考虑连接界面局部非线性的动力学分析方法

Dynamic Analysis for Local Nonlinearity of Joint Interface

连接界面上存在的多尺度、多物理场等复杂行为是引起结构阻尼和刚度非线性的主要原因。针对连接界面上典型的刚度软化、迟滞非线性行为,采用Iwan模型模拟连接结构进行力学建模,并推导了含有非线性连接的动力学微分方程。然后,采用时频交替方法求解非线性动力学方程在周期性激励作用下的稳态响应,并与数值积分方法计算的响应进行对比,最后研究了不同激励频率对连接界面非线性特性的影响。结果表明:Iwan模型能够较好地描述连接界面的刚度软化、迟滞特性,时频交替方法能够更加快速精确地求解非线性系统的稳态响应,随着激励频率的增加,位移响应最大值减小,迟滞曲线面积也相应减小。

The complex behavior of multi-scale, multi-physics behaviors on the interface is the main reason of the structure damping and stiffness nonlinearity, Aiming at the typical stiffness softening and hysteretic behavior of the connection interface, Iwan model is applied to characterize the nonlinear softening stiffness and hysteresis behaviors of joint interfaces. With the consideration of these typical nonlinear behaviors, the dynamic differential equation of joint interface is established. Then, the alternative time-frequency method is used to analyze the steady dynamic response of system equation under the cycle oscillating force. The proposed method is investigated by the comparison with numerical integration solution. The results show that Iwan model can better describe the nonlinear behavior of softening stiffness and hysteresis between force-displacement of joint interface, and the alternative time-frequency method can solve the nonlinear dynamic equation more efficient and agree well with the numerical solution. With increase of oscillating frequency, the maximum of displacement will become less, which will induce less area of hysteresis curve.