Method of extracting normal static stiffness of bolted joint interfaces

Joint interfaces static stiffness is closely related to the connection mode,bolted member stiffness and joint part stiffness. It is very difficult to measure and calculate the joint interfaces static stiffness directly. Taking bolted joint interfaces as research objects,a method of extracting the normal static stiffness of bolted joint interfaces was proposed. By combining the spplication of normal static stretching experiment and data processing,the joint part stiffness was obtained. Then an optimization calculation on bolted member stiffness was carried out and a corresponding refined analytic formula was provided. Based on the exploitation of relationships among the joint interfaces static stiffness,bolted member stiffness and joint part stiffness the normal static stiffness of bolted joint interfaces was seperated from the whole bolted joint part stiffness. In accordance with the above analysis results,the nonlinear characteristic curve of normal static stiffness of bolted joint interfaces corresponding to effective contact pressure was extracted. The method proposed provides a new way to the in-depth study about joint interfaces static stiffness.