Detailed Nonlinear Analysis of Bolted Joint

Abstract

Bolted joints are widely used in industrial applications due to their strength and ease of assembly. The most important characteristic of a bolted joint is its ability to prevent sliding motion between the joint parts when subjected to vibrations as well as external loading, by exerting a compressive force on the joint members. The clamping force generated during the assembly process is a function of various factors like the applied torque, material of the joint, behaviour of contact interfaces, as well as external conditions such as temperature. This project aims to understand the behaviour of a bolted joint during the assembly process with an applied torque. The finite element method is used to analyse the interaction between different components of a bolted assembly during its tightening process. A detailed 3D model is implemented in the finite element software ABAQUS. Torque is applied and then removed to simulate the tightening and torque tool removal. How friction affects this process is studied by varying the friction coefficient at the under-head interface. Results obtained from finite element analysis show agreement with commonly used handbook calculations for bolted joints. Varying under-head friction shows that the bolt preload does not drop significantly during torque removal; however, the friction under the head is found to affect the rate of preload drop after assembly. The analysis presented in this study can be further adapted to study the effect of other factors, like material properties, loading rate during tightening, as well as the response under external loads