Material & crack growth data

Zencrack provides a variety of options for input of material & crack growth data. This includes temperature dependancy and, for fatigue crack growth, dependency on stress ratio.

The basic material data that can be input are values for Young's modulus and Poisson ratio. These are used to convert between stress intensity factors and energy release rates. In addition, plane strain and plane stress fracture toughness can be provided along with yield stress. The fracture toughness value are used to determine failure and the yield stress is used if retardation modelling is activated. All of these materials properties may be temperature dependent.

For a crack growth analysis the additional crack growth data can be as simple or complex as is available or required for the analysis being carried out. Crack growth data can be input in the standard Paris and Walker forms. A "single curve" option is also available. For more complex data a tabular option is available for da/dn vs deltaK curves as a function of stress ratio. All of these options can include temperature dependency.

In addition to the crack growth data, options are available for threshold definition and, as mentioned above, for input of fracture toughness values. The appropriate threshold option depends partly on the available growth data but options available include a single deltaKth value and deltaKth as a function of stress ratio. Temperature dependency is also allowed.

For users with proprietary data or other non-standard data, a number of user subroutine options are available for definition of both the crack growth data and/or threshold definition.

Sustained load crack growth analyses can be carried out with Zencrack and these require data in the form of da/dt against K (rather than da/dn against deltaK for fatigue). As with fatigue growth data, a variety of options provide flexibility of input from simple single curve data through to user subroutines.