Reliability-based robust design optimization of vehicle components,Part I: Theory

The reliability-based design optimization, the reliability sensitivity analysis and robust design method are employed to present a practical and effective approach for reliability-based robust design optimization of vehicle components. A procedure for reliability-based robust design optimization of vehicle components is proposed. Application of the method is illustrated by reliability-based robust design optimization of axle and spring. Numerical results have shown that the proposed method can be trusted to perform reliability-based robust design optimization of vehicle components.     

基于四阶矩技术的连杆的可靠性灵敏度设计

基于四阶矩技术,提出了1种连杆的可靠性灵敏度设计的数值计算方法,并对这种计算方法的精确性做了比较,给出了可靠性灵敏度的变化规律,研究了非正态分布参数的改变对连杆可靠性的影响,为分析和修改连杆的可靠性提供了理论依据.     

基于多目标非耦合优化策略的可靠性稳健优化设计

以实现多目标问题的可靠性稳健优化设计为目标,通过对目标函数和约束条件进行灵敏度分析,生成目标函数和约束函数的灵敏度附加项,建立了基于灵敏度附加目标函数的可靠性稳健优化设计模型;基于独立公理,使用正交试验和方差分析技术确定设计变量对各个设计目标的影响程度,将设计参数按无耦合或准耦合设计形式分组,把多目标优化问题单目标化,避免多个设计目标之间的反复权衡;结合增广乘子法,应用MATLAB的优化和符号工具箱来实现钳形盘式制动器的可靠性稳健优化设计。算例表明,提出的稳健设计方法具有较高的精度和可靠度。     

一种考虑参数相关性的可靠性优化设计方法

在求解具有非线性相关性结构的可靠性设计优化问题时,现有的相关性处理方法在某些情况下可能会得到精度较低的优化结果。基于Copula函数提出了一种可靠性优化设计方法,用于求解存在非线性相关性结构的可靠性优化设计问题。该方法根据已知的样本对各备选Copula函数进行参数估计,并根据AIC准则选出最优Copula函数。根据最优Copula函数,构建联合概率分布函数,最后求解结构可靠性优化设计问题。通过两个数值算例验证了该方法的有效性,并讨论了不同Copula函数对优化结果的影响。     

Reliability-based robust optimization design of automobile components with non-normal distribution parameters

In the reliability designing procedure of the vehicle components, when the distribution styles of the random variables are unknown or non-normal distribution, the result evaluated contains great error or even is wrong if the reliability value R is larger than 1 by using the existent method, in which case the formula is necessary to be revised. This is obviously inconvenient for programming. Combining reliability-based optimization theory, robust designing method and reliability based sensitivity analysis, a new method for reliability robust designing is proposed. Therefore the influence level of the designing parameters’ changing to the reliability of vehicle components can be obtained. The reliability sensitivity with respect to design parameters is viewed as a sub-objective function in the multi-objective optimization problem satisfying reliability constraints. Given the first four moments of basic random variables, a fourth-moment technique and the proposed optimization procedure can obtain reliability-based robust design of automobile components with non-normal distribution parameters accurately and quickly. By using the proposed method, the distribution style of the random parameters is relaxed. Therefore it is much closer to the actual reliability problems. The numerical examples indicate the following: (1) The reliability value obtained by the robust method proposed increases (>0.04%) comparing to the value obtained by the ordinary optimization algorithm; (2) The absolute value of reliability-based sensitivity decreases (>0.01%), and the robustness of the products’ quality is improved accordingly. Utilizing the reliability-based optimization and robust design method in the reliability designing procedure reduces the manufacture cost and provides the theoretical basis for the reliability and robust design of the vehicle components.     

鱼雷螺钉联接结构可靠性稳健优化设计

将可靠性优化设计理论与可靠性灵敏度分析方法相结合,应用可靠性稳健设计优化理论方法,对鱼雷螺钉联接结构进行了可靠性稳健优化设计.给出了计算分析结果.为工程实际的机械产品的可靠性稳健优化设计提供了理论依据.     

