3Design and Optimization for Reliability

3.1 Introduction

Design for reliability (DFR) encompasses a set of tools that support product and process management from concept development, prototyping, new product introduction, volume production, and all the way through retirement. With affordable repair and maintenance costs, the goal of DFR is to ensure that customer expectations for reliability are fully met across a product lifecycle. In this chapter, we introduce several DFR tools that are commonly used by reliability practitioners and design engineers: reliability and redundancy allocation (RRA), failure‐in‐time (FIT) design, design for six‐sigma (DFSS), fault‐tree analysis (FTA), and failure mode, effect, and criticality analysis (FMECA). While RRA is implemented at the component level, both FIT and DFSS are often used in the detailed design of subsystems or assemblies. FTA uses a top‐down approach to investigate the root cause of systems failure and to determine the ways to reduce the risk of such failures. FMECA allows the design engineers to identify and rank the potential failure modes in the early development phase, and further determine the remedies to remove or mitigate the risk of failures.

3.2 Lifecycle Reliability Optimization

3.2.1 Reliability–Design Cost

Reliability can be designed in during the product development and prototyping stage. It is generally agreed that the design and development costs increase exponentially with the reliability of the item, including ...

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