基于分数阶Maxwell模型的NEPE推进剂宽泛应变率力学行为研究OA

In view of the distinct mechanical responses exhibited by solid propellants across a wide range of strain rates,the three-dimensional fractional-order Maxwell constitutive model and its difference iterative scheme were derived by using the Grünwald-Letnikov definition of the fractional-order operator.The ability of the fractional-order viscoelastic model to characterize the constitutive relationship of NEPE propellants under a wide range of strain rates was systematically investigated.Based on the Split Hopkinson pressure bar tests and high-speed tensile experimental data of NEPE propellants,the parameters of the fractional Maxwell constitutive model were identified using a genetic algorithm,and the fractional Maxwell constitutive model was verified using the test data at strain rates of 3 500 s-1,4 100 s-1 and 4 600 s-1.The results demonstrate that this constitutive model exhibits a strong rate dependence.For the high,medium and low strain rates,the viscoelastic mechanical behavior under multiple strain rates can be well characterized by a set of parameters respectively.The relative errors between the full-duration experimental values and the analytical solutions are basically less than 20%,while those between the analytical solutions and finite element numerical solutions are less than 2%.This validates the feasibility and accuracy of the three-dimensional fractional-order Maxwell model in describing the mechanical behaviors of NEPE propellants over a wide range of strain rates.