Do my results appear to be correct?

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Coates93
Newbie
Beiträge: 1
Registriert: Do 23. Apr 2020, 10:41

Do my results appear to be correct?

Beitrag von Coates93 »

Hello there,

I hope it is OK for me to ask this question, I just need some reassurance that I'm using this software correctly, and that the results I am obtaining seem realistic.

The part I am performing FEA analysis on is a simple thick wall cylinder / pipe:

- Made from Stainless Steel
- Length = 250mm
- Internal Diameter = 25mm
- External Diameter = 35mm
- Thickness = 5mm

The mechanical properties of the stainless steel are:

- Elastic Modulus = 190,000 MPa
- Density = 7700 kg/m^3
- Poisson's ratio = 0.26

I then wish to analyse this component by fixing it at one end, preventing all displacement, and then applying a 500,000N (500kN) load at the other end in tension. I have set up these constraints within Z88Aurora as seen below:

- One end fixed (node set):
Capture 3.PNG
(99.39 KiB) Noch nie heruntergeladen
- One end tensile force applied (node set):
Capture 4.PNG
(101 KiB) Noch nie heruntergeladen
Solving this with a SICCG solver produces results showing a total deflection of approximately 200mm:
Capture 5.PNG
(64.69 KiB) Noch nie heruntergeladen
However, I've tried to run this analysis again and found the deflection to be only approximately 60mm. I believe I may have set the mesh up differently, but I'm not certain.

Can I please ask:

1) Why would the results vary so significantly when from what I can tell my parameters were the same?
2) Which of these 2 results appear to be the most logical and likely to be correct?

Thank you!

JohannesMohr
Support
Beiträge: 3
Registriert: Mo 12. Aug 2019, 08:57

Re: Do my results appear to be correct?

Beitrag von JohannesMohr »

Hello,

the error is due to the specification of the force. You have selected "Force (uniformly distributed)". This means that a force of 500000N is assigned to each of the selected nodes. Consequently, depending on how many nodes are located at the end of the pipe (which in turn is related to the creation of the mesh) a multiple of the specified force is applied. To solve the problem, you must select "Surface load".
If your example is recalculated analytically, you will get a rounded value of 1.4mm maximum displacement. If the "Surface load" type is selected in the force specification, a maximum displacement of 1.4mm is also calculated in Z88Aurora.
Many greetings

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