Examining of Mechanical Shock Waves on Nanosatellites

  • Abdulla Almesmari

Student thesis: Master's Thesis

Abstract

Spacecrafts experience intense dynamic and static loadings during launch. Especially, transient pyroshock events might lead to a catastrophic mission failure. Nanosatellites are integrated into the launch vehicle as secondary payloads which mitigates the risk of shock vibrations. However, due to the emerging technologies of micro-launchers and small rockets, nanosatellites would become the primary payloads and experience severe shock levels. Therefore, examining the effects of pyroshock events on Nanosatellites is becoming essential for future Nanosatellite developers. The primary objective of this research is to suggest a new CubeSat deployment system design that mitigates shock vibrations intensity. Space-qualified passive isolator thin-films were utilized to attenuate the transient shock events. The secondary objective of the research defines a complete set of Nanosatellites vibration testing protocol that includes sine, random and shock vibrations testing procedures. A metal-to-metal Mid-Field Shock Testing (MFST) facility was manufactured to analyze the attenuation strategy. It has the capability to generate shock waves up to 10,000 g for out of plane excitation and 5000 g for in-plane excitation. Sorbothane thin-film isolators (2 mm thickness) were sandwiched inside the dynamic envelope of the test pod to isolate the mass model at the rail-to-deployer contact interface. The experiments successfully attenuated the mechanical shock waves by 7 dB in total. Sorbothane isolators attenuated shock levels by 3 dB and the flat adapter (mechanical joint) attenuated shock levels by 4 dB. A practical solution was introduced to overcome in-plane configuration testing limitation. Commercial rubber pads were interfaced between the resonating plate and test equipment to rectify the lower frequency region of the SRS spectrum. This finding will prevent undertesting the future CubeSats missions for in-plane excitations. ABAQUS explicit analysis was utilized to develop numerical models and verify in-plane and out of plane experimental setups. The experiments were conducted based on the Cygnus acceptance level shock profile with standardized NASA testing tolerances. The research had highlighted the importance of revisiting the current CubeSat dispensing systems. Based on the experiments it is recommended to sandwich Sorbothan thin-films inside the dynamic envelope of the deployers. In terms of numerical analysis, sophisticated models shall be developed to understand the nature of wave propagations inside the electronics of the Nanosatellites.
Date of AwardApr 2020
Original languageAmerican English

Keywords

  • CubeSat Shock Testing
  • Shock Attenuation
  • Mid-Field Shock Testing Facility
  • Shock Response Spectrum.

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