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Stress criterion for brittle material

Posted Oct 18, 2020, 3:19 a.m. EDT Wave Optics, Structural & Acoustics, Structural Mechanics Version 5.5 3 Replies

Carmelo B. IJCLab/Université Paris-Saclay
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Hello everyone

I am going to simulate the thermal expansion of a mirror. Could you tell me what is the suggested criterion to evaluate the stress in the mirror?

As far as I know, von Mises is widely used for ductile materials.

Best regards.

3 Replies Last Post Oct 22, 2020, 2:36 a.m. EDT
Henrik Sönnerlind COMSOL Employee

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Posted: 4 years ago Oct 19, 2020, 7:42 a.m. EDT

I do not think that there is an universal answer to your question, but largest principal stress (solid.sp1) is a more common criterion for brittle materials.

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Henrik Sönnerlind
COMSOL
I do not think that there is an universal answer to your question, but largest principal stress (solid.sp1) is a more common criterion for brittle materials.
Carmelo B. IJCLab/Université Paris-Saclay
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Posted: 4 years ago Oct 21, 2020, 1:26 p.m. EDT

Dear Henrik Sönnerlind, Thank you for your message. I will take a look so on principal stress criterion. In your opinion, can I related the principal stress criterion with the Rankine fracture criterion? Indeed a crack initiates when the maximum principal stress reaches the material strength.

So I was thinking to calculate all principal stresses (x,y, and z) in glass and if one of them exceed material strength, I will consider the damage of the material.

What do you think about it?

Carmelo Barbagallo

Dear Henrik Sönnerlind, Thank you for your message. I will take a look so on principal stress criterion. In your opinion, can I related the principal stress criterion with the Rankine fracture criterion? Indeed a crack initiates when the maximum principal stress reaches the material strength. So I was thinking to calculate all principal stresses (x,y, and z) in glass and if one of them exceed material strength, I will consider the damage of the material. What do you think about it? Carmelo Barbagallo
Henrik Sönnerlind COMSOL Employee

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Posted: 4 years ago Oct 22, 2020, 2:36 a.m. EDT

The Rankine criterion is built-in; see the attached screenshot.

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Henrik Sönnerlind
COMSOL
The Rankine criterion is built-in; see the attached screenshot.

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