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Urgent : Which stress should i use ?
Posted May 23, 2012, 11:40 a.m. EDT Structural Mechanics Version 4.2 1 Reply
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Hi everyone plz help , this is urgent.
In my model pressure is being applied to the top surface of a cube. ( say pressure is applied along z axis )
I want to study the the variation in stress perpendicular to the pressure ( x axis ). To make it clear , pressure is applied along z axis , to the face of the cube in xy plane . I am trying to find stress variations along x axis.
Now i don't understand which which how to find the stress along the x axis. The options available are First Principal stress , piola kirchoff stress , von mises stress etc.
Plz tell me which of these is applicable in the above case i have mentioned.
I have another basic doubt , wats the difference between surface stress plot and volume stress plot ? And to study variation of stress along x axis i have to use 'Cut line' in the surface stress plot or in the volume stress plot ?
Thanks in advance
In my model pressure is being applied to the top surface of a cube. ( say pressure is applied along z axis )
I want to study the the variation in stress perpendicular to the pressure ( x axis ). To make it clear , pressure is applied along z axis , to the face of the cube in xy plane . I am trying to find stress variations along x axis.
Now i don't understand which which how to find the stress along the x axis. The options available are First Principal stress , piola kirchoff stress , von mises stress etc.
Plz tell me which of these is applicable in the above case i have mentioned.
I have another basic doubt , wats the difference between surface stress plot and volume stress plot ? And to study variation of stress along x axis i have to use 'Cut line' in the surface stress plot or in the volume stress plot ?
Thanks in advance
1 Reply Last Post May 23, 2012, 1:33 p.m. EDT
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Posted:
1 decade ago
Hi
Stress is represented by a tensor for most materials, hence it has many components, tensile components, shear components ..., and different ways to combine them.
Then it can be expressed in the material (second Piola-Kirschoff stress tensor) or the spatial frame (typically 9 components for the Cauchy stress, but with some symmetries), or as a frame mapping (First Piola-Kirschoff stress tensor) or as an reasonable average (von Mises)
You can find much more in any good textbook, such as the Timeschenko's, or the more recent "Continuum mechanics and Thermodynamics" by E.B. Tadmor et al. Cambride, 2012
It's not "quickly done" and it is very important to understand it well.
I would sugest to start to plot out, on a cut plane, your different Cauchy stress tensor elements, check the doc for the COMSOL names, or find them in the pull down list, then compare i.e. to the von Mises Stress value. and the others
You can then change the Poisson ratio of your material and see the effects ...
--
Good luck
Ivar
Stress is represented by a tensor for most materials, hence it has many components, tensile components, shear components ..., and different ways to combine them.
Then it can be expressed in the material (second Piola-Kirschoff stress tensor) or the spatial frame (typically 9 components for the Cauchy stress, but with some symmetries), or as a frame mapping (First Piola-Kirschoff stress tensor) or as an reasonable average (von Mises)
You can find much more in any good textbook, such as the Timeschenko's, or the more recent "Continuum mechanics and Thermodynamics" by E.B. Tadmor et al. Cambride, 2012
It's not "quickly done" and it is very important to understand it well.
I would sugest to start to plot out, on a cut plane, your different Cauchy stress tensor elements, check the doc for the COMSOL names, or find them in the pull down list, then compare i.e. to the von Mises Stress value. and the others
You can then change the Poisson ratio of your material and see the effects ...
--
Good luck
Ivar