Le. Asp, THE EFFECTS OF MOISTURE AND TEMPERATURE ON THE INTERLAMINAR DELAMINATION TOUGHNESS OF A CARBON EPOXY COMPOSITE/, Composites science and technology, 58(6), 1998, pp. 967-977
HTA/6376C composite has been investigated for influence of temperature
and moisture content on the interlaminar delamination toughness in mo
de I, mode II and mixed mode conditions. Dry and moisture-saturated sp
ecimens were tested over the temperature range -50 degrees C to 100 de
grees C. Evaluation methods based on load/displacement and load measur
ements were employed. In pure mode II the critical strain-energy relea
se rate drops with moisture content and increase in temperature. In mi
xed mode the critical strain-energy release rate also decreases with m
oisture content, but no general trends in the dependence on temperatur
e is observed. The critical strain-energy release rate in pure mode I
is unaffected by changes lit moisture content and was found to increas
e slightly at elevated temperatures. During crack propagation, enhance
d fiber bridging due to increases in temperature and moisture content
promotes R-curve behavior in the pure mode I tests. The resulting mode
mixity of the mixed-mode bending (MMB) tests is found to be severely
affected by the evaluation methods. Methods based an load measurements
only are considered to give unreliable strain-energy release rates as
the measured compliance/displacement relationships were found to he n
on-linear even prior to crack growth. Further studies are needed to as
sess the mixed-mode ratio in the MMB test. (C) 1998 Elsevier Science L
td. All rights reserved.