Member stiffnesses and interface contact characteristics of bolted joints

Bolted joints including bolts and members act like elastic springs under assembly and operating conditions. The bearing and transferring of the initial preload and the operating force are mainly dependent on the stiffness of both the bolts and their corresponding members. To obtain the deformation mechanism of bolted members, a systematic study on the prediction of the member stiffness and the characterization of the interface contact conditions is developed in this paper. Firstly, a parameterization process is performed to relate all the geometric dimensions of each bolted joint with the corresponding bolt diameter, so the corresponding dimensionless dimensions can be conveniently gotten by dividing the dimensions by the bolt diameter. Based on this, a novel and efficient finite element (FE) model is constructed to simulate the behaviors of bolted joints with different geometrical sizes and material properties. After characterizing the member stiffness, the interface contact characteristics of bolted joints including contact pressure and the dimensionless contact diameter are further identified through special FE post-processing efforts. Finally, a series of semi-apex angles are obtained through an inverse calculation approach in which an author-modified empirical formula is adopted. The calculation results based on the proposed method may be considered as a simple and practical guideline for the design and assembly processes of bolted joints.