6061 aluminum Ultimate Tensile Strength calculates as less than Yield Strength

[Anonymous]

Using Inventor Pro 2019 I did a static analysis of a 12"sq x .75" 6061 Aluminum plate.

Constrained on one side and center loaded with 1,000#

My Yield Strength safety factor = 8.66

My Ultimate Tensile Strength safety factor = 7.18

Performing the same test with Mild Steel

My Yield Strength safety factor = 6.37

My Ultimate Tensile Strength safety factor = 8.26

Shouldn't Yield Strength always be less than Ultimate Tensile Strength?

Since the aluminum is brittle I'm guessing it will break not bend, but why am I getting a higher yield safety factor?

[mcgyvr]

nm

[TheCADWhisperer]

Attach your file(s) here.

[Anonymous]

files attached

[Cris-Ideas]

See mechanical properties for your materials.

Steel Ys 207MPa

Alu Ys 275 MPa.

Cris

[Anonymous]

What I have gathered is that the UTS and the YS are calculated based upon different stresses.
What I am trying to accomplish in Inventor is to calculate those numbers to show on a stress/strain diagram.

Should I base our safety factor rating on the the lesser of the two numbers?
Assuming my UTS calculation is correct, how can i find it's corresponding YS?

[Frederick_Law]

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@Anonymous wrote:

What I have gathered is that the UTS and the YS are calculated based upon different stresses.
What I am trying to accomplish in Inventor is to calculate those numbers to show on a stress/strain diagram.

Should I base our safety factor rating on the the lesser of the two numbers?
Assuming my UTS calculation is correct, how can i find it's corresponding YS?

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UTS/TS and YS is what entered in material property.  So Inventor calculate BASED on those number.

Safety factor is calculated from load applied to part and TS/YS.

Stress/Strain curve is from actual material load test.  That's how UTS and YS is found.

Simulation is to show loaded stress in the part.  Designer / engineer will compare those to design requirement.

I have no idea what you're trying to do calculating UTS and YS.

[Cris-Ideas]

Hi,

What exactly is that you would to calculate or get form the software?

As general remark:

Safety factor as such is what YOU the designed decides it is. It can be stress/yield stress it can stress/ultimate limit stress or any other value you desire.

It is YOU the designer that must judge what is safe for your project.

Cris.

[Anonymous]

Simply trying to find 2 numbers: The load # my part will begin to strain, and load # my part will start necking.

[Frederick_Law]

Put a load on the part.  Get max stress from simulation.

Try New Load = Old Load * YS/Max Stress.  Run Sim again and check if max stress is close to YS.

Repeat for TS.

Increase/decrease load until you get as close to TS/YS as you want.

[Cris-Ideas]

You will no get that as inventor only does linear analysis.

what you can calculate is only the load when max stress gets to yield stress. After that analysis must be plastic.

Cris