Investigation on the fatigue behaviour of pultruded fibre composites

摘要

Fibre composites existence in civil infrastructure and transportation is relatively new. Originally developed for aerospace, defence force and marine industries, composite materials did not make an appearance into large civil structures until the first legal road bridge was constructed in 2002. They have many advantages overudconventional materials such as improved durability and high strength to weight ratio just to name a few. The behaviour of pultruded fibre composites has been studied to help the design engineer to better understand the long term performance of composite structures.udThis research project seeks to investigate the fatigue behaviour of pultruded fibre composites to help develop the fatigue curve or better known as the fatigue life of audmaterial. Firstly a literature review was undertaken to help better understand the theory behind fibre composites and secondly a series of small scale (coupons) and large scale (Composite bridge girder) testing was done to prove these theories. This project also aimed to determine whether small scale testing can predict the fatigueudlife of large scale composite structures.udFatigue testing is a lengthy process with many researchers spending years just to develop one fatigue curve. Testing a particular sample to one million cycles at one hertz for example takes roughly 12 days to complete, and this does not including setup time. It may seem like the results obtained throughout this research project are quite small, however that one fatigue curve that is obtained is extremely important for the long term performance of pultruded fibre composites.udBy applying a prediction model to the small scale experimental data, the fatigue curve was developed. Initial results were not quite what were expected, however they did provide an insight into the fatigue performance of coupon testing as this was something that had never been done before on these products. There are minor flawsudin the coupon testing, however these did not become apparent until final tests were completed. Further research into the use of coupons for fatigue testing purposes would be recommended. The composite bridge girder on the other hand showed extremely satisfying results considering it was tested at more than double the serviceability load specified by the Queensland Department of Main Roads