1992 Fiscal Year Final Research Report Summary
Analysis of Crack Growth Behavior in A Polymeric Strip using Photo-Viscoelastic Method
| Project/Area Number |
03650087
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
材料力学
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| Research Institution | AOYAMA GAKUIN UNIVERSITY |
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Principal Investigator |
TAKASHI Masahisa Aoyama Gakuin University, Mechanical Engineering, Professor, 理工学部, 教授 (60082799)
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| Co-Investigator(Kenkyū-buntansha) |
OGAWA Kazuo Aoyama Gakuin University, Mechanical Engineering, Assistant, 理工学部, 助手 (60082864)
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| Project Period (FY) |
1991 – 1992
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| Keywords | Photo-Viscoelasticity / Scattered Light Method / Stress Function / Crack / Loading History / Stress Intensity Factor / I-integral / High Polymer |
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| Research Abstract |
In order to perform accurate analysis of stress and strain field around a moving tip of crack particalarly in viscoelastic materials, it should be emphasized that not only convenient and useful computer-aided algorithms but also techniques for handling image data of tremendous amounts have to be developed.
1) In this study, we developed a convenient algorithm for computer-aided stress analysis of the integrated fringe. The authors proposed a convenient technique to analyze the variation of the stress intensity factor K_I of CT type specimen from plane strain to plane stress state over the thickness of spesimen using a system with the improved devices of the Scattered Light Photoelasticity. Regarding to K_<III>, we can also be successful for accurate measurement in the same manner.
2) This study is concerned with a proposal of the functional approximation method to overcome the difficulty in analysis stress distribution near a singular point such as a crack tip and loading. Collapsed data
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of photoelastic fringe pattern in the neighborhood of a singular point will be well reconstructed, using a general form of Goursat stress functions, unknown parameters of which are determined by a nonlinear optimizing approximation technique. And, as an typical example, the stress intensity factor determined as one of the unknown parameters is successfully obtained by applying this method to a Mode I type cracked specimen.
3) Taking the time dependent mechanical behavior of the material into consideration, variation of crack growth behavior after changing displacement rate as several steps in length of crack growth is studied. Time dependent J'_I(t) and change in fracture surface roughness are investigated to proceed discussions on relationship between macro- and microscopic mechanisms of fracture taking molecular and entanglement structures of the material into consideration. Then, a new model of crack growth mechanism in sub-micro scale dimension is proposed to describe the time and temperature dependent behavior of crack growth in these materials. Less
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