Learning Forum

[goktug.yilmaz]

Hi everyone,

I have a parameter list below to do analysis on Ls-Dyna. However, I am struggling with obtaining or calculating some of them. For example, definition of the tangent modulus is that:

[ramgopisetti]

Hi Array , The answer to your question is an quite an complex ( gettign the tangent modulo of different grades of the Aluminium) unless you have tensile test data, if youhave such data you can use the following forum for calcuating the Tangent modulo
 E_tan_Calculated / E ratio may be closer to an Elastic-perfectly plastic case.
E_tan_Calculated = [(1+%EL/100)*S_ult - S_yield ]/ [(ln(1/(1-%RA/100)))- (S_yield/E)]
%EL= % Elongation
%RA= % Reduction in Area
E = Modulus
The strengths are self Explanatory.
If you don't know the %RA you can approximate as follows
%RA =200*%EL/(100+2*%EL)
If you have access to Granta Material library, you might get compleat Plasticity modelling Parameters.
Comment down your response for futher help.
Cheers, Ram

[goktug.yilmaz]

Thank you very much for your help dear Array . You have helped a lot. I am very grateful. However, what about other parameters? There is actually little information about the "hardening parameter(beta)" for example.

[Ram Gopisetti]

Hi Array , i encourage you to check the *MAT_003 *MAT_PLASTIC_KINEMATIC in LSDYNA documentation, It clearly explains how to derive those parameters, for K,n you need to so the curve fit with True stress=K.True strain^n and optimize the K,n coefficients. for beta you can assume your material undergo Kinematic hardening and use 1 .
Cheers, Ram

[Kyle]

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Hi goktug.yilmaz, I am new user in LS-DYNA software. I have a question for the output of LSDYNA. Basically, I have used the software to do tnesile test in numerically and I have an issue about output. My question is how to output the engineering stress/strain, and/or true stress/strain? Looking forward to hearing from you!

Sincerely,

Kyle

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[myeasygrader]

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