Assigning carbon fiber material for Tsai-Wu Theory Failure

Altair Forum User

I need to simulate the frontal vehicle collision using the carbon fiber composite hood material using the Tsai-Wu theory failure.

However, I do not know a lot of the required mechanical properties for this failure theory.

 

Attached file contains the information of the carbon fiber material properties and it is a quasi-isotropic material, therefore, I believe we can input equal mechanical properties in x and y direction (1 and 2 direction)

 

This simulation does not require the exact result and obtaining only the trend is sufficient.

Can you please take a look at the attached files and let me know which mechanical properties that we do not have are crucial to simulation?

 

 

Unable to find an attachment - read this blog

Pranav Hari

Hi j8jang

 

I think you can use Mat law 12 in Radioss which describes a solid material using the Tsai-Wu formulation that is usually used to model composites. This material is assumed to be 3D orthotropic-elastic before the Tsai-Wu criterion is reached.

 

if you are using shell elements then you can use Mat law 25 which describes the composite shell and solid material using the Tsai-Wu formulation

 

Refer Radioss reference guide where you will get more information regarding these material laws and the mechanical properties to be given as input.

 

 

<?xml version="1.0" encoding="UTF-8"?>

 

Also, have a look at the other composite material laws in Radioss

 

<?xml version="1.0" encoding="UTF-8"?>

 

Altair Forum User

Hi Pranav,

 

Thank you for your reply.

I read the RADIOSS reference guide, more specifically, Law 25 as we are using the shell element.

I realized that in the given example, which is also illustrated below, only certain parameters are put in. (RHO_I, E11, E22, NU12, E33, G12, G23, G31, wpmax, fmax, sig_1yt, sig_2yt, sig_1yc, sig_2yc, sig_12yc, sig_12yt)

 

 

They did not include parameters such as 'b', plastic hardening parameter or 'n', plastic hardening exponent.

Will inputting only these parameters still be sufficient for the analysis?

Pranav Hari

Hi j8jang

 

Altair Forum User said:

Will inputting only these parameters still be sufficient for the analysis?

 

That depends on whether your material goes into a non-linear condition or not. According to tsai-wu criterion, the material is assumed to be elastic until the Tsai-Wu criterion is fulfilled. After exceeding the Tsai-Wu criterion limit the material becomes non-linear. If the material exceeds the elastic state and passes into non-linear state then it is compared to a maximum value F(W_p) varying in function of the plastic work during work hardening phase. so here for comparing with F(Wp) you need to input  'b', plastic hardening parameter and 'n', plastic hardening exponent.

 

 

 

<?xml version="1.0" encoding="UTF-8"?>

 

So in your case, I feel its better to input 'b', plastic hardening parameter and 'n', plastic hardening exponent.

 

 

Altair Forum User

Hi thank you for the reply,

 

so addition to the input from the example, I have added a, b, and n.

Will this be sufficient or is there any other inputs that we must consider for the frontal vehicle crash analysis?

 

 

pohan

Hi

Once we use MAT 12, do we have to include any failure mode in the Properties part?