Integration of Failure Mode Identification with Design for Mechanical Components
by
J. L. Handrock
D. L. Marriott
Materials and Design Division
Department of Mechanical and Industrial Engineering
Abstract
Component failure is always expensive, even when failure is not an issue from a safety point of view. The cost of detecting and rejecting defective parts increases exponentially as the product development process advances. The ideal place to correct errors is right at the beginning of the process, before any commitment has been made to materials or manufacturing processing methods.
This paper considers the problem of identifying all sources of possible component failure, including such off-design situations as material substitution and gross human errors. Because of the large number of opportunities for such errors to exist in a typical production process, and recognizing the fact that relatively few of these errors are likely to be a real problem in a specific case, the problem which must be solved is one of searching for a sparsely distributed set of significant events in a large population of irrelevant events. A strategy is presented herein, which allows efficient use of existing information available to the designer to be used to converge rapidly onto the possible failure events, as a preliminary study to detailed analysis of each individual failure mechanism.
The strategy developed for failure mode identification is illustrated by application to an example of the manufacture of a vehicle suspension spring. The events leading to accelerated failure dur to error-induced fatigue mechanisms are identified, and the results of the study are used to illustrate how an analysis of this type might be used to plan Quality Assurance activities on a Fitness-for-Purpose basis.
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