Question about FEA simulation 2

[cchngtn]

Dear all respected Engineer,

I have a question about FEA simulation.


During the FEA simulation,

I want to analysis a hollow beam with Astm A500 gr A.
the yield strength is 230 Mpa.

Do I have to use Allowable strenght = 0.67 x yield strength
? or just compare the simulation result to the yield srength?

Please help me, I am full of confuse!

 

[PDMAdmin]

Either way should work, as long as you know how to interpret the results properly. Any factor of safety you want in the design should also be taken into account.

 

[Beggar]

From your comment, "I am full of confuse" I would suggest that you be very careful. You should certainly validate the results with some hand calculations and be sure that you have confidence in your model.

As PDMAdmin says, you should multiply your results by the desired factor of safety and compare that to the properties of your section and your material.

I presume that you realize that there are several failure modes beyond simple tensile yield.

You should be very, very careful if you're relying upon CosmosExpress. It provides few details about the model itself so the quality of its results are difficult to assess in cases beyond the very simple ones.

Be very, very careful.

--------------------
Bring back the HP-15

http://www.hp15c.org

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[cchngtn]

actually I use CosmosWork professional.

When I simulate with the material under cosmoswork, the simulation will directly analysis with the yield strength of 230MPa.

The result I get the Von mises result is about 200MPa.

I found that if I compare with allowable stress Sy = 0.67 x 230 = 154.1MPa, and I will meet failure in the simulation.

If I assume is yield strength, I still can pass the design.
because 230 Mpa > 200MPa.

therefore, I am very confuse!

 

[bassmanjax]

Von Mises stress is a failure criterion - it tries to simplify the stress field into a single value for yield comparison. The Von Mises stress is calculated from the principal stress components Sx, Sy and Sz.

Any good mech eng design book should give you a definition of Von Mises stress.

In your case, the VM stress is 200 MPa, below yield but not by much.

 

[SBaugh]

Actually this probably should be posted in forum1183

Regards,

Scott Baugh, CSWP

http://www.scottjbaugh.com

faq731-376