Development of Automated Model Generation and Analysis of Surface-Cracked Plates in Bending for Interpolated Elastic–Plastic J-Integral Solutions

Abstract

Abstract NASA’s Tool for Analysis of Surface Cracks (TASC) has been used since 2014 to perform elastic–plastic J-integral (J), crack mouth opening displacement (CMOD), crack front constraint, and deformation limit calculations for plates in tension. To date, no comparable database or tool exists for surface-cracked plates in bending. Existing tools and prior ASTM standards are limited to linear-elastic materials or simpler 2-D crack geometries. TASC uses a database of 600 models for interpolated solutions over a wide range of semielliptical surface crack geometries (0.2≤a/c≤1.0, 0.2≤a/t≤0.8) and material properties (100≤E/Sys≤1,000, 3≤n≤20). Here, a is the crack depth, c is the half-width of the crack, and t is the plate thickness, so that a/c is the crack aspect ratio and a/t is a normalized measurement of crack depth. E, Sys, and n are the plate’s elastic modulus, yield strength, and the Ramberg–Osgood power law hardening exponent, respectively. This report details the development of a bending model database covering the same range of crack geometries and material properties. It includes developing new criteria to determine if a model has reached sufficient plastic deformation and modifications to model boundary conditions to accurately capture the behavior of deeply cracked plates in bending. Python is the primary automation tool used in this process, including running FEACrack to create meshes, modifying material properties, iterating WARP3D boundary conditions to meet plastic deformation requirements, and converting WARP3D output into a reduced set of MATLAB-compatible data files. Bending model results from WARP3D are validated against Abaqus results for identical meshes. This report then shows the initial integration of bending models and results into the existing TASC code, laying the groundwork for a single tool for analysis of surface-cracked plates in tension or bending.