基于分数阶三参数模型的HTPB推进剂粘弹性力学响应分析OA北大核心CSTPCD

In order to extend the application of fractional-order model in HTPB propellant and study on predicting of dynamic modulus changes of propellants in the frequency domain using fractional-order viscoelastic models.Three-dimensional fractional-order three-parameter constitutive equations were derived,which were transformed into UMAT subroutine combining with the Grünwald-Letnikov definition.In order to calibrate the constitutive parameters,the analytical solutions of creep and relaxation with preloading were derived,and the constitutive parameters corresponding to the creep experiments at 0.4 MPa and 0.6 MPa stresses as well as the relaxation experiments at 10%and 30%strains were calibrated by genetic algorithm.The time-history relative errors between the cal-culated finite element values and the analytical solutions,the analytical solutions and the experimental values are less than 5%.The complex modulus formulation of the one-dimensional fractional-order three-parameter constitutive equation was used to fit the DMA experimental results at-5℃,25℃and 60℃to obtain the constitutive parameters,and the error between the complex modulus and the experimental results is less than 2%,while the calibrated constitutive parameters all reduce as the temperature increases,reflec-ting the softening phenomenon of propellant at elevated temperatures.The results show that the fractional-order three-parameter mod-el can accurately describe the variation of propellant modulus of multiple frequencies at different temperatures,which can provide a material constitutive model for the subsequent study of mechanical response of HTPB propellants under complex boundaries.