Device design for contact fatigue testing of remanufactured components

• Main Author: Low, Steiner Tze-Zhous'
• Other Authors: School of Mechanical and Aerospace Engineering
• Format: Final Year Project
• Language: English
• Published: 2014
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/60925
• Institution: Nanyang Technological University

This is the report for project title A177: device design for contact fatigue testing of remanufactured components. The project centred on the fretting process of materials and the design of a specimen contact device to impart a normal force on a specimen under cyclic loading. Fretting can be classified into two major components, namely fretting wear and fretting fatigue. Fretting wear concerns about the wear properties induced by the fretting action, which includes adhesion and abrasion, while fretting fatigue studies on the nucleation of cracks on the parts in contact due to the fretting process and how fretting reduces fatigue life of the part. In this project, four design iterations were carried out before the design of the specimen contact device was finalised for fabrication. The final design modelled a proving ring and comprised the main body, main body covers, contact pins and a LCM-300 load cell. Screws were used to secure the cover in place, while a bolt was used as the point of force application. As the bolt is tightened, it exerts a force on the load cell and contact pin, which in turn exerts a force on the specimen. To reduce the deformation on the contact pins, they were made using a steel alloy to achieve a high hardness value of HRC 60. The focus of the design was on modularity, whereby different contact types may be achieved by simply changing the contact pins. The different contact types in consideration were the single and double square-tip area contact, as well as the single and double ball-tip point contact. By allowing modularity in the contact pins, tests may be done for bridge type contact, single contact, complete and incomplete contacts on the specimen. The final design was also carefully investigated for redundant parts as they were removed to lower material and machine costs, which lead to cost-savings for both supplier and buyer. The specimen contact device was to be built around a Shimadzu Servopulser fatigue testing machine, but tests were unable to be carried out due to situational and time constraints.