Papers by Keyword: Undulation

Abstract: Experimental investigations were performed on strain characteristic of filament wound composite cylinder. Cylinders are wound with S-1 glass fiber and epoxy resin, and then subjected to an axial tension. During loading, strains at three fiber crossing position and one laminate region on cylinder’s surface are measured by gauges for better understanding strain field. For all specimens, strains at fiber crossing positions are larger than that of laminate region. This indicates that fiber undulation caused by winding process affects mechanical response of filament wound composites.

Abstract: To quantitatively evaluate the efficacy of stacking fault (SF) reduction methods, Monte Carlo simulations are carried out to reveal the SF distribution on a 3C–SiC (001) surface. SF density decreases with increasing epitaxial layer thickness and reducing size of the substrates. Additionally, SF density depends on interactions between adjoining SFs: annihilation of counter SF-pairs or termination of orthogonal SF-pairs. However, the SF is not entirely eliminated when growth occurs on undulant-Si or switchback epitaxy due to “spontaneous SF collimation”. The simulation shows that effective SF reduction methods, those that enhance the SF termination or annihilation, can theoretically attain the SF density on 3C–SiC (001) below 100 cm-1.

Abstract: SiC growth on as-received and striated Si(001) substrates was studied. SiC films were grown by pulsed-jet chemical vapor deposition using monomethylsilane as a gas source at 780°C. Two kinds of Si surfaces were prepared. One was an as-received Si(001) surface and the other was an striated (scratched) Si(001) surface. It was found that nucleation rate of SiC is quite different between these two kinds of surfaces. The film growth rate was very low for the as-received Si(001) surface compared with the striated surface, and after 8 hours of growth hardly any film was grown and only square-shaped islands were observed. On the other hand, for the undulant substrate about 100nm thick 3C-SiC film was grown after 8 hours of deposition. This film growth rate difference appears to be due to the difference in density of nucleation sites. For the as-received Si(001) surface, nucleation site density appears to be quite small due to the atomically flat surface. On the other hand, for the undulant surface, nucleation site density was large enough for the film to grow faster.