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• # Need Help | Calculation for plate that will be used for machine (i.e. mob crane body)

Discussion in 'Calculations' started by malberto, Jun 4, 2014.

1. ### malbertoNew Member

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Jun 2014
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How are you doing guys? I am new in doing calculation for machine. I am currently have a task to provide sample calculation on how to determine the thickness of plate to be used in a machine like mobile crane, tower crane, boom lift, building maintenance equipment. Need to know the formulas that needs to be used in order for me to come up with a correct thickness of plate knowing that there are some attachments in the plate (body) like motor, shaft and so on. Hope you guys can help me with this.

Thank you in advance!

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3. ### LochnagarWell-Known Member

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It is hard to know from your question - what your background is in engineering. However, if you had studied engineering at university, you should have acquainted yourself with the basics of how to do this type of problem. If you haven't had the benefit of a university education - then you might find it "difficult".

There are many people around the world who make things - who don't understand the precise reason how it takes the load - or fails to take the load - but that is not the professional way of doing things.

If you have just forgotten how to do these things - then here is a good book to bring it all back to you -it is Roark's Formulaes for Stress and Strain - which is the engineers "bible" for hand calculations.

Hope this helps.

http://materiales.azc.uam.mx/gjl/Clases/MA10_I/Roark's formulas for stress and strain.pdf

4. ### KevinCWell-Known Member

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Sounds like you may not be from a mechanical engineering background. This is actually pretty complicated problem, and it can't be really resolved to a some very simple equations here. But here is the general flow of calculation.

First you need to find all the forces that will be subjected onto the plate, the acceleration and velocity of the the moving parts will be needed to calcalate that as well. Then you'll have to know where this plate is located and where is the maximum stress occurs in the plate by the forces. Calculate the thickness required to satisfy stress requirement and also the factor of safety. Of course materials property, fatigue, may even need to compensate for the fact that it operates outside and is subjected to environmental effects.

Then you'll get your result.

5. ### K.I.S.S.Well-Known Member

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Please keep in mind that you are in the process of designing something that has the potential to seriously injure or even kill someone. If you aren't fully cognisant of the risk factors involved in this, then in good conscience, you should put your hands up and admit this. I'm not going to provide you with sketchy information, as I don't wish to possibly contribute to a unexpected failure with dire consequences.
Also, you must keep in mind that the loads and strains involved in any dynamic mechanism are precisely that - they are dynamic. It's one thing to calculate the deflection/load of a static beam at any angle that has a given force of Kilo Newtons applied to it in a given vector - but what happens when the crane operator applies full power to the winch? This (for example) is a very complex calculation and requires lots of inputs that I don't think you have available - what is the maximum rated torque on the motor and gearbox of the crane for example? Please don't do something like this if it has the potential to be put into production, not if you don't have all the data available to you.]

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