If I understand the outcome correctly, the tube should break under the load (red color everywhere), but this outcome doesn’t seem to be right to me. A steel tube of such properties (3m long, 25cm square, 5mm thick), should be able to hold (an evenly balanced) load of 675 Kg, right? This makes me think there is a problem with my simulation settings or my calculation of the load.

Could anyone more experienced please have a look? Thank you in advance.

Red color doesn’t necessary mean that the part will fail. Here colors are used to relate stress value with the color bar at the bottom. In your case, I see red corresponding to a value of 1.4 MPa, which is low for steel.

Anyway, please check that the red is the max computed value by right-clicking the color bar and selecting ‘Scale to full range’ from the pop-up menu.

You can also click the maximum numerical value and enter your allowable stress. This trick is used to show red zones to be above the allowable stress, thus actually behaving as you expect.

Ah ok, so the bar and colors basically mean something like “stress distribution” on the object, where blue is the minimum stress and red is the maximum stress from the range of stress calculated?

I’m looking to find out whether the tube can withstand certain pressure and/or alternatively what is the pressure under which the tube will “start failing”. Is there any easy way to do it in this case or could you please kindly point me to any resources I should read?

Edit: except for manually editing the bar range, I don’t know what values should I put there, are there any known min/max numbers for various materials?

I’m looking to find out whether the tube can withstand certain pressure and/or alternatively what is the pressure under which the tube will “start failing”. Is there any easy way to do it in this case or could you please kindly point me to any resources I should read?

For this you need a failure criteria, which is judged from the simulation results (for example, the maximum von mises stress compared to the yield stress and some safety factor).

This values are given in design codes such as for piping or structures.

Okay. If I understood everything correctly, in order to know when the tube fails by material properties solely (without any safety factor or project constraints)… I search the yield strength of steel on the internet, for instance, use it as the max value in the stress bar, and use 0 as the min value. Then I run simulations with various pressures and when it starts getting red, it means the tube will start failing at that point?

Hi, there are many different failure criteria, one of them based on the von mises stress. You should research in the literature (building codes, text books) for a proper failure criteria to apply to your model and how to apply it.