An Experimental and Numerical Study of Gun Barrel Fatigue Fracture
Erosion,wear and fatigue have great influence on gun barrel life.The former produces ran-dom erosion pits or micro-cracks on the gun bore surface during the firing,forming a large number of stress concentration zones.Under the action of fatigue,micro-cracks expand from the inner surface to the outer surface along the radial direction of the gun barrel and become macro-cracks.Once a crack reaches the critical size,the gun barrel will probably fracture after continuing firing.A hydraulic im-pact fatigue device was designed and fatigue fracture of gun barrel was reproduced in laboratory condi-tions by a series of simulated tests.The results show that the fatigue fracture under the impact includes load crack source,crack propagation zone and fast-fracture zone.The crack propagation zone presents typical beach fringes.There is an inherent mapping relationship between the evolution law of the peri-meter strain on the outer surface of the barrel and the crack propagation rate.This provides a new method for health monitoring and launch safety evaluation of gun barrel.The Johnson-Cook equation was adopted to describe the dynamic constitutive relation of the gun steel and the strain rate effect was taken into account in the simulation.The simulated results have a good agreement with the experimen-tal results.
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