MPC's
MPC's
(OP)
Hello all!
Well, my question is very easy for people who visit this forum (I am new in FEA).
Which is the difference between the types of MPC's (RBE2, RBE3, Explicit...) that I can model in PATRAN? I've been searching information and I've found the next:
"RBE2 is a rigid element that references a group of nodes to an independent node and RBE3 is a rigid element that references a dependent node to a group of independent nodes" Can somebody explain me this (an example, please) ?
THANK YOU ALL IN ADVANCE.
Well, my question is very easy for people who visit this forum (I am new in FEA).
Which is the difference between the types of MPC's (RBE2, RBE3, Explicit...) that I can model in PATRAN? I've been searching information and I've found the next:
"RBE2 is a rigid element that references a group of nodes to an independent node and RBE3 is a rigid element that references a dependent node to a group of independent nodes" Can somebody explain me this (an example, please) ?
THANK YOU ALL IN ADVANCE.





RE: MPC's
RE: MPC's
The main one is using RBE2's indavertently in a loop which becomes infinitely stiff. The bicyle wheel of RBE2's is also a common one to feed load into a hole which then becomes infinitely stiff and won't ovalise. The user then switches to RBE3's and a whole new set of problems emerge.
Read up well on these creatures and try lots of small test models where you know what the answer should be.
RE: MPC's
RE: MPC's
In over 25 years of FE analysis this was probably the worst example I have ever seen of inappropriate use of rigid body elements! As neither the lug or pin was free to ovalise and results were pure rubbish.
Since this was nothing more than 3 point loading the correct approach would have been to apply the lug load as a variable pressure distribution over the lug bore using the Gencoz empirical formulation. Similarly the same pressure formulation should have been used to apply loading at the bearing positions to a achieve a fully load balanced model. Minimal supports could have then been used to earth the model. And not a single rigid body element in sight!
RE: MPC's