叶片缘板阻尼器切向接触刚度及其微滑动摩擦建模

Modeling of Tangential Contact Stiffness in a Blade Underplatform Damper and Its Microslip Friction

关键词:  干摩擦  微滑动  切向接触刚度  迟滞环  阻尼比

Key words:  Dry friction  Microslip  Tangential contact stiffness  Hysteresis loop  Damping ratio

摘要:

为有效解决叶片缘板阻尼器的微滑动摩擦建模问题，针对带圆角的平板接触模型，推导得到了阻尼器切向接触刚度的解析表达式，包括初始切向接触刚度和微滑动阶段平均切向接触刚度，并将其与平面应变有限元模型的计算结果进行对比。结果表明:初始切向接触刚度的值仅与接触体的材料属性、阻尼器轴向长度与接触区半宽度的比值有关，平均切向接触刚度还与接触面的压力分布有关；利用有限元法计算得到的切向接触刚度值与理论解之间的计算误差与文献中有限元解的误差相比减小约7.1%。基于切向接触刚度的理论分析结果，发展了一种微滑动摩擦模型，给出了模型中实验系数[λ]的解析表达式，对于本文研究的带圆角平板接触模型，[λ]的值通常在1.00～1.15。将所发展的微滑动摩擦模型用于B-G型缘板阻尼器减振特性分析中，并与宏滑动摩擦模型的计算结果进行了对比，结果表明，所发展的微滑动摩擦模型可以用来计算阻尼器接触面发生微滑动时所能提供的阻尼比。

Abstract:

To effectively solve the modeling problem of the microslip friction of the blade underplatform damper， analytic expressions of initial tangential contact stiffness and average tangential contact stiffness of the damper were derived based on a flat rounded contact model. The results were compared with those of the finite element models in plane strain state and show that the initial tangential contact stiffness is only related to material properties of contact bodies， ratio of axial length of the dry friction damper to half-width of the contact area. In contrast， the average tangential contact stiffness is also related to the normal pressure distribution of the contact surface. The calculation error of the tangential contact stiffness between the finite element method(FEM) and theoretical approach reduces by about 7.1% compared with that of the results calculated by FEM in the literature. A microslip friction model was built based on the results of the flat rounded contact model， and the analytic expression of experimental coefficient [λ] in the model was derived. As for the contact model presented in this paper， the value of [λ] is nearly between 1.00～1.15. The developed microslip friction model was applied to the study of the vibration characteristics of the B-G underplateform damper. The results were compared with that of the macroslip model， and show that the developed microslip friction model can be used to calculate the damping ratio of the damper when contact interfaces are both in microslip phase.