Result error in choosing plane stress-strain thickness

[abc123ali]

Respected Users,I am simulating the hysteresis stress-strain behaviour of the given model but the output stress-strain results of the attached cae file shows the same results for the different values of plane stress-strain thickness which cannot be the same as the thin plates are more strong and exhibits more yield compared to thick once and have bigger loops.
Thanks

 

[FEA way]

You have the plane stress/strain thickness specified (as 0.2) only for one section. So the other 2 sections have a unit thickness by default. Check the generated input file to confirm this.

 

[abc123ali]

Yes but this is just the file to attach here but I changed the thickness to 0.3, 0.4 upto 1 but there is no variation in results.

 

[FEA way]

For all three sections ? I think that you should prepare an equivalent 3D model (the geometry is very simple so it shouldn’t be a problem), change its thickness (not in section definitions but in the actual geometry setup) and compare the results. Or simplify this to a single part (rectangle in 2D, cuboid in 3D) subjected to prescribed displacement u and use basic formulas like F=(uEA)/L, ε=u/L and σ=F/A to see which results change when you modify the thickness.

 

[abc123ali]

But if I do so then again how the plane stress-strain effect take place as it take place if and only if the geometry is in 2d and the model uis 2d planar as already discussed in another thread.
Thanks

 

[FEA way]

What I mean is that you already have a 2D model and want to see the effect of different thicknesses. So you can create an equivalent 3D model and change this thickness - not in the solid section settings because that won't have any effect in 3D but just in the geometry definition (e.g. extrusion depth).

 

[abc123ali]

I properly got your meaning even then changing the thickness in the part module making 3d doesnt have any effect on yield stress. It seems that the option of plane stress-strain seems to be superflous and have no meaning in ABAQUS to study thin shells and sheets. Kindly help if you have an alternative solution to this problem.
Thanks

 

[FEA way]

You are using prescribed displacement. Check the reaction forces with different thicknesses or apply force instead of displacement.

 

[abc123ali]

The reaction forces are varying with change in thickness; increasing the thickness increases the area of crossection hence increases rection force to kepp the stress constant but as far as thin sheets with plane stress-strain is concerned; it should affect the stress or strength of the sheet or simply the yield strength of the thin sheet is more than thick one which I am unable to get rather than getting more reaction force is not actually the goal of thin sheet plasticity. If I apply force the model will only be load control rather than displacement control and the resulting effects are just increase in reaction force with corresponding displacement.
Thanks

 

[FEA way]

If you claim that plane stress/strain model doesn’t capture some effects here then the only way is to use a 3D model since it has no simplifying assumptions and can capture everything if modeled correctly. It could even have just one layer of hex elements in the thickness direction to be equivalent to 2D model but without its limitations. Unless there are some changes in results in the thickness direction and multiple layers of elements are needed to represent them accurately. But then the model is just no suitable for 2D (plane stress/strain) analysis.

Can you share your 3D model or screenshots from it showing its variants with different thicknesses ? Just remember what we discussed before - that the plane stress/strain thickness setting has no meaning in 3D, it only affects 2D models.