Embedded stress sensors have previously been employed as part of health monitoring systems for solid rocket motors; however, the sensor readings were used to detect anomalies such as bore cracks and bondline delaminations. This work is unique because, instead of structural defects, the sensors are used to determine changes to both the modulus and the stress-free temperature: both of which are useful and difficult to obtain. To do this, sensors were embedded into a test motor (a small motor with a metal case, insulation, and an inert composite propellant formulation) and subjected to stepwise cooling cycles: the sensor readings at each plateau in the cooling cycle were a function of the stress-free temperature and modulus. When analyzed, the data gave both the modulus and stress-free temperature shift in the motor. The sensor and accompanying analyses were used to establish baseline readings; then, the motor was aged, and the procedures were repeated. Over an equivalent age of several years (about 4.5 years of aging at ambient temperature), the modulus changed by about 20%. Shifts in stress-free temperature were harder to detect and will be investigated in future work.
Characterization of Propellant Modulus and Rocket Motor Stress-Free Temperature Using Stress Sensors
Journal of Propulsion and Power ; 34 , 4 ; 901-908
2017-12-21
8 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
Embedded stress transducers for solid propellant rocket motor applications
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