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Methodologies to improve reliability engineering in early designO'Halloran, Bryan M. 11 October 2011 (has links)
This thesis is the summation of two publications with the motivation to move reliability analysis earlier in the design process. Current analyses aim to improve reliability after components have been selected. Moving specific analyses earlier in the design process reduces the cost to the designer. These early design analyses provide information to the designer so that critical design changes can be made to avoid failures. The first presents failure rates for function-flow pairs. These function-flow failure rates are used in the Early Design Reliability Method (EDRM) to calculate system level reliability during functional design. This methodology is compared to the traditional reliability block diagram for three examples to show its usefulness during early conceptual design. Next, an extension to the Function Failure Design Method (FFDM) is presented. A more robust knowledge base using Failure Mode/Mechanism Distributions 1997 (FMD-97) has been implemented. Then failure rates from Nonelectric Parts Reliability Data (NPRD-95) are added to more effectively determine the likelihood that a failure mode will occur. The proposed Functional Failure Rate Design Method (FFRDM) uses functional inputs to offer recommendations to mitigate failure modes that have a high likelihood of occurrence. This work uses a past example where FFDM and Failure Modes and Effects Analysis (FMEA) are compared to show that improvements have been made. A four step process is presented to show how the FFRDM is used during conceptual design. / Graduation date: 2012
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