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Durability Analysis

Creator
Creator

Hello everyone,

 

Actually I'm running a Durability analysis on a bending blade with Durability Wizard.

 

The blade is full fixed on one side and loaded on the other one.

 

This blade is made from a steel SUS304 with work hardening and I have this data : 

- Yield Strength : 1200 MPa

- Tensile Strength : 1300 MPa

- Fatigue Strength Coefficient : 1350 MPa

- Fatigue Strength Exponent : -0.12

 

I'm  doing my study with different scale load and for small stresses near the full fixed boundary condition ; like 100 MPa ; I have 10^10 Duty Cycle ; which what I expected.

But for high stresses ; near the yield strength (1000 MPa) ; I have 3 Duty cycles for result which is strange cause I did not pass the yield strength, and if I'm understanding right, after 3 cycles the blade should break, right ?

 

Can you help me understand why I have this result ?

 

Thank you in advance !

 

Arthus

6 REPLIES

Re: Durability Analysis

Solution Partner Legend Solution Partner Legend
Solution Partner Legend

Arthus,

 

If you entered 1 as the number of cycles in the wizard dialog, then the number of duty cycles is in fact the number of cycles to crack initiation.

 

So yes for the 1000 MPa stress level, the software computes 3 cycles. However, you need to set the fatigue life criterion to either strain life of Smith Watson Topper to get an accurate life prediction near the yield point. In other words, stress life won't be representative at that stress.

 

Phil


Philippe Tremblay
phillippe.tremblay.ext@siemens.com
www.mayahtt.com

Re: Durability Analysis

Creator
Creator

Phil,

 

Thank you for your answer,

However, when I set the fatigue life criterion to "Smith Watson Topper" or to "Strain Life", I don't have acces to Duty Cycles result.

I tried to add more parameters to "Durability" section for my material but it does not have any effect to fatigue life results.

 

Do you know why ?

 

Thank you.

 

Arthus

Re: Durability Analysis

Solution Partner Legend Solution Partner Legend
Solution Partner Legend

Arthus,

 

Does your material have fatigue ductility and cyclic parameters?

 

fatigue.jpg

 

Please send me your event xml file from the durability solution, it should be named something like this

sim2-Durability_2-Static_Event_1.xml

 

and it should contain quite a bit of data (as opposed to the solution xml file)

 

Phil


Philippe Tremblay
phillippe.tremblay.ext@siemens.com
www.mayahtt.com

Re: Durability Analysis

Creator
Creator

Phil,

 

 

I do have cyclic and ductility parameters for my material. Only the cyclic yield strength parameter was missing but I chose a value for it.

 

As requested, I send (via email) the xml file.

 

Arthus

Re: Durability Analysis

Solution Partner Legend Solution Partner Legend
Solution Partner Legend

Arthus,

 

Your .xml file looks fine.

 

Was the static solution performed with the stress wizard? If not, you need to request stress and strain...Did you do that?

 

Phil


Philippe Tremblay
phillippe.tremblay.ext@siemens.com
www.mayahtt.com

Re: Durability Analysis

Creator
Creator

Phil,

 

You were right, I needed to request both stress and strain results.

 

Thank a lot !

 

Arthus