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摘要
In order to represent time-dependent Poisson’s ratio of HTPB composite solid propellant，the inversion problem about determination of bulk and shear relaxation moduli from the uniaxial stress versus strain responses was studied based on the classical integral viscoelastic constitutive model. The collocation method with radial basis functions，as well as Gauss quadrature formulas for approximately singular kernels，was applied for solving the second-kind Volterra integral equations of the inversion problem. The obtained bulk and shear relaxation moduli were imported into Abaqus finite element software to simulate the mechanical behavior of HTPB propellant. The proposed inversion method was validated by comparing the finite element results with the results from uniaxial relaxation，creep，and constant-rate loading tests. Finally，parameter analyses were conducted to find out how the Prony series of viscoelastic Poisson’s ratio affects the relative relaxation moduli. The results show that，the curves of the relative bulk and shear relaxation moduli are separated when Poisson’s ratio is time dependent. The separation degree is affected by the difference between the long-term and instantaneous Poisson’s ratios，while the separation slope by the retarded time. With the correct volume and shear relaxation moduli，the classical viscoelastic constitutive model can reasonably predict not only the relaxation and creep behaviors of HTPB propellant，but also the time dependency of Poisson’s ratio. ? 2023 Journal of Propulsion Technology.
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