element method and fuzzy-Pareto based genetic algorithm

In this research non-isothermal forging process of an aerofoil blade was simulated using 3-dimentional finite element method. Then an optimization approach integrated with the finite element method has been applied to optimize the blade forging process. Preform shape and angular position of the die parting line were optimized in order to minimize the flash volume, strain non-uniformity and lateral forces generated during the forging operation. The optimization method includes the finite element approach and the response surface method for the formulation of the objective functions. Using the multi-objective genetic algorithm, Pareto front of global optimal solutions was generated. Then a fuzzy-based membership value assignment method was used to select the best compromise solution. The simulation of the blade forging process was verified by experimental test. Results show that the numerical results and experimental tests have a good agreement. Waste material and lateral forces generated during the forging operation is decreased with optimization method significantly. Therefore the proposed approach is an appropriate method for multi-objective optimization of the forging process of aerofoil blades.     

Investigation of the grinding temperature and energy partition during cylindrical grinding

In this study, the distribution of temperature and energy under the process parameter conditions and thermal physical parameters are investigated using a physics-based model via the finite element modeling (FEM) simulation and experimental validation during cylindrical grinding. A cylindrical grinding model is modeled to simulate the chip removal behavior in the grinding process and to measure the workpiece and chip temperatures by refining the temperature field. Workpiece speed affects the energy partition into chip more obviously than other grinding parameters. Reasonable selection of grinding parameters greatly reduces the energy partition into the workpiece from 80% to 50–30% or even lower. This study offers a comprehensive understanding of heating mechanisms during grinding and thus is very beneficial for process optimization.     

金属橡胶减振器随机振动有限元仿真

提出一种金属橡胶减振器随机振动有限元仿真方法,采用正交各向异性阻尼材料模拟金属橡胶材料。相关仿真参数由金属橡胶减振器正弦扫频试验确定。对金属橡胶减振器进行正弦扫频试验和随机振动试验,利用有限元仿真软件ANSYS Workbench对金属橡胶减振器随机振动进行有限元仿真模拟,并将仿真结果与试验结果进行对比分析。研究结果表明,所提出的有限元仿真方法能够很好地对金属橡胶减振器随机振动进行仿真,且计算结果具有较高精度。     

基于UG卷扬机卷筒结构的设计与优化

利用实体建模软件UG建立了卷扬机卷筒的虚拟样机,应用UG NX其"高级仿真"模块,建立卷筒的有限元模型,通过解算器NX NASTRAN对有限元模型进行分析求解,得到卷筒在受力作用下应变和应力分布情况,再根据设计要求对零件参数进行优化,使卷筒的结构既满足设计要求,达到体积小和成本低的要求。     

基于NX泊桥桥体有限元优化分析

在粱单元的基础上对泊桥桥体进行有限元强度的优化分析,提出了一种高效准确的方法,缩短了建模与后处理计算的时间,与UG软件相结合,详细的论述了泊桥桥体的建模及有限元仿真过程,运用NX／Nas．tran模块计算分析,保证了准确性。     

球头铣刀骨铣削力有限元建模与试验验证

在骨科手术中,铣削力对骨裂纹和加工表面质量影响较大。由于临床球形骨铣刀结构复杂,目前尚无有效的理论模型预测切削力。通过引入三维有限元模型模拟球形铣刀加工骨材料过程,评估不同加工参数下的铣削力值。搭建骨铣削试验平台模拟临床操作中的铣削过程,并利用采集到的加工信号分析铣削力。通过试验结果与仿真结果的对比,验证了有限元仿真模型的合理性。该骨铣削有限元模型能够满足不同加工参数下铣削力预测精度的要求,方便指导医生根据不同要求选择合适的加工参数。     

利用反演技术求解消声器内部结构参数

应用流体动力学理论研究消声器内部流场,建立消声器有限元模型,确定给定结构参数求解出口气流流速的正问题;在正问题基础上,将出口气流速度作为消声器结构参数变化时的响应,运用反演技术求解消声器内部结构参数,并将反演问题转化为最优问题,采用遗传算法和梯度法相结合的混合优化算法进行优化,得到了较理想的仿真实验结果,验证了反演技术应用于消声器设计的可行性.     

Characteristic verification and parameter optimization of airbags cushion system for airborne vehicle

Abstract： The major methods to investigate the airbags cushion system are experimental method, thermodynamic method and finite element method （FEM）. Airbags cushion systems are very complicated and very difficult to be investigated thoroughly by such methods For experimental method, it is nearly impossible to completely analyze and optimize the cushion characteristics of airbags of airborne vehicle because of charge issue, safety concern and time constraint. Thermodynamic method fails to take the non-linear effects of large airbag deformation and varied contact conditions into consideration. For finite element method, the FE model is usually complicated and the calculation takes tens of hours of CPU time. As a result, the optimization of the design based on a nonlinear model is very difficult by traditional iterative approach method. In this paper, a model based on FEM and control volume method is proposed to simulate landing cushion process of airborne vehicle with airbags cushion system in order to analyze and optimize the parameters in airbags cushion system. At first, the performance of airbags cushion system model is verified experimentally. In airdrop test, accelerometers are fixed in 4 test points distributed over engine mount, top, bottom and side armor plate of hull to obtain acceleration curves with time. The simulation results are obtained under the same conditions of the airdrop test and the simulation results agree very well with the experimental results, which indicate the established model is valid for further optimization. To optimize the parameters of airbags, equivalent response model based on Latin Hypercube DOE and radial basis function is employed instead of the complex finite element model. Then the optimal results based on equivalent response model are obtained using simulated annealing algorithm. After optimization, the maximal acceleration of airborne vehicle landing reduces 19.83%, while the energy absorption by airbags increases 7.85%. The performance of the airbags cushion system thus is largely improved through optimization, which indicates the proposed method has the capability of solving the parameter optimization problem of airbags cushion system for airborne vehicle.     

