Behavior of Nylon 66 Bolt Based on Self Loosening Under Cyclic Excitation

Abstract

Bolted joints are primary fasteners used in automobile and other mechanical parts and machinery. Bolted joints are used to hold the two parts together in many applications as they provide good fastening properties. But when bolted joints are subjected to cyclic loading, they lose their pretension and leads to excessive vibration. In bolted joints bolts and nuts are made up of metals such as steel, brass, aluminum, which are heavy in weight and increases weight of machine parts. In this study, the behavior of nylon 66 bolt based on self-loosening of bolt material under cyclic excitation is studied using finite element analysis on ANSYS Workbench 19 software. First, the FEA results of steel bolt were compared with experimental results from the literature. And then the same methodology is applied on the nylon bolt for performing transient structural analysis. Changes in bolt pretension with respect to number of loading cycles were observed. Results obtained for nylon66 bolts were compared with steel bolts. From the results, it is observed that plastic behaves better compared to steel in terms of self-loosening phenomenon under cyclic excitation. Nylon bolt does not lose its pretension suddenly in first few cycles and also the rate of losing preload is low compared to the steel bolt.