What MAT LAW should be used for plastic in Radioss?

James Lewis

Hi guys,

 

I want to simulate a drop test with my plastic part.

And I don't know what should mat law should I used for it.

I have stress strain curve csv file like below.

Thank you!

 

PaulAltair

Hi, LAW36 (PLAS_TAB) should be ok for this: It needs True Plastic Stress vs Strain (ratio) as input

I've assumed your data above is engineering stress vs strain(%)?

Converting to True Plastic Stress vs Strain for LAW36:

Offset stress/strain to 0,0 and divide strain by 100

True Strain: Take Natural Log of 1 + Eng Strain

True Stress: Eng Stress * Exponent (Eng Strain)

Estimate Elastic Modulus (E)

Plastic Strain = True Strain - True Stress/E

As Material: also attached as file (I have set density as 5g/cm^3 and poissons ratio as 0.3), you may modify those if you have better data

Hope this helps

PaulAltair

Hi, LAW36 (PLAS_TAB) should be ok for this: It needs True Plastic Stress vs Strain (ratio) as input

I've assumed your data above is engineering stress vs strain(%)?

Converting to True Plastic Stress vs Strain for LAW36:

Offset stress/strain to 0,0 and divide strain by 100

True Strain: Take Natural Log of 1 + Eng Strain

True Stress: Eng Stress * Exponent (Eng Strain)

Estimate Elastic Modulus (E)

Plastic Strain = True Strain - True Stress/E

As Material: also attached as file (I have set density as 5g/cm^3 and poissons ratio as 0.3), you may modify those if you have better data

Hope this helps

James Lewis

Paul Sharp_21301 said:

Hi, LAW36 (PLAS_TAB) should be ok for this: It needs True Plastic Stress vs Strain (ratio) as input

I've assumed your data above is engineering stress vs strain(%)?

Converting to True Plastic Stress vs Strain for LAW36:

Offset stress/strain to 0,0 and divide strain by 100

True Strain: Take Natural Log of 1 + Eng Strain

True Stress: Eng Stress * Exponent (Eng Strain)

Estimate Elastic Modulus (E)

Plastic Strain = True Strain - True Stress/E

As Material: also attached as file (I have set density as 5g/cm^3 and poissons ratio as 0.3), you may modify those if you have better data

Hope this helps

Hi Paul,

 

Thank you for your great explain.

I've applied your method and successfully created data for material.

 

But can I have a more question that, do you know how to convert material from .csv file using tcl scripts.

 

Best regards,

James

 

PaulAltair

James Lewis said:

Hi Paul,

 

Thank you for your great explain.

I've applied your method and successfully created data for material.

 

But can I have a more question that, do you know how to convert material from .csv file using tcl scripts.

 

Best regards,

James

 

There is a specific tool 'Altair Material Modeler' that is an interface for Compose,

Material Modeler

it does everything for you... but it is not 'free' (draws license units) 

James Lewis

Paul Sharp_21301 said:

There is a specific tool 'Altair Material Modeler' that is an interface for Compose,

Material Modeler

it does everything for you... but it is not 'free' (draws license units) 

That really helpful, thank you!