No abstract

An approach coupling Rosen's cumulative damage model [1,2] and Piggott's elastic-slip stress transfer model [3,4] is presented here, to demonstrate the effect of the interfacial shear strength on the longitudinal tensile strength of unidirectional fiber-reinforced polymer composites. It was found numerically that an interface strong in shear would increase the longitudinal tensile strength of the composite marginally. According to the approach developed, in the situations where the fiber strengths scattered markedly, or where the coefficient of friction between debonded fibers and matrix is very small, an increase in the interfacial shear strength would enhance the longitudinal tensile strength in a relatively significant manner. Additionally, an interface layer was introduced in Piggott's elastic-slip stress transfer model, so as to render the model conceptually more nearly correct. SCOPE T IS RECOGNIZED THAT THE ADVANTAGE OF POLYMER-MATRIX COMPOSITES LIESIin the high specific strength along the fiber direction, and that the fiber/matrix interface is generally the weakest part of the materials. However, the dependency of the longitudinal tensile strength of unidirectional composites on the interface strength appears to have received much less attention in the literature.

In this letter, we develop a nearly white-light-emitting device by integrating blue/green emission from a GaN-based lightemitting diode with red emission from a porous SiO 2 layer. The porous SiO 2 layer was fabricated by a novel process procedure to create Si nanocrystals on top of the n-type GaN layer. Red light is generated from the metal-oxide-semiconductor (Ni-Au-SiO 2 oxide-n-type GaN) structure due to the electron-hole recombination in the Si nanocrystals. The device shows a blue light emission at a low biased voltage and nearly white-light emission (green and red colors) at a bias voltage between 14 and 16 V. Our results show the potential of applying such an integrated structure to white-light illumination.

No abstract

No abstract