Extension of Stress and Strength Interference Theory for Conceptual Design-for-Reliability

Abstract

It has been recognized that design-for-reliability (DFR) during the conceptual design stage is very challenging. There are several gaps and deficiencies hindering the DFR implementation. The first gap is due to the disconnection between the output of the conceptual design and reliability parameters needed for the reliability modeling. The second gap is between the knowledge available during the conceptual design and the information needed for reliability analysis. The state of the art design-for-reliability research and implementation are primarily based on the traditional reliability stress and strength interference theory. The research to date has mainly focused on the embodiment design-for-reliability, since they take embodiment design data as inputs and derive reliability measures of the product as results. On the other hand, the conceptual design, in general, and functional design in specific are usually nonanalytical and nonquantitative and result in little information immediately useful for a detailed reliability analysis. Our research aims to address these gaps and deficiencies and to build a bridge between the reliability research and the conceptual design research in order to realize conceptual design-for-reliability. In this paper, we first review the state of research and practice in the fields of reliability and conceptual design. Building on the previous research, we extend the traditional reliability stress and strength interference theory and develop a conceptual stress and conceptual strength interference theory (CSCSIT) that parametrizes the conceptual design space by introducing reliability related parameters into functional design. Based on CSCSIT, a practical analysis framework is proposed to support functional design-for-reliability. A functional design example is presented to demonstrate the effectiveness of CSCSIT and the proposed framework.