Careful here, assuming the beam is loaded vertically (gravity), doubling the vertical dimension will reduce the deflection to 1/8. Doubling the horizontal dimension will result in 1/2 the dimension. Note that this is assuming the same weight. If we take that the weight doubles with the double width, then the deflection will be the same. agscal -AGSCalabrese wrote: > Thanks > Based on your suggestions, I looked around and found > http://www.mech.utah.edu/~bamberg/research/BeamBendingSimulation/BeamBendingApplet.html > It appears that doubling the width ( depth ) of the beam causes the > deflection to be reduced about 8-fold. > Michael > > > >> On Sep 30, 2008, at 9:18 PM, Sean Breheny wrote: >> >> Hi, >> >> This would be a good start: >> >> http://structsource.com/analysis/types/beam.htm >> >> On this page they write these formulas in terms of the moment of >> inertia of the beams. I'm not sure exactly which moment of inertia >> they mean but I'd guess that it is around the axis which is defined by >> the cross product of the length and the applied force, and computed at >> the center of mass of the beam. >> >> Your answer may depend upon how the ends are fixed (whether they are >> allowed to pivot or not). >> >> It is not entirely clear to me how you are defining width and >> thickness and the direction of the applied force. I think that the >> dimension which is not length and is also not in the direction of your >> force will make a linear change in the stiffness. I think that the >> dimension in the direction of the applied force makes a cubed change, >> and the length makes a change which is not a pure power but a >> polynomial. >> >> Sean >> >> >> On Tue, Sep 30, 2008 at 10:14 PM, agscal -AGSCalabrese > >>> wrote: >>> >>> >>> You have a beam that is ( theoretically ) x long, y wide and z >>> thick. Weight is applied perpendicular to the xz plane. Beam is >>> supported at both ends of the length. >>> What happens if you compare it to a beam of the same material x long, >>> 2y wide and z thick ? >>> ( Presume the weight of the beam itself is not an issue and the beams >>> are stabilized from sway) >>> >>> >>> For example: If you have a beam made of 7/16 inch OSB that is 21 >>> feet long and 8 inches wide. >>> How much stronger will a similar beam be if it is 16 inches wide ? >>> >>> TIA >>> >>> Michael Algernon >>> >>> >>> -- >>> http://www.piclist.com PIC/SX FAQ & list archive >>> View/change your membership options at >>> http://mailman.mit.edu/mailman/listinfo/piclist >>> >>> >> -- >> http://www.piclist.com PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist >> >> -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist