DISBOND CRITERION FOR POSTBUCKLED COMPOSITE PANELS

A major limitation in the use of lightlyloaded composite primary structures is the marked tendency for stiffeners to disbond from the panels they are intended to support. Current methods for the design o f stiffened-panels rely upon empirical formulae verified by experimental data and, in general, are only safely used for configurations that are relatively close to those tested experimentally. The present approach concentrates on an analytical determination of the normally-directed bondline stress t hat e xists between the stiffener and panel elements of a postbuckled panel. Correlation of the proposed theoretical/anal ytical approach to experimental data with many different configurations and geometries provides a measure of a ssurance that the stiffener disbonding failure mode is predictable.