Comprehensive Erosion Model for the 120-MM M256/M829 Gun System
Abstract
Most 120-mm M256 guns firing the M829 round as their "honest" kinetic energy round have been condemned because of fatigue. Despite this fact, it is still important to determine the erosion life of the M829 round, since M256 guns that have fired the most recent kinetic energy rounds (M829A1, M829A2) rely on the M829 round for baseline dispersion testing of that gun. Today this generally results in M256 guns that having an equal mix of M829 and M829A2 rounds, thus necessitating the consideration of M829 round effects for any erosion analysis. Variability exists for M256 guns with M829 rounds depending on round count, round type, round-conditioning temperature, and their order. Distinctive erosion patterns and mechanisms are emerging as our gun erosion database increases for in-service and out-of-service 120-mm M256 tubes with M829 rounds. Our M256/M829 gun system erosion model-with its interior ballistics, thermochemistry, and boundary layer components-is constantly being guided and refined by the erosion and materials analysis data from fired gun tubes. A recent refinement includes improvement of the gun steel subsurface exposure model due to high quality, difficult to obtain data from in-service M256 tubes. Other recent refinements to the boundary layer heat transfer model are based on thermal data from M256 tubes. These refinements include the improvement/incorporation of case gas cooling effects, turbulent gas mixing/heating effects, and a very minor contribution from forcing cone-induced vena contracta cooling effects. These latter refinements are calibrated away from crack walls by positional thermal wall repacking depth, thermal wall transformation depth, and thermocouple data.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1998
- Accession Number
- ADA358731
Entities
People
- C. Richard
- G. Pflegl
- P. O’hara
- P. Vottis
- S. Sopok
Organizations
- United States Army Armament Research, Development and Engineering Center