共查询到19条相似文献,搜索用时 156 毫秒
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《振动工程学报》2020,(3)
基于概率密度演化理论(PDEM),提出一种通过动力可靠度对简支梁在随机行人荷载下的响应进行评估的方法。选取步频、步长、体重以及各行人的到达时间为随机变量,确定性结构动力响应由显式Newmark法计算给出,通过PDEM理论可以方便地计算出行人通过简支梁时任意时刻响应的概率信息,以及不同舒适度阈值水平下跨中加速度的动力可靠度。算例验证表明,简谐荷载下分布参数体系的概率密度演化分析结果与统计结果吻合良好。通过对单人以及多人荷载下响应随机演化过程的分析表明,行人荷载随机性对结构响应具有显著影响,建议利用动力可靠度对结构进行振动响应分析以及人致振动舒适度评价。 相似文献
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针对随机智能梁结构参数的不确定性建立了其闭环控制动力响应随机模型.从结构动力响应的Duhamel积分出发,利用求解随机变量函数矩法导出了在三种情况下横向位移、转角位移和应力响应的数字特征表达式.并通过算例分析了在随机荷载作用下控制前后其物理参数、几何参数和控制力对闭环结构系统动力响应的影响.结果表明基于随机方法处理压电... 相似文献
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本文对在考虑地震烈度和场地土分类的模糊性的基础上所建立的含模糊参数的地震地面运动随机过程模型,采用分步等效线性化及状态方程法,求出了结构模糊随机变形和能量反应的统计矩;基于单参数(变形或能量)及双参数(变形和能量)的模糊破坏准则,分析了抗震结构的模糊随机动力可靠性。最后给出了两个自由度结构的数值算例,表明双参数准则更为合理和安全。 相似文献
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Dynamic Response Analysis of Fuzzy Stochastic Truss Structures under Fuzzy Stochastic Excitation 总被引:1,自引:1,他引:1
A novel method (Fuzzy factor method) is presented, which is used in the dynamic response analysis of fuzzy stochastic truss structures under fuzzy stochastic step loads. Considering the fuzzy randomness of structural physical parameters, geometric dimensions and the amplitudes of step loads simultaneously, fuzzy stochastic dynamic response of the truss structures is developed using the mode superposition method and fuzzy factor method. The fuzzy numerical characteristics of dynamic response are then obtained by using the random variable’s moment method and the algebra synthesis method. The influences of the fuzzy randomness of structural physical parameters, geometric dimensions and step load on the fuzzy randomness of the dynamic response are demonstrated via an engineering example, and Monte-Carlo method is used to simulate this example, verifying the feasibility and validity of the modeling and method given in this paper. 相似文献
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A novel intelligent fuzzy input estimation method that estimates the uniform input load on a beam structural system is presented in this article. The uniform input load acting on a beam structural system is estimated from the measured dynamic responses using the inverse method. The algorithm includes the fuzzy Kalman filter and the fuzzy-weighted recursive least square method. This study presents an efficient estimator accelerated and weighted using fuzzy-accelerating and -weighting factors proposed based on the fuzzy logic inference system. The capability of the proposed algorithm is demonstrated through several beam structural system examples with different types of boundary conditions. The simulation results are compared by alternating between the constant, adaptive, and fuzzy weighting factors. The results demonstrate that the presented method applied to beams with various structural system boundary conditions is successful. 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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This paper presents the results of a study on the response of structures with uncertain properties such as mass, stiffness and damping. The effect of the uncertain parameters on the response and the effect of the modelling of the uncertainties on the response are investigated. In particular, two types of uncertainties are distinguished: random and fuzzy uncertainties. Two kinds of models are studied: probabilistic and fuzzy set models. The two approaches to uncertainty modelling are compared with regard to their impacts on the analysis and on the uncertain structural response obtained. The study considers free vibration, forced vibration with deterministic excitation, and forced vibration with Gaussian white noise excitation. It is concluded that, in general, fuzzy models are much easier to implement and the associated analysis easier to perform than their probabilistic counterparts. When the available data on the structural parameters are crude and do not support a rigorous probabilistic model, the fuzzy set approach should be considered in view of its simplicity. 相似文献
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Present paper proposes a fuzzy neural network (FNN)-based modelling for the identification of structural parameters of uncertain multi-storey shear buildings. Here, the method is developed to identify uncertain structural mass, stiffness and damping matrices from the dynamic responses of the structure without any optimization processes that are generally used to solve inverse vibration problems. Uncertainty has been taken in term of fuzzy numbers. The governing equations of motion are first solved by the classical method to get responses of the consecutive stories. Further the governing equations of motion are modified based on relative responses of consecutive stories in such a way that the new set of equations can be implemented in a cluster of FNNs. As such the model starts solving the nth floor by FNN modelling to estimate the structural parameters. Subsequently, series of FNN models are used to estimate the parameters for (n ? 1)th storey to the first storey. One may note that single layer FNNs have been used for training for each cluster of the FNN such that the converged weights give the uncertain structural parameters. The initial weights in the FNN architecture are taken as the design parameters in uncertain (fuzzy) form. In order to validate the present model, various example problems of different multi-storey shear structures have been considered. Related results are incorporated in term of tables and graphs. Comparisons between theoretical and identified results are carried out and are found to be in good agreement. 相似文献
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Interval spectral stochastic finite element analysis of structures with aggregation of random field and bounded parameters 下载免费PDF全文
Duy Minh Do Wei Gao Chongmin Song Michael Beer 《International journal for numerical methods in engineering》2016,108(10):1198-1229
This paper presents the study on non‐deterministic problems of structures with a mixture of random field and interval material properties under uncertain‐but‐bounded forces. Probabilistic framework is extended to handle the mixed uncertainties from structural parameters and loads by incorporating interval algorithms into spectral stochastic finite element method. Random interval formulations are developed based on K–L expansion and polynomial chaos accommodating the random field Young's modulus, interval Poisson's ratios and bounded applied forces. Numerical characteristics including mean value and standard deviation of the interval random structural responses are consequently obtained as intervals rather than deterministic values. The randomised low‐discrepancy sequences initialized particles and high‐order nonlinear inertia weight with multi‐dimensional parameters are employed to determine the change ranges of statistical moments of the random interval structural responses. The bounded probability density and cumulative distribution of the interval random response are then visualised. The feasibility, efficiency and usefulness of the proposed interval spectral stochastic finite element method are illustrated by three numerical examples. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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模糊结构有限元分析的一种新方法 总被引:11,自引:2,他引:9
本文利用信息熵的概念,将模糊变量转变为随机变量,将模糊结构视为随机结构进行处理,从而提出了模糊结构有限元分析的一种新方法。当模糊结构转换的随机变量处于小扰动情况下,利用摄动法得到有限元递归方程组,解之可以得到响应量的均值和方差。 相似文献