| Summary: | 碩士 === 國立臺灣海洋大學 === 機械與機電工程學系 === 97 === The optimization in the engineering and management fields needs modeling. However, as to the manufacturing process, modeling will take lot of time and inconveniency. In this dissertation, we separated use the Extensional Set Theory and Grey System Theory in the manufacturing process optimization of injection molding process in impact fatigue specimen of short glass fiber reinforced polycarbonate composites.
In this dissertation, the effects of fiber orientation on impact fatigue of polycarbonate composites reinforced with short glass fiber are studied. The specimens were prepared under various injection molding conditions, such as filling time, melting temperature, mold temperature and holding pressure. For the design research of the manufacturing process optimization in the injection molding, we use the short glass fiber reinforced polycarbonate composites materials to make the impact fatigue specimen being the goal of research. This method can replace the traditional 「change-one-parameter-at-a-time」 approach which is very inefficient, costly, time consuming and almost impracticable to yield an optimum solution. In the mean time, the prediction of fiber orientation microstructures were examined with a C-Mold software to determine the short glass fiber orientation and share layer thickness to check the results of CAE simulation. The results indicated that two distinct layers (skin layer and core layer) are observed from surface to core at various injection molding conditions. The short glass fiber orientation is perpendicular to the melt flow direction in core layer, but it has the opposite direction in skin layer. From the CAE analysis, we have gotten opposite process parameters to obtain the thicken skin layer that was our target. We simultaneously use the standard specimen of impact fatigue testing to study. It will be better when the fiber direction is parallel to external load. So, to obtain the thickest skin layer is our target. The results indicate that the most important control factor is only the filling time, the others can be neglected. That is completely different form the impact fatigue specimen at the same processing conditions in the previous study. In the same way, we use the Gray System Theory and the Extensional Set Theory to replace the Experimental Design method of Taguchi, we found the results of both are nearly the same.
As to the injection molding conditions, to obtain the best strength (the optimal fiber orientation) were filling time 5s, melting temperature 270℃, mold temperature 80℃ and holding pressure 100%. The addition of short glass fiber to the polycarbonate can effectively increase the strength. The trend of strength is in good agreement with the layer thickness in which the fiber orientation is parallel to the melting polymer direction. This creation of manufacturing process optimization is really the largest contribution in this dissertation.
|
|---|
