Difference Between FEA Result and Hand Calculation in Beam Bending?

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SUMMARY

The discussion focuses on the discrepancies between hand calculations and Finite Element Analysis (FEA) results for beam bending. The user calculated a maximum deflection of -2.39mm using analytical methods, while Ansys reported an average deflection of 0.3mm and a maximum deflection of 0.8mm. The user identified an error in their calculations, specifically neglecting a negative sign, which led to conflicting results. The conversation highlights the importance of axis orientation and clarity in calculations for accurate FEA results.

PREREQUISITES
  • Understanding of beam bending mechanics
  • Familiarity with Finite Element Analysis (FEA) principles
  • Proficiency in using Ansys software for structural analysis
  • Knowledge of analytical calculation methods for deflection
NEXT STEPS
  • Review Ansys documentation on beam bending analysis
  • Study the effects of axis orientation in FEA simulations
  • Learn about common errors in hand calculations for structural analysis
  • Explore advanced techniques for validating FEA results against analytical methods
USEFUL FOR

Structural engineers, FEA analysts, and students studying mechanics of materials will benefit from this discussion, particularly those looking to reconcile analytical calculations with FEA results.

Kajan thana
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TL;DR
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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