Failure analysis of mechanical and electrical components

• Main Author: Lee, Jeff Ka Mun.
• Other Authors: Tan Ming Jen
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Materials::Material testing and characterization
• Online Access: http://hdl.handle.net/10356/54125
• Institution: Nanyang Technological University

In this work, the failure analysis procedure was carried out on various industrial mechanical and electrical components, namely gear train components of an overhead travelling crane and polymer coatings from an induction motor stator winding. The gear components include a large driven gear in which all its teeth have been lost from apparent frictional wear, a smaller driving gear with partially broken-off teeth and a shaft which has broken clean in half. Windings extracted from one slot of a large AC induction motor stator were made up of 8 strands of copper conductors which have debonded from each other and both their polymeric enamel and glass fibre coatings appear to be peeled off. The main objectives were to investigate the failure mechanisms involved in the final failure and to finally deduce the most probable main root causes of failure for the respective components. Various analytical procedures were carried out to achieve the preceding objectives, such as fractography and metallography using scanning electron microscopy (SEM) and electron dispersive x-ray spectrometry (EDX) for metallic samples, and thermal analysis using thermogravimetry (TGA) and differential scanning calorimetry (DSC) for polymeric samples. Results indicated that large concentrations of defects were found within two of the three gear train components provided with lack of fatigue failure features, thus suggesting failure of the travelling overhead crane due to overloading. Visual observations of the polymer coatings in its as-received condition strongly indicated signs of thermal degradation. No solid proof of contamination or corrosion was found in both samples. Suggestions for future work were also put forth in order to improve the findings which were obtained.