- #1

svishal03

- 129

- 1

I’ve been struggling with this for quite some time and will be grateful if someone can help me.

I have got the data for some tension and torsion tests performed on standard specimen- the tests were done by someone else- not me.

I’m trying to do a material modelling based on the tests carried out.

I computed the elastic modulus of from the tension tests by fitting a straight line to initial points on the curve of true stress vs true strain (see attached jpg file- modulus_of_elasticity)

I now want to compute the shear modulus (modulus of rigidity) by results of torsion test.

And I ought to be satisfying the relationship between elastic constants as well (just to make sure that I’ve done things correctly) that is:

G = E / 2 (1+mu)

Where;

G = shear modulus

E = modulus of elasticity

mu = Poisson’s ratio.

Actually, just like tension test, for torsion test too, I plotted shear stress vs shear strain - shear strain being = gamma /2 where gamma = angle of twist (in radians) * radius of the specimen / gauge length.

I did this but could not satify the relation (difference being over 50!) G = E / 2 (1+mu)

I have got the data for some tension and torsion tests performed on standard specimen- the tests were done by someone else- not me.

I’m trying to do a material modelling based on the tests carried out.

I computed the elastic modulus of from the tension tests by fitting a straight line to initial points on the curve of true stress vs true strain (see attached jpg file- modulus_of_elasticity)

I now want to compute the shear modulus (modulus of rigidity) by results of torsion test.

And I ought to be satisfying the relationship between elastic constants as well (just to make sure that I’ve done things correctly) that is:

G = E / 2 (1+mu)

Where;

G = shear modulus

E = modulus of elasticity

mu = Poisson’s ratio.

Actually, just like tension test, for torsion test too, I plotted shear stress vs shear strain - shear strain being = gamma /2 where gamma = angle of twist (in radians) * radius of the specimen / gauge length.

I did this but could not satify the relation (difference being over 50!) G = E / 2 (1+mu)

Before going into the details of the shear stress vs shear strain curve, I’m attaching the load set data for torsion test (refer file load_set.xls)given by the experimentologist and shall be grateful if someone shows me the computation of shear stress, angle of twist for just one reading of this set. I feel that I’m missing something here.Before going into the details of the shear stress vs shear strain curve, I’m attaching the load set data for torsion test (refer file load_set.xls)given by the experimentologist and shall be grateful if someone shows me the computation of shear stress, angle of twist for just one reading of this set. I feel that I’m missing something here.