Experimental characterization of thermal creak response of deployable space structures

The phenomenon of thermal creak in deployable space structures is Investiga ted. Thermal creak is a disturbance that occurs when thermally induced stre ss in a statically indeterminate structure is suddenly released via a slip internal to a joint or other frictional mechanism. A representative deploya ble truss is suspended in a thermal chamber, where its temperature is cycle d, in order to determine whether thermal creak occurs in such a structure. High-bandwidth accelerometers distributed across the truss are used as the primary sensors for detecting structural events. Thermal creaks are found t o occur during the thermal transients before steady state Is achieved throu ghout the truss. The truss response to the impulsive and broadband disturba nces is characterized in both the time and frequency domains. The transient response exhibits telltale signs of structural behavior, including multimo de or dominant-mode excitation, and reasonable modal damping in the time de cay. An analytical model of the thermal creak mechanism is presented that q ualitatively captures the structural behavior.