Abstract: Machined joint surfaces may often work under dynamic conditions, making contact state of the joint surfaces deviates from static operating one, and causing the contact stiffness to change. In order to reveal the variation of dynamic contact stiffness, The average contact stiffness model of a vibration cycle within each deformation stage is developed based on contact mechanics that the deformation transitions from elastic, through elastic-plastic, to eventually to the plastic, respectively. On this basis, an analytical model of the rough surface dynamic contact stiffness is developed based on the Gaussian distribution assumption. This model reveals the influence of contact pressure, vibration frequency and relative displacement amplitude on the dynamic contact stiffness, and be compared with the experimental results and the static contact stiffness. The results show that the relationship of normal dynamic contact stiffness, static contact stiffness and the contact surface pressure is roughly consistent, but there is a certain deviation. The degree of the deviation increases with dynamic displacement amplitude and frequency of vibration, respectively linearly and non-linearly.

Key words: asperity, dynamic contact stiffness, normal joint surface