Safety
Use the Safety node to set up variables that can be used to check the risk of failure according to various criteria. Four different variables describing the failure risk will be defined as described in Table 9-3. You can add any number of Safety nodes.
Table 9-3: Variables for Safety Factor Evaluation.
Variable
Description
Criterion Fulfilled
Criterion violated
Failure index, FI
For a linear criterion, this is the ratio between the computed value and the given limit.
FI<1
FI>1
Damage index, DI
A binary value, indicating whether failure is predicted or not. DI is based on the value of FI.
DI=0
DI=1
Safety factor, SF
For a linear criterion, this is 1/FI.
SF>1
SF<1
Margin of safety, MoS
SF-1
MoS>0
MoS<0
Beam Properties
This section is only present in 3D, since in 3D the physics interface formally uses the layered technology. There is no need to make changes here.
Failure Model
Select a Failure Criterion — von Mises Isotropic, Tresca Isotropic, Rankine Isotropic, Bresler–Pister, Willam–Warnke, or Ottosen.
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When Failure Criterion is von Mises Isotropic, enter Tensile strength σts.
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When Failure Criterion is Tresca Isotropic, enter Tensile strength σts.
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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 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 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).
For all input fields, the default is to take the value From material. Change to User defined to enter other values or expressions.
For a detailed description of the various criteria, see Safety Factor Evaluation in the Structural Mechanics Theory chapter.
Location in User Interface
Context Menus
Beam Cross Section>Homogeneous Cross Section>Safety
Ribbon
Physics tab with  Physics tab with Homogeneous Cross Section selected
Attributes>Safety