Spring Positioning on a Cantilever beam

[HawkOkeoJr]

Hallo guy,
I hope its not asking too much, but i really need help with this, Urgently.
I have a cantilever, with point load P=100 at the end tip.
A spring(K=500) attached to the cantilever perpendicularly at UNKNOWN position.
I KNOW the deflection at the end tip. and the rest of the parameters, the only thing UNKNOWN is the POSITION where i can place this spring to generate the known deflection at the tip.
Can somebody help me formulate a formula which can help me get this position.
I will appreciate your help guyz, am really stuck on this.
I hope its well understood, if not, i can generate a drawing and attach it.
Thank you guyz.

 

[paddingtongreen]

Is it a known spring or do you have to make one? Is the spring going to push up or down?

There is probably some calculus method of doing this but I see an iterative process.
Calculate deflection without spring.
Calculate the forces at points along the beam to push it to the desired position. See the force required and the deflection at the point of application. That gives you the parameters if you are designing the spring, or, pick the best fit position if it is a known spring. repeat around that spot to approach the exact fit position.



Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[HawkOkeoJr]

@paddingtongreen
the Spring is a known spring of e.g K=500. if i were to lay out an iteration process, How would i go about it?...cause actually, i have to do the problem for varying thicknesses of my beam which correspond to the different spring constants.am trying to work it out in MS Excel.

I will try the force approach and see how it will move.

 

[rb1957]

it sounds like you have a cantilever with a point load applied, with a support (the spring) somewhere, and you know the tip deflection ... this sounds suspiciously like a student problem ?

 

[JAE]

Is this a classroom problem?

 

[rb1957]

my thought too, but i guess it's bearly possible that it might be a real problem ... the "known" tip deflection might be the required tip deflection (but then you'd think the problem would be expressed as "a tip deflection less than x" ... which is a much easier problem to solve).

also i'd've thought a real problem would be more like "i can support a beam at a couple of possible places, what spring stiffness is needed to get a tip deflecction less than x"; it unusual to have a spring lying around. then there's the nugget in the 2nd post referring to tapered sections, which really compounds the problem !

 

[YoungTurk]

Must be the advanced course, last semester we knew the location and only had to calculate the deflection

http://www.eng-tips.com/viewthread.cfm?qid=333709

 

[yakpol]

Write down formulas for beam deflections at the tip and at the spring. You will end up with two equations and two unknowns - location of the spring and beam deflection at the spring. Solve it on Excel or Mathcad or by hand. See attached.

Regards,

Yakpol