EFFECTS OF DISPLACEMENT VELOCITY TO FRACTURE OF LAMINATE

1998 Fiscal Year Final Research Report Summary

• Project/Area Number: 09650110
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Materials/Mechanics of materials
• Research Institution: KAGOSHIMA UNIVERSITY
• Principal Investigator: TOYA Masayuki FACULTY OF ENG.KAGOSHIMA UNIVERSITY PROFESSOR, 工学部, 教授 (90026279)
• Co-Investigator(Kenkyū-buntansha): ODA Mikio FACULTY OF ENG.KAGOSHIMA UNIVERSITY RESEARCH ASSOCIATE, 工学部, 助手 (30274856) ; ARITOMI Masao FACULTY OF ENG.KAGOSHIMA UNIVERSITY ASSOCIATE PROFESSOR, 工学部, 助教授 (60094116)
• Project Period (FY): 1997 – 1998
• Keywords: Laminated Construction / Delamination / Natural Frequency / Natural Mode of vibration / Growth of Delamination / Mutual Contact / Energy Release Ratio

Research Abstract

Laminated beams containing an edge delamination subjected to impulsive loads are studied. By measuring the impact loads that cause delamination growth, relations between the maximum impact load, initial delamination length and the distance of growth of the delamination are obtained. As a result, it is found that there exists a region of initial crack length for which delamination growth cannot occur easily. Finite-element analyses are also carried out, where by assuming the mutual contact of crack faces, energy release rates are obtained by the local compliance method. It is shown that there exists the region of crack length for which delamination cannot easily occur, agreeing with experimental results. Therefore it is concluded that the delamination growth can be predicted well from numerical analyses.
Study is also made for free vibrations of both a laminated beam containing an initial delamination and a laminated plate containing a disk-shaped delamination. Basic assumption is that parts of a beam or plate above and below the crack faces are contacting one another. Analyses and experiments are carried out for the effects of the delamination length (or the diameter of a disk shaped crack), the location of delaminations and elastic moduli of constituent materials on the characteristic frequencies and modes of vibrations. Distributions of mutual contact forces are also analyzed. Theoretical and experimental results agree well, which validates the analytical models assumed in our present study. This study gives a means to determine the length (or diameter) of delaminations and their locations from the measurement of the change of vibration behaviour.