State of stress, strain and hookes law

AI Thread Summary
The discussion centers on applying Hooke's Law to determine the state of stress from a given state of strain. The user calculates stress components using the provided material properties and strain values but finds discrepancies between their results and the expected answers. They express uncertainty about whether their calculations are incorrect or if the reference answers might be erroneous. Additionally, they seek clarification on how to compute the shear stress component. The conversation highlights the complexities of stress-strain relationships in materials and the potential for errors in reference materials.
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in the following question i am asked to find the state of stress given the state of strain.
http://lh6.ggpht.com/_H4Iz7SmBrbk/SwBtHnG3qkI/AAAAAAAAB9M/rFS_orHMbGo/Capture.JPG
i went about solving this using hookes law

\sigmaxx=E[(1-v)\epsilonxx + v(\epsilonyy+\epsilonzz)]/[(1+v)1-2v)]

using the given
E=30*106
v=0.3
\epsilonx=0.001
\epsilonxy=-1.25*10-3
\epsilony=-0.005

i get
\sigmaxx=-4.6154*104
\sigmayy=-1.8462*105
\sigmazz=-6.9231*104

but as you can see these are not the correct answers according to the question.
can anyone see where i have gone wrong ?

also how do i find \tauxy?
 
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\tauxy=G*\gammaxy=-0.0025*(30*106/2(1.3)=-0.0025*11.53846*106=-2.8846*104

from this i already see that the answers are not going to be the same as the answers in the book, and there is nowhere i have gone wrong with the math here,

am i doing something fundamentally wrong or could they be wrong with their answers,??
 
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