Stuck in creating a contact

Doruk Samiloglu

Hello everyone,

I am kinda a new user of CAE and Hypermesh and this is my first question in this community. I am trying a create a contact between a sheet metal and injection molded plastic part. By considering their thickness to lenght ratios, I modelled both parts with shell elements. 

I am considering the parts as the plastic part will be assembled the holes of the sheet metal part. I am planning to observe the structure's torsional strength with OptiStruct and applying a contact with a friction between the parts. The gap between the parts is approximately 0.5 mm.

I could not manage to create a contact since the parts are not located on top of each other with respect to their normals. I thought that maybe I can model the parts with 3D elements but since the sheet metal thickness is too low, I will need to use very small elements.

 

I am kindly asking your ideas for how to apply contact to efficiently simulate this scenario. Thanks in advance.

 

Rogerio Nakano_21179

Hi

If I understood well your case, the blue part does not cover or have normal projection to the red part.

if this is the case, in physical scenario , there is not contact and the blue part would fall thru the red part openings..

 

In other hand , if in the real case, you do not expect separation between the blue part edge and the red part, you may consider using rbe2 elements or 

extend a bit the surface mesh of the blue part to have the projection and use the tie contact.

 

I Hope this is helpful

Regards

 

Adriano_Koga

Rogerio Nakano_21179 said:

Hi

If I understood well your case, the blue part does not cover or have normal projection to the red part.

if this is the case, in physical scenario , there is not contact and the blue part would fall thru the red part openings..

 

In other hand , if in the real case, you do not expect separation between the blue part edge and the red part, you may consider using rbe2 elements or 

extend a bit the surface mesh of the blue part to have the projection and use the tie contact.

 

I Hope this is helpful

Regards

 

As mentioned by Rogerio, you could:

- build a node-to-node connection by making your elements connected from the beginning, making the interface nodes equivalent

- or extend a little further one of the components, and create a tied contact, with a little overlap

Doruk Samiloglu

Thanks for your kind replies. After I sent the post, I thought the model once again I found out two solutions same as yours. I am happy about that. 

I entended the blue parts mesh to the red one and run the analyses. In my opinion, stress value is logical but there is almost no stress occurred in the blue part as it is seen on the image. Do you have a opinion?

Since I was expecting the blue plastic part to somewhat squeezed by the red one as the plastic part has lower strength than the steel part. Torque was applied from the center of the steel part.