Reliability: Modeling, Prediction, and Optimization

CHAPTER 14

Reliability Prediction and Assessment

14.1 INTRODUCTION

Determination of product reliability is important in all phases of the life cycle of a product. The process begins at the design stage, where predictions of reliability are made based on whatever information is available at that point, continues through the development and testing stages as additional information becomes available, and proceeds through the production and operational stages of the life cycle. At each of these stages, still more reliability-related information may be obtained, and updated reliability assessments are made periodically as appropriate.

Reliability prediction may be interpreted in several ways. First, it may mean prediction of system reliability in the conceptual stage of product development, where little or no “hard” information is available for many of the parts and components of the system. Second, predictions may be made later in the development cycle in situations where test data and other information are available on components and on the system as a whole. Third, predictions may by made regarding future reliabilities in situations involving reliability growth. In all of these cases, prediction from a statistical point of view is basically equivalent to use of statistical estimates for prediction purposes, with confidence intervals calculated as appropriate in this context.

Reliability assessment is basically concerned with evaluation of the current reliability of a product or system. ...