Accelerated stress testing in a time-driven product development process

In order to compete in the market, companies have to produce the right products with a shorter time to market and at lower costs than before. Shorter time to market requires the product development process (PDP) to change the way of working from the classical ‘wait and react’ to anticipating and preventing problems as early as possible in the development process. This requires a new, and different role for the quality and reliability tests used. While in a classical PDP products could be tested when available from (pilot) production, a modern, time-driven development process requires optimisation long before larger series of products are available. Accelerated stress testing (AST) is a classical solution for the implementation of tests where product failures need to be activated faster (and cheaper) in a well-controlled environment at the early stage of the PDP. This paper reviews the classical AST strategy and some most recent AST strategies. It demonstrates that these accelerated test strategies are mainly based on generic lists of failure mechanisms and have only very limited relation with the actual failure rate curve of products. The theoretical background of the four-phase roller coaster failure rate curve is addressed and from this an alternative AST strategy is developed based on the relevant phases of the roller coaster curve using a concept called stressor-susceptibility analysis. A discussion, on the application of the proposed AST strategies and their impacts on the four-phase roller-coaster curves, is given at the end