Characterisation of fatigue damage process in carbon fibre reinforced composites

• Main Author: Fun, Ronnie.
• Other Authors: Chai Gin Boay
• Format: Final Year Project
• Language: English
• Published: 2012
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/50069
• Institution: Nanyang Technological University

The use of carbon fibre reinforced composites (CFRP) is ever increasing in the world today, especially in the automobile and aerospace industries. Porosity is a very common problem in the manufacture of CFRP. As such, research has to be done in this area to determine how the presence of porosity voids influences the properties of CFRP. CFRP is a new material, and not much research has been done regarding the fatigue properties of CFRP with porosity. This project aims to fill that gap by serving as a stepping stone upon which future research in this topic can base their research upon. In this project, porosity content had to be varied and measured. Porosity variation was done by placing the resin used to make the specimens in various conditions in a vacuum chamber. The measurement was done by a scanning electron microscope and a program called ImageJ. Standard fatigue tests were then applied to the specimens, and the S-n curves were obtained for various porosity contents. This project compared the differences in the porosity content produced by different batches of resin. It then compared the fatigue lives of samples of various porosity contents using the S-n curves and attempted to find the difference, if any. In the process, some generic observations regarding the fatigue failure process of the specimen were observed and recorded. Results showed no significant difference in the fatigue lives for samples ranging from 10.3% porosity to 12% porosity. However, there was a difference between the fatigue life of the specimen with 12% porosity and the others when the force applied was 50% of ultimate tensile stress. These are interesting results which can be looked at for future research.