Engineering failure is useful: Page 2 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.
statistical pattern of failure, and suggested where some investigation was needed. As an engineering "summer student" at the time, I was given the task of investigating a failure in a video vectorscope, a display-based instrument that draws vectors showing at a glance whether a video color signal is within specification. I quickly found that the base drive to an NPN transistor was too negative, causing base-emitter junction breakdown. In time, the transistor would fail. Once a failure is localized, the search for its cause is narrowed sufficiently that even a sophomore student could find it.

Vectorscope failures were merely inconveniences to television stations, illustrating the contrast in consequences between most electronics design and civil engineering failures. We can afford to push the limits more readily than airplane or bridge designers, for electronics failure is usually a nuisance and nothing more. 

Is it possible that one factor contributing to the rapid advance of electronics is that failure can be tolerated more readily in electronic engineering? 

It is nothing to pop a few transistors in the course of a good day's bench work, but a chemical engineer can hardly be so casual about the design of a petroleum refinery. While the single failure of a jet aircraft can trigger a long, involved study, and hopefully lead to a clear identification of the failure mechanism, multiple failure events daily occur during electronics bench sessions, often leading to insights into how not to design the prototype circuit, or what its catastrophic limits are.

Petroski identifies the goal of the engineer as the elimination of failure. While EEs do not like failure, we can tolerate more of it than our CE counterparts, and we do.

Power electronics is one of the areas where catastrophic failure is most likely. Converters and motor drives are power-limited devices and when they fail, they do so by distributing bits of plastic and silicon to the surroundings. Electrolytic capacitors are


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