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A novel unified characterization parameter of in‐plane and out‐of‐plane constraints based on critical CTOA
Author(s) -
Zhen Ying,
Chang Qun,
Cao Yuguang,
Niu Ruiyan
Publication year - 2021
Publication title -
fatigue and fracture of engineering materials and structures
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.887
H-Index - 84
eISSN - 1460-2695
pISSN - 8756-758X
DOI - 10.1111/ffe.13430
Subject(s) - plane stress , constraint (computer aided design) , characterization (materials science) , plane (geometry) , fracture toughness , structural engineering , fracture (geology) , materials science , finite element method , plasticity , mechanics , geometry , mathematics , composite material , engineering , physics , nanotechnology
There is much controversy in using laboratory specimens to predict the fracture behavior of large industrial constructions because of their different constraints. Although several parameters have been proposed to characterize the constraint effect, there are still some limitations. To address this issue, a novel unified characterization parameter of constraint based on the critical crack tip opening angle (CTOA C ) is defined. Firstly, the calibrated finite element technologies for simulation of static and dynamic crack are used to determine the equivalent plastic strain ( ε p ) distribution around the crack tip and the evolution history of CTOA for specimens with different in‐plane and out‐of‐plane constraints, respectively. Secondly, the feasibility of the equivalent plastic strain at the crack tip when CTOA reaches its critical value to unified measure both in‐plane and out‐of‐plane constraints is investigated. The results indicate that the area A PEEQ surrounded by the isoline of equivalent plastic strain ε p can describe both in‐plane and out‐of‐plane constraints and the interaction between them. Finally, a novel constraint characterization parameter η is defined. It is found that there is a linear relationship, which depends only on the material and regardless of the selection of the ε p isoline, between the normalized fracture toughness CTOA C /CTOA ref and η 1/2 . The work in this paper is expected to realize the matching of constraints between different laboratory specimens or industrial constructions.