Need to use a geometry without a contraint

[EzequielRuizNicolini]

Hello! I am trying to create a model consisting in two geometrys (image attached). The first one is a fixed sheet. The second one it´s a pin. This pin is part of a bigger geometry that is trying to move in Z direction. The pin is supossed to constraint that displacement by it's Contact interaction with the sheet. Mi question: i do not want to put a constraint to the pin, i would like to put just the load and the only constraint i want is due to de Contact interaction. is it posible? it seems Femap is asking me for more constraints when i run the analysis and read the error window. thank you in advance.
I am sorry about my poor english!

 

[corus]

Firstly, you'd be better meshing the pin in brick elements as you have used with the sheet, you'll get better results that way. I don't know about femap, but in Abaqus you need to apply a displacement to the pin to create an initial contact with the sheet or else you'll have problems as it thinks there is nothing to restrain the pin from moving. In a 2nd step you remove that displacement on the pin and apply the force you require. At that stage the pin will be in contact with the sheet and the program will think things are just fine and will run.

 

[rb1957]

sounds like you want to use a contact/gap element ?

another day in paradise, or is paradise one day closer ?

 

[tbuelna]

It does not appear that the pin free end is properly constrained, so your analysis case is indeterminate. If you want to simulate a simple contact between the pin body and the free edge of the sheet, then you'll need some way of representing the sliding, bending and frictions at the contact interface. As rb1957 suggests, one way would be to use gap elements between the contact surface nodes that have translational/rotational spring rates which approximately simulate a sliding contact. But you'll also need to create a representation of the structural boundary conditions existing at the opposite end of the pin. The stiffness characteristics at this interface will have an effect on the contact between the pin body and sheet edge.

 

[EzequielRuizNicolini]

Thanks for your advices. i just did it constraining 5 DOF (not the Z displacement) on the face of the pin that is not in contact. it seems that the contact is enough as a constraint for the 6th DOF.
Thank you very much