Mechanical Properties and Model Parameter Calibration of a Novel GAP/RDX/TEGDN Propellant at Wide Range of Strain Rate
The accuracy of mechanical model parameters of high-energy and low-vulnerability solid propellant is of great significance to the prediction of its macroscopic mechanical response.In order to decouple the parameters of the viscoelastoplastic damage model of solid propellant,a model parameter calibration method based on experiment is proposed.The viscoelastoplastic damage parameters of GAP/RDX/TEGDN(GRT)solid propellant are calibrated by the quasi-static and dynamic tests using a universal testing machine and a split Hopkinson pressure bar device.The mechanical properties and damage mechanism of GRT at a wide range of strain rate are analyzed.The experimental results show that the mechanical behavior of GRT propellants is obviously strain rate-dependent,and the tensile strength and elongation are increased by 75％and 43.33％,respectively,with the increase in the tensile rate(1-1 000 mm/min).With the increase in quasi-static compressive strain rate(0.001-1 s-1),the yield strength is increased by 16.67％.With the increase in dynamic compressive strain rate(2 100-4 100 s-1),the yield strength is increased by 72.98％.The fracture strain of the material is related to the stress state.The fracture strain is decreased by 36.36％with the increase in stress triaxial degree(η=0.33 to η=0.74).In addition,according to the microscopic characterization of GRT propellants,the main failure mechanism is interface debonding under quasi-static stretching,and the main failure mechanism is particle breakage under quasi-static and dynamic compressions.On this basis,the parameters of Plastic-Kinematic constitutive model are calibrated by quasi-static and dynamic compression tests,the parameters of Prony series are calibrated by stress relaxation test,and the parameters of fracture damage model are calibrated by notch test and quasi-static tensile test.Therefore,the model parameters could be calibrated more accurately by the proposed method.It provides support for the prediction and analysis of macroscopic mechanical properties of propellants.
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