共查询到18条相似文献,搜索用时 640 毫秒
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针对由有界噪声、泊松白噪声和高斯白噪声共同构成的非高斯随机激励,通过Monte Carlo数值模拟方法研究了此激励作用下双线性滞迟系统和Bouc-Wen滞迟系统这两类经典滞迟系统的稳态响应与首次穿越失效时间。一方面,分析了有界噪声和泊松白噪声这两种分别具有连续样本函数和非连续样本函数的非高斯随机激励,在不同激励参数条件下对双线性滞迟系统和Bouc-Wen滞迟系统的稳态响应概率密度、首次穿越失效时间概率密度及其均值的不同影响;另一方面,揭示了在这类非高斯随机激励荷载作用下,双线性滞迟系统的首次穿越失效时间概率密度将出现与Bouc-Wen滞迟系统的单峰首次穿越失效时间概率密度截然不同的双峰形式。 相似文献
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针对由有界噪声、泊松白噪声和高斯白噪声共同构成的非高斯随机激励,通过Monte Carlo数值模拟方法研究了此激励作用下双线性滞迟系统和Bouc-Wen滞迟系统这两类经典滞迟系统的稳态响应与首次穿越失效时间。一方面,分析了有界噪声和泊松白噪声这两种分别具有连续样本函数和非连续样本函数的非高斯随机激励,在不同激励参数条件下对双线性滞迟系统和Bouc-Wen滞迟系统的稳态响应概率密度、首次穿越失效时间概率密度及其均值的不同影响;另一方面,揭示了在这类非高斯随机激励荷载作用下,双线性滞迟系统的首次穿越失效时间概率密度将出现与Bouc-Wen滞迟系统的单峰首次穿越失效时间概率密度截然不同的双峰形式。 相似文献
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本文采用非线性滞后函数模型,对于粘弹性系统的随机振动问题,应用等效线性化和方差分析的方法进行了分析研究,给出了白噪声激励下的响应计算解。 相似文献
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结构在随机激励下的非线性响应分析是具有高度挑战性的困难问题.对于白噪声或过滤白噪声激励,求解FPK方程将获得结构响应的精确解.遗憾的是,对于非线性多自由度系统,FPK方程难以直接求解.事实上,其数值解法严重受限于方程维度,而解析求解则仅适用于少数特定的系统,且多是稳态解.因此,将FPK方程进行降维,是求解高维随机动力响应分析问题的重要途径.本文针对幅值调制的加性白噪声激励下多自由度非线性结构的非平稳随机响应分析问题,将联合概率密度函数满足的高维FPK方程进行降维.针对结构速度响应概率密度函数求解,通过引入等价漂移系数,原FPK方程可转化为一维FPK型方程.建议了构造等价漂移系数的条件均值函数方法.进而,采用路径积分方法求解降维FPK型方程,得到速度概率密度函数的数值解答.结合单自由度Rayleigh振子、十层线性剪切型框架和非线性剪切型框架结构在幅值调制的加性白噪声激励下的非平稳速度响应求解,讨论了本文方法的精度和效率,验证了其有效性. 相似文献
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结构在随机激励下的非线性响应分析是具有高度挑战性的困难问题. 对于白噪声或过滤白噪声激励,求解FPK方程将获得结构响应 的精确解. 遗憾的是,对于非线性多自由度系统,FPK方程难以直接求解. 事实上,其数值解法严重受限于方程维度,而解析求解 则仅适用于少数特定的系统,且多是稳态解. 因此,将FPK方程进行降维,是求解高维随机动力响应分析问题的重要途径. 本文针 对幅值调制的加性白噪声激励下多自由度非线性结构的非平稳随机响应分析问题,将联合概率密度函数满足的高维FPK方程进行降 维. 针对结构速度响应概率密度函数求解,通过引入等价漂移系数,原FPK方程可转化为一维FPK型方程. 建议了构造等价漂移系数 的条件均值函数方法. 进而,采用路径积分方法求解降维FPK型方程,得到速度概率密度函数的数值解答. 结合单自由度Rayleigh 振子、十层线性剪切型框架和非线性剪切型框架结构在幅值调制的加性白噪声激励下的非平稳速度响应求解,讨论了本文方法的精 度和效率,验证了其有效性. 相似文献
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剪切梁随机地震响应的李兹法 总被引:1,自引:0,他引:1
本文将常规的李兹法与虚拟激励法相结合以分析非均匀剪切梁的平稳随机地震响应。这方法对于各种正交或非正交阻尼,白噪声或非白噪声激励,都同样方便有效。 相似文献
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Calculating response spectral moments by complex modal analysis 总被引:1,自引:0,他引:1
Response spectral moments are useful for system reliability analysis. Usually, spectral moments are calculated by the frequency
domain method. Based on the time domain modal analysis of random vibrations, the authors present a new method for calculating
response spectral moments through response correlation functions. The method can be applied to both classical and non-classical
damping cases and to three kinds of random excitations, i.e., white noise, band-limited white noise, and filtered white noise.
