AFGROW is a Damage Tolerance Analysis (DTA) framework that allows users to analyze crack initiation, fatigue crack growth, and fracture to predict the life of metallic structures. AFGROW (Air Force Grow), was originally developed by The Air Force Research Laboratory. It is now being developed and maintained by LexTech, Inc.
AFGROW is one of the most efficient and widely used crack growth life prediction tools available today. AFGROW is mainly used for aerospace applications; however, it can be applied to any type of metallic structure that experiences fatigue cracking. AFGROW is also a very flexible and user-friendly computer program.
The classic stress intensity factor library provides solutions for over 30 different crack geometries (including axial, bending and bearing loading for many cases). In addition, an advanced, multiple crack capability allows AFGROW to analyze two independent cracks in a plate (including hole effects), non-symmetric corner cracked holes, and a continuing damage solution. Finite Element (FE) based solutions are available for two, non-symmetric corner cracks at holes as well as cracks growing toward holes. This capability allows AFGROW to handle cases with more than one crack growing from a row of fastener holes.
AFGROW implements five different material models (Forman Equation, Walker Equation, Tabular lookup, Harter-T Method and NASGRO Equation) to determine crack growth per applied loading cycle. Other AFGROW user options include five load interaction (retardation) models (Closure, FASTRAN, Hsu, Wheeler, and Generalized Willenborg), a strain-life based fatigue crack initiation model, and the ability to perform a crack growth analysis for structures with a bonded repair. AFGROW also includes useful options such as: user-defined stress intensity solutions, user-defined beta modification factors (ability to estimate stress intensity factors for cases, which may not be an exact match for one of the stress intensity solutions in the AFGROW library), and a residual stress analysis capability. Tools are included to allow for spectrum filtering, K-solution filtering, spectrum cycle counting, and the ability to automatically transfer output data to Microsoft Excel. AFGROW allows data to be transferred (via cut and paste) between Windows applications.
The standard GUI includes real time crack growth animation, crack length vs. cycle plotting, and crack growth rate model plots with data overlay capability. English and metric units may be converted on the fly.
AFGROW provides COM (Component Object Model) Automation interfaces that allow users to use AFGROW in other Windows applications to perform repetitive tasks or control AFGROW from these applications.
AFGROW also includes a plug-in stress intensity solution interface that allows AFGROW users to develop additional stress intensity factor (K) solutions. Users may create their own stress intensity solutions by writing and compiling dynamic link libraries (DLLs) using relatively simple routines. This includes the ability to animate the crack growth as is done in all other native AFGROW solutions. This interface also makes it possible for FE analysis software to pass stress intensity information to AFGROW throughout the crack life prediction process, allowing for a tremendous amount of analytical flexibility.