Static performance of hot bonded inserts in honeycomb panels

An investigation on the structural performance of inserts within honeycomb sandwich panels is presented. The investigation only considers metallic inserts in all aluminum sandwich panels and emphasis is placed on the structural performance difference between hot bonded and cold bonded inserts. The former are introduced during panel manufacture while the latter are potted into existing panels. The investigation only deals with the static performance of the two insert systems subject to loads in the normal direction to the facing plane, which corresponds to their main mode of operation. The experimental part of the work presented involved carrying out pullout tests on hot bonded and cold bonded reference samples by loading them at a centrally located insert. As expected the hot bonded reference samples outperformed the cold bonded reference samples in terms of load carrying capabilities. An analytical model which allows the prediction of shear stress distribution in a circular sandwich panel normally loaded at a centrally located insert is used in an analytical approach for calculating the load carrying capability of inserts. The results from this analytical approach were found to correlate well with the experimental ones for the hot bonded inserts but not for the cold bonded inserts which actually failed at a significantly lower load than was predicted.