I've been through it already; it doesn't say how exactly the contacts remain bonded, regardless of the algorithm I choose. I'll give you a little more context, you'll see my real problem. I'll be modeling hip implants in my thesis, which means there will be bone-implant or bone-cement interfaces. These interfaces change with time (osseointegration occurs, securing the implant, or ostelysis, which loosens it), and these changes can be approximated with damage mechanics: hence, bonded contacts with a cohesive zone material. The only problem with that technique is that interface micromotions (contact sliding distance) are a key parameter in determining what happens at the interface, so I can't afford to use bonded contacts as a black box, I need to know what they do.
The other contact parameters I will have to use are: penalty or Augmented Lagrangian (they give the same results on my models) with user-defined stiffness. MPCs are out of the question, I need friction in there.
So, the trouble is not how to use them so much as how do I justify using them if I don't know what they do...
Thanks for trying! Christiane
PhD Student at Ecole de Technologie Superieure
Weisman, Bram wrote: > I don't know how much help this will be, but I would recommend you read > the on-line documentation "Contact Technology Guide" in it's entirety. > Along the way you should find some clues. Be aware that there are > several algorithms to choose from when doing bonded contact, some are > stiffness and/or penalty function based, and others are constraint > equation based (MPC). > > Best regards, > > Bram Weisman, P.E. > Overcoming ANSYS deficiencies since 1998. > > > SBM Atlantia > Suite 400 > 1255 Enclave Parkway > Houston, TX 77077-1608 > > This message is not provided as an SBMA employee. > > > "The reasonable man adapts himself to the world; > the unreasonable one persists in trying to adapt > the world to himself. Therefore all progress > depends on the unreasonable man." > - George Bernard Shaw > > > > -----Original Message----- > From: xansys-bounces_at_xansys.org [mailto:xansys-bounces_at_xansys.org] On > Behalf Of Christiane Caouette > Sent: Friday, May 02, 2008 2:02 PM > To: xansys_at_xansys.org > Subject: [Xansys] [STRUC] Bonded contacts > > > Hello everyone, > This is my first post; I hope I have done everything properly... > My question is about bonded contacts: I have looked everywhere I > could > think of (ansys help, google, library...), but I haven't been able to > find the mathematical description of these elements, only that of > standard contact elements. So what does Ansys do to keep those bonded > elements from opening? Is it a restriction on allowed nodal > displacement? Like, they can't move out of the pinball region, or > can't > move relative to one another (target nodes vs contact nodes)? > If anyone has any suggestions (or references I could check) to shed > some light on this... thanks! > Christiane Caouette, jr eng. > PhD Student at Ecole de Technologie Superieure > > > ^-------------------------------------------------------- > | XANSYS - www.xansys.org | > | The Discussion List for users of ANSYS, Inc. Software | > | Hosted by PADT - www.padtinc.com | > ^-------------------------------------------------------- > > ^-------------------------------------------------------- | XANSYS - www.xansys.org | | The Discussion List for users of ANSYS, Inc. Software | | Hosted by PADT - www.padtinc.com | ^--------------------------------------------------------