Thanks for the shear and moment diagrams!Sun wrote: ↑Fri Jan 12, 2018 11:37 pmIn regards to post #1:
Your approach is correct, you can resolve the long axis of the board into a beam bending case. Naturally the short axis of the board is different, but I agree that this is an appropriate first step for sizing, as the long axis should experience the greatest load.
However, you should review the shear and bending moment diagram for that load case before you make the statement "the board is the most evenly loaded and all parts of the board contribute towards supporting the load"
For the load case you presented, the general shape of the shear and moment diagrams would look something like the attached rough sketch:
Shear Moment Diagram.jpg
Without knowing the relative magnitudes of the applied loads, I cannot exactly tell you where you will experience the highest bending moment, but it is likely to be the middle of the board. The foot pads may experience the highest load, and will be more likely to as the tips get longer relative to the distance between the footpads. However, there are clearly local maxima around the middle of the board and the footpads. The point which experiences the maximum bending moment experiences the maximum stress. This is usually why beams (or boards) supported in this fashion are thickest in the middle.
First diagram:rynhardt wrote: ↑Sun Jan 14, 2018 10:39 amThanks for the shear and moment diagrams!
Let me rephrase then: The load (water pressure) is the most evenly distributed, and the reactive forces are mostly symmetrical around the centre, which implies that the forward half of the board doesn't work any harder than the back half. is
Unless someone wants to volunteer to do a plate analysis I'm going to assume the short axis can be treated as uniform across the entire board.
Well sure. But I have to start somewhere. It's easier for me to understand one scenario at a time, and I simply picked the easiest one to start with
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