John Doyle
Ansys Employee

How are you post processing the friction coefficent?

From Table 178.3 and 178.4, it should be available via ETABLE as an NMISC item via   'ETAB,lab,nmisc,8'.  Make sure you also execute 'OUTRES,all,all' prior to solving so the info is saved to the rst file.

It is also worth mentioning that CONTA178 is node-node contact and really should only be used for small sliding.  You might want to consider CONTA172 (for 2D) or CONTA174 (for 3D) if you anticipate large sliding.

Also, this might just be a book keeping issue.  Make sure that your material attribute number is set to "3"  (via "MAT,3") before creating the CONTA178.