Reply To: Honeycomb Shear modulus Calculation based on Analysis – ASTM 273

[peteroznewman]

Bonded contact is a simulation object you may have used in your model to connect the foil. You mentioned that your model uses bonded contact. Maybe that was only to connect the edges of the core to the face of the test plate and you created the 2t effect on the shell model by entering twice the thickness on the shell. You could have used bonded contact between two shell elements each of thickness t.  In either case, the model does not have a low modulus adhesive layer between the foil layers that are found in the physical product.

A stiffer connection between the foil in the model would result in a higher shear modulus, but this may only be a tiny effect due to the very thin layer of adhesive, while the first error I mentioned of the adhesive in the product could be a huge effect by comparison and this goes in the opposite direction, making the product stiffer than your model.

Another source of error in the model for the measured shear modulus is the formulation for the bonded contact between the edges of the core and the face of the test plate.  Some bonded contact formulations connect the edges to the face using what you can think of as springs. These springs are automatically calculated in the solver. Those springs will reduce the modulus you measure compared with other formulations that don't use springs.