STrength of BAR
STrength of BAR
(OP)
Hi ALL.
I am supposed to calculate the bending stresses on the A-36 STL Beam. Please refer the attachment for the loading conditions.
1.Can this scenario be considered as a Cantilever at clamp (A) and simply supported at the Wall (B)?
2.HOw to calculate the Maximum bending stresses induced in the Beam.(what formulas to use?)
3. In order to caculate the Reactions RA and RB at points A & B, CAN I USE THE EQNS,
F1=RB-RA
∑M=0 at A, RB*y +F1*(x+y)=0.
PLease advise.
Thanks in Advance.
I am supposed to calculate the bending stresses on the A-36 STL Beam. Please refer the attachment for the loading conditions.
1.Can this scenario be considered as a Cantilever at clamp (A) and simply supported at the Wall (B)?
2.HOw to calculate the Maximum bending stresses induced in the Beam.(what formulas to use?)
3. In order to caculate the Reactions RA and RB at points A & B, CAN I USE THE EQNS,
F1=RB-RA
∑M=0 at A, RB*y +F1*(x+y)=0.
PLease advise.
Thanks in Advance.





RE: STrength of BAR
2) the usual.
Is this for school?
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: STrength of BAR
2) no, a propped cantilever is a redundant structure and you have to analyze it as such.
3) the reactions will be different (your's are for a simply supported beam), but other than that it's "straight forward"
RE: STrength of BAR
RE: STrength of BAR
RE: STrength of BAR
RE: STrength of BAR
RE: STrength of BAR
As far as I know they usually get deleted. I think there's something about them in the forum rules.
NX 7.5
Teamcenter 8
RE: STrength of BAR
possibly someone has, and Dave "the man" is looking into it.
maybe it is a student post ... it doesn't seem to be a real world problem, it does seem to be (IMHO) a dam'd fool way to support a beam ... as shown, as understood ...
RE: STrength of BAR
First of All,I apologise for not putting a clear problem infront of you which gave way to all these discussions. Since i was not supposed to disclose the actual problem conditions i was trying to simulate it in a simpler way but never imagined it would sound stupid.
Here is the actual Problem.The beam is actually a pipe. The wall is a die and the CLamp is circular. The pipe passes through the clamp and extends a foot after clamp.The pipe is pressed against the die and bent to some angles.
Now out of your expertise i need to know what would be the best Free body diagram for this condition and how to resolve this. I am just a new budding designer with a lot of aspirations to be succesful in this area. Since i am a contractor i cannot share the equipment details here. Any help you can provide will be great. I hope this is not a simple classroom problem.Based the Reactions and forces on the clamp, die and pipe i need to design a stronger fixture to test the equiment itself later on.
I once again apologise for any inconvenence it might have caused.
RE: STrength of BAR
the clamp can be fully fixed. the wall reaction can be modelled as a single pt load ... where you place it is open for discussion ... form your description i'd place it at the LH edge, closer to the "manulipating" force.
this is a propped cantilever problem. Roark has canned solutions for this geometry. this is a standard problem dealt with as a "redundant structure" or "indeterminate structure".
RE: STrength of BAR
But my confusion is, as the pipe starts bending the exertion point of force at the wall (Die) keeps moving from may be center towards the LH end of the Pipe.Am i correct in interpreting this?
IF yes, then how do we calculate teh stresses in that case.
RE: STrength of BAR
when do you want to recover stresses ?
1) initial setup ... pretty boring zero everywhere,
2) towards the end of the deformation ... quite likely, wall is a pt force at the LH edge,
3) somewhere inbetween, like just as the pipe begins to yield ... try a couple "wall" reactions" ...
a) pt force at the LH edge,
b) triangular disributed for over the LH 1/2,
c) ...
i don't think you should see a significant difference.
RE: STrength of BAR
My take on your problem is as follows: (1) Your die must be shaped to cradle each pipe size, a half circle in shape to match the pipe O.D. For smaller pipe sizes the die is actually a wheel with a radius which produces a bend which prevents buckling or crimping of the pipe for that dia. and various wall thicknesses. The wheel's outer surface or rim is shaped to that pipe O.D. (2) Your lever arm "x" is a changing length as you bend the pipe around the die and depending upon how and where force "F" is applied. "x" will start at the tangent point of the pipe and die at zero force, and then start decreasing as the pipe bends. At the same time, the force required to keep bending it will be increasing, but then "F" will start decrease as the pipe starts to yield. You must also support the pipe so that it doesn't buckle or turn to an oval in the bending process. (3) Most small pipe and bar benders have the "F" force vector applied perpendicular to the pipe at the point of its application and actually moving radially around the die wheel. Thus, "F" will be pointing at your wall at a 90° pipe bend. Thus, "x" may not change much. The force applying mechanism looks similar to the die wheel so it cradles and supports the pipe too, and "x" is a fairly small dimension to improve the pipe support situation. You can calc. the force required to start causing the pipe to yield and have a permanent bend, at the max. "x," this should basically be the max. force req'd. After that the force req'd. should actually start dropping (at least no longer increasing) unless your system does something to radically change "x" or the way the force is applied. But, when you've gone to all this trouble, adding 25 or 50% to the force application system and to the entire machine to sustain these forces is not real expensive.
Google pipe bending machines and pipe bending vendors and study their web sites. You should see some of the above.
RE: STrength of BAR
I agree with your points of view on this problem.
Like rb1597 mentioned i think it is a overhanging Cantilever Beam situation. I am trying to find the Roarks eqns.
I basically need to calculate the Stresses in this pipe for a given force and the distance values, die stresses and clamp stresses.
I once again thank you dhengr and rb1597.
RE: STrength of BAR
so plastic stresses are another thing you're going to have to look into. and then there a whole bunch of real world issues, like preventing the pipe from crushing itself at the radius block which'll require either careful loading or temporary support (like filling the pipe with sand, which'll change your applied forces ...
RE: STrength of BAR
I am still unable to find the Roark's eqns. Looks like i need to buy the book. Is it avalibale Anywhere on the web?
Any formulas on top of your head to try for me.
Well, as you mentioned the pipe crushing and egging etc are all taken care. Based on the things I mentioned earlier (Stresses in the pipe,Wall and Clamp) i need to design a test Fixture to test the equipment. This test fixture should never bend and be reused but the equipment will be operated at its full specs.
RE: STrength of BAR
google "propped cantilever", plenty of hits.
solve it for yourself (if you can).
RE: STrength of BAR
I think i solved the problem. will get back if i need any further guidance.