Summary and Conclusions

Accelerated testing is often promoted as a solution to saving test time and costs. However, if ignorance about the true significance of accelerated test models prevails, then these tests could result in penalties to cost-effective product development efforts rather than the hoped-for reductions. Using physics of failure models, this paper emphasizes that:

1. There are no "magic" analytical modes that simply, conveniently, and accurately estimate the life of complex manufactured assemblies and products.
2. Each analytical model describes physical change mechanisms associated with specific material when subjected to particular environmental loading conditions.
3. Because product assemblies consist of many different materials and structural configurations, a product's wearout behavior must be evaluated in terms of several different, sometimes competing, physical change models.
4. In real-life and in accelerated testing, different elements of a product will age or fatigue at different rates, depending on what they are made of, how they are used, and what environmental loading conditions prevail at the site of each element.
5. Accelerated testing is assumed to provide leverage for increasing the rate at which knowledge is gathered about a product as well as saving test time and costs. However, because exaggerated conditions are generally involved, accelerated testing can also magnify the negative effects of invalid assumptions and poorly defined boundary conditions.
6. Successful accelerated testing relies on ensuring that all parties involved have reasonable expectations of what this product development tool can and cannot do just as much as on good laboratory procedures.

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