Use the Cumulative Damage node to define the analysis type, solution field, cycle counting parameters, damage model parameters, and generalized load. The Cumulative Damage feature can be applied to domains, boundaries, edges, or points. If points are selected, results for Counted stress cycles and Relative usage factor are created for each point.

From the Physics interface list select the physics interface where the stress-strain 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.

To define how the load cycle is evaluated, select the analysis Type — Solution history or Generalized loads.

The Solution history processes the stress cycle, load step by load step. The Generalized loads processes a few basic load cases, and a list of weighting coefficients, and can thus handle very long load cycles.

Select how the stress is evaluated from the Stress σ list — Principal stress, Signed von Mises (principal), or Signed von Mises (hydrostatic). See Cycle Counting Options for details.

Under Discretization, enter values or expressions for the Number of mean value bins Nm and Number of range bins Nr. Both are dimensionless numbers with the default value 10. These parameters define the number of discrete points used to define the load cycle distribution and are thus strongly connected to the computational time.

Select the S-N curve σa(R,N) from the list. It contains all functions defined under Global Definitions. See Damage Estimation for details.

Enter the Number of block repetitions m. The default is 1. A block is a sequence of load events that define a representative fatigue load cycle.

Under Evaluation settings enter a value for the Cycle cutoff Ncut. The default is 1010. Based on the S-N curve, the Cycle cutoff implicitly provides the highest stress value that gives no contribution to the fatigue usage factor. From the evaluation point of view this stress can be seen as the endurance limit.

This section is available when Generalized loads is selected under Analysis.

For the load history, enter values or expressions for the Initial step si and the Final step sf. The default is 1 for both. Under Generalized load history, specify load history functions for all generalized loads. The number of generalized load functions must equal the number of load cases in the study specified as the Physics interface under Solution Field.