Engineering failure is useful: Page 4 of 5

February 19, 2016 //By Peter Clarke
Engineering failure is useful
Dennis Feucht discusses the works of the engineering author Henry Petroski and what he had to say about failure.
as a controlled design variable. In pushing the concept of controlled failure, cost can be traded off for a product that fails reliably just after its warranty expires. As warranties on automobiles, for instance, are competitively extended, designers are driven toward one-hoss shay design.

Perhaps it is the no-hoss shay that will realize the no-weak-link product, suitable only for hauling to the dump once it breaks.

Failure and normative design

New technologies are not well understood and designs are conservative. Mature technologies, such as beverage cans (see Petroski's book, Invention by Design , for interesting case studies of this kind) are pushed to their minimalist limits. Once a technology is mastered and reliability becomes a design variable, the engineer has the power to choose alternative approaches to design based on differing values.

A company with a reputation for high-quality products will allow engineers to exercise their seeming escape from original sin to design the best product possible. But a competitor, realizing an increased profit margin through stealthy corner-cutting, pressures the quality supplier to do the same to compete. The eventual result is a marketplace filled with junk, and a society with a throw-away mentality.

I will leave it to economists to work out a new economic cycle describing this phenomenon. Recovery from the bottom of the quality-junk cycle involves much more than engineering-related issues. One of the questions is whether the financial state of buyers has anything to do with it. An affluent market may be just as inclined to spend more repeatedly for product replacements than to spend the same amount once for a long-lasting product. Perhaps a preference for the former is a factor in the shortening of design cycles, which gives engineers less time to design a refined product, thus reinforcing the descent into a world of techno-trash.

While Petroski laments the lack of dissemination and even cover-up of failure analyses in civil engineering, and what a

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