3. Modern Definitions in Reliability Engineering

To better understand the parametric ALT that is a core of this book, this chapter will briefly review the basic definitions of reliability engineering that can be used widely for reliability testing. It consists of bathtub, reliability index, fundamentals in statistics and probability theory, statistical distributions like Weibull, and experimental design. When product is designed, engineer knows if final design has problems and is satisfied with the reliability target. Engineer should fully recognize the basic concepts that reliability testing is required. From customer’s standpoint, reliability depends on the product design and can be explained as two separate concepts—product of lifetime and failure rate. Engineer for reliability theory may feel complex because it requires an extensive concepts of probability and statistics. To conduct the reliability testing of mechanical product and obtain the reasonable test data, mechanical engineer should understand the modern definitions that can be used. When product is subjected to repetitive stresses (sole factor) and there is design faulty in it, product will fail. However, there is no current methodology because product failures rarely happen in its lifetime. As an alternative, we might suggest parametric ALT in Chap. 8.