Plate Bending Problem

[zliu]

Hello everyone,

I was wondering if I could analyze a door (hinge and latch) under load with classical hand analysis.

Boundary Condition: The door is hinged on one side, allowing rotation, while the latch will only react in the vertical direction (Ty).
Loading: Assume there will be 3 different loads at b/2, and various location along length l.

Goal: Determine where to place the latch to minimize the deflection in the y-deflection of the door.


I checked Roark's formula, but none of the boundary conditions match what I have here. Since the latch is assumed to be simply supported at a single location, and all the classical hand calculations assumed the entire edge is simply supported.

I will be modeling this in FEM, but I was wondering if it's possible to analyze this situation through hand analysis.

Any help is appreciated. Thank you!

 

[Ng2020]

Is the door large enough that it would be prudent to have 2 latches for redundancy?

If you only have 1 latch to play with, then I think the best you could do is determine the centre of pressure for the applied loads then place the latch on the edge adjacent to that.

 

[zliu]

Is the door large enough that it would be prudent to have 2 latches for redundancy?

If you only have 1 latch to play with, then I think the best you could do is determine the centre of pressure for the applied loads then place the latch on the edge adjacent to that.

2 latches would be the next step, if 1 latch is not enough to keep the deflection under the limit.

As of center of pressure of the applied loads, are you talking about the centroid of the 3 loads like a weighted average?

 

[rb1957]

I'm sorry, I can barely understand your post !?

what moves, and what is fixed ?? can you explain the sketch some more ?

why does the latch only react Ry (out-of-plane) loads ?

As for one latch or two, is this an interior monument ? if so there are FAR requirements about latching (that over-rule prudence).
I'm assuming this is on an aircraft.

 

[Sparweb]

If there's any ambiguity in the analytical model, then you load test it.
That way (a) you don't need to waste your time and your employer's money with building a FEM and (b) hand calcs will get you close enough that you can be sure the test will pass.
A properly set-up test will prove the structure without question, in compliance with FAR 25.305 and 307, and for less time that your FEM set-up will take.
Before you are tempted to boast about how fast you can set up a FEM, note that I am comparing the time taken to set up a valid load test against a valid FEM, not a quick data dump into ANSYS. The valid load test is universally faster by a substantial factor, especially when it comes to a cabinet door.

 

[rb1957]

BTW, plates are lousy in bending ... add stiffeners, or sandwich panels.