Bending modified J–Q theory and crack-tip constraint quantification |
| |
Authors: | Xian-Kui Zhu Brian N Leis |
| |
Affiliation: | (1) Battelle Memorial Institute, 505 King Avenue, Columbus, Ohio 43201, USA |
| |
Abstract: | It is well known that the J–Q theory can characterize the crack-tip fields and quantify constraint levels for various geometry and loading configurations
in elastic–plastic materials, but it fails at bending-dominant large deformation. This drawback seriously restricts its applications
to fracture constraint analysis. A modification of J–Q theory is developed as a three-term solution with an additional term to address the global bending stress to offset this
restriction. The nonlinear bending stress is approximately linearized in the region of interest under large-scale yielding
(LSY), with the linearization factor determined using a two-point matching method at each loading for a specific cracked geometry
in bending. To validate the proposed solution, detailed elastic–plastic finite element analysis (FEA) is conducted under plane
strain conditions for three conventional bending specimens with different crack lengths for X80 pipeline steel. These include
single edge notched bend (SENB), single edge notched tension (SENT) and compact tension (CT) specimens from small-scale yielding
(SSY) to LSY. Results show that the bending modified J–Q solution can well match FEA results of crack-tip stress fields for all bending specimens at all deformation levels from SSY
to LSY, with the modified Q being a load- and distance-independent constraint parameter under LSY. Therefore, the modified parameter Q can be effectively used to quantify crack-tip constraint for bending geometries. Its application to fracture constraint analysis
is demonstrated by determining constraint corrected J–R curves. |
| |
Keywords: | J– Q theory Crack-tip field Fracture constraint Bending stress Large-scale yielding X80 steel |
本文献已被 SpringerLink 等数据库收录! |
|