Jiun-Ren Hwang

Driver Fatigue and Highway Driving: A Simulator Study

Long duration of driving is a significant cause of fatigue-related accidents on motorways or major roadways. The fatigue caused by driving for extended periods acutely impairs driver alertness and performance and can compromise transportation safety. This study quantitatively measured the progression of driver fatigue and identified the conservative safe duration of continuous highway driving. Thirty young male subjects were analyzed during 90 min of laboratory-simulated highway driving. Sleepiness ratings (SSS) and reaction time (RT) tests were used to assess impairment of driver alertness and vigilance. Additionally, various measures of driving performance recorded throughout the experiment were used to measure temporal deterioration of driver performance from alert to fatigued using principal component analysis (PCA). The analytical results revealed that SSS scores, reaction times (RTs) and unstable driving performance significantly increased over time, indicating that excessive driving time is a significant fatigue factor and potential cause of fatigue-related accidents. Moreover, the analytical results indicated that 80 min was the safe limit for monotonous highway driving. Based on the experimental findings of this study, public awareness of the adverse affects of driver fatigue during long-distance driving should be enhanced. This study provides explicit information of fatigue development that can be used to prevent fatigue-related accidents.

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.

Optimization of the Wear Properties of Polyoxymethylene Components Under Injection Process Conditions

This study investigates the influences of two processing conditions on wear properties of Polyoxymethylene (POM) polymer, and further determines the optimal parameter setting for the injection molding process to achieve optimal wear quality. This study uses two experimental designs, including the conventional single factor design and Taguchi L9 orthogonal design. Moreover, morphology of worn surfaces was analyzed by scanning electron microscopy (SEM). Analytic results confirm that combining the Taguchi experimental design with the analysis of variance (ANOVA) can link controlled parameters and targeted output, and rapidly predict the optimal parameter settings for various injection-molding conditions.

Accelerated durability assessment of motorcycle components in real-time simulation testing

Abstract The rapid development of the vehicle industry has made reducing product development time a major concern. This study seeks to identify a suitable accelerated approach to durability analysis for motorcycle components. This investigation involves field data acquisition, laboratory road load simulation, accelerated durability testing, and fatigue life prediction. Two methods, ‘strain range editing technique’ and ‘racetrack editing technique’, were applied to edit field strain histories for accelerated durability tests. Furthermore, four methods, including the ‘S–N approach with fatigue property of base metal’, ‘Eurocode 3 approach’, ‘BS 5400 approach’, and ‘BS 5400 approach with Gurney thickness modification’, were employed to assess fatigue life. Three road types and four damage levels were also used. The results demonstrated that the ‘BS 5400 approach with Gurney thickness modification’ is a suitable method of assessing the durability of welded motorcycle components when the fatigue properties of critical points are not available. Both the ‘strain range editing technique’ and ‘racetrack editing technique’ can effectively edit strain histories with the expected quantity of fatigue damage, and demonstrate satisfactory agreement between the experimental data and predicted data.

The Effect of Process Conditions on the Fiber Orientation and Tribological Characteristics of Polyoxymethylene Composites

This study investigates the influence of two process conditions on fiber orientations and tribological characteristics of POM/GF composites. The morphologies of fiber layers were observed to elucidate wear mechanisms, and the correlation between fiber orientation and fiber layer thickness. Experimental results indicate that there are three distinct layers from top surface to the core—a solidified layer, intermediate layer, and core layer. The tribological characteristics decreased as thickness of solidified layer decreased. Furthermore, minor grooving and debonded fibers were the major wear mechanisms for P-direction specimens. Severe cracks and cut fibers were the major wear mechanisms for AP-direction specimens.

Development of a ride comfort evaluation method with a laboratory testing system

The ride comfort qualities of different Sport–Utility Vehicles (SUVs) were determined using road load simulation in the laboratory via road and bench tests. The point vibration total value and Overall Vibration Total Value (OVTV) based on the ISO 2631 standard and the Seat–Effective Amplitude Transmissibility (SEAT) value were evaluated. The linear correction factor was derived as OVTVcorrected bench = 0.9335 × OVTVbench, and the correlation coefficient was 0.9908. Furthermore, the mean error of the OVTV for the road and bench tests ranged from 9.75% (original) to 0.2% (after correction). Finally, the procedures for ride comfort evaluation using a laboratory test system (four–poster) are described.

Responses in a manual tracking and visual detection task

To investigate interference between the sustained and occasional attention required in driving, performance of 36 participants engaged in a focal manual tracking task and a peripheral detection task, representing sustained and occasional attention, respectively, was studied. Error ratio, tracking distance, tracking speed, and root mean squared tracking distance error were taken for manual tracking, and response times were measured on the detection task. Analysis indicated that multiple tasks or highly sustained attentional demands preceded lower performance on sustained attention tasks. Performance on occasional attention tasks after multiple tasks may also decrease, but occasional attention performance improved when the participants were engaged concurrently in a task involving higher sustained attention. Furthermore, the association between sustained and occasional attention was strengthened as the number of tasks or the demands of sustained attention increased.