Burning Rate Measurements on Damaged Propellant Samples under Mechanical Loads

摘要

Among the various aspects of the deflagration of composite solid rocket propellants for aerospace applications, one deserving further attention is the dependence of the propellant regression rate on its mechanical state, properties and the loads applied to the material during deflagration. Beside structural-ballistic interaction phenomena occurring on a motor level, i.e. affecting the whole grain or large portions of it, the structural properties of a propellant and the mechanical loads acting on it during deflagration can significantly alter its combustion behavior on a microscopic scale, leading to what can be considered as an "intrinsic" coupling mechanism. This can affect the performance of a solid rocket motor even without the presence of macroscopic cracks or excessive grain deformation, and has been the subject of several experimental and theoretical investigations performed at the SPLab (Laboratorio di Propulsione) of Politecnico di Milano on AP-HTPB based composite propellant formulations. The same mechanism can also alter the IM properties of an energetic material which has been subjected to mechanical damage and chemical aging.