Effect of Glass Fiber Hybridization on the Behavior Under Impact of Woven Carbon Fiber/Epoxy Laminates

The low-velocity impact behavior was studied in hybrid laminates manufactured by RTM with woven carbon and glass (S2) fabrics. Specimens with different thicknesses and glass fiber content (from 0 to 21 vol.%) were tested with impact energies in the range 30–245 J and the resulting deformation and fracture micromechanisms were studied using X-ray microtomography. The results of these analyses, together with those of the impact tests (maximum load and energy absorbed), were used to elucidate the role played by glass fiber hybridization on the fracture micromechanisms and on the overall laminate performance under low-velocity impact

Effect of solute content and temperature on the deformation mechanisms and critical resolved shear stress in Mg-Al and Mg-Zn alloys

The influence of solute atoms (Al and Zn) on the deformation mechanisms and the critical resolved shear stress for basal slip in Mg alloys at 298 K and 373 K was ascertained by micropillar compression tests in combination with high-throughput processing techniques based on the diffusion couples. It was found that the presence of solute atoms enhances the size effect at 298 K as well as the localization of deformation in slip bands, which is associated with large strain bursts in the resolved shear stress ($\tau_{RSS}$)-strain ($\epsilon$) curves. Deformation in pure Mg and Mg alloys was more homogeneous at 373 K and the influence of the micropillar size on the critical resolved shear stress was much smaller. In this latter case, it was possible to determine the effect of solute content on the critical resolved shear stress for basal slip in Mg-Al and Mg-Zn alloys

Interface characterization in fiber-reinforced polymer-matrix composites

A novel methodology is presented and applied to measure the shear interface strength of fiber-reinforced polymers. The strategy is based in fiber push-in tests carried out on the central fiber of highly-packed fiber clusters with hexagonal symmetry, and it is supported by a detailed finite element analysis of the push-in test to account for the influence of hygrothermal residual stresses, fiber constraint and fiber anisotropy on the interface strength. Examples of application are presented to determine the shear interface strength in carbon and glass fiber composites reinforced with either thermoset or thermoplastic matrices. In addition, the influence of the environment (either dry or wet conditions) on the interface strength in C/epoxy composites is demonstrated.This investigation was supported by the Ministerio de Ciencia e Innovación of Spain through the Grant MAT2012-37552, by the Comunidad de Madrid through the program DIMMAT (P2013/MIT2775), and by the European Community's Seventh Framework Programme FP7/2007-2013 under Grant Agreement 213371 (MAAXIMUS, www.maaximus.eu). In addition, the support of Airbus through the project SIMSCREEN ("Simulation for Screening Properties of Materials") is gratefully acknowledged