TABLE OF CONTENTS The analytical techniques discussed in this chapter are usually the most cost-effective means of failure prevention. They can be carried out early in the development and thus minimize rework and retesting. Analysis is cheaper than modeling and much cheaper than testing. Analytical approaches to failure prevention fall into two broad classes:
Analyses performed to demonstrate that the performance requirements will be met (and therefore, by implication, that the item will not fail in normal use). Examples of these analyses are stress and fatigue analysis for mechanical items, worst-case analysis and thermal analysis for electronic circuits, and stability analysis for control systems.
Analyses performed to demonstrate that safety and reliability requirements are met. Examples of these are failure modes and effect analysis, fault tree analysis, and sneak circuit analysis.
The former are highly domain specific, as can be seen from the examples. The techniques that are required, and to an even greater extent the procedures, vary widely even among such functionally similar items as an electromechanical relay, a solid state relay, and a digital decoder. These analyses are typically performed by the designer rather than a reliability engineer, but the latter should be aware of the results of the analyses. Some examples in Section 8.3 refer to these analyses but details on their conduct must be obtained from specialized references. Within the scope of this chapter, we focus on the second, reliabilityspecific, type of analyses.
This is a mainstay of analytical techniques for failure...
