Open AccessAN EXPERIMENTAL STUDY ON THE RELAXATION OF BOLTS
Author(s) -
Мuhammad Abid,
Muhammad Khalil,
Hafiz Abdul Wajid
Publication year - 2015
Publication title -
iium engineering journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.141
H-Index - 6
eISSN - 2289-7860
pISSN - 1511-788X
DOI - 10.31436/iiumej.v16i1.539
Subject(s) - gasket , embedment , creep , relaxation (psychology) , flexibility (engineering) , structural engineering , stress relaxation , joint (building) , materials science , engineering , composite material , mathematics , psychology , social psychology , statistics
Loss of pre-load with time, commonly known as ‘Relaxation’ is an established phenomena. Behaviour of a bolted joint depends upon the pre-load in the bolts in use, not the pre-load introduced by the mechanic. Loss of pre-load is expected due to the many factors such as embedment relaxation, gasket creep, elastic interactions, and vibration loosening or stress relaxation. In a gasketed joint, due to the gasket flexibility, relaxation is always substantial during preliminary passes, as 80 to 100% loss is not uncommon in almost all the bolts, resulting in a dynamic behaviour. Pre-load in a gasketed joint is stabilized and retained to certain extent in the final passes only. In a non-gasketed joint, due to no gasket and no rotation its static behaviour is concluded. This paper highlights the factors affecting the amount of relaxation with time and presents important considerations that can reduce this. Both the short and long term relaxations are recorded and a ‘best fit’ model for relaxation behaviour is derived.