Effect of Interfacial Properties on the Fiber Fragmentation Process in Polymer Matrix Composites

Fiber Fragmentation test or Single Fiber Composite test (SFC) has been widely used to characterize the interfacial behavior in composites. Though it is accepted that SFC gives useful information about the interfacial bond quality and the fiber strength, there is no clear consensus on how to interpret the data and quantify the interfacial properties. In this paper, the fiber fragmentation test is modeled with the objective of studying the effect of interfacial bond strength and post-debonding factional effects on the progress of the fragmentation process. The load transfer at the fiber-matrix interface is modeled using the shear-lag principles and the statistical variation of fiber strength is incorporated using Weibull theory. A parametric study of the variation of interfacial shear properties on the mean fragment length and debond progression with applied strain is conducted. It is found that in the case of weak interfaces saturation of fiber fragments occurs at much lower applied strain values and is usually associated with extensive debonding. The numerical simulation shows that the fragmentation results are very much sensitive to the frictional effects as it controls the debonded length. The results from the model are correlated with experimental data to validate the model and for extracting the interfacial properties from the test data.