Nonlinear Effects of Loosely Constrained Deployable Mass on Instrument Dynamic Testing and Analysis

Many instruments utilize launch locks (pin-pullers, frangibolts, etc) to restrain deployable assemblies during launch to survive launch vibration and acoustic environments. Non-linear responses have been observed during vibration testing for instruments where the restrained mass represents a significant portion of the total mass. The non-linearity is particularly notable when the mass is loosely constrained and sees large relative displacement compared to the primary structure of the instrument. Three recent instruments, Multi-Angle Imager for Aerosols (MAIA), Radar for Europa Assessment and Sounding: Ocean to Near Surface (REASON), and Europa Clipper Magnetometer (ECM) Magboom, demonstrated non-linear behavior due to this phenomenon, each in different manners with differing impact to the test and/or subsequent analysis. The effect of the non-linear response is presented for each instrument as well as the adjustments to the test procedure and subsequent analysis. Finally, recommendations for improvements to analysis and test procedures is made for future instruments with loosely constrained deployable mass.