Bend to surface or plane, or small bends

[sschneiderXHH8R]

Hi all,

I'd like help bending this simplified roller gate for a dam.  There are conflicting reports of this gate deflecting 3/8" or 1 1/2" when under load, and because of its design it won't behave as a tube or solid cylinder for mathematical problem solving.

Due to its large physical size, a small change in deflection yields a big difference in the size of the gap with its weir, leading to a big difference in the amount of water lost.

I have labeled the important planes to help.

-The roller gate bends while holding water.  It bends along Bend direction plane towards Target plane, with maximum deflection at Centerline plane.

-I have tried bending it at Work plane 4 (the "vertical" plane of the main cylinder), Forward bend profile plane and Rear bend profile plane.

It appears that I can't have an arc length longer than the length of the dam, which makes sense.  However, it also appears that there are radii that the Bend Part command "simply won't do."

In an ideal world, I'd tell Inventor to bend at the sketched line until the front edge of the gate at Centerline plane touched Target plane, which is currently set 3/8" back from the tip.  Still in the ideal world, I'd change the amount of offset of Target plane, which would then rebuild the bend.

Any help would be greatly appreciated, thanks.

Steve

[swalton]

I'm not sure that the simple arc represents the deflection of the gate correctly.  I'd be tempted to use a simple beam calculation, assuming the gate has a constant Moment of Inertia in the load direction.  You can use your cross-section sketch to calculate the Moment of Inertia

Either way, I would not use Bend to show the deflected shape.  Instead I'd use a Sweep.  Make a sketch of the gate cross section and a second sketch showing the edge deformation.  Use references to constrain the second sketch geometry that give you the dimensional control you want.  You can use a simple arc if that is "good enough" or you could use an equation curve and the deflection equation that best matched your loads and constraints.  Use the Sweep command to generate your 3d solid, add the end plates and you are done.

What is the goal of this model? 

[sschneiderXHH8R]

Hi and thanks for the quick reply. I hadn't thought of getting the moment
of inertia along the deflection direction; I'll give that a try.

The ultimate goal is to protect baby fish as they migrate. They are being
turned to chum as they pass through the gap between the roller gate and its
weir. I will export STL files of the roller gate and the weir for the flow
gurus to perform CFD modeling using FLOW-3D to find the maximum flow
gradient as the water passes through the dam. For the positions with the
dam 6" or 12" open, the deflection is moot and the ideal, undeflected
roller gate model will be fine.

But for the shut position, the gap matters considerably, which is why I'm
trying to bend this part. The original designers expected 3/8" deflection,
but operators claim it's 1 1/2". With those two deflections, we'd be able
to find theoretical flows and flow conditions, to find out what we're up
against in trying to design a seal.

Thanks,
Steve