Fracture toughness of nitramine and composite solid propellants

Test results of compact tension (CT) specimens, are presented for fracture toughness evaluation of nitramine (in extruded and slurry cast conditions) and composite solid propellants. For notched strength evaluation of cracked configurations, failure assessment diagram is generated utilizing the inherent flaw model. Testing of solid propellant CT specimens need specialized facilities as the spring force of the clip-on type crack opening displacement (COD) gauge, generally used for metallic materials, is high enough to open-up the crack even before commencement of actual test. Therefore, a non-contacting type video extensometer was employed. Fracture toughness of the extruded nitramine propellant is found to be higher, compared to those of slurry cast nitramine and composite propellants.