Browsing by Author "Jang, Wen-Yea"

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DEVELOPMENT AND CHARACTERIZATION OF A PORTABLE ATMOSPHERIC-PRESSURE ARGON PLASMA JET FOR STERILIZATION
(2016)
Lin, Zhi-Hua
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Wu, Jong-Shinn
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Tschang, Chen-Yon Tobias
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Su, Chi-Feng
;
Wu, Tuoh
In this study, we would like to develop a portable round argon atmospheric-pressure plasma jet (APPJ) which can be applied for general use of bacteria inactivation. The APPJ was characterized electrically and optically, which include measurements of absorption power, gas temperature and optical properties of plasma generated species. Measured OH* number density at 5 mm downstream was estimated to be 5.8 x 10(15) cm(3) and the electron density and electron temperature were estimated to be 2.4 x 10(15) cm(-3) and 0.34 eV, respectively, in the discharge region. This APPJ was demonstrated to effectively inactivate E. coli within seconds of treatment, which shows its great potential in the future use of general bacteria inactivation and sterilization.
Lightweight Torque Sensor Based on a Gradient Grating Period Guided-Mode Resonance Filter
(2019-08-15)
Wang, Yen-Chieh
;
Jang, Wen-Yea
;
Huang, Cheng-Sheno
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機械工程學系
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Department of Mechanical Engineering
This paper describes the design, fabrication, and testing of a lightweight and compact torque sensor system based on a gradient grating period guided-mode resonance (GGP-GMR) filter and a flexure-elastic-force-sensing element. The GMR filter exhibits a characteristic resonant reflection, when illuminated with a broadband light source at normal incidence. Instead of a fixed grating period, the GGP-GMR filter consists of grating periods varying from 250 to 550 nm with an increment of 2 nm. Given the flexibility of the plastic-based GGP-GMR filter, it can be bent conform to the cylindrical surface of the flexure. The applied torque induced deformation of the flexure and angular displacement of the attached GGP-GMR. For a stationary light source, the angular displacement of the GGP-GMR filter results in illumination at different locations (grating periods), leading to a shift of the resonant reflection wavelength. The magnitude of shift in the reflection wavelength can be correlated to the magnitude of deformation and the applied torque. In addition, commercial software based on the finite element method was used to simulate the proposed design, which indicates that the flexure made of medium-carbon steel can withstand the torque of 35 Nm without yielding. Furthermore, the simulation results (torque-induced deformation) were consistent with those obtained using the proposed torque sensor system. Torque measurements from 0 to 25 Nm showed good linearity. The limit of detection achieved was 0.77 Nm.
Microstructure and mechanical properties of ALPORAS closed-cell aluminium foam
(2015-09-01)
Jang, Wen-Yea
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Hsieh, Wen-Yen
;
Miao, Ching-Chien
;
Yen, Yu-Chang
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機械工程學系
In recent years, closed-cell foam has drawn increasing attention in applications ranging from energy absorption devices to serving as the core material of light-weight structures. Although closed-cell foams are critical in many applications, the microstructural characteristics and mechanical properties of these foams are not fully understood. In this paper, we performed a comprehensive study on the commercially available ALPORAS closed-cell aluminium foam by means of experiment. First, inspection of the foam microstructure was systematically performed. Based on this inspection, the geometric features of the foam were characterised. Crushing experiments were subsequently conducted on specimens under various conditions to examine the effect of each of the testing parameters such as the specimen size and geometry as well as the loading direction, on the mechanical response of closed-cell foam. We found that the cells were irregular polyhedra with approximately 14 faces and that each face had approximately 5 sides. The cell wall was thinnest in the middle section, became increasingly thicker towards the edges, and eventually formed circular fillets as it intersected with neighbouring walls. The foam was geometrically and mechanically anisotropic. The factors that most influenced the mechanical properties were the loading direction and relative density. In this paper, we also compare the experimental results on the foam mechanical properties with existing equations from the literature. (C) 2015 Elsevier Inc. All rights reserved.
On the buckling and crushing of expanded honeycomb
(2015-02-01)
Jang, Wen-Yea
;
Kyriakides, Stelios
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機械工程學系
;
Department of Mechanical Engineering
Commonly used hexagonal honeycomb is manufactured by cold expansion of a laminate of thin metal foils that are bonded along periodically placed strips. The process results in nearly hexagonal cells with double walls in one direction, small rounding at the bent corners, and leaves behind residual stresses. This paper evaluates the effect of the expansion on the compressive response of the honeycomb. A finite element model of a characteristic cell is developed using shell elements and by applying to it the appropriate periodicity conditions. The model is first expanded mechanically producing the realistic geometry and changes to the mechanical properties of the material. The cell is subsequently compressed laterally leading first to buckling, followed by collapse by progressive folding, all similar to the behavior of ideal, stress free hexagonal honeycomb. The calculated buckling stress is about 10% higher than the ideal case, the collapse stress about 5% lower and the average crushing stress somewhat higher. In addition, the buckling and collapse stresses show some sensitivity to the size of periodic domain analyzed, as indeed was the case for the ideal case. (C) 2014 Elsevier Ltd. All rights reserved.
The effect of cell-size dispersity on the mechanical properties of closed-cell aluminum foam
(2018-01-01)
Su, Bo-Yuan
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Huang, Chun-Min
;
Sheng, Hao
;
Jang, Wen-Yea
;
機械工程學系
The mechanical properties of open-celled and closed-celled metallic foam are strongly influenced by the cellular microstructure and material properties of the base material from which the foam is made. The present study investigated the microstructure and mechanical properties of ALPORAS closed-cell Al foam. In particular, the effect of cell-size dispersity on the Young's modulus of foam was investigated through crushing experiments and numerical simulations. Crushing experiments were first conducted on two mutually perpendicular directions. Numerical models of varying cell-size dispersity and complexity were subsequently developed, including the monodispersed model that is based on the Kelvin structure, the bidispersed model, and the polydispersed model that is based on the random Laguerre tessellation algorithm. The numerical models were discretized using shell elements, and the simulations were conducted using the ABAQUS finite element method software. Relative Young's moduli with various relative densities were predicted, and the numerical convergence on the model size was studied accordingly. Numerical results obtained from all three numerical models developed were found to overestimate the experimental results by a factor of approximately 3. The difference between the numerical and experimental results can be attributed to the difference in detailed microstructural characteristics. Furthermore, the difference among numerical results obtained from the three models was insignificant.
The mechanical properties of monodisperse foam scaffolds
(2019-05-01)
Yang, Cheng-Nan
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Liang, Li-Syuan
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Lin, Keng-hui
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Jang, Wen-Yea
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機械工程學系
Tissue engineering scaffolds provide mechanical supports and microenvironment for cells to grow in the third dimensionality (3D). Inspired by the recent advance to fabricate monodisperse foam scaffold by self-assembly of monodisperse liquid foam created by the microfluidic method, we investigated the mechanical properties of an open-cell solid foam with pores packed in the face-centered cubic (FCC) structure. We first characterized the microstructural geometry of solid foam with different porosities made by the microfluidic technique. We then developed both analytical and finite element method (FEM) models based on the measured geometric features. We computed mechanical parameters such as the elastic modulus, Poisson's ratio, and the shear modulus. Finally, we performed mechanical measurements of FCC solid foam fabricated by a 3D printer. All experimental, analytical, and numerical results show good agreement, which validate the FEM models.