Failure Modes

Learn about impulse and excessive strain, with an emphasis on accepting the failures rather than ignoring them and the importance of designing failure modes.

Catastrophic failure

Impulses and excessive strain can both trigger catastrophic failure. In either case, some component of the system will start to fail before everything else does.

In Inviting Disaster [Chi01], James R. Chiles refers to these as “cracks in the system.” He draws an analogy between a complex system on the verge of failure and a steel plate with a microscopic crack in the metal. Under stress, that crack can begin to propagate faster and faster. Eventually, the crack propagates faster than the speed of sound and the metal breaks explosively. The original trigger and the way the crack spreads to the rest of the system, together with the result of the damage, are collectively called a failure mode.

No matter what, the system will have a variety of failure modes. Denying the inevitability of failures, robs us of our power to control and contain them.

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