基于随机有限元的接触问题可靠性形状优化设计

针对含接触的结构可靠性形状优化设计问题，在简要介绍结构可靠性形状优化设计的基础上，重点推导并给出了接触问题的随机有限元的灵敏度全解析分析的表达式，包括可靠度指标的灵敏度分析、接触条件的灵敏度分析及相应的边界支配方程、结构响应量的灵敏度分析等。通过算例，验证了所提出的优化方法的正确性。     

面向可靠性设计优化的响应面偏差修正方法

在基于仿真的汽车设计中,针对响应面模型普遍存在的精度不高的问题,研究了基于贝叶斯推断的模型外推预测方法,提出了模型不确定性下基于偏差修正的模型外推及可靠性设计优化方法,并通过一个汽车轻量化设计实例验证了所提方法的有效性。     

非正态分布参数的多失效模式机械系统可靠性鲁棒设计

在机械系统可靠性设计理论、可靠性灵敏度分析和鲁棒设计方法的基础上,讨论了非正态分布参数的多失效模式机械系统可靠性鲁棒设计问题,提出了非正态分布参数的多失效模式机械系统可靠性鲁棒设计的计算方法．把可靠性灵敏度融入可靠性优化设计模型之中,将机械系统可靠性鲁棒设计归结为满足可靠性要求的多目标优化问题．在基本随机参数的前四阶矩已知的情况下,可以迅速准确地得到机械系统可靠性鲁棒设计信息．     

基于通用生成函数的结构可靠性优化策略

为提高工程结构可靠性设计优化(RBDO)的求解精度,提出一种基于通用生成函数(UGF)的RBDO新方法.一方面通过系列响应面建立设计变量与概率指标的动态映射,消除传统双循环算法的内层循环;另一方面引入UGF进行可靠性分析,避开传统矩法在处理随机变量非正态、功能函数高度非线性问题时精度低或无法收敛的劣势.同时,结合非均匀...     

任意分布参数的梁结构可靠性优化设计

在可靠性设计理论和优化设计方法的基础上,讨论了任意分布参数的梁结构可靠性优化设计问题,提出了任意分布参数的梁结构可靠性优化设计的计算方法。在基本随机参数的前四阶矩已知的情况下,通过计算机程序可以实现任意分布参数的梁结构可靠性优化设计,迅速准确地得到任意分布参数的梁结构可靠性优化设计信息。     

Multi-objective reliability-based optimization for design of trapezoidal labyrinth weirs

In the present research, the reliability-based design optimization (RBDO) of labyrinth weirs has been investigated. The optimization problem is formulated such that the optimal shape of trapezoidal labyrinth weir described by a number of variables is found by minimizing the volume of the trapezoidal labyrinth weir and maximizing the reliability index. The constraint conditions are the weir geometric shape and its different ratios. In order to achieve this purpose, a framework is presented whereby non-dominated sorting genetic algorithm (NSGA-II) is integrated with monte carlo simulation (MCS) method to solve the RBDO approach of trapezoidal labyrinth weirs. The proposed method is applied to UTE Dam labyrinth weir, and the results are compared with the real one. The results show the need for design based on reliability in the labyrinth weirs that propose using RBDO for weir design. The results showed that RBDO approach can achieve a more reliable design in addition to reducing the volume of the trapezoidal labyrinth weir. Finally, the sensitivity analysis of the parameters effective on the reliability index revealed that three design variables of weir width, total upstream head and discharge coefficient are the main parameters affecting weir RBDO solution.     

空心传动轴的可靠性稳健优化设计

在以单目标为主要型式的普通可靠性优化设计模型的基础上，考虑把可靠性灵敏度也作为一个目标函数融入到可靠性优化设计中，建立起空心传动轴的多目标可靠性稳健优化设计模型。并结合实例说明可靠性稳健优化设计方法比传统设计方法更实用。     

车辆转向机构运动精度的可靠性稳健优化设计

在车辆转向机构设计中,考虑了可控因素和噪声因素对运动精度的影响,将可靠性优化和稳健设计方法相结合,以转向机构运动精度为目标函数建立转向机构的可靠性稳健优化数学模型.把运动精度的可靠性灵敏度溶入可靠性优化设计模型之中,将可靠性稳健优化设计转化为满足可靠性要求的多目标优化问题.实例计算表明,考虑制造误差、运动副间隙等不确定因素的影响,可靠性稳健优化设计方法能有效保证转向机构的运动精度和可靠性.     

