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KEY TERMS:
NASGRO 
FLAGRO
life assessment
crack growth
fracture
mechanics
damage tolerance
structural integrity
analysis
materials
database
consortium
software
stress intensity
factor
boundary element
method
fracture control
critical crack size
NASA

NASGRO® Crack Growth Equation

The NASGRO crack growth equation accounts for stress ratio effects using a simple crack closure model and also treats the near-threshold and near-instability regions explicitly with multiple parameters.

 

The user can provide a different crack growth equation or input 1-D or 2-D tabular da/dN vs. ΔK data if desired. The effects of stress ratio and crack size on threshold are also modeled, as well as the changes in toughness for different thicknesses or for surface cracks.

For variable amplitude loading, five different load interaction models are available:

  • Generalized Willenborg

  • Modified generalized Willenborg

  • Walker-Chang Willenborg

  • Constant closure

  • Strip yield crack closure model

Materials Engineering Department Structural Engineering Department
  Mechanical Engineering Division SwRI Home

Southwest Research Institute® (SwRI®) is an independent, nonprofit, applied engineering and physical sciences research and development organization with 9 technical divisions using multidisciplinary approaches to problem solving. The Institute occupies 1,200 acres and provides nearly two million square feet of laboratories, test facilities, workshops, and offices for more than 2,600 employees who perform contract work for industry and government clients.