Critical transfer length

Since fiber pull-out length, p , is difficult to measure with any accuracy from the fracture surface of composite specimens containing high V(, Rpo is often expressed in terms of the inherent properties of the composite constituents. There are three cases considered here depending on the fiber length relative to the critical transfer length. 

In Eq. (6.8) an upper bound estimate of tf is made by the apparent bond strength Tj for the critical transfer length, i.e., 4 fffd/2Tf, based on the early work of Kelly and Tyson (1965). Therefore, Rpo is shown directly proportional to the critieal transfer length. 

The failure processes in thermoplastics composites with aligned glass fibers of sub-critical transfer length have been characterized (Lauke and Schultrich, 1983, 1986a, b Lauke et al., 1985 Lauke and Pompe, 1988) in terms of matrix fracture mode which is determined mainly by the ductility of the matrix material, loading rate and temperature. The total specific work of fracture, / t, is expressed as the sum... 

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