Abstract: A testing apparatus and methods for use with a tensile testing machine for simulating thermal, acceleration, and ignition pressurization loads upon a grain support system of a solid rocket motor during ignition. The apparatus includes a pair of antisymmetrically disposed L-shaped test fixtures within which is attached a test specimen. The test specimen is configured to simulate two propellant grain support systems. The grain support systems in the test specimen are antisymmetrically disposed, thereby permitting two specimens to be tested simultaneously by the application of uniaxial tension to the apparatus.