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Need Help Modeling Belleville Washer in FEMAP

Need Help Modeling Belleville Washer in FEMAP

Need Help Modeling Belleville Washer in FEMAP

(OP)
It looks like the only option I have is to use DOF Springs. I created a dimensionless load vs displacement function and applied to the DOF Spring. Then between End A and End B, I apply 3 of these DOF Spring elements, each representing stiffness in the three coordinate directions. Is this the proper way to do this? Do End A and End B have to be coincident? Is there a better way than using DOF Springs? Thanks.

RE: Need Help Modeling Belleville Washer in FEMAP

In general, DOF springs should not be used unless the nodes are coincident, bad things can happen. If your nodes are not coincident, and actually even they are, I would suggest using Spring/Damper element. If you want enter a force/displacement curve, then click on the "nonlinear/freq response" button and you will be able to reference your force/displacement function.

Regards,

Joe

RE: Need Help Modeling Belleville Washer in FEMAP

(OP)
Thanks Joe. I don't like DOF Springs and always use CBUSH. I didn't see any way to input my load/displacement function. Thanks for giving me a lead.

RE: Need Help Modeling Belleville Washer in FEMAP

(OP)
Update Joe. In initially the run failed but after I put in an initial value for stiffness in the DOF Spring stiffness window, it ran. Unfortunately the results are not what I expected, and I can fix that later. My question is this: I do not believe I have the non-linear FEMAP module (I'm yet to check on that). So, by invoking the non-linear stiffness, does FEMAP ignore my L-D curve and just use that initial stiffness I provided?

RE: Need Help Modeling Belleville Washer in FEMAP

Use of a load-displacement curve requires a nonlinear(iterative solution) analysis, so you will need a nonlinear license, and will have to use the nonlinear analysis type in the Femap analysis manager.
If you submit a linear analysis, then the nominal stiffness value on the CBUSH entry is used by the Nastran solver.

Regards,

Joe

RE: Need Help Modeling Belleville Washer in FEMAP

(OP)
That's what I thought. I'll dig into this some more. Thanks Joe.

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