Original Article
  • A New Evaluation Method for Interfacial Properties of Composites using the Gradual Multi-Fiber Fragmentation Test
  • Joung-Man Park, Jin-Won Kim, Koichi Goda
  • 단계적 다섬유 Fragmentation 시험법을 이용한 복합재료의 계면적 특성에 대한 새로운 평가방법
  • 박종만(경상대학교 고분자공학과, 항공기부품기술연구센타), 김진원(경상대학교 고분자공학과, 항공기부품기술연구센타), Koichi Goda(Dept. of Mechanical Engineering. Yamaguchi University. JAPAN)
Abstract
A new evaluation method for the interfacial properties of fibrous composites based on a fragmentation technique is proposed by using the gradual multi-fiber composite, in which the inter-fiber spacing is gradually changed. The results showed that as the inter-fiber distance increased, the aspect ratio of broken fibers decreased while the interfacial shear strength between the fiber and matrix increased. When the reciprocal of the inter-fiber distance was taken for the above relations, both the aspect ratio and interfacial shear strength showed a saturated value. This means that the gradual multi-fiber composite indicates an upper bound in aspect ratio and a lower bound in interfacial shear strength, while the single fiber composite shows a lower bound in aspect ratio and an upper bound in interfacial shear strength. It was concluded that this fragmentation test could be a new method for composite evaluation, since reducing a difference between these two bounds is effective for composite strengthening. In addition an elastoplastic finite element analysis was carried out to relate the above results with fiber stress a distribution around fiber breaks. It was proved that the bound obtained in the gradual multi-fiber composite test is closely related to stress concentrations caused by a group of multi-fiber breaks.

A new evaluation method for the interfacial properties of fibrous composites based on a fragmentation technique is proposed by using the gradual multi-fiber composite, in which the inter-fiber spacing is gradually changed. The results showed that as the inter-fiber distance increased, the aspect ratio of broken fibers decreased while the interfacial shear strength between the fiber and matrix increased. When the reciprocal of the inter-fiber distance was taken for the above relations, both the aspect ratio and interfacial shear strength showed a saturated value. This means that the gradual multi-fiber composite indicates an upper bound in aspect ratio and a lower bound in interfacial shear strength, while the single fiber composite shows a lower bound in aspect ratio and an upper bound in interfacial shear strength. It was concluded that this fragmentation test could be a new method for composite evaluation, since reducing a difference between these two bounds is effective for composite strengthening. In addition an elastoplastic finite element analysis was carried out to relate the above results with fiber stress a distribution around fiber breaks. It was proved that the bound obtained in the gradual multi-fiber composite test is closely related to stress concentrations caused by a group of multi-fiber breaks.

This Article

  • 1999; 12(2): 10-25

    Published on Apr 30, 1999