Scanning Acoustic Microscopic of Single Fiber Fragmentation
High performance fibers are reinforced into polymers, metals and ceramic to produce high strength, high modulus and lower density materials. The mechanical properties of the composites materials not only depend on the constituents but also on the properties of the interface/interphase region between the fiber and the matrix [1,2,3]. It has also been established that the interphasial region determines the load transfer from the matrix to the fiber and from broken fibers to the surviving fibers. Since the overall mechanical properties, load bearing and transferring abilities of a composite decides its effectiveness, it is important to measure and understand the properties of the interphasial region. Such a study will guide in tailoring the performance of composite materials. A parameter that is often used in quantifying the properties of the fiber matrix interface is the Interphasial Shear Strength (IFSS). Several direct and indirect measurement techniques  have been developed in the last three decades to measure the IFFS in composite materials. Measurement of interlaminar shear strength, transverse shear strength, flexural strength, on full scale composite have been observed to be indirectly related to the interfacial shear strength. Direct measurement of IFSS are usually performed on individual fibers in a matrix. Some of the well established techniques in this category are fiber pull out, fiber push in, shear debond[5,6], microindentation and the single fiber fragmentation tests. Though these tests provide quantitative results they are dependent on the sample geometry and the model of the stress field around the fiber. Of all the direct IFSS measurement techniques single fiber fragmentation technique is believed to have stress transfer characteristics that are similar to that of full scale composites. Because of its simplicity it is receiving lot of attention.
KeywordsAcoustic Emission Acoustic Impedance Interfacial Shear Strength Fiber Break Acoustic Image
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