Investigation of Plastic Zone Development in Dynamic Tear Test Specimens - Phase 3
Abstract
This study is a continuation of efforts to investigate plastic zone development in three-point bend fracture specimens to provide an understanding of crack tip blunting (stretch zone) to plastic zone size (radius), in order to be able to predict the upper limit where elastic plastic fracture becomes invalid. Finite element analyses of an 8mm specimen made of 350WT steel were performed with the aim of investigating the effects of various modeling (mesh) parameters on the behaviour of 2-D finite element models; and 3-Dmodeling to investigate shear lip behaviour. The ABAQUS finite element code was used to perform incremental elastic-plastic analysis of the specimens. The results computed included the progression of plastic strain, plastic radius (r (sub y)), stretch zone width (SZW),and the r(sub y)/SZW ratio with plastic displacement. It was found that the plastic radius and maximum plastic strains were not too sensitive to the mesh size around the crack tip, whereas the SZW is highly sensitive to mesh size around the crack tip. Thus the r(sub y)/SZW ratio also depends on mesh configuration. In creating meshes around the tip, it is necessary to ensure that the sizes of the elements around the tip are such that several elements are contained in the region from the crack tip to the side of the crack where the yield line intersects the side of the crack. The 3-D analyses confirmed the in-plane plastic zone patterns obtained from the 2-D analyses and provided some insight on the shear lip behaviour. However, the results obtained from the analyses did not provide a distinct point at which to measure the shear lip. At a plastic displacement of 0.0975B(B = specimen thickness) the shear index was estimated to be 0.6 at the point where the yield lines were closest. Further studies are required to provide more accurate estimates of the shear lip size.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2001
- Accession Number
- AD1003764
Entities
People
- B. K. Gallant
- T. S. Koko