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Holographic Interferometry Measurement and Theoretical Analysis of Deformations of Composite Laminates due to Interlaminar Stresses

Research Project

Project/Area Number 01420019
Research Category

Grant-in-Aid for General Scientific Research (A)

Allocation TypeSingle-year Grants
Research Field Aerospace engineering
Research InstitutionUniversity of Tokyo

Principal Investigator

KONDO Kyohei  Univ.of Tokyo, Faculty of Engineering, Professor, 工学部, 教授 (20011190)

Co-Investigator(Kenkyū-buntansha) KOYAMA Kazuo  Univ.of Tokyo, Faculty of Engineering, Lecturer, 工学部, 講師 (60010906)
Project Period (FY) 1989 – 1990
Project Status Completed (Fiscal Year 1990)
Budget Amount *help
¥11,400,000 (Direct Cost: ¥11,400,000)
Fiscal Year 1990: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1989: ¥9,400,000 (Direct Cost: ¥9,400,000)
KeywordsComposite materials / Laminate / Interlaminar stress / Delamination / Free edge / Transverse crack / Holographic interferometry / Finite element method / 二重露光法 / 複合材料積層板 / 準三次元応力解析
Research Abstract

Deformations due to the interlaminar stresses in the composite laminates subjected to the uniform mechanical and hygrothermal loadings were investigated in order to understand the mechanism of the delamination which is one of the most frequently observed fallure modes of the laminates.
By the quasi three-demensional finite element method, the deformations in the vicinity of the free edges or the transverse crack tips were analyzed assuming that the stresses do not vary along the direction of the free edge or the transverse crack. The superposition method was proposed where the free edge problem and the transverse crack tip problem are transformed to the superpositions of the infinite laminate under uniform stresses and the configurations with external loads applied on the free edge surface and the transverse crack surface, respectively. The superposition technique can eliminate the deformations not resulting from the interlaminar stresses.
By the holographic interferometry, the deformations of the graphite-epoxy laminates coupons under the pure bending moment or the uniform tensile load were measured. The delaminations were introduced by the cyclic tensile loading at the free edges. The overall deformations by the bending moment coincided with the theoretical predictions for the deformations of the infinite laminates based on the classical lamination theory. The deformation near the free edges due to the interlaminar stresses could not be detected since they were small compared to the overall bending deformations. The deformation near the free edges due to the interlaminar stresses in the laminates under the tensile loads were observed for the coupons with delaminations, verifying the numerical results by the finite element method.

Report

(3 results)
  • 1990 Annual Research Report   Final Research Report Summary
  • 1989 Annual Research Report
  • Research Products

    (9 results)

All Other

All Publications (9 results)

  • [Publications] Kyohei Kondo: "Energy Release Rate of Delamination at Transverse Crack Tips" Proc.the Fifth Japan-U.S.Conference on Composites Materials,1990,Tokyo. 169-176 (1991)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1990 Final Research Report Summary
  • [Publications] Kyohei Kondo: "Superposition Method for Analysis of Energy Release Rates of Delamination" Proc.the Third International Conference on Composite Materials,Univ.Patras,Greece,1990. 141-151 (1991)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1990 Final Research Report Summary
  • [Publications] Kyohei Kondo: "Influence of Hygrothermal Stresses on Transverse Crack Tip Delamination" Proc.the Eigth Internaiotnal Conference on Composite Materials,1991,Hawaii. 27-D-1-27-D-12 (1991)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1990 Final Research Report Summary
  • [Publications] Kyohei Kondo: "Energy Release Rate of Delamination at Transverse Crack Tips" Proc.the Fifth Japan-U.S.Conference on Composite Materials, 1990, Tokyo. 169-176 (1991)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1990 Final Research Report Summary
  • [Publications] K.Kondo: "Superposition Method for Analysis of Energy Release Rates of Delaminations in Composite Laminates" Proc.the Third International Conference on Composite Materials.Univ.of Patras, 1990, Greece. 141-151 (1991)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1990 Final Research Report Summary
  • [Publications] K.Kondo: "Influence of Hygrothermal Stresses on Transverse Crack Tip Delamination" Proc.the Eigth International Conference on Composite Materials, 1991, Hawaii. 27. 1-12 (1991)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1990 Final Research Report Summary
  • [Publications] Kyohei Kondo: "Energy Release Rate of Delamination at Transverse Crack Tips" Proc.the Fifth JapanーU.S.Conference on Composite Materials,1990,Tokyo. (1991)

    • Related Report
      1990 Annual Research Report
  • [Publications] Kyohei Kondo: "Superposition Method for Analysis of Energy Release Rates of Delamination" Proc.the Third International Conference on Composite Materials,Univ.of Patras,Greece,1990. (1991)

    • Related Report
      1990 Annual Research Report
  • [Publications] Kyohei Kondo: "Influence of Hygrothermal Stresses on Transverse Crack Tip Delamination" Proc.the Eigth International Conference on Compoisite Materials,1991,Hawaii. (1991)

    • Related Report
      1990 Annual Research Report

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Published: 1989-04-01   Modified: 2016-04-21  

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