Fail-Safe Thermal Activation Components for Insensitive Munitions

Cornerstone Research Group, Inc. (CRG), proposes the further development of heat-activated pressure venting mechanisms actuated by shape memory polymers (SMP) for meeting insensitive munitions (IM) requirements for ammunition containers and solid rocket motors. SMP composite materials provide the same strength as conventional composites at normal operating temperatures. However, at a threshold activation temperature, these novel materials soften to a controlled modulus of elasticity and thereby allow a predictable deformation under load. In cook-off conditions, at the threshold temperature specified by the propellant type, the SMP’s transition temperature is exceeded and the SMP actuates in a controlled geometry (rather than simply melting). SMP-actuated pressure venting mechanisms coupled with conventional ammunition containers will provide failsafe venting during slow cook-offs. CRG has demonstrated the internal SMP ring as a venting system at a prototype level during Phase I. Phase II will continue the internal ring design concept for prototype testing on an analog 7-inch solid rocket motor in a slow cook-off situation, and prepare the technology for Phase III transition. By the end of Phase II slow cook-off testing, the SMP mechanism for IM will be at a Technology Readiness Level (TRL) of 6, system/subsystem model or prototype demonstration in a relevant environment.