In-Situ Monitor for Cure-Induced Deviatoric Stress in Propellant Charges of Solid Rocket Motors

Abstract

Background

Deviatoric stress, as a pivotal factor influencing both the mechanical properties and durability of propellant, stands as a critical metric for assessing the quality of produced solid rocket motors (SRMs) and evaluating the processing parameters. The inherent characteristics of SRMs significantly restrict the application of existing methods in cure-induced stress measurements, thereby hindering the calibration of finite element models and optimization of the manufacturing processes.

Objective

This study is to develop a method for in-situ monitoring of cure-induced deviatoric stress.

Methods

Prefabricated structures with strain sensors are embedded for monitoring cure-induced deviatoric stress, and full-scale experiments were conducted to compare the influence of different cure technologies. Coupled thermo-chemo-mechanical simulations are performed to verify the feasibility of the proposed method.

Results

The Pearson correlation coefficient of the strain in the prefabricated structure and the cure-induced deviatoric stress is up to -1.000, which proves the feasibility of the proposed method. A 55.87% reduction in signal with pressure cure technology could be observed, which may help to prove the mitigation of pressure cure technology in cure-induced deviatoric stress.

Conclusion

The proposed method is capable of in-situ monitoring of cure-induced deviatoric stress in propellant charges during the curing and cooling phases. Pressure cure technology can help to lower the residual deviatoric stress during the curing phases, while during the cooling and pressure-releasing process, the rate of variation in deviatoric stress is more prominent.