DURABILITY OF STIFFENED COMPOSITE PANELS UNDER REPEATED BUCKLING

An experimental study of the durability under repeated buckling of Graphite/Epoxy stiffened panels subjected to shear and axial compression was carried out. The shear panels were hybrid Wagner beams with composite webs bonded to an aluminum alloy frame, whereas the axial compression specimens were "I" and "J" stiffened cocured composite panels. The test results demonstrate that composite stiffened panels are less fatigue sensitive than comparable metal ones. In the shear panels repeated buckling, even when causing extensive damage, does not reduce the residual strength by more than 20 percent. For the axial compression panels no reduction in residual strength was observed. Safe design of stiffened Graphite/Epoxy panels well beyond their initial buckling is therefore feasible. This can lead to more efficient structures. © 1990.