## General Mechanical

#### Define gap with contact element CONTA178

• saraahf1
Subscriber

Hi!

I'm trying to create a contact between 2 nodes and I would like to define a initial gap between this two elements because initially they are separated with 5mm and the contact only can occurs if the force is sufficient to move both elements more than the defined gap. Does anybody know how to define the dimensions of the gap?

This is the part of code where I've created the contact.

ET,8,CONTA178

type,8

e,NODE(xpos1,ypos1,zbsuk+0.1),1

• peteroznewman
Subscriber

Hi saraahf1,

You should read this thread for info on COMBIN40 element which allows you to easily define a gap between two nodes.

Regards,
Peter

• saraahf1
Subscriber

Is it the same way to use it with CONTA178?

• peteroznewman
Subscriber

Both CONTA178 and COMBIN40 will use the initial locations of the two nodes as the initial gap.

CONTA178 keeps track of 3 DOF for the contact and supports sliding friction when the gap closes.

COMBIN40 keeps track of 1 DOF for the contact and requires a spring rate for the contact.

I had some models in the other thread that you can download and try each element.

What version of ANSYS are you using?

• saraahf1
Subscriber

I'm using ANSYS APDL 15.0 and also have the same version of Workbench.

• peteroznewman
Subscriber

So build a 2 beam, 4 node model with a gap between the end points the beams as I did in this post, and try each element to see what works for you.

• saraahf1
Subscriber

I'll keep in mind the building of the proposed model.

I was reading about the options for the initial gap for the CONTA178 and I've seen that you can define them by the keyopt(4)=1, but then it is necessary to define the gap with the real constant (real constan 2 I think). Maybe my question is very basic but I don't know how to define this in the code. Would it be like this (the real constant parameter is defined in this way)?

ET,8,CONTA178

keyopt(4)=1

r,8,2,GAP

type,8

e,NODE(xpos1,ypos1,zbsuk+0.1),1

• DheerajKarki
Subscriber
I was just wondering if you have find the answer to your question. I am having similar situation as yours. I need to define a gap contact element on connected elements. Can you please advise how to do that?Regards,nDheerajn
• j.drozdowski
Subscriber
Hello. I'm trying to solve a benchmark which is done in Femap Nastran. Author is using GAP element with compression stiffness only defined. Is it possible to do something similar in Workbench ?.Is the CONTA178 an Ansys equiwalent ?nnn