基于累积递增塑性变形的船体裂纹板断裂韧性研究.pdf

第20卷第6期
船舶力学
Vol20 No6
2016年6月
Journal of Ship Mechanics
Jum.2016
rticle ID):1007-7294(2016)06-0748-10
Research on the Fracture Toughness for Ship Cracked Plates
Based on the Accumulative increment Plastic Deformation
DENG Jun-lin 2, DU Bo, YANG Png CHEN Yuan
(1a. Key Iaboratory of High Performance Ship Technology, Ministry of Education; b. School of
Transportation, Wuhan University of Technology, Wuhan 430063, China; 2. Depls of Naval
Architecture, Ocean and Structural Engineering, School of Mechanical and Ship Engineering
Zhou University, Qinzhou 535000, China)
Abstract: The crack tip opening displacement(CTO D)is an important parameter to evaluate materi
al fracture toughness and analyze the crack propagation due to low-cyele fatigue damage. An analyt
ical model is presented to determine CTOD for the Ship cracked plates subjected to low-cyclic axial
in-plane loadings. Combined with Dugdales model, the accumulation plastic deformation at the
crack tips is used as controlling parameter to estimate cyclic CTOD for low-cycle failure analysis of
the ship central-through cracked plates. The second order polynomial for the normalized CTOD
defined as a function of the accumulative plastic strain, the ratio of mean stress to the yield stress
and the crack length is fitted by the least square method. The new accumulative plastic strain based
on CTOD estimation presented in this paper provides a new way for low-cycle fatigue analysis, con-
sidering accumu lative plastic damage for central-through cracked plates under high cyclic loadings
Key words: low-cycle fatigue; central-through cracked plate; accumulative plastic strain;
CTOD
CLC number:TG113.25U661.42 Document code:Adoi:10.3969/-is.1007-7294.2016.06.010
0 Introduction
The fatigue strength of ships structure has a very important significance on the sa
and survivability. Along with the increasing in ship dimensions and more use of high-strength
steel in recent years, the stress and deformation of ship structures are so high and large, which
result in a very prominent problem of ow-cycle-fatigue ([,CF)damage to large-scale shi
This has become the key issue demanding prompt solution in the development of large-scale
ships. For cracked plates of ship and marine structures, plastic strain would generate in the re
gion near crack tip when the local stress reaches the yield strength. When a ship is subjected
to cyclic loads in waves, plastic strain would accumulate in local region of the crack tip, and
Received date: 2016-04-10
Founded item: Supported by The National Natural Science Foundation of China(Grant No.51479153):
the Fundamental Research Funds for the Central Universities(Grant No. 2015-yb-004
Biography:DENGJUN-LIN(1983-).malePh.d.studentE-mail:junlin.deng(@163.com
DUBo(1979-).male,lecturer/tulorofQinhouUniversityF-mail:dubo_332@sina.com
YANGPing(1955-),male,professor/tutorE-mail:pang@whut.edu.com:
CHENYuan(1992-),malegraduatestudentE-mail:chendayuans(@163.com