MOHR'S CIRCLE ANALYSIS

[LAgriffJDM97]

Working on Mohr's circle analysis here, I have drawn the correct circle diagram but having difficulty analysing it to get angles etc.

queries I am having -

- where do you read the angle 2theta from (is it from the x to sigma 2)
- maximum shear plane is read from x to vertical?

see attached picture of the circle.

Thanks

 

[msquared48]

Man does that bring back memories - all bad.

Mike McCann
MMC Engineering

 

[rb1957]

i believe that the angle is with respect to your x-direction. i'm not sure whether it is the same direction as shown (ie CCW) or opposite ... would if wiki can help ?

maximum shear stress is as shown. note it also works the other way (looking for the minimum shear stress, 'cause shear isn't signed).

sure this isn't homework ? if so, read the big bold red text under "reply to this thread"

Quando Omni Flunkus Moritati

 

[BAretired]

The angle 2θ is measured counter clockwise from the x plane to any other plane. In the sketch, the x plane (the plane normal to the x axis) has a tensile stress of 80MPa and a shear stress of -59MPa. The angles 2θ on the Mohr's circle are 67^o and 157^o to the principal planes. On the actual element, they are θ = 33.5^o and 78.5^o to the planes of maximum tensile stress and maximum shear stress respectively.

BA