Shao-Yi Hsia

Optimization of Microextrusion Preforming Using Taguchi Method

Micropin head geometry significantly influences surface contact and electrical conductivity. In this paper, the preforming process of extrusion is investigated to establish it as a viable process for microforming. Here, the numerical simulations using DEFORM-3D software are used to examine the effect of preformance and pin shape on the extrusion of microbrass pins with a minimum diameter of 0.88 mm under several design parameters. These parameters are planned with the Taguchi method and help to discover better conditions for the minimum extrusion loads. For obtaining the required parameters to enable the finite element software, a compression test is first performed to determine the true stress and true strain curve of the materials. The result acquired from the experiment is compared with the simulation outcome and verified the accuracy. The consequences show that the optimal microextrusion forming conditions appear on stage rod length 0.015 mm, extruding angle 60°, upper front-end taper 60°, and bottom stage angle 60° to minimalize the forming load, and the dimensions of the deformed micropin reveal a good identification with the simulation. The study hence shows a potential tool for the combination of Taguchi method and finite element software to analyze the microforming process in the fastener industry.

Wear Improvement of Tools in the Cold Forging Process for Long Hex Flange Nuts

Cold forging has played a critical role in fasteners and has been widely used in automotive production, manufacturing, aviation and 3C (Computer, Communication, and Consumer electronics). Despite its extensive use in fastener forming and die design, operator experience and trial and error make it subjective and unreliable owing to the difficulty of controlling the development schedule. This study used finite element analysis to establish and simulate wear in automotive repair fastener manufacturing dies based on actual process conditions. The places on a die that wore most quickly were forecast, with the stress levels obtained being substituted into the Archard equation to calculate die wear. A 19.87% improvement in wear optimization occurred by applying the Taguchi quality method to the new design. Additionally, a comparison of actual manufacturing data to simulations revealed a nut forging size error within 2%, thereby demonstrating the accuracy of this theoretical analysis. Finally, SEM micrographs of the worn surfaces on the upper punch indicate that the primary wear mechanism on the cold forging die for long hex flange nuts was adhesive wear. The results can simplify the development schedule, reduce the number of trials and further enhance production quality and die life.

Optimization of Biohydrogen Production with Biomechatronics

Massive utilization of petroleum and natural gas caused fossil fuel shortages. Consequently, a large amount of carbon dioxide and other pollutants are produced and induced environmental impact. Hydrogen is considered a clean and alternative energy source. It contains relatively high amount of energy compared with other fuels and by-product is water. In this study, the combination of ultrasonic mechanical and biological effects is utilized to increase biohydrogen production from dark fermentation bacteria. The hydrogen production is affected by many process conditions. For obtaining the optimal result, experimental design is planned using the Taguchi Method. Four controlling factors, the ultrasonic frequency, energy, exposure time, and starch concentration, are considered to calculate the highest hydrogen production by the Taguchi Method. Under the best operating conditions, the biohydrogen production efficiency of dark fermentation increases by 19.11%. Results have shown that the combination of ultrasound and biological reactors for dark fermentation hydrogen production outperforms the traditional biohydrogen production method. The ultrasonic mechanical effects in this research always own different significances on biohydrogen production.

Fabrication Improvement of Cold Forging Hexagonal Nuts by Computational Analysis and Experiment Verification

Cold forging has played a critical role in fasteners and has been applied to the automobile industry, construction industry, aerospace industry, and living products so that cold forging presents the opportunities for manufacturing more products. By using computer simulation, this study attempts to analyze the process of creating machine parts, such as hexagonal nuts. The DEFORM-3D forming software is applied to analyze the process at various stages in the computer simulation, and the compression test is also used for the flow stress equation in order to compare the differences between the experimental results and the equation that is built into the computer simulation software. At the same time, the metallography and hardness of experiments are utilized to understand the cold forging characteristics of hexagonal nuts. The research results would benefit machinery businesses to realize the forging load and forming conditions at various stages before the fastener formation. In addition to planning proper die design and production, the quality of the produced hexagonal nuts would be more stable to promote industrial competitiveness.

Assessing the Hardness of Quenched Medium Steel Using an Ultrasonic Nondestructive Method

Developing new materials or improving their heat treatment techniques is key to industrial upgrades for increasing fastener product quality. Nowadays, high tensile strength bolts are heat-treated to achieve desired mechanical properties such as hardness, strength, toughness, and resistance to fatigue and wear. Ultrasound detection is one widely used nondestructive inspection technique. Based on the characteristics of wave transmission, the refraction, diffraction, and scattering of ultrasound wave velocity and attenuation in a material are governed by its grain boundary characteristics. In this study, C1045 middle carbon steel was heat-treated at various temperatures and then water-quenched, and the relationships among grain size, ultrasonic velocity, attenuation, and material hardness were then determined using two ultrasound sources. Our experimental results show that a smaller average grain size as well as higher hardness can be obtained from higher quenching temperatures. Faster acoustic velocities and slower attenuation coefficients are caused by higher material hardness. A scattering effect is more obvious for higher transducer frequencies. Our results demonstrate another nondestructive test that can assess the quenching process in the fastener industry.

