L-270 Mechanical and Thermal Properties: Description and Test
September 2021Kevin M. Jaansalu, CD, PhD, PE, PEng, Morgan Bolton
Mechanical properties of energetic materials dictate how a material will respond to a mechanical load. Mechanical properties that are useful to measure for energetic materials include traditional static and quasi-static properties, such as elastic properties, strength, and fracture toughness, and dynamic properties, such as storage and loss modulus, and relaxation modulus. Other properties to be aware of include glass transition temperature and thermal expansion coefficient. There are various techniques and apparatus that can be used to investigate the mechanical properties of an energetic material including uniaxial tension and compression tests, dynamic mechanical analysis (DMA), thermomechanical analysis (TMA), and Hopkinson bar apparatus. Thermal properties play a role in the generation of stress during heating and cooling. Related experimental techniques are briefly described, along with an example demonstrating how rapid temperature change can generate significant stresses (in excess of the tensile strength) at the surface of an energetic material. Much this material can find their parallels in many materials textbooks, but not in the same textbook nor from the perspective of energetic materials.