In this paper, a recently developed nondestructive approach for characterizing advanced composite materials will be presented. This new methodology uses ultrasonic waves to characterize the fiber-matrix interface based on the shear wave back reflectivity (SBR) and normal incidence longitudinal wave interrogation techniques and enables evaluation of composite consolidation and characterization of the interfacial elastic properties at a localized level. This approach is nondestructive in nature in contrast to traditional destructive characterization techniques which are tedious and render the samples unusable for other experiments. Further, novel methodologies for imaging nondestructively the fiber microcracking and the interface failure have been developed. The nondestructive imaging of failure modes in composites can provide critical information to materials researchers for micro-mechanics modeling studies to evaluate fracture and fatigue behaviour of composites. The characterization of the interface is of great interest to the researchers who are developing new composite systems. In order to determine the optimum interface properties, a model monofilament composite is usually used which has an interface with tailored properties depending on the choice of the fiber and the matrix materials, the fiber coating and the processing conditions. Many investigators have employed a number of experimental destructive techniques including fiber push-out, fiber fragmentation, transverse loading tests, etc. to characterize the interface in model composites. In this paper, the recent development of novel nondestructive techniques for
- the evaluation of the consolidation in composites,
- the monitoring of the fiber fracture during the fragmentation test,
- the evaluation of interface failure during the transverse test, and
- the evaluation of the elastic properties of the fiber-matrix interface, will be presented.
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