Interply interface

Figure 7.8 Representative volume element used in modeling the intimate contact achievement of a cross-ply interply interface...

The ultrasonic C-scan technique is the most widely used nondestructive method of locating defects in the composite microstructure. The through transmission C-scan is easy to implement and a large composite panel can be scanned in a matter of minutes. The problem with this technique is that a C-scan cannot reveal the type of defect present. Hence, there is no way to determine if a flaw detected by the C-scan is due to incomplete contact of an interply interface or some other type of defect in the composite microstructure. 

The most efficient approach to measuring intimate contact of a multiple ply composite laminate would probably be to first use the C-scan technique or some other nondestructive method to determine the location of any flaws in the panel. The cross-sections of the panel that contain the flaws can then be examined by preparing optical micrographs of those areas, and the interply interface examined for complete contact. 

The unidirectional interply interface model (see Eq. 7.4) was used to calculate the degree of intimate contact versus time for unidirectional samples consolidated at different temperatures and pressures. The surface characterization parameters for T300/P1700 and... 

Considering the complexities involved in the formation of the cross-ply interface during consolidation, the cross-ply interply interface model predicted degrees of intimate contact... 

Figure 7.17 Comparison between models and the data for angle-ply interply interfaces...

Figure 7.18 shows the consolidation time versus consolidation pressure for unidirectional and cross-ply interply interfaces. As can be seen from both figures, the consolidation time decreases rapidly as pressure increases. Above 1000 kPa for T300/P1700 and 500 kPa for APC-2, increases in the consolidation pressure do not significantly decrease consolidation time. 

---