Some solid propellant stress transducer considerations

Accurate measurement of bond stress in a solid propellant rocket motor has been obtained with a unique stress transducer design. This transducer is embedded within the nonlinear viscoelastic solid propellant which is a highly corrosive material and experiences large material property changes with age and temperature variation. The solid propellant rocket motor bond stress changes over a wide range during storage, thermal excursions, and ignition history. This transducer has been stabilized using special metal conditioning processes, epoxy filtering and cure processes and mechanical and thermal cycling. Corrosion protection is provided by eliminating all adhesive joints by exclusively using electron beam welded seals and bringing electrical leads out using a glass-to-metal header and maintaining the leads in 10-ft long stainless steel tubes.