Autofrettage, Cooling, and Dynamic Loading of Fiber Reinforced MMC Jacketed Gun Barrels

The DD 21 Advanced Gun System (AGS) currently under development will be required to fire at high pressures and muzzle velocity at high sustained rates of fire. Currently, monolithic materials, including high strength steel do not provide the necessary specific strength, thermal conductivity or bore erosion resistance to meet these future mission requirements. The Phase I program developed an innovative fabrication process to enable the use of advanced fiber reinforced aluminum as a structural jacket in the AGS barrel. Analysis indicated that this material reduces the bore temperature and the thermal stress by a wide margin, thereby enabling the barrel to meet future mission requirements. The proposed Phase II program will further develop the technique for swage autofrettage of the metal matrix composite jacketed steel lined gun barrel. Additionally, a computer model of the composite jacketed gun will be developed and verified through full bore diameter sample testing. The method of overcoming the low strain to failure ratio of typical ceramic fibers used in Phase I will be further developed at large diameter sample sizes. This program will enable the fabrication of AGS barrels with significantly improved bore and fatigue life with new high temperature propellants.