The Interlaminar Mode I Fracture of IM7/LaRC-RP46 Composites at High Temperatures
- 1 August 1998
- journal article
- Published by SAGE Publications in Journal of Composite Materials
- Vol. 32 (16), 1508-1526
- https://doi.org/10.1177/002199839803201603
Abstract
In this paper, the interlaminar Mode I fracture behavior of a IM7/LaRC-RP46 composite laminate at elevated temperatures was investigated by DCB (double cantilever beam) static fracture testing. Straight-sided DCB specimens were made from unidirectional laminates and tested at three high temperature levels of 232°C (450°F), 288°C (550°F) and 343°C (650°F) at five crosshead rates from 0.51 mm/min. (0.00033 in./sec) to 6.1 mm/min. (0.004 in./sec). Unlike the linear load-displacement response observed at room temperature, the load-displacement response at high temperatures behaves nonlinearly before reaching the maximum load. Two crack growth regions of slow crack extension and relatively fast crack propagation were observed and the slow crack extension caused the nonlinear load-displacement response. The initial fracture toughness, G IC decreased slightly, while the propagation value increased by nearly 30% to 100% with increased temperature. The materials exhibited the highest fracture toughness at 288°C among the three different tested temperatures. The complex combination effects of fiber bridging and the change of matrix properties and fiber/matrix interfacial adhesion at elevated temperatures are found to be the major reason resulting in the variation of G IC with temperature. After the temperature increased beyond T g (glass transition temperature), which is approximately 310°C, the propagation fracture toughness decreased drastically and aging effects of the high temperature on the matrix are observed. No significant effects of crosshead rate on the G IC were observed in the range of the present rates. However, the crosshead rate is found to significantly influenced the crack growth rate.Keywords
This publication has 6 references indexed in Scilit:
- The Effects of Geometry, Rate and Temperature on the Mode I, Mode II and Mixed-Mode I/II Interlaminar Fracture of Carbon-Fibre/Poly(ether-ether ketone) CompositesJournal of Composite Materials, 1990
- Interlaminar Mode-I Fracture TestingPublished by Elsevier ,1989
- End corrections for orthotropic DCB specimensComposites Science and Technology, 1989
- Rate-dependent mode I interlaminar crack growth mechanisms in graphite/epoxy and graphite/PEEKComposites Science and Technology, 1987
- Moisture and Temperature Effects on the Mixed-Mode Delamination Fracture of Unidirectional Graphite/EpoxyPublished by ASTM International ,1985
- Hygrothermal influence on delamination behavior of graphite/epoxy laminatesEngineering Fracture Mechanics, 1985