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| Bending |
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furby100 Member since: 3/13/2000 From: London, United Kingdom |
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 Posted - 1/18/2002 4:17:54 PM |
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| When a beam is held in position at one end, and a force is applied at the other end of the beam, causing the beam to bend, is the force applied proportional to the angle the beam makes or to the the distance the beam is moved downwards, or is the relationship more complex? |
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Jesper T Member since: 6/1/2001 From: Bergen, Norway |
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Posted - 1/18/2002 4:23:25 PM |
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| Im not 100.0% sure, but I would say that the force needed to bend the beam increases exponentially the more you want to bend it. This depends on what material the beam is made out of offcourse, but I assume you mean it is elastic to a certain point, like wood or stainless steel. But, if it was made out of say.. lead, then it would be different. [edit = damn typos] Edited by - Jesper T on January 18, 2002 4:25:11 PM |
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Fruny Moderator Member since: 11/16/2001 From: Paris, France |
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Posted - 1/18/2002 8:24:53 PM |
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| Cantilever beam deflection : go there. |
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Dredge-Master Member since: 12/13/2001 From: Australia |
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Posted - 1/19/2002 12:28:16 AM |
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What you are after is deflection. You need the above to work out the deflection. The second moment of inertia is the value that "defines" the shape and size of the beam itself. This is the I . A square beam will bend differntly to an i-beam or a t-beam or a cylindrical pole. You get the idea. I have posted the equation for any rectangular beam (which includes squares) If you have no idea what the second moment of inertia is or how to get it, ask. As I said above, it changes for different shaped and sized beams. Oh, E is the modulus of elasticity. All of the stuff is in SI units. Use Newtons (not pounds) for the load, and mm for the size if you are using 207000 MPa (n/mm^2). Otherwise change the units. Pretty logical, but if you use the wrong units you get really weird answers. I know from experiance.  Beer - the love catalyst good ol' homepage edit because I got the units wrong Edited by - Dredge-Master on January 19, 2002 9:08:05 PM |
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BSXrider Member since: 1/13/2002 From: United Kingdom |
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Posted - 1/19/2002 12:58:06 PM |
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| Very interesting. I don't quite understand it though. What's the siginificant of the drawn "axis" x about a third of the way along the beam? - seb |
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Fruny Moderator Member since: 11/16/2001 From: Paris, France |
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 Posted - 1/19/2002 4:19:17 PM |
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| I think it's the indication of a cut-out or section view . You can tell from the mixed dash pattern of the line. It could have been a cylinder axis too, but obviously not. |
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BSXrider Member since: 1/13/2002 From: United Kingdom |
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Posted - 1/19/2002 6:31:27 PM |
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| No it's not. For some reason the deflection y is being measured at a point x from the source of the force.... - seb |
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Dredge-Master Member since: 12/13/2001 From: Australia |
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Posted - 1/19/2002 9:07:04 PM |
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| The x-x shows an axis along the length of the beam. It can also be used as a cut-away. If you ever use a beam other than a rectangular or cylindrical shape, you need to use this x-x axis to find the centre (and therefore the I value. The reason why you would use the x distance is when you want to find the deflection at any given point of the beam. This is because it doesn't bend like a straight line, it curves. To find the maximum bend (where the load is) you don't need the X (it is zero) but for anywhere else you do need it. PS - X can be any length on the beam. It can even be up the far end of the beam ______________V x or it can be at one end, and the load in the middle (x taken at V, and the rest of it is should be linear - makes it easy if you have the slope at V to do this - see next post - edit) _______V____x sorry bout the bad drwaing. if the formating is screwed. Beer - the love catalyst good ol' homepage Edited by - Dredge-Master on January 20, 2002 11:50:56 PM |
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BSXrider Member since: 1/13/2002 From: United Kingdom |
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Posted - 1/20/2002 5:14:04 AM |
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| Ah.... yes I didn't think of subbing x=0 to see what I got. Thanks! Very interesting. - seb |
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Dredge-Master Member since: 12/13/2001 From: Australia |
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Posted - 1/20/2002 7:31:14 AM |
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| no problem If you had it in a text book or other document, it show you how to get the three parts of the equation, and how to cut it down for Ymax. It also shows how to calculate the slope which I haven't included. If you need that I can post it aswell. Seeya, James. Beer - the love catalyst good ol' homepage |
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Vlion Member since: 2/10/2000 From: Moscow, USA |
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Posted - 1/21/2002 2:31:27 AM |
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| offtopic: nice technical render. the bugle4D engine; a new dimension in graphics... [link]http://members.tripod.com/thefivelions/bugle4d/[/link] |
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Dredge-Master Member since: 12/13/2001 From: Australia |
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Posted - 1/21/2002 5:21:46 AM |
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| noticed your signature is a bit screwed. use the standard a href="http://members.tripod.com/thefivelions/bugle4d" html link. Incidently, the software I use for design and stuff (like above) is called SolidEdge. Only CAD software I use now. Edited by - Dredge-Master on January 21, 2002 5:24:24 AM |
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