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test example for convergence

Question asked by Magnum So on Aug 28, 2014
Latest reply on Sep 5, 2014 by Jared Conway

Hi,

I am trying to practice the convergence to make sure accurate simulation result. The following is the test example model:

 

model : steel pipe( diameter 100mm, length 150mm) with an extension(30mm diameter, length 150mm)

material: cast iron

study: static

fixture: fixed geometry at the end of extension

force: 20000N action at the bottom of pipe

 

Picture2.jpg

Result:

Picture4.jpg

mesh density including

coarse: 13mm

default: 6.5mm

fine: 3.2mm

 

Sine the coarse to  fine mesh density cannot result in a convergence, so I have input smaller mesh density(2mm and 1mm) and then get a convergence.

Based on this example, I have two questions:

Q1. I have also input mesh density to 0.5mm, but the solidworks shows a mesh fail message, I am doubted as I always expect only large mesh size will cause mesh fail, right?

Q2. The result is a convergence so it is accurate and reasonable. But, I have found that the total displacement is only 0.4mm due to the external force

Picture3.jpg

I have checked that the displacement is a convergence so it is also reasonable.

The max. stress at the joint is about 550MPa which is over the tensile stress of cast iron, so this example result shows that a 20000N will deform the steel pipe and the joint of extension will break.

But in reality, we cannot see the breakdown of a steel pipe with only 0.4mm displacement, right? 0.4mm displacement seems to be an insignificant value and may not result any crack or failure, so I am doubted that if my simulation concept is wrong.

 

Hope this example will make more discussion here. 

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