Reliability-based topology design for large-scale networks

Network topology has a critical effect on its reliability. Due to the complexity of networks, how to design a more reliable network topology is one of the fascinating and significant challenges. In this paper, inspired by the multi-scale model of biological systems which range from gene to individual cells, and up to the individual organism, we provide a novel method to design a reliable topology of large-scale networks. By means of fractal theory and its application in complex networks, a network topology can be described as consisting of the superposition of basic units, called fractal-cells, which are made up of several components and their connections. Based on this fractal-cell structure, we find that a fractal-cell network has structural similarity with its primitive structure, and then develop a method to build a reliable topology which is generated from a primitive ring structure. Numerical simulation compared with the existing methods and performing on real networks show that our proposed method is effective.     

车身结构概念设计集成系统的实现

为了弥补车身在概念设计阶段所产生的缺陷,提出了集车身几何建模、分析、优化于一体的集成设计系统VCD-ICAE.该系统支持"分析驱动设计"的新概念设计思想,以计算机辅助工程技术为核心,融合模板技术、参数化技术和优化技术,对车身结构慨念设计的整个过程进行有效的支持,能够自动、快速地建立参数化车身几何模型和有限元网格模型,准确、有效地进行车身强度和模态的计算和校核,并实现以车身总体性能为设计目标的参数优化和形状优化,为用户提供最优的产品设计方案.介绍了该软件的特点、功能和结构流程,以某车型为实例,验证了该软件的有效性.     

行星齿轮减速器稳健优化设计

在优化设计中主要存在设计变量的初值选取,设计变量的随机波动和外来干扰造成的可靠性和稳健性问题。为了解决此问题提出了6σ稳健设计和序列二次规划法相结合的方法,并以行星齿轮减速器为例进行了优化研究,通过与确定性优化的对比,验证了所提出的优化方法具有良好的优化效果。     

Reliable Space Pursuing for Reliability-based Design Optimization with Black-box Performance Functions

Reliability-based design optimization (RBDO) is intrinsically a double-loop procedure since it involves an overall optimization and an iterative reliability assessment at each search point. Due to the double-loop procedure, the computational expense of RBDO is normally very high. Current RBDO research focuses on problems with explicitly expressed performance functions and readily available gradients. This paper addresses a more challenging type of RBDO problem in which the performance functions are computation intensive. These computation intensive functions are often considered as a "black-box" and their gradients are not available or not reliable. On the basis of the reliable design space (RDS) concept proposed earlier by the authors, this paper proposes a Reliable Space Pursuing (RSP) approach, in which RDS is first identified and then gradually refined while optimization is performed. It fundamentally avoids the nested optimization and probabilistic assessment loop. Three well known RBDO problems from the literature are used for testing and demonstrating the effectiveness of the proposed RSP method.     

Robust design approach to the minimization of functional performance variations of products and systems

Frontiers of Mechanical Engineering - Functional performance variations of products and systems are often used to measure the qualities of products and systems considering the changes in the design...     

Multi-parameter Sensitivity Analysis and Application Research in the Robust Optimization Design for Complex Nonlinear System

The current research of complex nonlinear system robust optimization mainly focuses on the features of design parameters, such as probability density functions, boundary conditions, etc. After parameters study, high-dimensional curve or robust control design is used to find an accurate robust solution. However, there may exist complex interaction between parameters and practical engineering system. With the increase of the number of parameters, it is getting hard to determine high-dimensional curves and robust control methods, thus it’s difficult to get the robust design solutions. In this paper, a method of global sensitivity analysis based on divided variables in groups is proposed. By making relevant variables in one group and keeping each other independent among sets of variables, global sensitivity analysis is conducted in grouped variables and the importance of parameters is evaluated by calculating the contribution value of each parameter to the total variance of system response. By ranking the importance of input parameters, relatively important parameters are chosen to conduct robust design analysis of the system. By applying this method to the robust optimization design of a real complex nonlinear system-a vehicle occupant restraint system with multi-parameter, good solution is gained and the response variance of the objective function is reduced to 0.01, which indicates that the robustness of the occupant restraint system is improved in a great degree and the method is effective and valuable for the robust design of complex nonlinear system. This research proposes a new method which can be used to obtain solutions for complex nonlinear system robust design.