Hertz contact between 2 spheres in Abaqus
Hertz contact between 2 spheres in Abaqus
(OP)
Hi everyone,
I'm trying to solve a Hertz contact problem between two spheres.
My model is axisymmetric and comprising 2 elastic semi-spheres that are initially in contact (on single point at the top of the spheres).
I use a surface-to-surface contact with a "Hard contact" normal behavior and frictionless.
If I impose a displacement to one of the spheres, the simulation converges. But if I apply a pressure or a concentrated force on one of the spheres, it does not.
I tried to use the contact controls stabilize option but it did not help.
I want to validate my simulation against the analytical solution that is defined for an applied load...that's why I really need to make my simulation work in this configuration.
Thanks in advance for your help.
Regards.
I'm trying to solve a Hertz contact problem between two spheres.
My model is axisymmetric and comprising 2 elastic semi-spheres that are initially in contact (on single point at the top of the spheres).
I use a surface-to-surface contact with a "Hard contact" normal behavior and frictionless.
If I impose a displacement to one of the spheres, the simulation converges. But if I apply a pressure or a concentrated force on one of the spheres, it does not.
I tried to use the contact controls stabilize option but it did not help.
I want to validate my simulation against the analytical solution that is defined for an applied load...that's why I really need to make my simulation work in this configuration.
Thanks in advance for your help.
Regards.





RE: Hertz contact between 2 spheres in Abaqus
RE: Hertz contact between 2 spheres in Abaqus
1. Make sure nonlinear geometry is checked NLGEOM
2. Reduce your minimum step size and initial step size
3. Have the load reference an amplitude using smooth step
4. If both spheres are the same you can model 1 with a rigid symmetry plane to contact with.
I hope this helps.
Rob Stupplebeen
www.optimaldevice.com
RE: Hertz contact between 2 spheres in Abaqus
@ corus
I m afraid that between having both spheres initially in contact and applying a displacement to put them in contact, it does not change anything.
@ rstupplebeen
1. Check
2. Done
3. I m afraid I did not understand. What should I use instead of a ramp?
4. You re right, and I m in this case, but replacing the two spheres by one sphere against a rigid plane did not help.
Otherwise, if I use node-to-surface interaction instead of surface-to-surface interaction, it's working but I m not confident in the results. In the Abaqus documentation it is stated that the error with the node-to-surface interaction is much bigger than with the surface-to-surface one. Do you have any thoughts about this?
RE: Hertz contact between 2 spheres in Abaqus
1. How do you know that the two spheres are, in fact, in contact? Have you looked at the COPEN in *Preprint?
2. Add *contact stabilization
3. Check the documentation for *Amplitude and smooth step.
Are you new to this forum? If so, please read these FAQ:
http://www.eng-tips.com/faqs.cfm?fid=376
http://www.eng-tips.com/faqs.cfm?fid=1083
RE: Hertz contact between 2 spheres in Abaqus
1. Yes, I had a look at the COPEN output.
2. Already done. That's what I meant by "I tried to use the contact controls stabilize option".
RE: Hertz contact between 2 spheres in Abaqus
Also, what type(s) of warning messages do you see in .dat/.msg files?
You may look at the residuals and warnings in the Job Diagnostics menu as well in order to understand what's going on with your model.
Are you new to this forum? If so, please read these FAQ:
http://www.eng-tips.com/faqs.cfm?fid=376
http://www.eng-tips.com/faqs.cfm?fid=1083
RE: Hertz contact between 2 spheres in Abaqus
0,0
1,1
It's basically a ramp with a asymptotic ramp at the beginning and end.
Reference this Amplitude in your force.
Another option is to put the parts in slight interference and in the first step's contact definition click 'interference Fit' 'gradually remove' 'Automatic'
Basically the contact will push the nodes until they are no longer in contact with each other.
On a separate note I'm sure that I have helped with this exact problem before so try searching with my name and you can probably find it.
I hope this helps.
Rob Stupplebeen
www.optimaldevice.com