Can Maximum Bending Strain Be Calculated Without Knowing Young's Modulus?

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SUMMARY

Determining maximum bending strain in a beam without knowing Young's modulus (E) is not feasible. The discussion highlights that while bending stresses can be calculated using Euler's formula, which relates stress to bending moment and the second moment of area, the calculation of strain and deflection inherently requires knowledge of Young's modulus. The Euler-Timoshenko model further emphasizes the necessity of E in evaluating shear stresses and strains. Thus, the maximum bending strain cannot be accurately calculated without incorporating Young's modulus into the equations.

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  • Knowledge of Young's modulus and its significance in material mechanics
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maniaciswicke
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Very simply put.
Is it possible to determine bending stress in a beam without knowing the young's modulus of the material used? All equations I've seen seem to include in some form an E value ( young's modulus), which is used in conjunction with a stress value to evaluate the strain.
 
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The forces and therefore the stresses in many beams are statically determinate so they do not depend on the material. Euler's model of beam bending gives.

\frac \sigma y = \frac M I

Where \sigma is the stress, y is the offset from the neutral axis, M is the bending moment and I is the 2nd moment of area.

The Euler-Timoshenko model also includes shear stresses.

The strains, and therefore the amount of deflection of the beam, DO depend on Young's modulus.
 
This is what i thought.
It is a homework problem but i wasn't asking for the answer, merely if it was possible to solve. The dimensions of the beam are known so i agree the stresses are quite straightforward. The question very clearly asks for the "maximum bending strain" though. Could i perhaps give the answer in terms of the known stresses and E?
 

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