Reliability-based design for automobiles in China

The level of automobile design and manufacturing is an important sign of leadership in science and technology and economic power. The achievements of theories and methods for reliability-based design of automobiles in China are reviewed. For reliability-based design, the theories and practices, optimization, sensitivity, and robustness are estimated. The techniques of reliability-based design for automobiles are developed. The techniques service to the “hollow” phenomena of kernel technology, product innovative power, and independent development power can be solved.     

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。     

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。     

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.     

利用ANSYS实现零件的可靠性优化设计

基于ANSYS参数化设计语言(APDL)的数学运算功能,运用可靠性理论的摄动分析法,利用APDL编程实现零件的可靠度计算,避免了有限元建模、分析和结果的参数化提取等步骤.利用ANSYS的设计优化模块,以摄动分析法计算的零件可靠度为约束条件,以零件的最小体积为优化目标寻求设计参数的优化设计.开辟了一个利用ANSYS进行可靠性优化设计的途径,扩展了ANSYS的分析范围.     

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.     

Multidisciplinary design optimization of vehicle instrument panel based on multi-objective genetic algorithm

Typical multidisciplinary design optimization(MDO) has gradually been proposed to balance performances of lightweight, noise, vibration and harshness(NVH) and safety for instrument panel(IP) structure in the automotive development. Nevertheless, plastic constitutive relation of Polypropylene(PP) under different strain rates, has not been taken into consideration in current reliability-based and collaborative IP MDO design. In this paper, based on tensile test under different strain rates, the constitutive relation of Polypropylene material is studied. Impact simulation tests for head and knee bolster are carried out to meet the regulation of FMVSS 201 and FMVSS 208, respectively. NVH analysis is performed to obtain mainly the natural frequencies and corresponding mode shapes, while the crashworthiness analysis is employed to examine the crash behavior of IP structure. With the consideration of lightweight, NVH, head and knee bolster impact performance, design of experiment(DOE), response surface model(RSM), and collaborative optimization(CO) are applied to realize the determined and reliability-based optimizations, respectively. Furthermore, based on multi-objective genetic algorithm(MOGA), the optimal Pareto sets are completed to solve the multi-objective optimization(MOO) problem. The proposed research ensures the smoothness of Pareto set, enhances the ability of engineers to make a comprehensive decision about multi-objectives and choose the optimal design, and improves the quality and efficiency of MDO.     

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．     

基于改进遗传算法的离散公差模糊稳健优化设计

为了解决离散变量优化设计问题，采用了一种面向设计、制造的设计变量离散化处理方法。通过改进最优个体保护策略和混沌移民算子，并引入家族竞争遗传机制对基本遗传算法进行了改进。开发了混合离散变量的改进遗传算法程序LSGA2005，用该程序解决了箱体零件尺寸链的离散公差模糊稳健设计问题。实例表明，该算法全局收敛能力强，具有较好的实用价值。     

产品质量模糊稳健优化设计截集水平解法

综合考虑产品质量设计中的随机不确定性和模糊不确定性,运用概率理论和模糊集合理论.将传统稳健设计思想延展到更一般情形,建立产品质量等级的模糊判定和约束稳健可行域的模糊判别,形成模糊稳健设计的三准则.利用模糊集合理论的分解定理,将复杂的模糊概率运算又回归到常规概率计算,建立了更灵活、更符合工程实际的常规稳健优化数学模型.该模型可根据工程实际.具体设定设计方案的质量水平、合格品率或优质品率,以及设定约束水平、约束概率等关键参数.最后讨论了该模型最优设防水平的求解方法.     

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.     

