Catastrophic Failures, Designed For Failure, And Adventures In Mechanics One Credit Freshman Mechanics Seminars

Abstract

As part of its mission to provide, through service courses, the fundamentals of mechanics and materials, the Penn State Engineering Science and Mechanics Department created the following one-credit freshman seminars: Catastrophic Failures, Designed for Failure, and Adventures in Mechanics. The objectives of these three one-credit mechanics/materials-related seminar courses include: • initiate meaningful dialog between students and faculty, • inform students as to ethical expectations, • orient students as to particular options of study, • demonstrate via case studies what engineers 'do', and • provide laboratory awareness and experiences. Catastrophic Failures Engineered systems sometimes fail in catastrophic ways.... bridges collapse, buildings burn, airplanes explode, ships break in two, spontaneous combustion occurs, autos crash, etcetera. Virtually all such failures occur because the designers, builders, and/or users have overlooked some unexpected combination of inputs; they seldom fail due to simple overload. For example, a bridge designer may have overlooked the potential danger of aerodynamic loading and mechanical resonance, or having a bridge mooring struck by a tugboat; the building designer may not have considered an earthquake; the ship designer may not have expected a combination of very cold weather and large waves, nor 'bad material' etc. This seminar explores such design deficiencies through the study of case histories of a number of infamous failures, such as the explosion of the Challenger (modern era) and the sinking of the Titanic, which caused catastrophic loss of life. A primary objective of reliving such failures is to alert students to the various factors that must be considered for a safe and effective engineering system, and to encourage them to broaden their education so that they will not repeat the mistakes of the past in their own careers. An example of a bad result is summarized below. Broken Engine Mount Recall Engine designed prior to pressurization for re-burning vapors, pressurization led to oil leaks, oil leaks onto rubber engine mount, mount degraded to point it could not restrain upward motion, on hard cornering (centrifugal acceleration) and acceleration (engine torque), engine lifted out of support cradle, and in some cases jammed accelerator as well as gear selection. Result; auto goes out of control.