Extended spring–mass method for joint stiffness prediction of single-lap multi-bolt composite joints considering assembly gap and gap shimming

Abstract

A multi-bolt spring–mass method considering assembly gap and shim was developed to predict the shear stiffness and bolt stiffness of the single-lap composite joints. Based on the premise that the highly stressed portions of adjacent holes have no overlap, multi-bolt joints can be converted into individual single-bolt joint with considering the conical and spherical stress envelope, gradual elimination of the bolt-hole clearances, and irregular assembly gap shape. The proposed method was validated by both experiment and finite element method for typical three-bolt composite joints with relative error of shear stiffness <3%, and that of bolt stiffness <20%.

Keywords:

• Analytical modeling
• spring–mass method
• composite joints
• assembly gap
• shimming

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [No. 51875079], China Postdoctoral Science Foundation [No. 2020M680937 & No. 2020M670734], National Key Research and Development Project [No. 2020YFB2009805], Fundamental Research Funds for the Central Universities [No. 3132021220], LiaoNing Revitalization Talents Program [No. XLYC1907196] and National Defense Basic Scientific Research program of China [No. 2019-JCJQ-JJ-547]. The authors would like to acknowledge the above financial support.