Influence of fracture of coating layer on fiber strength

✍ Scribed by Shojiro Ochiai; Kozo Osamura; Kuniaki Honjo

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 485 KB
• Volume: 154
• Category: Article
• ISSN: 0921-5093
• DOI: 10.1016/0921-5093(92)90340-7

✦ Synopsis

When a circumferential notch is formed on a fiber surface owing to premature fracture of the coating layer, the fiber strength is reduced. In order to describe the fracture strength of the fiber for such a case, a calculation method is presented which is based on the concept of strain energy release rate using the shear lag analysis technique. This method shows that the stress in the fiber increases with increasing Young's modulus of the coating layer and increasing coating thickness, especially in front of the notch. As a result, a high Young's modulus and large thickness of the coating layer lead to a large reduction in the strength of the fiber. The application of this method to TiC-coated graphite fiber shows that the critical strain energy release rate of fiber with a high modulus is 3 J m-2 and that of fiber with a high tensile strength is 2Jm -2.