基于修正Iwan模型的螺栓结合面非线性建模研究

准确建立高保真的螺栓结合面非线性力学模型是分析高端装备的前提和基础。针对螺栓结合面的迟滞非线性力学问题，提出了一种修正Iwan模型的力学建模方法，使得传统唯象的Iwan模型各参数物理意义更加明确。首先，根据多尺度理论和数理统计方法，建立了具有连续光滑接触特性的结合面法向接触模型；然后，通过考虑动态和静态摩擦因数的差异并利用库仑摩擦定律，将修正后的Iwan唯象模型与具体的法向接触模型联系起来，提出了新的螺栓结合面切向响应模型；最后，基于Matlab仿真和已有的试验数据，验证了所建模型的正确性，并探究了加载条件、塑性指数和动静摩擦因数比对结合面接触特性的影响。研究表明：一个周期加、卸载的能量耗散是随着位移幅值的增加而递增；相比于塑性指数，动静摩擦因数比的改变对结合面切向载荷的影响更为显著，在后续研究中需重点考虑；微凸体临界滑移力分布受其他因素的影响主要体现在接触微凸体的数目、峰值点的位置以及曲线收敛速度的改变。

Research on Nonlinear Modeling of Bolt Joint Surface Based on Modified Iwan Model

Accurately establishing a high-fidelity non-linear mechanical model of the bolt joint surface is the prerequisite and basis for the analysis of high-end equipment. A mechanical modelling method for modifying the Iwan model is proposed to address the hysteresis nonlinear mechanical problem of the bolt joint surface, making the physical meaning of the parameters of the traditional phenomenological Iwan model clearer. First, the normal contact model of the bolt joint surface, which has continuous smooth contact characteristics, is established based on the multi-scale theory and mathematical statistics. Then, by considering the difference between the dynamic and static friction coefficients and using the Coulomb friction law, the revised Iwan phenomenological model is connected with the specific normal contact model, and a new bolt joint surface tangential response model is proposed. Finally, based on Matlab simulation and existing experimental data, the correctness of the model is verified. The influence of loading conditions, plasticity index and dynamic and static friction coefficient ratio on the contact characteristics of the joint surface is explored. Research shows that the energy dissipation of a cycle of loading and unloading increases with the increase of the displacement amplitude. Compared with the plasticity index, the change of the dynamic and static friction coefficient ratio has a more significant effect on the tangential load of the joint surface, so it needs to be considered in the follow-up research. The critical slip force distribution of the asperity is affected by other factors, which is mainly reflected in the number of contact asperities, the position of the peak point and the change of the curve convergence speed.