Strain rosette, Mohr's circle

[GBA13]

Homework Statement

I have used a strain rosette with two gauges at 0 and 90 degrees to find strain on a beam under force and an trying to plot Mohr's circle for the problem. As the gauges are at right angles finding the xx and yy strain is easy but I am lost about how to find the xy strain, which I need to plot the circle. How can I find xy from the xx and yy strain values?

Homework Equations

The Attempt at a Solution

I have got xx and yy but I honestly have no idea how to find xy[/B]

 

[Chestermiller]

How does the orientation of these gages relate to the principal axes of strain for this particular deformation? Do you know?

Chet

 

[GBA13]

How does the orientation of these gages relate to the principal axes of strain for this particular deformation? Do you know?

Chet

Hi Chet, I'm not sure how to tell to be honest! All I know is that the gauges are put on a long beam, one parallel to the edge of the beam and the other perpendicular and then the beam was forced downwards on the unsupported end.

I'm also told to think of it has a simple, uniaxial stress in x direction if that makes any difference.

 

[Chestermiller]

Your gages are aligned with the principal directions. If you understand the kinematics of bending, then you will know why.

Chet

 

[GBA13]

Oh OK. Does that mean that the readings on the gauges are the principle strains?

 

[Chestermiller]

Oh OK. Does that mean that the readings on the gauges are the principle strains?

Sure..