Photoelastic investigation on the Crack-arrest capability of a pretensioned stiffened plate

Dynamic photoelasticity, employing a 16-spark-gap Cranz-Schardin camera system, was used for dynamic analysis of propagating cracks in stiffened panels. The method of finite elements was used for a corresponding static analysis. Photoelastic models included 0.009525×0.25×0.25 m Homalite-100 plates with 10- and 25-percent pin-joined and bonded stringers. Static and dynamic strain-energy release rates, kinetic-energy release rates and stringer-load concentration factors were determined in stiffened panels that were pretensioned and then impacted by a projectile. It was found that the arrest capability of a stiffened panel could be assessed through the kinetic-energyrate concept. Also bonded stiffeners were found to be more effective in arresting a propagating crack than a corresponding pin-joined stiffened panel.