VNUHCM Journal of Engineering and Technology

Using Taguchi Method to Investigate Surface Roughness in Finishing with Ultrasonic Vibration-Assisted Machining (UVAM) on Conventional Machine Tools

2025-10-22T19:32:49+07:00

Ultrasonic vibration-assisted machining (UVAM) has attracted considerable attention in recent years due to its potential to significantly enhance machining performance. This technique is particularly effective in extending tool life, minimizing surface roughness, and reducing cutting forces, which are critical factors in precision manufacturing. Unlike many previous studies that focus on high-speed spindles or specialized machining centers, the present research investigates the application of UVAM in finishing operations performed on conventional machine tools. The study specifically targets small, narrow surfaces with intricate profiles where the use of high-speed spindles is either impractical or unavailable. This approach broadens the scope of UVAM by demonstrating its feasibility in more common manufacturing environments. The ultrasonic vibration-assisted cutting tool used in this research is designed to be structurally similar to a conventional stand-alone cutting tool, allowing it to be integrated easily into traditional machining setups without requiring major modifications. To systematically evaluate the effects of key machining parameters on surface quality, the Taguchi method was employed as the experimental design framework. The parameters examined include vibration frequency (f), voltage supplied to the ultrasonic actuator (V), and spindle speed (n), which collectively influence the machining dynamics. The primary goal of the study was to achieve a surface roughness (Ra) below 1.6 μm while maintaining spindle speeds not exceeding 180 revolutions per minute, conditions relevant to conventional machine tool capabilities. Experimental results clearly indicate that vibration frequency exerts the most significant influence on surface roughness, followed by the voltage input to the ultrasonic actuator, while spindle speed within the tested range has a minor effect. Several experimental trials successfully achieved Ra values lower than the 1.6 μm target, confirming the effectiveness of UVAM under these constraints. These findings underscore the potential of ultrasonic vibration-assisted machining to improve surface finish quality on complex geometries even when using standard machining equipment. Ultimately, this work contributes valuable insights into expanding the practical application of UVAM, offering a promising solution for manufacturing scenarios where advanced high-speed machines are not accessible, thereby enhancing surface quality in resource-limited production settings.

Chẩn đoán hư hỏng động cơ trên xe điện cỡ nhỏ bằng phương pháp mô phỏng

2025-10-22T19:02:46+07:00

Nghiên cứu phương pháp chẩn đoán các hư hỏng có thể xảy ra trong động cơ một chiều không chổi than (Brushless Direct Current, BLDC) dùng trên xe điện cỡ nhỏ trong các trường hợp ngắn mạch, điện trở cao, hở mạch, …là một trong những phương pháp xác định hư hỏng đang tồn tại làm cho cho động cơ tụt giảm công suất hoặc hoạt động không hiệu quả. Bằng các mô hình toán học được xây dựng dựa trên sơ đồ nguyên lí tương ứng của loại động cơ này có thể xây dựng mô hình chẩn đoán hư hỏng và mô tả diễn biến của từng lỗi mà động cơ đang xảy ra hư hỏng. Xây dựng mô hình chẩn đoán bằng phương pháp này có thể tìm ra các giá trị đáp ứng của động cơ khi hoạt động dòng điện các pha, momen điện từ và tốc độ trục rotor ứng với từng chế độ lỗi thu được trong môi trường Matlab Simulink. Phân tích kết quả mô phỏng, nhóm nghiên cứu tìm được biểu hiện của động cơ BLDC khi xảy ra các lỗi trong các trường hợp đã nêu và thêm các sự cố ngắn mạch và điện trở cao đều xuất hiện những dấu hiệu tương ứng với biểu hiện từng trường hợp lỗi này. Đây là phương pháp khá khó để nhận biết nếu không có các thiết bị đo và phương pháp chẩn đoán hợp lí trong thực tế, chính điều này gây ra sự hư hỏng nhanh chóng của động cơ nếu lỗi không được phát hiện sớm. Kết quả chẩn đoán trên mô hình này cung cấp một phương pháp thuận tiện và kinh tế để phân tích về các lỗi trong động cơ một chiều không chổi than cỡ nhỏ khi xây dựng các mô hình lỗi chẩn đoán trực tiếp trên các xe điện cỡ nhỏ (SBEV) hiện nay.

