 | | From: | bgal | | Subject: | Deflection calculation | | Date: | 23 Dec 2004 08:42:35 -0800 |
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 | Morning,
I am running a deflection calculation to size the amount of force
needed to pre-bow a piece of rectanglur steel 2mm. I have run the
calculation two ways and am getting different results. Can someone
point me to where my error is? Thanks in advance
Here is one run
Y= P(L^3)
--------
3EI
P=7500 lbs
L(length of moment arm) = 4.8inches
E(Modulus of elasticity) = 205 Gpa = 29732737 psi
I(Moment of inertia) = .781 in^4
Deflection = 7500 * ((4.8)^3)
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3 * (29732737) * (.781in^4)
Y = 829,440
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69663802
Y = .011 in = .254 millimeter
Here is the other run
P=7500lbs = 3401 kg
L = 4.8 in = 12.192 cm
E = 205 Gpa = 2090418 kg force/cm^2
I = .781 in^4 = 1.9 cm^4
Y = (3401)*((12.192)^3)
-------------------------
3 (2090418) (1.9)
Y = 6163558
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11915382.6
Y = .51cm
Y = 5.1mm
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| | From: | dmartin at newarts.com | | Subject: | Re: Deflection calculation | | Date: | 23 Dec 2004 16:17:15 -0800 |
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| There's a big error in your moment of inertia units conversion. There
are 41.63 (cm/in)^4
Dave
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