Ansys Contact Elements

[AdvancedEngineering]

I am trying to model an overhead travelling crane in AnsysV8.1 and am
having trouble with the contact between the crab/trolley and the
supporting beam. The contact should model a simple gravity connection
between the wheels and the supporting beam i.e. compressive forces pass

straight through the connection to the beam and tensile forces cause
uplift of the wheel with no force applied to the beam. I have tried a
number of contact elements but they either compress immediately (which
is not what I am looking for) or the node will displace excessively and

cause an incomplete solution.

Any advice would be gratefully received, or if someone could point me
in the direction of some good web resources.

Kind Regards,

Lee

[Martin Liddle]

Post by AdvancedEngineering
I am trying to model an overhead travelling crane in AnsysV8.1 and am
having trouble with the contact between the crab/trolley and the
supporting beam. The contact should model a simple gravity connection
between the wheels and the supporting beam i.e. compressive forces pass
straight through the connection to the beam and tensile forces cause
uplift of the wheel with no force applied to the beam. I have tried a
number of contact elements but they either compress immediately

Not sure I understand what this means; can you elaborate?

Post by AdvancedEngineering
(which
is not what I am looking for) or the node will displace excessively and
cause an incomplete solution.

What contact elements have you tried? What elements are you used to
model the rest of the crane?

[AdvancedEngineering]

You could consider the contact to be similar to that between a car and
the road. Any force going through the wheel goes directly into the road
whilst any overturning of the car would cause the wheel to leave the
road. In my analysis things are a little more simple. The analysis is
static and the crane doesnt move so there is no friction needed.

I am trying to find out what the forces are in each of the wheels and
determine if uplift occurs for a given loading.

Hope this clarifies things a little.

Lee

[Martin Liddle]

Post by AdvancedEngineering
You could consider the contact to be similar to that between a car and
the road. Any force going through the wheel goes directly into the road
whilst any overturning of the car would cause the wheel to leave the
road. In my analysis things are a little more simple. The analysis is
static and the crane doesnt move so there is no friction needed.
I am trying to find out what the forces are in each of the wheels and
determine if uplift occurs for a given loading.

Sorry but that does not answer any of my questions. To reiterate:

What do you mean by "compress immediately" in your first post?

What contact elements have you tried?

What element types are used in the rest of the model?

[AdvancedEngineering]

OK, in answer to your questions, after the analysis I read in the last
results and a couple of the contact elements have reduced to zero
length whilst the others remain at the initial length (300mm). The
contact elements are in as 2 noded elements (in the current model I am
using CONTAC52, capable of compression only. Contacts are modelled with
a height of 300mm because that is the height at which the horizontal
load is applied and causes overturning. The remaining elements in the
model are 3D beam elements BEAM4.