Interference of Die Equipment for Hexagonal Flange Nut Forming Process

Most cold forging die insert materials are powder sintered tungsten steel materials, which can hardly bear the circumferential tension and stress that the die insert longitudinal fracture is easily caused. For this reason, this study intends to investigate effects of die insert pre-stress resulted from shrink fit interference on the die to prevent the product accuracy and service life from being reduced due to the die failure in the forging process. The die effective stress distribution is also calculated in this study, and the interference is added between tungsten steel die inserts and cases to prevent tungsten steel from being damaged by the circumferential stress. The die stress distribution caused by common shrink fit interference in the industry is also investigated. The optimal interference acquired under the design criteria of decreasing equivalent stress presents 0.4%, 0.2%, 0.1%, 0.8%, and 0.1% at different stages. The research results could be the reference to select the optimal parameter for the die design and further shorten the product development effectiveness and reduce the costs.

Traffic Noise Propagating from Vibration of Railway Wagon

Traffic noise has become a serious environmental hazard as more cars are purchased and driven. To help objectively and subjectively reduce perceived noise load, methods to analyze traffic noise offer an important means of creating a design to reduce noise output from main sources and transmission routes. Acoustic analysis using BEASY and dynamic analysis using ANSYS are conducted to forecast noise at a distance of 15 m from a railway wagon travelling at 100 km/h. This noise is based on structural vibration only and it excludes other noise sources from the railway wagon. The simulation results demonstrate that the overall noise at 15 m from a railway wagon car is 85.1 dB(L) from linear energy weighting calculation and 72.9 dB(A) from the A-weighting calculation. In this study, noise level propagating from vibration of the railway wagon is measured or calculated using A-weighting filter to simulate the frequency response of the human ear. The study results can be useful to factories, companies, or organizations and can provide an important resource and help reduce traffic noise. This can be achieved by predetermining the test location and structure configuration and adapting local planning and thus preventing excessive traffic noise in residential areas.

Numerical Analysis of Indoor Sound Quality Evaluation Using Finite Element Method

Indoors sound field distribution is important to Room Acoustics, but the field suffers numerous problems, for example, multipath propagation and scattering owing to sound absorption by furniture and other aspects of decor. Generally, an ideal interior space must have a sound field with clear quality. This provides both the speaker and the listener with a pleasant conversational environment. This investigation uses the Finite Element Method to assess the acoustic distribution based on the indoor space and chamber volume. In this situation, a fixed sound source at different frequencies is used to simulate the acoustic characteristics of the indoor space. This method considers the furniture and decoration sound absorbing material and thus different sound absorption coefficients and configurations. The preliminary numerical simulation provides a method that can forecast the distribution of sound in an indoor room in complex situations. Consequently, it is possible to arrange interior furnishings and appliances to optimize acoustic distribution and environmental friendliness. Additionally, the analytical results can also be used to calculate the Reverberation Time and speech intelligibility for specified indoor space.

Improvement on acoustic characteristics of a small space using material selection

Purpose – Recently, the acoustic characteristics of indoor spaces have been perceived to be more important due to the economic development needs of societies. At the same time, container houses have gradually become more widely used in many applications because of their sustainability and ease of use. In spite of their convenience, these container units still need to foster pleasant and quiet sound environments. The paper aims to discuss these issues. Design/methodology/approach – In this paper, commercial software, designed by Ecotect Analysis, has been used to evaluate the sound characteristics of container houses. As a result, the decorated materials in such a small indoor space have been redesigned for the acoustic comfort of users based on the optimal reverberation time (RT). First, a three-dimensional model of the container house was constructed using the software’s default tools. Then, the indoor acoustic characteristics of various design conditions were obtained from the simulation process underta...

Efficiency Enhancement on Thermal Comfort Assessment of Indoor Space with Air-Conditioner Using Computational Analysis

Thermal comfort providing is one of the biggest uses of energy in building. For giving better human comfort, the suitable operation conditions of air-conditioner are the most important. The quick and right approach is necessary. In this paper, a small office is studied to improve office staff staying for a long period of time and achieve the thermal comfort environment for reducing energy consumption. Commercial software, Solidworks, is utilized for modeling the facilities and the Flow Simulation module for analyzing the air properties of the indoor space. Four types of air-conditioner operation are applied to set the simulated conditions, including exterior temperature, outlet temperature and wind speed of air-conditioner, and location of air-conditioner. Predicted mean vote (PMV) and predicted percent dissatisfied (PPD) at specific office areas are further acquired through dynamic anthropometry. For seeking the optimal control factors, both of the full factorial method and Taguchi method are utilized to obtain the PMV of specified location. The analyzed result shows the evaluation speed of indoor thermal comfort by Taguchi method is faster than the full-factorial method. It is concluded that software simulation with Taguchi method shows the successful implementation and higher efficiency for thermal comfort assessment.