Impact of Machining

In aerospace materials quality assurance testing, research and development, and design allowables database development, tens of thousands of specimens are tested every year. Many factors dictate the measured property averages, standard deviations, skewness, etc. Often those factors are of interest (e.g., the impact of changing suppliers) but other times those factors are desired and assumed to be kept constant (e.g., specimen dimensions, testing environment, etc.). If the impact of those assumed-to-be-constant parameters on measured properties were to be better understood it would be possible to direct energy and resources into the appropriate aspects of testing to improve consistency, and reduce standard deviations, potentially increasing the a- and b-basis allowables, permitting the manufacture of lighter aerospace structures with no change in material systems, or reduction in safety and performance. The student team tested a number of parameters, normally assumed to be constant, on the mechanical properties of cured neat resin. With this knowledge, they designed a revised set of test requirements to improve the precision of test data, in the style of a proposed change to an ASTM standard.

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