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# Patran Results: Shell Force, Force Resultant - von Mises quantity vs. force magnitude?

## Patran Results: Shell Force, Force Resultant - von Mises quantity vs. force magnitude?

(OP)
Hello,

If the title is confusing, let me explain. I'm trying to extract loads from a Patran shell model in the x and y directions. I could just separately extract the x and y components of the shell forces, but I noticed there is a quantity called "von Mises". I know that von Mises stress is a yield failure criteria, but is the von Mises shell force the magnitude/resultant? And if yes, then can I just extract it and resolve it into its x and y components?

Thanks

### RE: Patran Results: Shell Force, Force Resultant - von Mises quantity vs. force magnitude?

Von Mises stress is equivalent stress calculated from stress tensor components. You can also extract those components individually. But if you need forces then you have to stick with their output variables.

### RE: Patran Results: Shell Force, Force Resultant - von Mises quantity vs. force magnitude?

(OP)
Thanks FEA way, but does this also apply to shell forces? What is a Von Mises "Force" extracted from a shell element?

### RE: Patran Results: Shell Force, Force Resultant - von Mises quantity vs. force magnitude?

I’ve never seen such variable in FEA software. Check Patran’s documentation, it should explain how this quantity is calculated.

### RE: Patran Results: Shell Force, Force Resultant - von Mises quantity vs. force magnitude?

I suspect it is von mises stress * thickness = force per unit width (like the normal forces).

What is it in reality ? don't know, von mises is a combination of principal stresses. Principal loads would make more sense.

### RE: Patran Results: Shell Force, Force Resultant - von Mises quantity vs. force magnitude?

This variable look strange. Von-Mises stress don't have a direction, if you multiply it by surface area you don't get force because you need vector stress value, not scallar.

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