Transverse Ply Cracking in Toughened and Untoughened Graphite/Epoxy and Graphite/Polycyanate Crossply Laminates

Abstract

Transverse ply cracking of five toughened and untoughened graphite/epoxy and graphite/polycyanate laminates was studied using crossply laminates. Two different theoretical approaches, variational mechanics and resistance curves based on shearlag approximation, were used to analyze the data. Resistance of the laminates to transverse ply cracking was determined. Both theories show the same ranking of the laminates with respect to their resistance to microcracking. These results were compared with the critical strain energy release rate data obtained on the resins and the laminates.

Probabilistic energy based model for prediction of transverse cracking in cross-ply laminates

“…Many investigators have carried out experiments counting the number of microcracks during quasi-static loading. Microcracks density results have been reported for different ½0 n =90 m s laminates: Boniface and Ogin (1989) Highsmith and Reifsnider (1982); Caslini et al (1987); Wang et al (1985); Takeda and Ogihara (1994a,b); Ogihara et al (1997); Adolfsson and Gudmundson (1999); Yalvaç et al (1991); Nairn et al (1993); Liu and Nairn (1992); Nairn and Hu (1994) All the results are qualitatively similar: after formation of the first microcrack there is a rapid increase in microcrack density with increasing applied load. Eventually the rate of increasing in microcrack density slows down and it reaches a saturation level.…”