Bi-directional fabric - MAT_054 model

[Ramdas Chennamsetti]

Hi everyone:

I am simulting failure in a composite plate using Chang-Chang model (MAT_054). The plate is constructed using bi-directional (BD) plain weave fiber (six plies). Hence, 2WAY flag is set.

As per the help manual, in case of a uni-directional fabric (reinforcement) history variables (HVs) # 1and 2 give fiber failure in tension and compression, respectively, whereas, 3 and 4 give matrix failure in tension and compression, respectively.

When BD fiber (same properties in warp and weft directions) is used, then the HVs # 1 and 2 give fiber failure in tension and compression in warp and weft direction. 

Q1: What do HVs # 3 and 4 give (in BD fabric case)? 

I have found from the simulations (fringe plot) that HV#1 becomes zero from unity after a certain time. This is checked by plotting HV#1 vs time. Both the fringe plot and HV#1 vs time match. 

Q2: When I plot (fringe) HV#2, the fringe plot has unity all over the elements throughout simulations. But, when I plot HV#2 vs time, it shows failure (the HV#2 drops from unity to zero at a certain time). I couldn't understand this point.

It is appreciated, if someone answers questions 1 and 2.

Thanks and warm regards,

Ramadas

[James M. Kennedy]

Dear Ramdas,

 

Taken form Vol. II user Manual under *mat_054

 

History -  Variable Description               - Value

 

1 ef(i)       tensile fiber mode                  1 – elastic, 0 – failed

 

2 ec(i)      compressive fiber mode         1 – elastic, 0 – failed

 

3 em(i)     tensile (shear for 2WAY)      1 – elastic, 0 – failed

                matrix mode

 

4 ed(i)      compressive matrix mode      1 – elastic, 0 – failed

 

5 efail      max[ef(ip)]                             1 – elastic, 0 – failed

 

6 dam     damage parameter                 −1 – element intact

                                                             10−e – element in crashfront

                                                              1 – element failed

 

The variables in the table above are labeled by LS-PrePost simply as history variables

 

-------------------------------------------

 

Research was completed to characterize the root behavior of the LS-DYNA *MAT_054 composite orthotropic material model. This primarily involved investigating the constitutive relations, ply failure (damage onset), ply deletion, damage factors, and element deletion:

 

Osborne, M., "Single-Element Characterization of the LS-DYNA MAT54 Material Model", Master's Thesis, Department of Aeronautics and Astronautics, University of Washington, Seattle, Washington, 2012.

 

https://digital.lib.washington.edu/researchworks/bitstream/handle/1773/22526/Osborne_washington_0250O_11236.pdf

 

The basic behavior of a progressive failure model that simulates laminated composite materials was investigated. To evaluate the fundamental elastic, failure initiation, and post-failure behaviors of *MAT_054, as well as the suitability of *MAT_054 to model fabric composite material systems, a series of single-element simulations was performed. The simulation used a carbon fiber/epoxy material system with various lay-ups, including UD tape and plain-woven fabric variants:

 

Wade, B., Feraboli, P., Osborne, M., and Rassaian, M., "Simulating Laminated Composite Materials Using LS-DYNA Material Model MAT54: Single-Element Investigation", DOT/FAA/TC-14/19, U.S. Department of Transportation, Federal Aviation Administration, William J. Hughes Technical Center, Atlantic City International Airport, New Jersey, February, 2015.

 

http://www.tc.faa.gov/its/worldpac/techrpt/tc14-19.pdf

 

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Sincerely,

James M. Kennedy

KBS2 Inc.

September 18, 2022

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