结合面切向接触等效黏性阻尼分形模型

Fractal Model of Equivalent Viscous Damping for Tangential Contact in Joint Interfaces

基于MB接触分形理论、结合面切向接触阻尼耗能机理以及阻尼损耗因子的定义,建立了结合面切向接触等效黏性阻尼的分形模型及其损耗因子模型。所建模型表明,结合面切向接触等效黏性阻尼与结合面法向接触载荷、摩擦系数、材料塑性指数、结合面上的切向动态载荷幅值与法向接触载荷之比(简称切法向载荷比)、结合面分形维数以及分形粗糙度参数之间具有复杂的非线性关系,而结合面切向接触阻尼损耗因子与结合面分形维数和分形粗糙度参数无关,仅与切法向载荷比和摩擦系数有关。模型的仿真结果表明,结合面切向接触阻尼损耗因子随着切法向载荷比的增大而增大,随结合面摩擦系数的增大而减小;结合面切向接触等效黏性阻尼随着结合面法向接触载荷、摩擦系数、材料塑性指数的增大而增大,随着结合面分形粗糙度的增大而减小;结合面切向接触等效黏性阻尼随结合面分形维数的变化规律较为复杂,先随着分形维数的增大而增大,在分形维数值1.65附近出现最大值,而后随着分形维数的增大而减小。

Based on the MB contact fractal theory and the mechanism of energy dissipation of tangential contact damping in joint interfaces as well as the definition of damping energy dissipation factor,the fractal model of equivalent viscous damping for tangential contact in joint interfaces and its energy dissipation factor model are proposed.It is shown from the models that there exist complex nonlinear relationships between the equivalent viscous damping of tangential contact in joint interfaces and such factors as the normal contact load,the friction coefficient,the plastic index of contact materials,the ratio of the tangential dynamic load amplitude to normal contact load（named tangential-normal load ratio for short）,the fractal dimension,and the fractal roughness of joint interfaces.However,the energy dissipation factor of tangential contact damping is independent of the fractal dimension and fractal roughness,but only depends on the tangential-normal load ratio. Numerical simulations of the models show that the energy dissipation factor increases with the tangential-normal load ratio,but decreases with the friction coefficient of joint interfaces. The tangential contact equivalent viscous damping of joint interfaces increases with the normal contact load,the friction coefficient,and the plastic index ofcontact materials,but decreases with the fractal roughness.The variation rule of equivalent viscous damping with the fractal dimension is very complex：firstly it increases with the fractal dimension,and approaches a max value when the fractal dimension is equal to 1.65 or so,then decreases with the fractal dimension.