Research on Damaged Constitutive Model for HTPB Composite Base Bleed Grain

In order to achieve mechanical properties of HTPB composite base bleed grain (CBBG), quasi-static uniaxial compressive and tensile experiments were conducted at room temperature (28℃). Based on the analysis of HTPB CBBG's nonlinear mechanical properties at finite deformation, a five-component viscoelastic-viscoplastic damaged constitutive model was developed. Model predictions present that the developed model can characterize well both compressive and tensile mechanical responses of HTPB CBBG. Damage evolution curves indicate that the increment of cumulative damage value D and damage factor f is approximately linearly dependent on the increment of strain ε when ε is larger than yield strain εy. When strain rate ε˙ decreases by upto four orders of magnitude, the damage degree at the compressive strain of -0.62 and tensile strain of 0.24 increases by a factor of 10.64 and 22.28, respectively. Tensile stress can lead to much severer damage than compressive stress. The user subroutine VUMAT was then written according to the developed model and implemented into the finite element program ABAQUS/Explicit to simulate uniaxial tension experiments. Simulation results indicate that numerical stress-strain curves show satisfactory agreement with experimental data and the accuracy of the VUMAT is verified. © 2019, Editorial Department of Journal of Propulsion Technology. All right reserved.