Prediction versus reality in aerospace composite ageing studies

The aim of the project that is described in this paper is to develop low-cost chemical and physico-chemical methods of testing and analysis of new composite materials. This will enable the aerospace industry to predict aspects of the lifetimes of composite aerospace parts without the standard, but very expensive, mechanical testing regimes normally required. The initial section of the project has been designed to build up an under-standing of what are the environmental conditions seen by materials on modern aircraft and which of these are critical to the determination of composite lifetimes. Preliminary accelerated testing trials have shown which types of chemical analyses give the most relevant information. It has also been shown that extensive calibration of equipment and careful experimental design are required, especially when the testing conditions get closer to the "in service" environments. Results of analyses from some actual aerospace samples have also been carried out for comparison purposes.