Delaminations in composite laminates may de-velop from small cracks due to fabrication and impact load-ing,or from places of high stress concentration.The locationsof the delaminations are not determinate.In this rese...Delaminations in composite laminates may de-velop from small cracks due to fabrication and impact load-ing,or from places of high stress concentration.The locationsof the delaminations are not determinate.In this research,ananalytical solution for the free vibration of a composite beamwith two overlapping delaminations is presented.The dela-minated beam is analyzed as seven interconnected beamsusing the delaminations as their boundaries.The continuityand equilibrium conditions are satisfied between the adjoin-ing regions of the beams.Classical beam theory is applied toeach of the beams.Complex vibration behaviors emerge fordifferent sizes and locations of the delaminations.Compar-ison with analytical results reported in the literature verifiesthe validity of the present solution.展开更多
Silicon carbonitride (SiCN) coatings were deposited on silicon and tungsten carbide substrates by co-sputtering silicon and carbon in argon and nitrogen mixture atmosphere using magnetron-sputtering system. The effect...Silicon carbonitride (SiCN) coatings were deposited on silicon and tungsten carbide substrates by co-sputtering silicon and carbon in argon and nitrogen mixture atmosphere using magnetron-sputtering system. The effect of the N2 concentration, RF substrate bias voltage and target current on film deposition rate, roughness, adhesion, mechanical and tribological properties of coatings were investigated. The deposition rate was found to increase with the increasing nitrogen concentration. X-ray photoelectron spectroscopy analysis showed that high nitrogen concentration in the nitrogen-argon gas mixture enhanced the incorporation of C and N but reduced the incorporation of Si. SiCN coatings have good tribological properties at a N2 concentration of approximately 60%.展开更多
Dry etching of silicon is an essential process step for the fabrication of Micro electromechancal system (MEMS). The AZ7220 positive photo-resist was used as the etching mask and silicon micro-trenches were fabricated...Dry etching of silicon is an essential process step for the fabrication of Micro electromechancal system (MEMS). The AZ7220 positive photo-resist was used as the etching mask and silicon micro-trenches were fabricated with a multiplexed indu ctively coupled plasma (ICP) etcher. The influence of resist pattern profile, an d etch condition on sidewall roughness were investigated detail. The results sho w that the sidewall roughness of micro-trench depends on profiles of photo-resis t pattern, the initial interface between the resist bottom surface and silicon s urface heavily. The relationship between roughness and process optimization para meters are presented in the paper. The roughness of the sidewall has been decrea sed to a 20-50nm with this experiment.展开更多
The end effect on the output voltage of a twin-wire depth probe was investigated both theoretically and experimentally,It was found that the contribution of the end of the probe to the output voltage depends upon the ...The end effect on the output voltage of a twin-wire depth probe was investigated both theoretically and experimentally,It was found that the contribution of the end of the probe to the output voltage depends upon the distance between the boundary and the end of the probe and the geometrical configuation of the probe.By mounting a piece of plate to the end of the electrodes,the end effect can be reduced.However,the size of the plate required to eliminate completely this effect is much larger than that usually mounted on commercially available probes.Comparison between theoretical and experimental results was made.Reasonable agreement was obtained.展开更多
文摘Delaminations in composite laminates may de-velop from small cracks due to fabrication and impact load-ing,or from places of high stress concentration.The locationsof the delaminations are not determinate.In this research,ananalytical solution for the free vibration of a composite beamwith two overlapping delaminations is presented.The dela-minated beam is analyzed as seven interconnected beamsusing the delaminations as their boundaries.The continuityand equilibrium conditions are satisfied between the adjoin-ing regions of the beams.Classical beam theory is applied toeach of the beams.Complex vibration behaviors emerge fordifferent sizes and locations of the delaminations.Compar-ison with analytical results reported in the literature verifiesthe validity of the present solution.
文摘Silicon carbonitride (SiCN) coatings were deposited on silicon and tungsten carbide substrates by co-sputtering silicon and carbon in argon and nitrogen mixture atmosphere using magnetron-sputtering system. The effect of the N2 concentration, RF substrate bias voltage and target current on film deposition rate, roughness, adhesion, mechanical and tribological properties of coatings were investigated. The deposition rate was found to increase with the increasing nitrogen concentration. X-ray photoelectron spectroscopy analysis showed that high nitrogen concentration in the nitrogen-argon gas mixture enhanced the incorporation of C and N but reduced the incorporation of Si. SiCN coatings have good tribological properties at a N2 concentration of approximately 60%.
文摘Dry etching of silicon is an essential process step for the fabrication of Micro electromechancal system (MEMS). The AZ7220 positive photo-resist was used as the etching mask and silicon micro-trenches were fabricated with a multiplexed indu ctively coupled plasma (ICP) etcher. The influence of resist pattern profile, an d etch condition on sidewall roughness were investigated detail. The results sho w that the sidewall roughness of micro-trench depends on profiles of photo-resis t pattern, the initial interface between the resist bottom surface and silicon s urface heavily. The relationship between roughness and process optimization para meters are presented in the paper. The roughness of the sidewall has been decrea sed to a 20-50nm with this experiment.
文摘The end effect on the output voltage of a twin-wire depth probe was investigated both theoretically and experimentally,It was found that the contribution of the end of the probe to the output voltage depends upon the distance between the boundary and the end of the probe and the geometrical configuation of the probe.By mounting a piece of plate to the end of the electrodes,the end effect can be reduced.However,the size of the plate required to eliminate completely this effect is much larger than that usually mounted on commercially available probes.Comparison between theoretical and experimental results was made.Reasonable agreement was obtained.
