Experimental study of the cocure process with the vacuum bag method for honeycomb sandwich structure

By using glass fiber/epoxy 648 as panel and Nomex honeycomb as core, the effects of resin flow behavior on the area of fillet and panel quality in the honeycomb sandwich structure were investigated with the vacuum bag cocure process, and the relationships between bonding strength and fillet area were discussed by testing the flatwise tensile strength of samples. It is found that the fillet area first increases then decreases as the application time of vacuum is put off. The fillet area between bottom panel and honeycomb core is larger than that between top panel and honeycomb core. As resin viscosity varies, the mechanisms of porosity elimination change, which can also be influenced by the distribution of gas passage in the sealed bag. Moreover, the results of the mechanical test show that the improvement of flatwise tensile strength can be achieved by increasing the fillet area. However, if the bonding strength surpasses the tensile strength of the honeycomb core, it has limitation to characterize the bonding property by the flatwise tensile strength.