peteroznewman
posted this
13 December 2017

- Last edited 13 December 2017
One small source of error introduced by lengthening the bridges to reach the midplane of the shell elements is the mass that is being added to the model that is not there in the physical model. This could have a slight effect on the modal frequencies.

One way to eliminate this additional mass is to construct the bridge geometry to the correct height, and leave a gap to the midplane of the shell elements of exactly half the shell thickness.

When viewed with thick shells, there is no "overlap" of the solid and the shell.

It is worth splitting the surface body at the tops of each bridge, then adding contact between these faces.

If the contact formulation is set to MPC, the contact elements can be seen after the solving the model.

This model has the correct mass of the physical system.

The table on the left has the results from this model with contact, the table on the right has the model in the previous post. Note the reduction in natural frequency caused by the added mass.

Save the attachment, change the extension from .txt to .wbpz and use ANSYS 18.2 to Restore Archive and you can see the examples in this and the previous post.

Regards,

Peter