Abstract:The effects of pretightening force on the equivalent stiffness and the critical response of micro and macro sliding of the bolted joint were investigated in order to realize the tightening and reliability of bolted joints.A singlelap single bolted joint plate was used to analyze the relation of contact pressure of joint surfaces and the pretightening forces,its equivalent stiffness model was built by analyzing the characteristic of the displacementloading,a parametric finite element model of the singlelap and single bolted joint plate with a variable pretightening force was developed,and a calculation method of response of displacementloading was proposed.The effects of pretightening force on the response of displacementloading of bolted joint plate at micro sliding phase,as well as the equivalent stiffness and the critical response amplitude of micro and macro sliding were discussed.Results indicate that when the response amplitude of displacementloading of the free end of the bolted joint plate is smaller than 0.075 mm,the pretightening force has no influence on the response of displacementloading,and the equivalent stiffness of the bolted joint plate is getting harder.When the response amplitude of displacementloading is greater than 0075 mm,the pretightening force has obvious influence on equivalent stiffness.There is an approximate linear relationship between the critical response amplitude of micro and macro sliding and the pretightening force.When the pretightening force is \[0.15~0.33\] F0max(F0maxis the maximum pretightening force) or \[0.45 ~ 0.70\] F0max,the pretightening force has less influence on equivalent stiffness,while the effect of pretightening force on the equivalent stiffness reaches to 50%.The conclusions show that the critical response amplitude and the equivalent stiffness of the bolted joint plate can be adjusted by changing the prettightening force.It is very helpful to the design of bolted joint plate by considering both of them.