1997 Fiscal Year Final Research Report Summary
Fracture Mechanics Study for Toughening Fiber Reinforced Composites
| Project/Area Number |
08650085
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Materials/Mechanics of materials
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| Research Institution | Tohoku University |
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Principal Investigator |
HASHIDA Toshiyuki Tohoku Univ.Faculty of Engng, Assoc.Prof., 工学部, 助教授 (40180814)
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| Co-Investigator(Kenkyū-buntansha) |
SATO Kazushi Miyagi National College of Technolog, Mechanical Engng.Dept., Lecturer, 機械工学科, 講師 (80235324)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Composite / Distributed Microcracking Material / Fracture Mechanics / Material Design Model / Sparle Plasma Sintering Method / Ceramics / Fiber / Toughening |
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| Research Abstract |
The objective of this research is firstly to develop a fracture mechanics based micromechanical model for the design of pseudo strain hardening composites reinforced with random discontinuous and aligned continuous fibers, and then to propose a method for optimizing the strength and the toughness of composites on the basis of themicromechanical model. The following tasks form major subjects of this research.
Task (1) Development of Design Model
We developed a micromechanical model which provides a link between the composite properties (strength and toughness) and the composite parameters (fiber parameters : dimensions, volume fraction and mechanical properties ; matrix parameters : toughness and elastic moduli ; interface shear strength ; snubbing coefficient). The model is applicable to both the cases of fiber pull-out and fiber rupture.
Task (2) Preparation and Evaluation of Fiber Reinforced Composites
Using a spark plasma sintering method, we prepared continuos carbon fiber reinforced SiC composites and LAS/wolastonite composites reinforced with short random fibers of a 304 type stainless steel. It was shown by conducting three point bend tests that the micromechanical model has a capability of predicting the mechanical properties of the prepared composites. Furthermore, the LAS/wolastonite composites were shown to produce pseudo strain hardening behavior.
Task (3) Optimization of Composite Parameters
Based on the micromechanical model, we devised a design chart which embodied the conditions for pseudo strain hardening, uniform fiber distribution, and fiber rupture. Finally, we proposed a methodology of optimizing the fiber parameters for high toughness composites by conducting parametric studies.
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