Ball and Plane contact in Abaqus

[alialsaffar]

Hello There , I am using Abaqus CAE to simulate contact between a ball and plane . Surface-to-surface contact , hard ‎contact is being used . The CPRESS and COPEN distribution are consistent with Hartzian theory except the node before the ‎last in the contact area . This node has a CPRESS value and a postive COPEN value at the same time , I do not know why ? ‎‎. what I know if there is a CPRESS value then COPEN should be zero or negative value , and if CPRESS equal zero then COPEN ‎should be postive value . Please see the table below for a line path in the contact area .‎
If any one has an idea , this will be good .‎
Thanks for help .‎
Ali
X-axis CPRESS COPEN
‎0‎ ‎4.81E+09‎ ‎-2.18E-08‎
‎4.98E-05‎ ‎4.79E+09‎ ‎-2.17E-08‎
‎9.95E-05‎ ‎4.75E+09‎ ‎-2.16E-08‎
‎0.000149‎ ‎4.68E+09‎ ‎-2.12E-08‎
‎0.000199‎ ‎4.58E+09‎ ‎-2.08E-08‎
‎0.000249‎ ‎4.44E+09‎ ‎-2.02E-08‎
‎0.000298‎ ‎4.26E+09‎ ‎-1.94E-08‎
‎0.000348‎ ‎4.03E+09‎ ‎-1.83E-08‎
‎0.000398‎ ‎3.75E+09‎ ‎-1.70E-08‎
‎0.000448‎ ‎3.40E+09‎ ‎-1.55E-08‎
‎0.000498‎ ‎2.95E+09‎ ‎-1.35E-08‎
‎0.000548‎ ‎2.31E+09‎ ‎-1.09E-08‎
‎0.000598‎ ‎1.29E+09‎ ‎-4.99E-09‎
‎0.00064‎‎8‎ ‎1.12E+0‎‎9‎ 5.66E-0‎‎7‎
‎0.000698‎ ‎0‎ ‎2.21E-06‎
‎
‎

‎

 

[rstupplebeen]

I believe the confusion is over CPRESS and CFORC. Abaqus calculates the forces on the nodes and then interpolates based on nodal forces and the elements contact area. I hope this helps.

Rob Stupplebeen

https://sites.google.com/site/robertkstupplebeen/

 

[alialsaffar]

Thanks Rob
I think there is no problem with the CPRESS and CNORMF as you can see the table below
X-axis CPRESS COPEN CNAREA CNORMF
‎0‎ ‎4.81E+09‎ ‎-2.18E-08‎ ‎6.46E-10‎ 3.11E+00‎
‎4.98E-05‎ ‎4.79E+09‎ ‎-2.17E-08‎ ‎1.94E-10‎ ‎9.28E-01‎
‎9.95E-05‎ ‎4.75E+09‎ ‎-2.16E-08‎ ‎3.87E-10‎ ‎1.84E+00‎
‎0.000149‎ ‎4.68E+09‎ ‎-2.12E-08‎ 5.80E-10‎ ‎2.72E+00‎
‎0.000199‎ ‎4.58E+09‎ ‎-2.08E-08‎ ‎7.74E-10‎ ‎3.55E+00‎
‎0.000249‎ ‎4.44E+09‎ ‎-2.02E-08‎ ‎9.68E-10‎ 4.30E+00‎
‎0.000298‎ ‎4.26E+09‎ ‎-1.94E-08‎ ‎1.16E-09‎ ‎4.95E+00‎
‎0.000348‎ ‎4.03E+09‎ ‎-1.83E-08‎ ‎1.36E-09‎ ‎5.47E+00‎
‎0.000398‎ ‎3.75E+09‎ ‎-1.70E-08‎ ‎1.55E-09‎ ‎5.81E+00‎
‎0.000448‎ ‎3.39E+09‎ ‎-1.55E-08‎ 1.75E-09‎ ‎5.93E+00‎
‎0.000498‎ ‎2.94E+09‎ ‎-1.35E-08‎ 1.94E-09‎ ‎5.71E+00‎
‎0.000548‎ ‎2.29E+09‎ ‎-1.09E-08‎ ‎2.14E-09‎ 4.90E+00‎
‎0.000598‎ ‎1.27E+09‎ ‎-4.99E-09‎ ‎2.03E-09‎ 2.59E+00‎
‎0.000648‎ ‎1.10E+09‎ ‎5.66E-07‎ ‎3.01E-10‎ ‎3.30E-01‎
‎0.000698‎ ‎0‎ ‎2.21E-06‎ ‎0‎ ‎0‎

Thanks
Ali

 

[rstupplebeen]

I do not currently have access to the manual but my second guess is that it is associated with your contact algorithm and if it is nodal or surface based. I hope this helps.

Rob Stupplebeen

https://sites.google.com/site/robertkstupplebeen/