Fatigue And Fracture Behavior Of Al-Alloy Plates With U And V Notches Subjected To Fatigue Loadings

Heng, Zheng Wang (2015) Fatigue And Fracture Behavior Of Al-Alloy Plates With U And V Notches Subjected To Fatigue Loadings. Project Report. UTeM, Melaka, Malaysia. (Submitted)

Text (24 Pages) Fatigue And Fracture Behavior Of Al-Alloy Plates With U And V Notches Subjected To Fatigue Loadings.pdf - Submitted Version Download (314kB)

Abstract

Fatigue may occur when a member is subjected to repeated cyclic loadings. The fatigue phenomenon started in the form of cracks developing at the critical locations in the structure. Structures subjected to repeated cyclic loadings can undergo progressive damage which initiated by the propagation of cracks. This damage is called fatigue and is represented by a loss of resistance with time. The good mechanical properties of aluminium-alloy in many fields result in the importance of research on this material under fatigue loadings since the imperfection of aluminium-alloy with defects significantly weaken its performance in service. Thus, the understanding of aluminium-alloys behaviour with SCFs is important. In this thesis, aluminum-alloy plates are used to conduct experiment to determine its fatigue performance under notched condition. A total of 23 test specimens were fabricated according to the specified design in ASTM standard for the U and V-notched specimens for tensile and fatigue tests. Certain machining processes have to be considered in order to prepare the test specimen to the required dimension. Based on the dimensions of U and V-notches the values of stress concentration factors were determined. The mechanical properties of materials were determined to obtain the ultimate and yield strengths. The fatigue test was conducted at constant R-ratio by using the Universal Testing Machine (UTM). The results obtained from these studies are plotted as the S-N curves and the fatigue strength of the notched specimens are determined. Based on the overall results, the fatigue strength of U-notched specimen is higher than V-notched specimen. It can be said that the higher value of stress concentration factor result in shorter fatigue life. However, there are differences between the experimental and theoretical fatigue strength for the test specimens due to a number of factors which include stress raiser, surface condition and stresses applied. Finally the fatigue fracture surface is analyzed where it shows three different regions.

Actions (login required)

View Item