Design and Verification Study of HTPB Propellant Aging Safety Detection Sensor

Aging detection of hydroxyl-terminated polybutadiene (HTPB) propellant in solid rocket motors is crucial for preventing launch accidents. To achieve nondestructive aging assessment of HTPB propellants, the design of dedicated sensors is essential. In this study, HTPB propellant was selected as the research object, and a three-point contact model under spherical indentation was established. The deflections of both cantilever straight beams and curved beams were derived and calculated using the deflection curve differential equation and the Karl Fischer theorem, respectively. Polydimethylsiloxane (PDMS) materials with different curing agent ratios, along with sensor components, were fabricated through wire electrical discharge machining and 3-D printing. The sensor’s performance was experimentally verified and analyzed. The results demonstrate that the proposed sensor can effectively measure modulus variations within the range of 0.5163–12.1150 MPa and can distinguish HTPB propellants with varying degrees of aging, thereby enabling nondestructive aging detection. This research expands the current methods for HTPB propellant aging assessment by enabling safety monitoring based on changes in modulus-related parameters, ultimately contributing to enhanced reliability of solid rocket motors and a reduction in launch accident risks.