Guide to Accelerated Testing

INTRODUCTION The proposition of specifying, designing, or constructing a new system or one or more of its sub-elements (e.g., production articles, assemblies, components, or constituent materials) is one that is common and familiar to most engineers. Admittedly, no one engineer is involved in all aspects of bringing a new system from product definition through deployment, but rather, each is more likely to confine his activity to his individual technical specialty. Regardless of their level of involvement in the evolutionary process of a product, most engineers have a vested interest in ensuring that a system or its subcomponents all meet their required form, fit, and function. Designing systems and their components to meet specified form, fit, and function requirements is vital to successful product development. Ultimately, the degree to which a system complies with the initial stated objectives (usually in the form of a specification) is the single best measure of its performance. For too many engineers, however, their concept of performance is defined by how well the system operates the day it leaves the factory. Traditionally, little or no attention has been paid to how such a system would perform in the years or decades after deployment. Out of this relative ignorance to long-term system performance a new engineering paradigm has evolved that places greater importance on fully understanding a system’s useful lifespan, and how and under what conditions a system can or will fail. In addition, the analysis of what effect a given type of failure may have on a system has unearthed a whole new level of material properties that are taken into account when developing a new system. This new paradigm has fostered an evolution in the way new systems are designed and fielded systems are evaluated. Today, the emphasis is placed on the total life cycle of the system. System performance and incurred costs through each stage of the life cycle (definition, design, production, sustainment, and retirement/ disposal) are all considered in evaluating the degree of system success. When assessing the efficiency of a new or fielded system, three questions need to be asked: • How well does the system fulfill its mission requirements at a given point in time? • What is the probability the system will carry out its function when called upon to do so? • How long will the system be useful and cost-efficient? The answers to these questions embody the qualities that are most indicative of a system’s ability to fulfill its mission over the period of time that it is in active service. These three qualities, respectively, are performance, reliability, and life.