基于MSRE的机械产品质量特性稳健优化设计方法

为了解决产品质量特性优化设计过程中设计参数发生变差时,最优解变为违反约束条件的不可行解的问题,对产品质量特性的稳健性和稳健性度量进行了分析,建立了基于最小灵敏域估计的产品质量特性稳健优化数学模型,提出了多目标产品质量特性稳健优化设计流程。根据该模型,采用广义差分多目标进化算法求得多目标质量特性稳健优化问题的Pareto稳健优化解集,并使用基于模糊集合理论的方法选择出最优解。在满足产品质量特性设计要求的前提下,优化产品质量特性,提高产品质量特性性能对设计参数变差的稳健性。最后,应用该方法对高速工业平缝机挑线机构进行质量特性稳健优化设计,证明了该方法在工程应用中的正确性与高效性。     

摆动活齿减速器的模糊稳健优化设计

应用基于正交设计的稳健设计法,建立了摆动活齿减速器的优化设计模型,对摆动活齿减速器进行了模糊稳健优化设计,应用模糊综合评判法对该优化设计的结果进行评判,得到了该减速器设计变量的稳健优化设计最优组合。     

A response surface based hierarchical approach to multidisciplinary robust optimization design

A multidisciplinary robust optimization design framework, concurrent subsystem robust design optimization, is proposed to obtain robust optimum solution in the large-scaled and coupled system. In this framework, response surfaces in the form of artificial neural networks provide information pertaining to system performance characteristics, and individual subsystems engage in performing robust optimization design in parallel while communicating with the system level. This optimization approach incorporates uncertainty analysis and generates a global robust optimum solution in an iterative fashion. Two applications are considered, and the results demonstrate that the approach yields a reasonable robust optimum solution, and it is a potential and efficient multidisciplinary robust optimization approach .     

工字型吊钩优化设计研究

利用有限元方法模拟了吊钩在不同载荷角下吊起1000t重物的过程,并计算了吊钩内部的应力分布,确定了最大应力位置和最危险工况。在保证原有形状尺寸的基础上,将吊钩截面改为工字型,并在腹板增加圆孔。利用有限元优化模块对工字型截面和孔径进行多参数优化,在满足强度要求下使吊钩的重量最小化。     

基于遗传退火算法的装配线设计多目标优化方法

针对混装配线设计这一有约束的多目标优化问题,建立了数学模型。将基于Pareto的解的分级方法与Lp-范数形式的非线性机制相组合,构建了基于遗传退火算法多目标优化方法。重点阐述了个体编码、染色体检修、多目标处理机制等关键技术。设计了算法流程图,并开发了优化程序。该方法克服了加权和方法的不足,用模拟退火改善了遗传算法全局寻优性能。计算实例表明,随着迭代次数的增加,每代的非受控点逐渐收敛于Pareto最优边界,是一种混装线设计多目标优化的新方法。     

稳健设计研究现状与模糊稳健设计研究进展

阐述了稳健设计理论的研究现状,对稳健设计研究的热点问题进行了分析,指出了稳健设计理论研究中存在的主要问题,提出了模糊稳健设计的概念。传统稳健设计方法的数学基础是数理统计与概率论,仅考虑随机性干扰因素,因而不能满足工程设计需要。模糊稳健设计是综合考虑产品设计、制造、使用过程中客观存在的各种随机因素与模糊因素,研究这些因素引起产品质量不确定性的规律,从而使产品设计达到优质低价的现代设计方法。讨论了模糊稳健设计的研究内容,对当前的研究进展进行了评述,并指出了稳健设计的发展趋势。     

基于均值1阶Esscher近似的可靠性稳健设计

将均值1阶Esscher近似可靠性分析方法、灵敏度分析技术及稳健设计方法相结合,提出了一种新的可靠性稳健设计方法,即基于均值1阶Esscher近似可靠性的稳健优化设计。可靠性稳健设计方法将质量和灵敏度作为目标,可靠度作为约束,最终归结为一个多目标优化问题。均值1阶Esscher近似可靠性方法适用于基本随机变量是正态或非正态、连续或独立的失效概率的计算,但要求这些随机变量相互独立,有矩母函数,并且极限状态函数具有显示表达式。因此,提出的可靠性稳健设计方法对于含非正态变量的稳健优化设计问题具有较高的计算精度。