why in tarnation do you want to model the fastener holes? you are not going to get a correct local stress distribution with RBE3 or RBE2 connections to the holes, nor even if you try to incorporate contact between the fastener and hole. just eliminate the holes in the model, connect with...
Do it in Excel.
Output all of the node definitions - ids and coordinates
Sort by coordinate locations.
Coincident nodes should be adjacent.
Create CBUSH cards in Excel using character strings.
Out CBUSH cards and read into Hypermesh.
If you are modelling the bolts with solid elements, well, to be frank, that is gross overkill and its not going to be accurate anyway. All it does is make for a very complicated model and will generate lot and lots of output for which you won't know what to do with. What are you going to do...
are you going to model the bolts with solid elements?
or are you modelling the bolts with bars/springs/etc?
are you going to attempt to model the fastener preload? which is quite difficult.
there have been many thousands of aerospace fastened joints analyzed with FE models with simple fastener...
If you are gapping the joint you do not have a good joint design. Either increase fastener torque, or add bolts, or something.
You can use either one or two models, just have to consider the limitations of each. Both are an approximation to reality.
rb - the dirty little secret is that FEA codes have NO clue about a ply being discontinuous (well, unless someone models the laminate with separate 3D elements for every ply). The stiffness matrix is generated for each element separately using the laminate stack for that element. There is no...
Ply 1 is typically the bottom (z=-t/2) ply.
Of course, just to be annoying, Nastran plate moment sign convention is the opposite of laminated plate theory moment sign convention.
Make a one element test case with +ve Mx applied and sort out the results.
Agreed, FEA is gross overkill for this. Make simple free body diagrams of the loads on each part, then simple hand calcs for strength and buckling for each part.
BeBtr - you need fatigue S-N curves for your material. Then given an R-ratio (min/max fatigue load) you can compare your static stresses to appropriate S-N curve to see where you fall re potential fatigue failure.
It depends highly on the application. There simply is no universal answer. If its a one time use thingy, then probably no need to bother with fatigue analysis. If its designed for 40 years, and going to see lots of cyclic loads, then its probably a good idea to do a fatigue analysis.
The other...
The use of RBE2s to connect to the shell elements will give rubbish local stresses (because it is a rigid element).
Spot weld allowable strength should be in terms of shear and tensile force, not local stresses.
So the calculation of local stresses (even if one could accurately predict them...
Connection element: spring, beam, cbush, glue, etc - depends on the code you are using.
Presumably you have modeling the C channel and plates separately need to connect them.
Why exactly do you want to model the weld area in detail? And what results are you going to extract from the model in...
Why not just forget meshing the actual weld circle and just use connector elements between a uniform mesh to represent the weld joint stiffness and strength? Getting local stresses with a fine mesh in the weld area is basically useless.
do you actually have thermal conductivity vs joint clamp-up pressure data? Haven't worked spacecraft in a very long time but don't recall ever seeing that kind of data, or worrying about joint contact pressure.
contact pressure and area is relatively straight forward with a bolted joint since you can control the preload ah, well, you can (sort of) control the torque on the fastener, but the preload is highly dependent on a lot of not so easily controlled variables, friction, etc.
what kind of rivets...
