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Study on Fatigue life priduction of microstructural short crack region

Research Project

Project/Area Number 09555312
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section展開研究
Research Field 海洋工学
Research InstitutionKYUSHU UNIVERSITY

Principal Investigator

TOYOSADA Masahiro  Kyushu university, Faculty of engineering, Professor, 工学部, 教授 (30188817)

Co-Investigator(Kenkyū-buntansha) ONO Hideo  Kawasaki heavy industries, LTD., Akashi research center, Manager, 明石技術研究所強度研究部, 研究員
YAMAGUCHI Kikuji  Kyushu university, Faculty of engineering, Research Associate, 工学部, 助手 (70037943)
NIWA Toshio  Kyushu university, Faculty of engineering, Assistant Professor, 工学部, 講師 (10208267)
GOTOH Koji  Kyushu university, Faculty of engineering, Associate Professor, 工学部, 助教授 (60274487)
Project Period (FY) 1997 – 1998
Project Status Completed (Fiscal Year 1998)
Budget Amount *help
¥8,900,000 (Direct Cost: ¥8,900,000)
Fiscal Year 1998: ¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 1997: ¥5,600,000 (Direct Cost: ¥5,600,000)
Keywordsfatigue life priduction / fatigue surface crack / crack closure / coalescence of surface crack / DELTAK_<RP> / fatigue damage region size / △KRP / 微視き裂 / 【.upper filled triangle.】K_<RP> / 変動荷重 / 荷重波形計数法
Research Abstract

It is that a purpose of this study establishes algorithm to estimate crack growth curve without initiation life. Fatigue life of microstructural short crack region must estimate it as follows. When a notch is deep, fatigue life must be evaluated using yield stress under static condition. When a notch is slight, effect of cyclic loading needs to be considered and fatigue life must be evaluated using yield stress under cyclic condition. Fatigue life of physically small crack region and a long crack region must be calculated using the logarithmic curve of da/dN-DELTAK_<RP>. Therefore, Crack growth curves are calculated for a crack emanating from a notch root. without distinguishing between crack initiation and propagation. This result can be considered in establishing a unified fatigue life assessment theory to replace the combined S-Ncurve and crack propagation curve of linear fracture mechanics.

Report

(3 results)
  • 1998 Annual Research Report   Final Research Report Summary
  • 1997 Annual Research Report

URL: 

Published: 1997-04-01   Modified: 2016-04-21  

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