共查询到15条相似文献,搜索用时 437 毫秒
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针对随机结构在平稳随机激励下线性二次最优控制的权参数选取问题,提出了基于人工鱼群算法的随机结构AMD控制系统权矩阵优化设计方法。该方法以结构随机响应和控制力均方值的加权组合为目标函数,考虑了结构和外激励的随机性对于控制效果的影响。其优化结果不仅保证了控制器的控制效果,而且降低了控制效果对于随机参数的敏感性,增强了控制器的鲁棒性。最后结合数值算例,验证了所述方法的有效性和正确性。 相似文献
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随机结构随机激励下的响应灵敏度分析 总被引:1,自引:0,他引:1
对于随机激励下随机结构动力响应的灵敏度分析问题,提出基于点估计法的随机结构随机动力响应灵敏度分析方法.所提方法从随机结构响应均方值的均值表达式出发,首先将随机结构响应均方值的均值对基本随机变量分布参数灵敏度转化成求期望值问题,再由求解随机变量函数矩的点估计方法导出求解动力响应灵敏度的计算公式.算例分析表明该方法的计算结果是合理的,并且由于点估计法具有较高的效率和精度,因而所提方法具有一定的工程意义. 相似文献
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本文通过具有随机结构参数的四分之一车辆模型研究了具有不确定性结构参数的车辆在受到来自道路的随机激励作用下的振动响应问题。文中将簧上质量、簧下质量、悬挂阻尼、悬挂刚度以及轮胎刚度均认为是随机变量。将路面的不平整引起的对车辆的激励看作高斯随机过程并通过简单指数功率谱密度来建立力学模型。利用蒙特卡洛方法得出了车辆的固有频率和模态振型的均值、标准差以及变异系数。利用随机变量函数矩方法在频域中建立了车辆的随机响应的均方值的数字特征的计算表达式。通过工程算例表明了车辆结构参数的随机性对其动力响应的影响。本文所做的工作可拓展应用于车辆结构参数的灵敏度分析和动力优化设计。 相似文献
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演变随机响应问题的统一解法 总被引:8,自引:0,他引:8
演变随机过程是指平稳随机过程按确定性调制规律演化而得的一种非平稳随机过程。无论是时不变或时变系统在演变随机激励下的响应,还是时变系统在平稳随机激励下的响应,均属演变随机响应,求解演变随机响应问题的关键在于找到该响应的确定性调制规律,最近提出的线性系统的演变随机响应问题的统一解法指出:求解有关演变随机响应的调制规律等价于求解原系统在某种确定性激励下对应于零初始条件的瞬态响应,在一般情形下,这类瞬态响应均可用现成的数值解法,例如Runge-Kutta法求得。上述统一解法原本是针对确定性系统提出的,但结构Monte-Carlo法、或随机摄动法、葺随机正交展开法,就可推广用于随机结构的演变随机响应分析,本文将系统地介绍这个统一解法及其新进展。 相似文献
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The random interval response and probabilistic interval reliability of structures with a mixture of random and interval properties are studied in this paper. Structural stiffness matrix is a random interval matrix if some structural parameters and loads are modeled as random variables and the others are considered as interval variables. The perturbation-based stochastic finite element method and random interval moment method are employed to develop the expressions for the mean value and standard deviation of random interval structural displacement and stress responses. The lower bound and upper bound of the mean value and standard deviation of random interval structural responses are then determined by the quasi-Monte Carlo method. The structural reliability is not a deterministic value but an interval as the structural stress responses are random interval variables. Using a combination of the first order reliability method and interval approach, the lower and upper bounds of reliability for structural elements, series, parallel, parallel-series and series-parallel systems are investigated. Three numerical examples are used to demonstrate the effectiveness and efficiency of the proposed method. 相似文献
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A new two-factor method based on the probability and the fuzzy sets theory is used for the analyses of the dynamic response
and reliability of fuzzy-random truss systems under the stationary stochastic excitation. Considering the fuzzy-randomness
of the structural physical parameters and geometric dimensions simultaneously, the fuzzy-random correlation function matrix
of structural displacement response in time domain and the fuzzy-random mean square values of structural dynamic response
in frequency domain are developed by using the two-factor method, and the fuzzy numerical characteristics of dynamic responses
are then derived. Based on numerical characteristics of structural fuzzy-random dynamic responses, the structural fuzzy-random
dynamic reliability and its fuzzy numerical characteristic are obtained from the Poisson equation. The effects of the uncertainty
of the structural parameters on structural dynamic response and reliability are illustrated via two engineering examples and
some important conclusions are obtained. 相似文献
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Juan Ma Peter Wriggers Wei Gao Jian Jun Chen Shahab Sahraee 《Computational Mechanics》2011,47(6):627-640
In this work, a reliability-based optimization technique is addressed to obtain the minimum mean value of random mass of the
structures with random parameters under stationary stochastic process excitation. The challenge of the problem lies in randomness
involved from both structural parameters and dynamic load, which renders the structural reliability becoming the random dynamic
reliability of the first passage problem. In order to obtain minimum mean value of random gross mass, element and system dynamic
reliability constraints are constructed, respectively, and the structural sizing and shape optimization models based on the
dynamic reliability are then presented. Moreover, among two optimal strategies proposed for optimization models, the second
one can effectively reduce the workload by avoiding the computation of the variance of the dynamic response during the iterative
process. Finally, the implementation of three examples is discussed to display the feasibility and validity of optimization
technique given. 相似文献
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研究了具有区间参数的桁架结构在区间力作用下的有限元分析方法。利用区间因子法,桁架结构材料物理参数、几何尺寸和外荷载均可表达为其区间因子和其确定性量的乘积,进而结构的位移和应力响应也可表达成区间因子们的函数。利用区间算法,推导出了结构位移和应力响应的上、下限和均值的计算表达式。通过算例,分析了结构参数和外荷载的不确定性对结构响应的影响,并验证了模型和方法的合理性与可行性。该方法的优点是能够反映结构某一参数的不确定性对结构响应的影响。 相似文献