【摘要】 提出了采用模式搜索法修正含铰桁架中铰链非线性刚度的方法。首先根据描述函数法建立了非线性桁架的动力学模型,假设铰链力学特性呈立方非线性,采用谐波平衡法对桁架结构进行动力学响应分析。在此基础上,以试验和计算频响函数之间的残差最小为目标函数,利用模式搜索法进行铰链非线性刚度修正。以含铰悬臂梁和单跨平面桁架为研究对象,开展仿真研究。在无噪声情况下,对非线性刚度的初始误差分别为15%和50%两种情况,选取合理的迭代步长和收敛准则,能够得到较好的修正结果;当考虑信噪比分别为0.5%,1%和2%时,修正结果误差分别为0.2%,2.2%,2.2%;当考虑多修正参数时,修正后非线性刚度的误差分别为1.9%和0.7%。结果表明,提出的非线性结构模型修正方法,可以对非线性结构的动力学参数进行修正,该方法具有较高的精度和一定的抗噪能力。更多还原

【Abstract】 An approach for the model updating of the nonlinear stiffness of a truss with joints using the patternsearch method was proposed. The modeling of the nonlinear truss was conducted based on the describing function method.The dynamic responses of the truss were analysed supposing the joints were of cubic nonlinearity. Based on this,an objective function was constructed with the minimum error between the experimental and simulated FRFs,and was used to update the stiffness of structure by the pattern-search method. A cantilever beam with one joint and a one-bay truss were taken as the objectives of simulation. The initial errors of nonlinear stiffness are 15 % and 50 % respectively in these two cases without noises and a reasonable step size and convergence criteria were chosen to improve the acouracy of the updated stiffness. When the FRF data are contaminated by noise of 0. 5 %,1 %,2 %,the errors of updated stiffness are0. 2 %,2. 2 %,2. 2 %,respectively. When multiple parameters are needed to be updated,the errors of the results are only 1. 9 % and 0. 7 %,respectively. These results demonstrate that the pattern search method is an effective method for nonlinear structural model updating.更多还原