Fabric law 58 defined by stress-strain curve

Simon Križnik

Hi,

 

the fabric law 58 is defined by stress-strain curves and parameters found in the referenece guide, which are scaled 1000x to be consistent with the tonne, mm, s unit system. However, all elements get deleted at the start of simulation with the message:

 -- DELETE 3N SHELL ELEMENT :        10 AT TIME : 0.9001E-05

 

Altair Forum User

Hi @Ivan

 

Can you add DT/NODA/CST to the engine with Scale of 0.6 and Tmin of 1e-6 and check if that helps?

Simon Križnik

Adding  DT/NODA/CST does not resolve the issue- the elements still get deleted at the start, even though there is no such message in the out file.

This is strange since the imposed displacement (+ 0.1 strain) should be within stress-strain curve.

Please find the model attached bellow.

Unable to find an attachment - read this blog

Simon Križnik

Hi,

 

can someone please provide some example model where law 58 is defined with stress-strain curves?

Altair Forum User

HI,

 

From RADIOSS help:

 

 #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/<span>LAW</span><span>58</span>/1/1 Altair test fabric <span>LAW</span><span>58</span> #              RHO_I                8e-07 #                 E1                  B1                  E2                  B2                FLEX                 0.38                   0                0.38                   0                   1 #                 G0                  GT              AlphaT                 Gsh           sensor_ID               0.0035              0.0055               7.175                   0                   1 #                 Df                  Ds               GFROT                             ZERO_STRESS                 0.00                0.00                   0                                       1	  #       N1        N2                  S1                  S2               FLEX1               FLEX2          1         1                   0                   0                   0                   0 #  fct_ID1                       Fscale1        500                             1 #  fct_ID2                       Fscale2        501                          1.07 #  fct_ID3                       Fscale3        502                             1 #---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----| /FUNCT/500 stress-strain curve dir 1 #        true strain         true stress    0.0000000000e+000                   0    9.9503308532e-003   2.9636979188e-003    1.9802627296e-002   5.3682944250e-003    2.95<span>58</span>802242e-002   7.1312474875e-003    3.9220713153e-002   8.7543744167e-003    4.8790164169e-002   1.0626227281e-002    5.8268908124e-002   1.2828957400e-002    6.76<span>58</span>648474e-002   1.5214981140e-002    7.6961041136e-002   1.7923677525e-002    8.6177696241e-002   2.09310474<span>58</span>e-002    9.5310179804e-002   2.4244941875e-002    1.0436001532e-001   2.8050134750e-002    1.1332868531e-001   3.2157106333e-002    1.2221763272e-001   3.6791281562e-002    1.3102826241e-001   4.1811352500e-002    1.3976194238e-001   4.718<span>58</span>17708e-002    1.4842000512e-001   5.3009665500e-002 /FUNCT/501 stress-strain curve dir 2 #        true strain         true stress    0.0000000000e+000                   0    9.9503308532e-003   3.7850414917e-003    1.9802627296e-002   6.6041801875e-003    2.95<span>58</span>802242e-002   8.9026150938e-003    3.9220713153e-002   1.1200598067e-002    4.8790164169e-002   1.3569178437e-002    5.8268908124e-002   1.6244941225e-002    6.76<span>58</span>648474e-002   1.9356706823e-002    7.6961041136e-002   2.2930409250e-002    8.6177696241e-002   2.7109342313e-002    9.5310179804e-002   3.1773431250e-002    1.0436001532e-001   3.6903321313e-002    1.1332868531e-001   4.2590270333e-002    1.2221763272e-001   4.8734555250e-002    1.3102826241e-001   5.5311888000e-002    1.3976194238e-001   6.2350489167e-002    1.4842000512e-001   6.9690045000e-002 #---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----| /FUNCT/502 stress-strain curve dir 12 #              angle         true stress   -16.170000000e-000  -1.5741500000e-003   -7.1750000000e-000  -4.3750000000e-004    0.0000000000e+000   0.0000000000e+000    7.1750000000e-000   4.3750000000e-004    16.170000000e-000   1.5741500000e-003 #ENDDATA /END #---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

Simon Križnik

Hi,

 

this example fabric material from Radioss help was used in the previously shared model. However, the elements get deleted right at the start of simulation.

Altair Forum User

Hi Ivan,

 

I need to check if there is any material data for law 58 which can be made public apart from the help.

Simon Križnik

Thanks Prakash,

 

I am not interested in material data as such but a functioning demonstration model with fabric law 58 defined by stress-strain curves would be appreciated.

Simon Križnik

Hi,

 

in the attached file the material model is duplicated verbatim (imported solver deck copied form Radioss help), but the elements still get deleted from the start. Therefore I suspect this material model is not functional with stress-strain curve input. Please verifiy at your end.

Unable to find an attachment - read this blog