# State of stress, strain and hookes law

1. Nov 15, 2009

### 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 [Broken]
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?

Last edited by a moderator: May 4, 2017
2. Nov 16, 2009

### 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,??