Detectability of Delaminations in Solid Rocket Motors with Embedded Stress Sensors

A finite element model is used to investigate the effect of delaminations on the radial stress distribution along the bondline during the cooling process of a solid rocket motor composed of propellant, insulation, and casing. Under the assumption of stress sensors evenly distributed along the circumference of the interface between the propellant and insulation, a relationship is established between the debond angle, the number of sensors, and the required sensor accuracy. Two approaches are proposed to detect debonds based on the radial stress readings from these embedded sensors. In addition, a quantitative mapping is obtained between the debond size and the sensor data to inversely estimate the extent of the delamination. It is demonstrated that the proposed framework can detect delaminations in solid rocket motors.