Doctor of Philosophy
Civil and Environmental Engineering
Dr. Wenxing Zhou
The fracture toughness resistance curve, i.e. the J-integral resistance curve (J-R curve) or the crack tip opening displacement resistance (CTOD-R) curves, is widely used in the integrity assessment and strain-based design of energy pipelines with respect to planar defects (i.e. cracks). This thesis deals with issues related to the experimental determination of the J(CTOD)-R curves using the newly-developed single-edge (notched) tension (SE(T)) specimens. In the first study, the plastic geometry factor, i.e. the ηpl factor, used to evaluate J in a J-R curve test based on the SE(T) specimen is developed based on the three-dimensional (3D) finite element analysis (FEA). In the second study, 3D FEA is carried out on SE(T) specimens to develop the plastic constraint factor, i.e. the m factor, used to evaluate CTOD from J. The third study reported in this thesis focuses on the compliance equation, which relates the crack length and specimen’s compliance (i.e. inverse of stiffness) in the J(CTOD)-R curves testing. Three-dimensional FEA of clamped SE(T) specimens is performed to examine the accuracy of the crack mouth opening displacement (CMOD) compliance equations reported in the literature. In the fourth study, the impact of the crack front curvature on the J-R curve measured from the SE(T) specimen is investigated through systematic elastic-plastic 3D FEA of SE(T) specimens containing both straight and curved crack fronts. The last study reported in this thesis is focused on developing the effective thickness that takes accounts for the side grooves effects on the estimations of the stress intensity factor (K) and J for SE(T) specimens. The outcomes of these studies will facilitate and improve the evaluation of J(CTOD)-R curves using the side-grooved SE(T) specimens.
Huang, Yifan, "Numerical Studies for Improving Fracture Toughness Resistance Curve Testing Using Single-Edge (Notched) Tension Specimens" (2016). Electronic Thesis and Dissertation Repository. 4102.