Biaxial Tensile Behavior of HTPB-Based Propellant: Effects of Displacement Rates and Ratios

This study investigates the mechanical response of composite solid propellants (CSPs) under biaxial loading conditions at various displacement rates and ratios. Biaxial tensile tests were performed on cruciform-shaped samples, where the Digital Image Correlation (DIC) technique was employed to measure strain fields. The tests were conducted at the displacement rate of 1, 50, and 1000 mm/min as well as at the displacement ratio of 1:1 and 0.5:1 (X:Y directions) to explore their effects on the biaxial response of the material. All the tests were carried out at temperature of 20 degree C. The obtained results reveal a non-linear stress-strain response that is highly dependent on displacement rate. An increase in displacement rate enhances the slope in the linear region and the failure stress for both the displacement ratios. Under the loading condition with a displacement ratio of 0.5:1, even though the displacement rate of the X direction is half that of the Y direction, the tensile modulus in the X direction is higher than in the Y direction due to Poisson’s effect.