RBE3 element Femap advice
RBE3 element Femap advice
(OP)
I am working on a structure which will lift a container(in Femap). I have modelled the slings using a RBE3 6DoF element and fixed the node of lifting(see attached picture)The structure is meshed with a plate element. And when i try to analyse it Femap tell me that there is 6 FATAL Errors associated to the C-BUSH (3DoF) element that i placed between a RBE2 and a RBE3 element.
I would like some help from someone who is a professional in Femap. If I replace RBE3 by RBE2 structure will be rigid and that's not good. There is not an element that represent sling in Femap ??
http ://files.e ngineering .com/getfi le.aspx?fo lder=f7a62 f9c-3605-4 a6c-90b4-4 2ad68865c2 5&file =MASS1.png
http: //files.en gineering. com/getfil e.aspx?fol der=f53faf 88-acf3-4b 10-a97d-04 1665ce76d9 &file= RBE2_2.png
Thanks,
SE
I would like some help from someone who is a professional in Femap. If I replace RBE3 by RBE2 structure will be rigid and that's not good. There is not an element that represent sling in Femap ??
http
http:
Thanks,
SE





RE: RBE3 element Femap advice
"On the human scale, the laws of Newtonian Physics are non-negotiable"
RE: RBE3 element Femap advice
"On the human scale, the laws of Newtonian Physics are non-negotiable"
RE: RBE3 element Femap advice
I used RBE2 element to model screws and make the hole rigid, but here the problem is related to RBE3 and not to RBE2, you mean I have to remove the RBE2 element and place a node at the center that I connect with RBE3? and I did not put two independent nodes on the RBE's Joined by spring.
each spring element is connected to one independant node on one side and to one dependant node on the other side.
Femap dislike maybe the way i defined the constrained node on the slave node of the RBE3 (slings.
i attached another picture to better explain the story of nodes.
(sorry for my english level)
Thanx
http
RE: RBE3 element Femap advice
"On the human scale, the laws of Newtonian Physics are non-negotiable"
RE: RBE3 element Femap advice
RE: RBE3 element Femap advice
"On the human scale, the laws of Newtonian Physics are non-negotiable"
RE: RBE3 element Femap advice
Best regards
RE: RBE3 element Femap advice
If the target is to study the structure, not the ropes, forget RBE3 elements, you can use CGAP NODE-TO-NODE elements of Tension-Only to simulate the guys, FIXING THE LIFTING NODE. You will have to play with the value of tension stiffness, a reasonable value could be say 1e6 N/mm (not bigger than 1000 times the stiffness of near elements). Use 1.0 for compression stiffness.
But you need to run a nonlinear static SOL106 analysis, this is the key when using CHAP elements to account for large displacements effect.
Best regards,
Blas.
~~~~~~~~~~~~~~~~~~~~~~
Blas Molero Hidalgo
Ingeniero Industrial
Director
IBERISA
48011 BILBAO (SPAIN)
WEB: http://www.iberisa.com
Blog de FEMAP & NX Nastran: http://iberisa.wordpress.com/
RE: RBE3 element Femap advice
After writting I realized that using rigid elements will cause incorrect results in buckling and differential stiffness analyses because the large displacement effects are not calculated.
Exceptions are zero length elements (e.g.,to simulate a hinge) and rigid elements constrained so that they don't rotate.
If solving a nonlinear analysis try to minimize the use of RBE2 elements.
Best regards,
Blas.
~~~~~~~~~~~~~~~~~~~~~~
Blas Molero Hidalgo
Ingeniero Industrial
Director
IBERISA
48011 BILBAO (SPAIN)
WEB: http://www.iberisa.com
Blog de FEMAP & NX Nastran: http://iberisa.wordpress.com/
RE: RBE3 element Femap advice
RE: RBE3 element Femap advice
Cheers