Study on micro-mechanism of impact fracture and combustion performance of porous gun propellant based on plane stress

The microscopic impact damage law and combustion performance of propellants are crucial for evaluating mechanical properties and ensuring the safety of propellant charge designs. The paper conducted transverse drop hammer impact tests at both normal and low temperatures, as well as closed bomb tests on the propellant after it sustained damage. The application of the discrete element method (DEM) was used to study the consistency of plane stress between two-dimensional and three-dimensional models of propellant. It was found that both the fracture shape of the end face and the drop hammer force are consistent across the models. Based on these findings, a detailed model of the propellant was constructed. Impact fracture simulations of the propellant at both normal and low temperatures were conducted. The results yielded the drop hammer force, maximum intact bond force, and the evolution of crack patterns. The error in the peak drop hammer force between the simulation and experimental results was 4.3 % and 3.6 %, respectively, indicating a strong correlation in the force curve amplitude and trend. These findings reveal the micro-evolution mechanism of bond fracture. The combustion performance of the fractured propellant was simulated using an equilateral triangle combustion model. The error in the degree of propellant fracture between simulation and experiment was 3.3 % and 4.9 %, respectively. This demonstrates that the established simulation model effectively elucidates the micro-mechanisms of impact fracture and the combustion performance of porous propellant. The research results provide valuable technical support for the evaluation of mechanical properties and the formulation design of propellant.