Use the Strain-Life node to calculate fatigue life based on a fatigue life curve that relates load cycle strain amplitude to life. The Strain-Life feature can be applied to domains, boundaries, edges, or points.

See Common Physics Interface and Feature Settings and Nodes for information about the Model Input.

From the Physics interface list select the physics interface where the strain-life response to the fatigue load is simulated.

If you select a Shell interface, also select a Through-thickness location — From shell interface, Top, or Bottom. This determines from which position in the shell stresses or strains are taken for fatigue evaluation. When you select From shell interface, the local z-coordinate given in the Default Through-thickness Result Location section in the settings for the Shell interface is used.

Select a Fatigue limit — E-N curve, Coffin-Manson, or Combined Basquin and Coffin-Manson. This specifies the fatigue model to be evaluated. See E-N curve Model, Coffin-Manson Model, and Combined Basquin and Coffin Manson Model for details about these models.

If Combined Basquin and Coffin-Manson model is selected, also specify Mean stress correction — None or Morrow, which controls how the effect of the mean stress should be evaluated.

If Coffin-Manson model is selected, also specify a Strain type — None or User Defined, which is used to specify strain type that controls fatigue. The list of the Strain type is populated with additional options when nonlinear materials are used. If the material has been modeled with Plasticity then Equivalent plastic strain is selectable. If the material has been modeled with Creep option also Equivalent creep strain is selectable. If the material has been modeled with Viscoplasticity option also Equivalent viscoplastic strain is selectable.

If Coffin-Manson model is selected with the User Defined option as Strain type, two additional input are required. First, you need to specify the Inelastic strain εi using the pattern <name>.<variable_name>, and second, you need to provide the integration order that was used to compute this strain.

When E-N curve is selected as the Fatigue limit, select a function from the list for the E-N curve fEN(N). The list contains all functions defined under Global Definitions. The Interpolation and Analytic functions are recommended for use with the model.

When Coffin-Manson is selected as the Fatigue limit, the material parameters Fatigue ductility coefficient εf’ and Fatigue ductility exponent c by default take values From material. For User defined specify other values in the fields as needed.

When Combined Basquin and Coffin-Manson is selected as the Fatigue limit, the material parameters Fatigue strength coefficient σf’, Fatigue strength exponent b, Fatigue ductility coefficient εf’ and Fatigue ductility exponent c by default take values From material. For User defined specify other values in the fields as needed.

Enter a value for the Cycle cutoff Ncut. The default is 1e10. This is the upper limit to the model prediction of the number of cycles to failure and is assigned as solution when the strain range is very small.