Principle stress states question, anyone help?

AI Thread Summary
The discussion revolves around calculating principal stress values (sigma 1 and sigma 2) from measured principal strains in an aluminum plate using neutron diffraction data. Given the Young's modulus of 70 GPa and Poisson's ratio of 0.3, the principal strains are ε1= 2400 με, ε2=0 με, and ε3=-350 με. Initial calculations yielded sigma values near 212 MPa and 83 MPa, but there was uncertainty about their accuracy. Participants confirmed that sigma 2 is indeed 83 MPa and emphasized the importance of rounding answers to three significant digits. The conversation highlights the need for precision in both calculations and terminology.
scw1
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Principle stress states question, anyone help??

Homework Statement


Neutron diffraction is used to measure the residual strains near to a weld in an aluminium plate. The aluminium has a young’s modulus E of 70GPa and a poisons ratio of 0.3. The three principal strains obtained are ε1= 2400 με ε2=0με ε3=-350με. What are the values of sigma 1 and sigma 2?


Homework Equations



Plane stress and strane equations

The Attempt at a Solution


Got an answer of an answer near to 212MPa and 83MPa
but not sure if its right
 
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[strike]Your current answer looks incorrect. Try again.[/strike]
 
Last edited:


nvn said:
Your current answer looks incorrect. Try again.

Hi there the sigma2 must be 83MPa? its all i keep getting
Many thanks
Stevo
 
My apologies, scw1. Your answer was right. Nice work. However, generally always round your final answer to three significant digits, not two significant digits. You rounded slightly too much. Also, you misspelled principal and strain, and omitted all punctuation.
 

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