Utot is way off

[dundermane]

It looks like utot is many orders of magnitude off. I've been trying different mesh's. I've triple checked that my units are correct. I might be doing something that's out of pycalculix's abilities? I'm applying pressures on arcs and the reactant force is the tension in the material. Displacement is more important to me than stresses.

[dundermane]

flex-spline.zip

[dundermane]

On second look, those stresses totally do not look right. Whats up here? The setup looks correct to me.

[spacether]

How are you constraining this in x, y, and z?

[spacether]

Your displacement is way too high, please check your units and input material properties. What does a hand calculation say the deflection should be for a thin ring?

[dundermane]

I have not constrained the Z (didn't think it was necessary, but I'll try it.) X and Y have a point constraint on an arbitrary outer point.

As far as a quick hand calculation: I just did a calc assuming an average pressure around the inner ring.

I'm using this to back me up: http://www.eng.fsu.edu/~kalu/ema4225/lec_notes/Web%20Class_6_final

10 (Pa) is my average pressure applied to the inner wall of the structure. 0.03 (m) is the diameter of the circle 0.002 (m) is the thickness of the circle 2.3e9 (Pa) is the elastic modulus of my material

Stress in the wall should be stress = (pressure * radius) / thickness

stress = (10Pa * 0.03m) / 0.002m stress = 150 Pa

Strain is Stress (Pa) / Youngs Modulus (Pa) Therefore the strain should be 150 (Pa) / 2.3e9 (Pa) = 6.5e-8 (m/m)

The circumference, which was 3.14 * 2 * 0.03 (m) would now be 3.14 * 2 * 0.03(m) * (1 + 6.5e-8) = 0.18849 (m)

The diameter would then be 0.18849 / 3.14 = 0.0600000039. It would barely change because 10Pa is a pretty small value. But the results file shows a 12m diameter ring. ¯_(ツ)_/¯

[spacether]

I am no longer maintaining this repo and will archive it