Fatigue strength of bolts / Mohd Zulkipli Abdul Majid

Fatigue of metals have been studied for the past 150 years but still many uncertainties have not been explored. Despite all the knowledge available nowadays fatigue failure still continue to occur especially in engineering and building construction. The extensive use of metals such as steel in the construction industries and many metal fatigue failure occurrence have lead researchers to focus their studies on the fatigue strength of metal. Bolts are widely used in many types of construction in jointing members of a structure. Thus the study of its fatigue strength are of vital importance. This experimental study carried out was to determine the fatigue strength of 12 mm diameter High Strength Friction Grip (HSFG) bolt under repeated tensile loading (cyclic loading). Using the stress- life ( S-N method) the metal specimens were being subjected to a stress within the elastic range of the material. The effect of fatigue parameter, the mean stress and stress range influence on the resultant lives (cycles to failure) of the bolts are studied based on a design monograph known as the S-N curve. Various test have been carried out in the laboratory namely the Static Tensile Test, Fatigue Sensitivity Test and the Fatigue Test using a special machines that was design to perform this test. From this experiments fatigue characteristic and fatigue strength can be observed.