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Cylinder Rod Buckling (ISO)

10/15/2009 5:40 PM

Hello Engineers,

I have a question I am reviewing ISO TS 13725, relating to cylinder buckling and notice there is a program written in Fortran. I am trying to layout the equations in excell and I guess it's become of a more tedious job than I expected. Does anyone know where I can find an excel version or a visual basic/program relating to the methods of buckling according to ISO 13725.

Thanks,

Maria
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JohnDG
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#1

Re: Cylinder Rod Buckling (ISO)

10/15/2009 7:33 PM

How big is the Fortran code (ie how many lines)?

If not too big you could post it & see if anyone can help. They'll be more inclined if you register as a CR4 member.

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MariaF
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#2
In reply to #1

Re: Cylinder Rod Buckling (ISO)

10/15/2009 9:08 PM

Hi JohnDG,

The Fortran code is actually quite large and complex, sub-program/matrix etc different code for different mounting styles. I would not be inclined to have anyone actually input the fortran code. That being said, I am sure some one has already or have created an excel sheet and hopefully willing to share, if not I guess I will have to spend some time and re-write the program in matlab or finish off my half-way job excel sheet.

Maria.
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JohnDG
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#3
In reply to #2

Re: Cylinder Rod Buckling (ISO)

10/16/2009 4:21 AM

Hi Maria,

Welcome to CR4 .

Wish you luck,

John

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Codemaster
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#4
In reply to #2

Re: Cylinder Rod Buckling (ISO)

10/16/2009 8:55 AM

Hello Maria

Why do you need a program? There's a formula to calculate it - buckling load =

pi2*E*I/L2 ..........E = elastic modulus, I = 2nd moment of area, L = effective length

and I = pi*d4/64........d = rod diameter so buckling load =

pi3*E*d4/64/L2.

Taking effective length = actual length (rod extended) is probably OK (depends on the detailed arrangement) but you need to decide that even if using a program, or enter rod end conditions, which amounts to the same thing.

This gives theoretical buckling load and for design usual to apply safety factor 3 - 4. There's not much point worrying about great accuracy as the difference is likely to be less than range of safety factor. Be interesting to know how above compares with program results.

Cheers........Codey

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MariaF
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#5
In reply to #4

Re: Cylinder Rod Buckling (ISO)

10/16/2009 10:56 AM

Hello Codemaster,

You are right by using Euler method with a safety factor of 3 is quite suitable for most buckling.

The only difference is the greater accuracy. The ISO method for buckling - takes into account the complete geometry of the fluid power cylinder, meaning it does not treat the fluid power cylinders as an equivalent bar as well it also takes into account the weight of the fluid power cylinder, meaning it does not neglect all transverse loads applied on the fluid power cylinder and possible off-axis loading.

I will compare both methods and provide the safety factor results and comments.

Thanks,

Maria
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Codemaster
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#6
In reply to #5

Re: Cylinder Rod Buckling (ISO)

10/16/2009 11:00 AM

OK thanks

Codey

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roncos
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#7

Re: Cylinder Rod Buckling (ISO)

06/22/2010 5:06 AM

Hi Maria

Did you resolve this query? did you write the program or find a commercial implimentation?

Best Regards

Ronan
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