rod buckling calculation
rod buckling calculation
(OP)
Can anyone give me the calculations (or send me to a site) necessary to compute the critical buckling stress for a hydraulic cylinder.
Thanks,
Calman
Thanks,
Calman
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RE: rod buckling calculation
RE: rod buckling calculation
Calman
RE: rod buckling calculation
I didn't use buckling analysis for a long time. But the info in Mchinery's handbook should be enough. You can also look at any machine design book such a Shigley, Norton. This is a very basic subject. What version of Macinery's handbook you have?
RE: rod buckling calculation
I just don't know what to use for the effective length "l".
The cylinder is mounted by two pins (one at end of rod, the other at rear of cyl.) and the open centercenter is 202".
Anyway,
I appreciate your help israelkk
RE: rod buckling calculation
RE: rod buckling calculation
Wouldn't the worst case be when the rod is fully extended out of the cylinder? That seems to be the most likely time for buckling failure to occur.
So let's say I used the "both ends free" case. What would that make my "k" factor?
Thanks
RE: rod buckling calculation
E  Modulus of elasticity
I  Rod section ineria = Pi*d^4/64
l  column maximum length
P=((Pi)^2*I*E)/(L^2)
RE: rod buckling calculation
RE: rod buckling calculation
RE: rod buckling calculation
answer my question. Thanks for your help israelkk!
RE: rod buckling calculation
eulers formula can be adapted for cylinders,
Fcr = pi2 x E X I/L2  (eULERS )
sub. pi x d4/64 for I ( solid round shaft )
and 2.07 x 10*5 foe E (steel )
Fcr = pi*3 x d*4 x 2.07 x 10*5/l*2 x 64
then Fcr = d*4 x 10*5/l*2
then d*4 = Fcr x l*2/1 x 10*5
d = 4th root of Fcr x l*2/1 x 10*5
where Fcr = critical force in newtons
E = modulus of elasticity, N/mm*2
I = moment of inertia of rod mm*4
l = effective length
this gives rod dia for criticalforce, that is the force at which the rod may start to buckle, you must apply a safety factor to be sur that it doe's not collapse
d > 4th root of Fa x l*2 x sf/1 x 10*5
Fa is allowable force in newtons
sf is safety factor

example.
cyl is 125mm dia p = 20Mpa extended rod 1000mm fixed at bottom free at end load factor 1,5 sf is 4
cyl force = 0,7854x(125)*2x20
= 2,45x10*5 N
Fa = 2,45x10*5x1,5
3,68x10*5 N
rod l = 1000x4
= 4000mm
d = 4th root 3,68x10*5x(4000)*2x4/1x10*5
d = 125mm dia rod
I hope this was of help to you.
greye.