Project supported by the National Natural Science Foundation of China. 相似文献
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Operational modal analysis techniques allow us to extract the modal properties of structures based on their response to non-measured
stationary white noise, i.e., by considering only the system response to operational excitations. In this paper we outline
a procedure to deduce modal parameters from operational response measurements. In particular, we discuss a novel approach
to analyze operational responses due to unknown harmonic excitation in addition to noise. Structural eigenfrequencies and
modal damping are computed using a modified least-squares complex exponential method. Once the poles of the system are identified,
mode shapes are obtained by post-processing. The robustness and accuracy of the approach are illustrated by performing tests
on a plate structure. 相似文献
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对工程结构进行环境激励下的模态参数识别具有重要意义, 而随机子空间法作为适合环境激励下模态参数识别的时域方法, 由于噪声和复杂激励的原因, 会产生虚假模态、真实模态遗漏、系统自动定阶难和计算效率等问题, 这些问题阻碍了该方法在实际工程中的广泛应用. 本文提出了基于Welch法的随机子空间方法, 通过Welch法对振动响应在频域进行去噪、降低环境激励和其他不确定性因素影响的处理, 把结构固有模态从噪声和激励频率中突显出来, 形成富含更多结构模态的Toeplitz矩阵, 然后进行奇异值分解和状态矩阵计算, 最后进行特征值分析. 为了实现自动定阶, 对不同奇异值分量构建的状态矩阵得到的特征参数, 进行模糊C均值聚类分析和模态的平均相位偏移分析, 剔除虚假模态, 实现结构模态参数的自动识别. 并把本文所提出方法应用于一座大跨悬索桥的实测加速度响应分析, 和一座七十层的高层建筑的加速度响应分析, 跟频域分解法、传统随机子空间法和基于相关分析的随机子空间法的计算结果进行了比较, 发现基于Welch方法的随机子空间法相比于传统随机子空间法和基于相关分析的随机子空间法, 在避免模态遗漏和计算效率方面有显著提高, 而相对于频域分解法则在自动识别和剔除虚假模态方面有明显优势. 相似文献
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A stochastic averaging method is proposed to predict approximately the response of quasi-integrable Hamiltonian systems to combined harmonic and white noise excitations. According to the proposed method, an n+α+β-dimensional averaged Fokker-Planck-Kolmogorov (FPK) equation governing the transition probability density of n action variables or independent integrals of motion, α combinations of angle variables and β combinations of angle variables and excitation phase angles can be constructed when the associated Hamiltonian system has α internal resonant relations and the system and harmonic excitations have β external resonant relations. The averaged FPK equation is solved by using the combination of the finite difference method and the successive over relaxation method. Two coupled Duffing-van der Pol oscillators under combined harmonic and white noise excitations is taken as an example to illustrate the application of the proposed procedure and the stochastic jump and its bifurcation as the system parameters change are examined. 相似文献
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A stochastic averaging method for predicting the response of quasi-integrable and non-resonant Hamiltonian systems to combined Gaussian and Poisson white noise excitations is proposed. First, the motion equations of a quasi-integrable and non-resonant Hamiltonian system subject to combined Gaussian and Poisson white noise excitations is transformed into stochastic integro-differential equations (SIDEs). Then $n$ -dimensional averaged SIDEs and generalized Fokker–Plank–Kolmogrov (GFPK) equations for the transition probability densities of $n$ action variables and $n$ - independent integrals of motion are derived by using stochastic jump–diffusion chain rule and stochastic averaging principle. The probability density of the stationary response is obtained by solving the averaged GFPK equation using the perturbation method. Finally, as an example, two coupled non-linear damping oscillators under both external and parametric excitations of combined Gaussian and Poisson white noises are worked out in detail to illustrate the application and validity of the proposed stochastic averaging method. 相似文献
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何军 《应用数学和力学(英文版)》2009,30(2):255-262
An approximate method is presented for obtaining analytical solutions for the conditional first passage probability of systems under modulated white noise excitation. As the method is based on VanMarcke's approximation, with normalization of the response introduced, the expected decay rates can be evaluated from the second-moment statistics instead of the correlation functions or spectrum density functions of the response of considered structures. Explicit solutions to the second-moment statistics of the response are given. Accuracy, efficiency and usage of the proposed method are demonstrated by the first passage analysis of single-degree-of-freedom (SDOF) linear systems under two special types of modulated white noise excitations. 相似文献