
Re: Tension & Compression Stress Plots for Linear Static Study
James Riddell Aug 29, 2016 6:43 AM (in response to Ajay S.)If I recall my Mohr's Circle for 3D stress correctly, if all the principal stresses are positive then they are all tensile loads. Any that are negative are compressive stress.

Re: Tension & Compression Stress Plots for Linear Static Study
Ajay S. Aug 31, 2016 7:22 AM (in response to James Riddell)Dear James,
Thanks for your contribution.
For the given load (as per attached image), positive & negative are existing in all the 3 plots (P1, P2, P3) and which one (among 3) would you consider ?

Re: Tension & Compression Stress Plots for Linear Static Study
James Riddell Aug 31, 2016 7:24 AM (in response to Ajay S.)Nothing was attached.


Re: Tension & Compression Stress Plots for Linear Static Study
James Riddell Sep 1, 2016 7:27 AM (in response to Ajay S.)What are the values of P1, P2, & P3? It would be logical that any which are positive are tensile and negative values are compressive.





Re: Tension & Compression Stress Plots for Linear Static Study
Keith Frankie Sep 1, 2016 5:15 PM (in response to Ajay S.)The highest of the three principal stresses at a given point is P1. The middle principal stress is P2, and the lowest principal stress is P3.
Positive values indicate tension, negative values indicate compression.
Thus if a point is at tension in all directions P1, P2, and P3 will all be positive. If a point is in mild tension in one direction but large compression in another direction P1 (which is positive) will be greater than P3 (which will be negative), but P3>P1
This may be helpful: 2016 SOLIDWORKS Help  Principal Stresses Definition
Thus your statement #1 is almost correct. Using the word "extreme" indicates taking the absolute value first, and that is incorrect. Instead it should read "The highest value of P1 indicates max tension, and the lowest value of P3 indicates max compression". This assumes the model contains both areas of compression and areas of tension.
Using Sx, Sy, and Sz to determine max and min values only works if the maximum stresses happen to lie in those directions.

Re: Tension & Compression Stress Plots for Linear Static Study
James Riddell Sep 6, 2016 6:06 AM (in response to Keith Frankie)Keith,
You are incorrect about one thing. P3 does not *always* have to be compression. P3 < P2 < P1 *is* always true. Seems college isn't teaching Mohr's Circle for 3D stress anymore.

Re: Tension & Compression Stress Plots for Linear Static Study
Ajay S. Sep 7, 2016 8:02 AM (in response to James Riddell)Dear Experts,
Kindly find the enclosed image for your reference pls,
ISMC 150 channel (part of subassembly of above attached image) is shown, at center the plot is taken and probed using SX stress plots.
Now, with intention of getting Tension & Compression in this midarea, what below probed value explains ?

Re: Tension & Compression Stress Plots for Linear Static Study
James Riddell Sep 7, 2016 8:20 AM (in response to Ajay S.)Positive values = tension
Negative values = compression
I might have expected the transition to be a little closer to the center of the section but, depending on loading, restraining, tides, phase of the moon  your mileage may vary.


