Learning Forum

[sofia.baroni2]

Hello everybody,

I am doing simulations using a model made up of a hollow cylinder and a slightly tapered pin positioned as in the first attached image. Load and boundary conditions are applied as in the second attached image in a longer hollow cylinder.

 I realized a mapped mesh so that each target (TARGE170) element corresponds to a contact (CONTA174) one. As a starting condition I need to assign different contact gap values randomly to the elements of the contact surface, in order to do that I created different real constants modifying CNOF. After the first simulation I create ETABLE in order to archive contact gap values for each contact element (ETABLE,cont_gap,CONT,GAP). After that I assigned different real constant (different Contact Surface Offset CNOF) to each contact element, and I run another simulation; creating again ETABLE with the new contact gap values, I get exactly same GAP values as before for each element. How can I fix this problem getting different contact GAP values according to the different CNOF values?                                                                 CONTA174 keyopts are like in the third attached image.

Thank you in advance for any help.

Sofia

[John Doyle]

Are you defining CNOF as a constant value or in tabular format? If you are just selecting each contact element and redefining CNOF as a constant, it will still be applied the same to all the contact elements that share the same real constant set. It is possible to define real constant CNOF in a tabular format as a function of X,Y,Z coordinates withÔÇÿRMODIF,NSET,10,%CNREAL10%ÔÇÖ command, for example but you need to define the table ÔÇÿCNREAL10ÔÇÖ first.Please see Section 3.9.1.2 of the MAPDL Contact Technology Guide for more details about this.

[sofia.baroni2]

Thank you for your answer.
Since I need certain percentage of contact elements choosen randomly to have gap zero and other percentages (choosen randomly as well) to have different gap values, I defined CNOF as a constant, but I changed the real constant set of each element from one simulation and the next. And if for example real constant set n.30 (which has -0.01 as CNOF value) has been assigned to contact element n. 23456 and after first simulation real constant set n.31 (which has -0.05 as CNOF value) has been assigned to the same element, in the ETABLEs created after each simulation I get exactly the same gap value (for element n. 23456) up to the last decimal digit. Plotting solutions I sow that results seem to be correct according to the new real constant set. The problem is just how values are stored in the ETABLE. I checked several times my script and I am quite sure that there are not errors in storing gap values.