Semi-empirical model for rubber shrinkage and debonding in solid rocket motors

• Published in: Journal of the Brazilian Society of Mechanical Sciences and Engineering Vol. 46; no. 8
• Main Authors: Rapozo, Rodrigo, Iha, Koshun
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.08.2024; Springer Nature B.V
• Subjects: Aging (metallurgy); Curing; Debonding; Design factors; Elastomers; Engineering; Life cycle analysis; Mechanical Engineering; Metal bonding; Physical properties; Propellant casting; Propellant storage; Propylene; Rocket cases; Rockets; Rubber; Solid propellant rocket engines; Solid propellants; Technical Paper; Thermal analysis; Thermal cycling; Thermal protection; Vibration analysis; Viscoelastic materials; Vulcanization; Solid rocket motor; Insulation; Shrinkage; EPDM; Bonding
• ISSN: 1678-5878; 1806-3691
• DOI: 10.1007/s40430-024-05067-7

Rubber-to-metal bonding is a common subject for many industries. Particularly, this kind of application is often an issue for solid rocket motors. Starting from the application of an adhesive, the bonding of a non-cured rubber, its curing/vulcanization in a oven or autoclave, its shrinkage, the solid propellant shrinkage, the thermal cycling, mechanical shocks and vibration due to transportation, and storage aging effects are factors that influence the design and the engineering solution for certain applications. In this work, a model is presented to evaluate the curing shrinkage of an elastomer to a steel rocket case from an Ethylene-Propylene-Diene-Monomer elastomer physical properties and the feasibility of the application of many layers without debonding, during the manufacturing steps prior to propellant casting and the subsequent mechanical/thermal loads presented along the life cycle of the motor. This work combines the current thermodynamic approach for viscoelastic materials with consolidated literature results, resulting in an innovative set of analytical tools for analyzing shrinkage due to curing loading applied to a representative rocket motor case-thermal protection interface.