Difference Between FEA Result and Hand Calculation in Beam Bending?

AI Thread Summary
The discussion highlights a discrepancy between hand calculations and FEA results for beam bending, with the hand calculation yielding a maximum deflection of -2.39mm, while Ansys reports a maximum deflection of 0.8mm. Key issues identified include unclear axis orientation and the readability of the hand calculation. The user discovered that a negative sign was overlooked in their analytical calculation, leading to conflicting values. This correction clarified the results and aligned them more closely with the FEA output. Accurate axis orientation and careful calculation are essential for reliable comparisons between methods.
Kajan thana
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Hi Guys,
I am doing some lab work on bending cantilever beam and its deflections in both directions y and z directions. For the deflection on the Z-axis, the ANSYS value is positive and the analytical value is negative. I don't know whether I am doing the calculation wrong or is there a specific reason why the direction differs? I have also made sure that the orientation of the axis is the same for both works.
1617313395321.png
This is the analytical working out. I substituted the value of 306mm ( the maximum length of the beam) to find the maximum deflection along the Z-axis. Which came out to be -2.39mm. But according to Ansys the average deflection is 0.3mm and the maximum deflection is 0.8mm.

1617313468207.png
This is the Ansys Values.
 
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There are at least two problems with your question.
1) You have not told us how the axes are oriented (there is no universal orientation),
2) Your hand calc is too small to be read.
Please fix these for us, and then maybe there will be help.
 
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I managed to find the error. Thank you.
 
Kajan thana said:
I managed to find the error. Thank you.
Can you share please?
 
berkeman said:
Can you share please?
I ignored a negative sign in my analytical calculation, this is why I had two values in the opposite direction.
 

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