The study of health effects on the residents caused by highway mobile source in the central air quality district of Taiwan, ROC

2025-10-15T15:49:03+07:00

This study assesses the externalities in health effect caused by carbon monoxide (CO) and nitrogen oxide (NO_X) from highway transport in the central air quality district, Taiwan. The utilization of typical vehicle emissions, dispersion model and monetary valuation had been adapted and integrated from the EU-based IPA. The outputs include the estimated CO quantities were 269 tons and NO_X quantities were 270 tons in 2005. Then, the prediction of the average ambient concentration obtained by combining CALINE-4 and GIS of CO was 5.9ppm and NO_X is 0.22ppm. The results conjectured for high impact area show that the emissions spread to the leeward side of highway. Moreover, the calculation of damage costs based on dose-response functions had been displayed by GIS grid distribution. Particularly, acute mortality caused by nitrogen oxide, dominate in terms of cost. Ultimately, the results have been scaled up nationwide, total environmental externalities due to CO & NO_X were totalized to USD 37.57 million ~ USD 521.21 million standing for 0.07% of the GDP of the study area in 2005.

A technique for monitoring diesel common-rail direct injection engines used in a bus fleet for preventive maintenance purposes

2025-10-15T16:54:39+07:00

This paper describes an IoT-based technique for gathering the operational data from EURO 4 diesel common-rail direct injection systems used in a bus fleet in real-time, and a methodology to monitor engine technical status basing on these collected data. The engine livedata acquisition system developed in this study has three major parts including OBD-II livedata recorders installed in buses, a local server located in the bus depot to collect daily livedata from the bus fleet, and a web server to store livedata from several bus depots and provides data mining services. By the combination of a local server and a web server, the operational cost can be reduced and the daily livedata can be simultaneously stored in both servers for safety reasons. A pilot system was successfully developed and tested in a real environment. Engine livedata were shown to be collected accurately, precisely, and robustly. The result of this research is an important technical platform to predict the degradation tendencies of sensors, actuators and mechanical components for engine preventive mainteance as well as to provide operational history for engine diagnostics and repair.

Research on physical, and chemical properties of viscose with spandex composition, application for the production of elastic denim fabric

2025-10-19T14:30:46+07:00

Spandex-blended viscose fiber used in apparel is a fiber that has the benefits of breathability, fit, comfort, and elasticity. Research on the mechanical and physical properties of viscose fiber blended with spandex helps in the selection of woven fabrics for the production of Denim fabric, as a suitable raw material for jeans. The present study investigates how some physical and mechanical properties, like fiber density, post-washing fiber size, tensile strength, tear strength, breathability, and so on, vary under different washing conditions.

Spandex is highly elastic and is soluble in extremely high solvents. Spandex is not susceptible to hydrolysis effects during normal laundering and hand washing or laundering processes that do not use the solvents commonly used in dry cleaning such as perchloroethylene or benzene. Spandex fibers have resistance to low concentrations of acid, alkali and oxidizers. However, they lose their elasticity when treated with acids and alkalis of high concentrations for a long time. Rapid loss in elasticity depends on temperature. Elastic spandex fibers have resistance to the active chlorine in the bathtub water.

Viscose which is a man-made fiber and is derived from cellulose rayon (man-made silk from wood) belongs to a group of regenerated fibers to create fibers used as textile materials at affordable prices. Viscose is produced via the wet spinning method in a coagulation bath. Viscose fiber has a lower tensile strength under wet conditions than under dry conditions. Besides, it has a higher elongation under wet conditions.