Laminate composite laminates notched strength

These values are determined by experiment. It is, however, by no means a trivial task to measure the lamina compressive and shear strengths (52,53). Also the failure of the first ply of a laminate does not necessarily coincide with the maximum load that the laminate can sustain. In many practical composite laminates first-ply failure may be accompanied by a very small reduction in the laminate stiffness. Local ply-level failures can reduce the stress-raising effects of notches and enhance fatigue performance (54). 

Soutis C, Lee J. Measuring the notched compressive strength of composite laminates specimen size effects. Compos Sci Technol 2008 68(12) 2359—66. 

Finally, of great importance are finite width effects. The strength of a composite laminate in the presence of a hole, a crack, or impact damage is drastically reduced as the size of the notch covers a significant percentage of one of the dimensions of the structure. Finite width correction factors have been obtained by Tan for holes [19]. 

PC/SAN blends have been found to exhibit maximal properties at 25-27 wt% AN. This was evidenced by the improvanent in lap shear adhesion of compression-molded laminated sheets of PC and SAN copolymers, and in tensile modulus and elongation at break, improved notched impact Izod strength, and inward shifts of the glass transition temperatures of PC and SAN blend components with respect to their homopolymer values. PC and SAN were found to be partially miscible. The 25-27 wt% AN was found close to the azeotropic composition of SAN. 

Distributions of Fatigue Life and Fatigue Strength in Notched Specimens of a Carbon Eight-Harness-Satin Laminate, Journal of Composite Materials, 17 (1983), p. 64 - 76... 

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