Load definition - overview

The loading requirements in a fracture mechanics analysis may vary considerably depending upon the goal of the analysis. Some possible examples include:

• Parametric study of crack sizes to determine stress intensity factors under a number of load conditions
• Evaluation of j-integrals at multiple load increments in a non-linear plastic collapse analysis
• Fatigue crack growth analysis with spectrum loading
• Sustained load crack growth analysis with load as a function of time
• Combined fatigue and sustained load crack growth in which da/dn and da/dt effects contribute significantly to the overall crack growth

This variety of possible requirements is tackled in Zencrack by the processing of the results of individual load steps from each finite element analysis combined with a load system methodology for crack growth.

The load system approach allows a framework to be constructed that defines the loading history to be applied to the structure. Any local mixed mode effects arising at the crack front as a result of the geometry and loading are embodied in the stress and displacement solution and are handled during the processing of the finite element results.

For crack growth analysis Zencrack has capabilities to impose static loading onto a cyclic fatigue load and to consider sustained load crack growth in addition to fatigue crack growth.

Other load-related capabilities

• use of non-linearities in the f.e. analysis (e.g. crack face contact)
• Willenborg retardation model