## Unload- reload, get Young's modulus and poisson's ratio.

## Unload- reload, get Young's modulus and poisson's ratio.

(OP)

Hello!

I'm a student and need help getting effective Young's modulus (E´50) and poisson's ratio (v´) from a unload reload drained test of clay material. See the figure below.

Would be really grateful if someone can helo me with this, been sitting whole day trying to figure out this.

Best regards,

Viktor

I'm a student and need help getting effective Young's modulus (E´50) and poisson's ratio (v´) from a unload reload drained test of clay material. See the figure below.

Would be really grateful if someone can helo me with this, been sitting whole day trying to figure out this.

Best regards,

Viktor

## RE: Unload- reload, get Young's modulus and poisson's ratio.

Nonetheless, the emphasis on the unload-reload loops makes me think they are not actually looking for E50, or they have their terminology mistaken. Stiffness is simply the change in stress over the change in strain (i.e. the gradient of the stress-strain curve). From this definition, determining any stiffness should be straightforward.

You can't get Poisson's ratio from the graph you have shown us. You need radial strain which you would typically get from volumetric strain in a drained triaxial test.

## RE: Unload- reload, get Young's modulus and poisson's ratio.

Another quick question, can we determine E' from the graph as well?

Or should E' be equal to E'50 which I have been read is common to assume?

Bests regards,

Viktor

## RE: Unload- reload, get Young's modulus and poisson's ratio.

_{d}), which is just the stiffness in the graph above because it is a drained test. Moreover, you wouldn't be able to get E_{u}(the 'undrained' Young's modulus) from the above test because it is not an undrained test.E'50 is the E50 I referred to in my previous post. In the context discussed (i.e. with emphasis on the unload-reload loops) I would expect they are asking you what the stiffness of those loops is. That stiffness is E'.

Do you have volumetric strain data with this test? If so, you can get the radial strain from axial and volumetric strain, then derive Poisson's ratio.

## RE: Unload- reload, get Young's modulus and poisson's ratio.

## RE: Unload- reload, get Young's modulus and poisson's ratio.

## RE: Unload- reload, get Young's modulus and poisson's ratio.