复合材料起落架舱门结构优化设计

基于有限元软件ANSYS建立复合材料起落架舱门参数化有限元模型,基于三明治夹芯板理论将蜂窝芯层等效为均质的厚度不变的层板,以蜂窝夹芯高度与复合材料面板各铺层厚度为设计变量,以铺层板、蜂窝夹芯的强度,结构稳定性以及结构刚度为约束函数,以结构质量最轻为目标函数,基于ANSYS优化模块首先选择零阶法进行优化得到粗略解,其次选择一阶梯度优化法进一步对夹层结构进行优化设计,得到最优蜂窝芯子厚度、蒙皮各铺层厚度.     

周期性复合材料微结构的多目标拓扑优化设计

基于多尺度均匀化方法,以组分材料用量为约束,以等效弹性模量矩阵主对角线上分量的加权组合最大为目标,建立周期性复合材料微结构的多目标优化设计模型。利用优化准则法控制设计目标与材料分布,以敏度过滤技术抑制棋盘格效应,实现微结构的构型优化。研究比较微结构网格粗细、材料组分比对不同目标元素优化结果的影响。通过典型算例验证优化模型和优化算法的有效性。     

永磁直线进给系统多柔性体机电耦合动力学特性分析

针对高精度数控机床直接驱动进给系统动力学特性易受机械部件弹性变形、电气系统控制参数影响的特点,从机电耦合角度出发,用有限元法将永磁直线进给工作台进行柔性化,应用拉格朗日-麦克斯韦方程建立直线进给系统多柔性体的机电耦合模型。结合有限元分析软件ANSYS、动力学仿真软件ADAMS建立直线进给系统多柔性体的机电耦合仿真模型,并对系统进行动力学仿真分析和实验验证。结果表明,工作台柔性化更接近真实的工作情况;电气控制参数对系统动力学特性有显著影响。直线进给系统多柔性体机电耦合模型的建立可为直接驱动系统结构优化设计提供依据。     

Finite Element Method on Shape Memory Alloy Structure and Its Applications

It is significant to numerically investigate thermo-mechanical behaviors of shape memory alloy(SMA) structures undergoing large and uneven deformation for they are used in many engineering fields to meet special requirements To solve the problems of convergence in the numerical simulation on thermo-mechanical behaviors of SMA structures by universal finite element software.This work suppose a finite element method to simulate the super-elasticity and shape memory effect in the SMA structure undergoing large and uneven deformation.Two scalars,named by phase-transition modulus and equivalent stiffness,are defined to make it easy to establish and implement the finite element method for a SMA structure.An incremental constitutive equation is developed to formulate the relationship of stress,strain and temperature in a SMA material based on phase-transition modulus and equivalent stiffness.A phase-transition modulus equation is derived to describe the relationship of phase-transition modulus,stress and temperature in a SMA material during the processes of martensitic phase transition and martensitic inverse phase transition.A finite element equation is established to express the incremental relationship of nodal displacement,external force and temperature change in a finite element discrete structure of SMA.The incremental constitutive equation,phase-transition modulus equation and finite element equation compose the supposed finite element method which simulate the thermo-mechanical behaviors of a SMA structure.Two SMA structures,which undergo large and uneven deformation,are numerically simulated by the supposed finite element method.Results of numerical simulation show that the supposed finite element method can effectively simulate the super-elasticity and shape memory effect of a SMA structure undergoing large and uneven deformation,and is suitable to act as an effective computational tool for the wide applications based on the SMA materials.     

周期狭长结构拼装模块尺寸效应与构型优化

针对狭长结构拓扑优化过程中存在的计算困难、有中间密度存在和优化构型复杂等问题,提出周期模块拼装方法,并建立混合梁单元模块有限元模型,开展了狭长结构的拓扑优化设计。以承受均布压力载荷的悬臂狭长结构为例,分析比较了不同模块数、不同材料用量以及不同截面梁对优化结果的影响。计算结果显示,采用周期模块拼装策略能获得规则简单易制造的优化构型,周期狭长结构具有尺寸效应且存在最佳模块尺寸来最大化拼装结构刚度。将混合梁单元模型的模块尺寸与拓扑协同优化结合,获得了清晰规则的类桁架构型。最后应用所提方法实现了周期狭长梯形结构的构型优化。     

农网配电网架空线路机器人攀爬机构参数优化研究

为了提升农网配电网架空线路机器人的综合性能,提出了一种新的农网配电网架空线路机器人攀爬机构参数优化方法。使用 Creo Parametric 软件构建农网配电网架空线路机器人攀爬机构的三维模型,在 Workbench 中导入该模型,通过网格划分完成攀爬机构有限元模型构建;根据所构建的模型对机器人攀爬机构实施有限元分析,分析攀爬机构的应力分配与整体变形情况;在攀爬机构的参数优化中,在确定相关设计变量后构建参数优化目标函数,通过枚举法求解参数优化目标函数,获取优化后的参数取值。仿真测试结果表明,设计方法实现了攀爬状态下驱动力矩的提升、加速度的平稳化、竖直方向相对质心位置的降低以及攀爬速度的提升,说明该方法可以有效提升农网配电网架空线路机器人的综合性能,有一定实际意义。