"Floating" an object in Structural FE
"Floating" an object in Structural FE
(OP)
Say you have a basic concept aircraft structural design.
In flying mode various loads will be put on the structure - by the flaps, elevator, rudder etc. which in the real world is taken up by rotational mass inertia of the aircraft structual materials.
FE support reaction member problem.
In an simple FE simulation hard reaction points are used to balance these loads - but this produces high reaction values at these local reaction points and "distorts" the local reaction member stresses.
Any solutions.
Thanks.
In flying mode various loads will be put on the structure - by the flaps, elevator, rudder etc. which in the real world is taken up by rotational mass inertia of the aircraft structual materials.
FE support reaction member problem.
In an simple FE simulation hard reaction points are used to balance these loads - but this produces high reaction values at these local reaction points and "distorts" the local reaction member stresses.
Any solutions.
Thanks.





RE: "Floating" an object in Structural FE
Of course, it's early and I may not be thinking clearly, but it seems to me that it should work.
RE: "Floating" an object in Structural FE
The first method is the most sensible, but the loads will need to be recalculated for each loadcase.
For instance, with a pneumatic tire running on the road, the easy way to put the load into the wheel is to load each node across an arc at the bottom of the wheel, which varies with location.
The other option would be to model the tire - a lot of work.
Both approaches are used.
Cheers
Greg Locock
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RE: "Floating" an object in Structural FE
in your first case (the airplane, yes, the plane's equilibrium is calculated, but a point on the plane (any point has to be "nailed down" to take out any imbalance loads and to provide the model with a reaction to the 6 rigid body freedoms.
same with your beam. if you don't like the very localised stresses near the hard constraint, then support your model on springs; this'll give the model some flexibility (instead of the infinite stiffness of a hard constraint).