Chun-Chia Hsu

The Effect of Injection Molding Process Parameters on the Tensile Properties of Short Glass Fiber-Reinforced PBT

This study investigates the influence of various injection molding process parameters and fiber amount on the tensile properties of short fiber-reinforced polybutylene terephthalate (PBT). The parameters that govern injection molding process are filling time, melt temperature, mold temperature, and packing pressure. The tensile properties of neat PBT, 15 wt%, and 30 wt% short fiber-reinforced PBT are obtained using a computerized closed-loop servohydraulic testing system. The frozen core morphology is observed by scanning electron microscopy (SEM), which can define the layer thickness. The observation can explain the influence of fiber orientation on the tensile properties. The fracture surfaces are also observed by SEM to understand the fracture mechanisms of different fiber orientations. It is found that the addition of short glass fibers can significantly strengthen neat PBT. The strength depends on the thickness of the layer where fibers are oriented in the loading direction. The layer thickness is strongly affected by the injection molding parameters and pin gate locations. Also, the fracture mechanisms of fiber pullout and across-matrix crack dominate the failure process in the layer where fibers are parallel to the direction of applied load. However, the failure of fiber–matrix interface dominates the fracture mechanism of the layer where fibers are mostly perpendicular to the applied load.

Fracture Toughness of Injection-Molded Poly(Butylene Terephthalate) Composites

Abstract: The influences of various fiber amounts and injection molding process conditions on the fracture toughness of injection-molded short fiber-reinforced poly(butylene terephthalate) (PBT) composites were investigated. Three materials of various fiber amounts, neat PBT, 15 wt.%, and 30 wt.% short fiber-reinforced PBT composites, were used in this study. The compact tension (CT) specimens were prepared by various injection molding process conditions, wherein filling time, melt temperature, mold temperature, and packing pressure were design parameters used to measure fracture toughness. The morphology of the specimens, which consisted of frozen, intermediate, and core layers, was evaluated by scanning electron microscopy (SEM) and related to the fracture toughness. The fracture surfaces were also observed by SEM to understand the difference between the fracture mechanisms of neat PBT and fiber-reinforced PBT. It was found that the fracture toughness of neat PBT was significantly increased by the addition of short glass fibers. However, the variation of the injection molding design parameter had little effect on the fracture toughness. The fracture toughness depended on the thickness of the layers where fibers oriented perpendicular to the crack direction. The layer thickness was strongly affected by the fiber amounts.

Effect of Visual-Verbal Load and Spatial Compatibility on Stimulus Response

This study examined the effects of visual-verbal load (as measured by a visually presented reading-memory task with three levels) on a visual/auditory stimulus-response task. The three levels of load were defined as follows: “No Load” meant no other stimuli were presented concurrently; “Free Load” meant that a letter (A, B, C, or D) appeared at the same time as the visual or auditory stimulus; and “Force Load” was the same as “Free Load,” but the participants were also instructed to count how many times the letter A appeared. The stimulus-response task also had three levels: “irrelevant,” “compatible,” and “incompatible” spatial conditions. These required different key-pressing responses. The visual stimulus was a red ball presented either to the left or to the right of the display screen, and the auditory stimulus was a tone delivered from a position similar to that of the visual stimulus. Participants also processed an irrelevant stimulus. The results indicated that participants perceived auditory stimuli earlier than visual stimuli and reacted faster under stimulus-response compatible conditions. These results held even under a high visual-verbal load. These findings suggest the following guidelines for systems used in driving: an auditory source, appropriately compatible signal and manual-response positions, and a visually simplified background.

The Development of a car-driving Training System for Sci Patients

In this study a car-driving training system for spinal cord injury (SCI) patients was developed. It consisted of three major components: a driving cabin, a three-screen synchronized projection system, and a suit of driving simulation software. Combined with the developed virtual driving scenarios, it can provide an environment for driving training. Two sets of results were collected and compared: one from SCI patients and the other from normal people. In the experiments, the driving behaviors were recorded and statistically analyzed. The results indicated SCI patients required using this training system repetitively seven times to achieve a stable operational performance in controlling the speed and position of the car, while for normal people, only two times of repetitive usage of this system were required. The SCI patients after achieving stable operation performance still showed less capable of controlling the car.