Experimental, numerical and analytical evaluation of structural integrity of experiment container subjected to reduced gravity flight testing

Abstract

An experiment container was designed, analyzed, fabricated and used for conducting a chemical experiment (calcium oxalate production) under reduced gravity conditions aboard a NASA-operated aircraft. The container was constructed of a welded and gusseted aluminum square-tubing frame and walled with polycarbonate panels that were lined in silicone and bolted to remain in-place while reinforced with square u-shaped side-wall supports. Blast cabinet gloves were fastened into the appropriate holes using mounting bolts and hardware. The bottom portion of the experiment container was separated into six compartments in order to house the experiment apparatus that was mounted in the secondary containment compartment. Eight tie-down straps secured the experiment container to the floor of the aircraft. For evaluation purposes, separate design loads resulting from 9-g's forward, 3-g's aft, 6-g's down, 2-g's lateral, and 2-g's up were imposed on the container. Analytical models (NASA-required design codes) were used to calculated margins of safety from forces and stresses. Numerical modeling (FEA) was used to determine stresses overall and at critical hotspots. Experimental methods were used to validate the analytical and numerical results. In general, the design codes provided factors of safety for the imposed loading conditions. As further validation of the design, the experiment container successfully flew on a reduced gravity mission onboard a NASA-operated aircraft. © The Society for Experimental Mechanics Inc. 2013.