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When you add a Safety node in one of the Shell, Layered Shell, or Membrane interfaces, a default plot with the failure index is generated. Such plots are placed in a group named Failure Indices. The label of these plots is derived from the label of the corresponding Safety node.
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This section is only present when Safety is used as a subnode to:
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When Failure Criterion is Rankine Isotropic, enter Tensile strength σts and Compressive strength σcs.
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When Failure Criterion is St. Venant Isotropic, enter Ultimate tensile strain εts and Ultimate compressive strain εcs.
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When Failure Criterion is Mohr-Coulomb Isotropic, select Material parameters — Cohesion and angle of friction or Tensile and compressive strengths to determine the type of input data.
When Cohesion and angle of friction is used, enter Cohesion c and Angle of internal friction φ. When Tensile and compressive strengths is used, enter Tensile strength σts and Compressive strength σcs. In either case, you can select Include elliptic cap to limit the allowed compressive stress. When selected, enter the Elliptic cap parameters pa and pb. |
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When Failure Criterion is Drucker-Prager Isotropic, select Material parameters — Drucker-Prager parameters, Tensile and compressive strengths, or Mohr-Coulomb parameters to determine the type of input data.
When Drucker-Prager parameters is used, enter Drucker-Prager alpha coefficient α and Drucker-Prager k coefficient k. When Tensile and compressive strengths is used, enter Tensile strength σts and Compressive strength σcs. When Mohr-Coulomb parameters is used, enter Cohesion c and Angle of internal friction φ. In either case, you can select Include elliptic cap to limit the allowed compressive stress. When selected, enter the Elliptic cap parameters pa and pb. |
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When Failure Criterion is Bresler-Pister Isotropic, enter Tensile strength σts, Compressive strength σcs, and Biaxial compressive strength σbc.
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When Failure Criterion is Willam-Warnke Isotropic, enter Tensile strength σts, Compressive strength σcs, and Biaxial compressive strength σbc.
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When Failure Criterion is Ottosen Isotropic, enter the Compressive strength σcs, Ottosen parameters a and b, the Size factor k1, and the Shape factor k2.
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When Failure Criterion is Jenkins Orthotropic, enter Tensile strengths σts, Compressive strengths σcs, and Shear strengths σss. All entries have three components, related to the principal axes of orthotropy.
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When Failure Criterion is Waddoups Orthotropic, enter Ultimate tensile strains εts, Ultimate compressive strains εcs, and Ultimate shear strains γss. All entries have three components, related to the principal axes of orthotropy.
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When Failure Criterion is Azzi-Tsai-Hill Orthotropic, enter Tensile strengths σts, Compressive strengths σcs, and Shear strengths σss. All entries have three components, related to the principal axes of orthotropy.
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When Failure Criterion is Norris Orthotropic, enter Tensile strengths σts, Compressive strengths σcs, and Shear strengths σss. All entries have three components, related to the principal axes of orthotropy.
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When Failure Criterion is Modified Tsai-Hill Orthotropic, enter Tensile strengths σts, Compressive strengths σcs, and Shear strengths σss. All entries have three components, related to the principal axes of orthotropy.
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When Failure Criterion is Tsai-Hill Orthotropic, enter Tensile strengths σts, Compressive strengths σcs, and Shear strengths σss. All entries have three components, related to the principal axes of orthotropy.
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When Failure Criterion is Hoffman Orthotropic, enter Tensile strengths σts, Compressive strengths σcs, and Shear strengths σss. All entries have three components, related to the principal axes of orthotropy.
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When Failure Criterion is Tsai-Wu Orthotropic, enter Tensile strengths σts, Compressive strengths σcs, and Shear strengths σss. All entries have three components, related to the principal axes of orthotropy.
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When Failure Criterion is Zinoviev Orthotropic, enter Tensile strengths σts, Compressive strengths σcs, and Shear strengths σss. All entries have three components, related to the principal axes of orthotropy.
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When Failure Criterion is Hashin-Rotem Orthotropic, enter Tensile strengths σts, Compressive strengths σcs, and Shear strengths σss. All entries have three components, related to the principal axes of orthotropy.
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When Failure Criterion is Hashin Orthotropic, enter Tensile strengths σts, Compressive strengths σcs, and Shear strengths σss. All entries have three components, related to the principal axes of orthotropy.
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Enter Tensile strengths σts, Compressive strengths σcs, and Shear strengths σss. All entries have three components, related to the principal axes of orthotropy.
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Enter the Fiber failure data: Ultimate tensile strain in longitudinal direction, εts1, and Ultimate compressive strain in longitudinal direction, εcs1. Also, enter the fiber material properties Young’s modulus of fiber in longitudinal direction, Ef1, and In-plane Poisson’s ratio of fiber, νf12. Enter a Mean stress magnification factor, mf. The default value is 1.3, a value commonly assumed for GFRP. For CFRP, the value 1.1 has been suggested.
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Enter the Interfiber failure data: Linear degradation stress, σ1D. Also, enter the Slope of in-plane fracture envelope, tension, ptl, and the Slope of in-plane fracture envelope, compression, pcl. The default values are 0.3 and 0.25, respectively. These values are common for GFRP. For CFRP, the values 0.35 and 0.3 have been suggested.
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Enter Tensile strengths σts, Compressive strengths σcs, and Shear strengths σss. All entries have three components, related to the principal axes of orthotropy. Also, enter the Ultimate tensile strain in longitudinal direction, εtsl.
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Enter the In situ transverse tensile strength,
 , and In situ in-plane shear strength,  . For both parameters, the default is to compute the value from the data given above, as indicated by the selections From transverse tensile strength and From in-plane shear strength respectively. You can also take the values From material, or select User defined to enter own expressions. |
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Enter Young’s modulus in longitudinal direction, E1, Young’s modulus in transverse direction, E2, In-plane Poisson’s ratio, ν12, and In-plane shear modulus, G12. For all four parameters, the default selection is From parent, indicating that the values are taken from the linear elastic properties in the parent node. You can also take the values From material, or select User defined to enter own expressions.
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Enter the Fracture plane angle under transverse compression, α0. The default value is 53°. Also enter the Fracture plane search angle, Δα. The default value is 3°. Under combined loading, the fracture plane angle will differ from α0, and a numerical search for the critical angle is performed in the range 0 < α < α0. The step in the search is Δα.
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When Failure Criterion is Tsai-Wu Anisotropic, enter Second rank tensor, Voigt notation f, and Fourth rank tensor F. Enter the components of the tensors with respect to the directions of the coordinate system in the parent node.
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When Failure Criterion is User defined, you enter two expressions describing the Failure criterion g(S), used in the failure index, and the Safety factor sf(S). As an example, if you would like to replicate the von Mises Isotropic criterion with tensile strength 350 MPa, you could enter g(S) as solid.mises/350[MPa]-1 and sf(S) as 350[MPa]/(solid.mises+eps).
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For a detailed description of the various criteria, see Safety Factor Evaluation in the Structural Mechanics Theory chapter.
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