Mechanical Design and Development of a Payload for Structural Health Monitoring Experiments on the International Space Station

This contribution reports design and development of a payload for structural health monitoring (SHM) experiments on the International Space Station (ISS). The payload was designed to operate in low earth orbit (LEO) environment and fit specifications of the Materials International Space Station Experiment (MISSE) module. In particular, LEO environmental factors such as a strong vacuum, thermal variations from −18°C to 60°C [1], and background radiation were considered. The payload is a rectangular multi-leveled structure which houses several SHM experiments, active sensors self-assessment, and electronic hardware with data storage and retrieval capabilities. SHM experiments include guided wave propagation in a metallic structure, monitoring of an imitated crack, assessment of a bolted joint, investigation of structural vibration via electromechanical impedance method, and acoustic emission monitoring. In addition, piezoelectric sensor self-assessment is realised using impedance diagnostics. It is anticipated that the payload will operate for one year in LEO and provide insights on the effect of space environment on SHM of future space vehicles during long-duration flights. This contribution focuses on mechanical design of the payload to support SHM experiment. Specific arrangement of payload elements and implementation of boundary conditions for SHM experiments are reported. Theoretical calculations and examples of SHM experimental data obtained in laboratory tests are presented and discussed in light of expected variations due to LEO environment. Measures to protect SHM hardware from harsh space environment are presented. Perspective applications of SHM as an integral component of future space systems are discussed.