Block Format Keyword
/MAT/LAW15 - Composite Shell Material
Description
This law is used to model composite shell elements, similar to law 25. The plastic behavior is based on the Tsai-Wu criteria (/MAT/LAW25 (COMPSH) for Tsai-Wu description) and failure is based on the Chang-Chang failure criterion is used.
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/MAT/LAW15/mat_ID/unit_ID or /MAT/CHANG/mat_ID/unit_ID |
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mat_title |
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E11 |
E22 |
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G12 |
G23 |
G31 |
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b |
n |
fmax |
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Ioff |
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c |
ICC |
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S1 |
S2 |
S12 |
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Fsmooth |
Fcut |
C1 |
C12 |
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#RADIOSS STARTER #---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----| /UNIT/1 unit for mat kg mm ms #---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----| #- 2. MATERIALS: #---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----| /MAT/LAW15/1/1 Carbon # RHO_I 1.8E-6 # E11 E22 NU12 41 3.3 .3 # G12 G23 G31 5.2 1.3 1.3 # b n fmax 8E-6 1 100000 # Wpmax Wpref Ioff 100000 0 0 # sigma_1yt sigma_2yt sigma_1yc sigma_2yc alpha .786 .1566 .786 .1566 0 # sigma_12yc sigma_12yt c Eps_dot_0 ICC .0655 .0655 0 0 0 # beta Tmax S1 S2 S12 1 .01 0 0 0 # Fsmooth Fcut C1 C12 0 0 0 0 #---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----| #ENDDATA /END #---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----| |
Where 1 is the fiber direction. The failure criteria for fiber breakage is written as: Tensile fiber mode: 11 > 0 Compressive fiber mode: 11 < 0
For matrix cracking, the failure criteria is: Tensile matrix mode: 22 > 0 Compressive matrix mode: 22 < 0 If the damage parameter is equal to zero or greater than 1.0, the stresses are decreased by using an exponential function to avoid numerical instabilities. A relaxation technique is used by gradually decreasing the stress:
with, and Where, t is the time, tr is the start time of relaxation when the damage criteria is assumed, is the time of dynamic relaxation, and is the stress components at the beginning of damage.
and
Where, is time when damage criteria is assumed. |