Browsing by Author "Hsu, Ray-Quan"

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Direct joining of 3D-printed thermoplastic parts to SLM-fabricated metal cellular structures by ultrasonic welding
(2018-10-01)
Tang, Sheng-Hung
;
Cheng, Chung-Wei
;
Yeh, Ren-Yu
;
Hsu, Ray-Quan
;
機械工程學系
The joining capability of metal cellular structures fabricated using the additive manufacturing (selective laser melting (SLM)) method is investigated herein. The metal cellular structures are composed of sub-millimeter holes and internal pores. The direct joining of 3D-printed ABS-M30i thermoplastic parts to metal cellular structures by ultrasonic welding is demonstrated. The SLM-fabricated structures comprised of partially melted powders provide micro-scale roughness, which enhances the micro-mechanical interlocking between joining parts. A shear strength 17.7MPa and normal tensile strength of 15.2MPa were obtained, up to 55 and 48% of ABS-M30i ultimate tensile strength, respectively. Moreover, normal tensile plastic strength up to 86% of the shear strength was obtained.
Direct numerical simulation of methane hydrate dissociation in pore-scale flow by using CFD method
(2017-10-01)
Yu, Pei-Yi
;
Sean, Wu-Yang
;
Yeh, Ren-Yu
;
Hsieh, Lin-Han Chiang
;
Hsu, Ray-Quan
The objective of this work is to establish a new pore-scale (m-mu m) model for estimating the dissociation rate of methane hydrate (MH) synthesized in laboratory-scale sediment samples. Finite volume method (FVM) with unstructured mesh were constructed in a representative face-centered cubic unit. The surface model of MH reported by Sean et al. (2007) has been employed. In the bulk flow, concentration of methane in water flow was analyzed by computational fluid dynamics (CFD) method. However, only water flow and solid MH are simulated without considering ice or gas phase. In this study, tentative cases with porosity 0.74, 0.66, and 0.49 is individually considered as representative cubic unit of MH array. The initial temperature, 253.15 (K) of MH pellets inside the cubic unit dissociated due to the driving force of fugacity variation, ex. 0.56 and 0.54 (MPa) while warm water of 282.15 and 276.15 (K) flow in. In the calculation, periodic conditions are imposed at surfaces of inlet/right/front sides updated every time step. The flux of methane at the surface are all regarded as being dissolved into the water in this high pressure state, and compared to Kim et al. (1987)'s correlation at Reynolds no. of about 50. Results of dissociation flux in cases 5 and 6 with porosity 0.49 show good agreements with Kim's correlation. However, as the porosity increases, flux increases due to the fast transport in bulk flow such as cases 1-4 in this study. If the transport process in bulk flow is faster than dissociation rate, then the surface flux becomes saturated as Reynolds no. greater than 100 in this work. (C) 2017 Elsevier Ltd. All rights reserved.
Observation of Growth of Human Fibroblasts on Silver Nanoparticles
(2007)
Wen, Hua-Chiang
;
Lin, Yao-Nan
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Jian, Sheng-Rui
;
Tseng, Shih-Chun
;
Weng, Ming-Xiang
Silver nanoparticles have drawn extensive attention as biomaterial components. Human fibroblasts were grown on various concentrations of silver nanoparticles during the period observation. Normal viability (0% silver particles) was increased from 6 to 72 hours, increasing the amount of human fibroblasts (1.5x10(4) to 7x10(6) cells/well) normally. Nevertheless, at higher concentrations of silver nanoparticles (50%) 1.11x10(5) cells/well remained after 72 hours. Results indicated that the increase in the concentration of silver nanoparticles reduced the number of fibroblasts and affected their fission. Silver nanoparticles were found under the membranes of fibroblast following dry treatment. The number of tissues declined because the silver nanoparticles interrupted the fission mechanism during their development in vivo.