Predicting material fatigue from material properties

Abstract

The primary purpose of this report is to study how the surface properties of an aluminium alloy changes, at the initial stage of test fatigue test. The surface properties of the aluminium sample include Young’s Modulus and surface roughness. Moreover

the changes took place in the indentation on the test sample will be studied. In order to obtain the data for the changes of surface properties, an aluminium alloy has been sent for fatigue test. In total, the aluminium alloy has gone through an accumulation of

300,000 cycles of fatigue test. The results obtained from the fatigue test indicate that the Young’s modulus increases when the numbers of cycles of fatigue test increases. As for the surface roughness, it increases till 23000 fatigue cycle and start to decrease after that. This may due to the initiation of micro-crack on the aluminium alloy. Moreover, the indentation depth decreases when the fatigue cycle increases. Analyzing work has been done to explain those changes. Lastly, the changes took place in the indentation were observed by both microscope and scanning electron microscopy (SEM).The surface properties data for the aluminium alloy are collected using surface profilometer, optical microscopy, ultrasonic flaw detector, scanning electron microscopy and hardness tester.