State of stress, strain and hookes law

[Dell]

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

$$\sigma$$xx=E[(1-v)$$\epsilon$$_xx + v($$\epsilon$$_yy+$$\epsilon$$_zz)]/[(1+v)1-2v)]

using the given
E=30*10⁶
v=0.3
$$\epsilon$$x=0.001
$$\epsilon$$xy=-1.25*10^-3
$$\epsilon$$y=-0.005

i get
$$\sigma$$xx=-4.6154*10⁴
$$\sigma$$yy=-1.8462*10⁵
$$\sigma$$zz=-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 $$\tau$$xy?

 

[Dell]

$$\tau$$xy=G*$$\gamma$$xy=-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,??

 

[Mene]

Your calculation for the state of stress appears to be correct, based on the given values and using Hooke's law. However, it is possible that there is a mistake in the given values or the question itself. It would be helpful to double check the values and make sure they are accurate.

To find the shear stress, \tauxy, you can use the formula:

\tauxy = G * \gammaxy

where G is the shear modulus and \gammaxy is the shear strain. The shear modulus can be calculated using Hooke's law as:

G = E / (2 * (1 + v))

Substituting the given values, we get:

G = (30 * 10^6) / (2 * (1 + 0.3)) = 15 * 10^6

Now, we can calculate the shear strain, \gammaxy, using the given value for \epsilonxy:

\gammaxy = \epsilonxy = -1.25 * 10^-3

Finally, substituting these values into the formula for shear stress, we get:

\tauxy = (15 * 10^6) * (-1.25 * 10^-3) = -18.75 * 10^3

Therefore, the shear stress is -18.75 * 10^3, which is the correct answer according to the given values.