连接结构接触界面非线性力学建模研究

NONLINEAR MECHANICS MODELING FOR JOINT INTERFACE OF ASSEMBLED STRUCTURE

连接界面上存在的跨尺度、多物理场和非线性行为是引起结构复杂非线性动力学的主要原因.由于连接界面的力学行为的复杂性,以及难以对连接界面进行直接试验观测,连接界面的力学建模一直是非常具有挑战性的科学问题.本文首先从分析结合面的跨尺度物理机理入手,将名义的光滑平面视作凹凸不平的粗糙面,考虑单个微凸体的黏滑摩擦行为,建立接触载荷与变形的非线性关系,然后采用GW(Greenwood and Williamson)模型数理统计方法建立整个粗糙界面的跨尺度力学模型,并与公开文献中试验结果进行对比.考虑连接界面具有典型非线性特征,提出一种改进的Iwan唯象模型,利用精细有限元方法获得非线性特征结果,采用系统辨识理论建立连接结构的降阶力学模型,并利用有限元结果进行模型验证.结果表明,本文提出的粗糙界面跨尺度模型在法向载荷较小时与试验结果吻合较好,改进的Iwan模型能够较好描述连接界面的非线性特征,并与有限元结果吻合较好.

The existence of complex multi-scale,multi-physics and nonlinear behaviors on joint interfaces is mainly response for the complex dynamics of assembled structures.Modeling for mechanical joint interfaces is also a challenging scientific problem,due to the complexity of interface behaviors and difficulties of direct experimental observation.Firstly,the multi-scale physics of contact surface is considered.The namely smooth surface is assumed as a rough surface covered with asperities with random height distribution.The micro-scale stick-slip physics of asperity contact is analyzed to conduct the relationship between the tangential load and deformation.The statistical theory of GW model is used to yield the formulation of total contact load of rough surface and verified by a comparison with published experimental results.Then,an improved Iwan constitutive model is proposed to describe the nonlinear behaviors of joint interface.The nonlinear behaviors calculated by the finite element analysis are used to identify the parameters of proposed Iwan model,and verified by a comparison with the results of finite element analysis.The results show that the total contact load of rough surface predicted by the proposed multi-scale model agrees very well with the experimental results at lower normal load.The nonlinear behaviors predicted by the proposed Iwan model also agree very well with finite element analysis.