VIRTUAL TESTING OF NOMEX HONEYCOMB SANDWICH PANEL INSERTS

The present study develops a detailed progressive failure model based on the Finite Element Method (FEM) for the widely used fully potted threaded sandwich insert under pull-out loading. The investigated sandwich panel consists of phenolic resin reinforced by glass fiber fabric as face sheet and a Nomex honeycomb core. The model is developed for three configurations where the core height is the only varying parameter. The numerical results are compared with extensive experimental data for each configuration. The model shows good agreement between numerical and experimental results well beyond the first failure mechanism of cell wall buckling for all three configurations. With increasing core height, the debonding of honeycomb core and face sheet becomes dominating with regards to the global joint strength. However, this failure mechanism has not yet been included in the model. It therefore overestimates the joint strength for the configurations with increased core height.