An easy-to-use design tool was developed in response to a large number of documented cases of critical (flight and ground) hardware failing after experiencing drops during commercial shipment. By entering the mass of the hardware to be protected, and the drop height, the software helps the user select the type and dimensions of the shock attenuating foam needed. Hundreds of drop tests were conducted with metal plates instrumented with accelerometers that were protected by common shipping foams of different thicknesses, along with foam compression tests conducted at various speeds to develop mathematical material models for these foams. The foam drops were video recorded at a very high rate of speed to capture foam deformation due to drop.
A foam modeling algorithm was invented that accurately predicts the shock attenuation and peak foam deflection. The algorithm yielded extremely high coefficients of correlation with test data (over 90%). Further sample testing revealed that this methodology did accurately predict the peak acceleration loads and foam displacement. This algorithm was implemented in an Excel-based design tool containing Visual Basic macros. A simple, easy-to-use graphical user interface was provided for a shipping clerk to use.
This work was done by Christopher Sangster and Satish Reddy of Jacobs Engineering for Johnson Space Center. For further information, contact the JSC Technology Transfer Office at (281) 483-3809. MSC-25515-1