stress - Strain diagram

There is no problem, you can even recall the axis. For example, instead of X write "Horizontal AXIS Of Great Sagar". 

If we are going to draw some graph so we take the
independent variable on the x axis and the dependent variable on the y axis. So
the same concept apply here i.e. Stress is depending upon strain and strain is
independent therefore strain is always on the x-axis and stress is on the
y-axis.

Assessing, I say the diagram  got the concord to appear in this manner in   books or codes.

I think in the experiment that what we are controlling is the external force or pressure, which produce strain and the strain causes stress (which is the internal reaction of the material per unit area). So again stress is dependent on strain.

I also think that since that stresses can be defined by strain, and it is convention for the graph to be displayed in this way.

Hi

           We take stress on the Y-axis and strain on the X-axis. We cannot change these axis because on X- axis we take independent variable and on the Y -axis we take dependent variable i.e y is dependent on x .  Here stress is dependent on strain. Actually here stress means  the interatomic force between the atoms. This interatomic force depends on the distance between the atoms which will change by change in length ie by strain. So the stress is dependent on strain. So Stress is a dependent variable and should be taken on Y- axis with strain the independent variable on X- axis.

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Siva Srinivas Kolukula
Junior Research Fellow

Hi,

In my opinion this particular choice of axis is only a convention.  However, since we are so much familiar with this convention, it appears almost like a rule...

Some time back there was a thorough discussion on "stress or strain: which is more fundamental", which appeared to suggest that strain is more fundamental.  Please see the similar links section on right...

In my opinion, strain and stress both are defined for our convenience, and "energy" should be the more fundmental thing. Just to point out... even the "hypothetical" rigid body has stress in it without any strain.  Also there can be practical situations of thermal strains, where stress and strains are independent.

Can someone help me to understand how stress and strain will be related if we have to use multiplicative decomposition of deformation tensor into elastic and plastic parts?

Thanks and regards,

Jayadeep U.B.

I think for displacement control experiments, strain is more direct and independent measurement and stress is derived though the load. Also, strain is the only quanity we (can) measure not stress.

However, while calculating 'Energy' which is even more fundamental path to define stress, the choice of axis doesn't matter, it's about considering correct side of the diagram to claculate the energy.

There is somehow related discussion at http://imechanica.org/node/1001.

Regards,

Sandip Haldar