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유리섬유의 특성이 열가소성 복합재료의 기계적 성질에 미치는 영향
이중희,이정권,이경엽,Lee, Jung-Hui,Lee, Jeong-Gwon,Lee, Gyeong-Yeop 대한기계학회 2000 大韓機械學會論文集A Vol.24 No.7
This study has been performed to investigate the effects of glass fiber characteristics on the mechanical properties of thermoplastic composite. The surface of glass fiber was coated with the silan e to enhance the bonding strength between fiber and matrix. A micro-droplet pull-off test was performed to investigate the influence of the silane concentration on the bonding strength. The maximum bonding strength was observed around 10.8% silane concentration. In order to examine the influence of the fiber length and fiber content on the properties of the composite, the composite materials involving tile fiber lengths of 5mm, 10mm, 15mm 20mm, and 25mm were tested. The composites used contain 20%, 30%, and 40% by weight of glass fibers. Tension and flexural tests were performed to investigate their mechanical properties of the composites. The tensile strength and tensile modulus of the composite increase with increasing the glass fiber content. The tensile modulus increases slightly with increasing the fiber length. The maximum tensile strength is observed around the fiber length of 15-20mm. The flexural modulus and strength also increase slightly with increasing the fiber length.
이중희,최창우,Lee, Joong Hee,Choi, Chang Woo 영남수학회 2021 East Asian mathematical journal Vol.37 No.2
The purpose of this thesis is to analyze the effect on formation of computational abilities and dispositions to the first grade of elementary school students by applying of communicative teaching and learning activity. As a result of analysis, we could get some suggestive points and also we could make sure that computational abilities and dispositions of the first grade students are formed by applying of communicative teaching and learning activity. However, help and control of teacher have to be with it.
열가소성 복합재료의 압축성형조건에 따른 기계적 특성 변화
이중희,이호언,Lee, Jung-Hui,Lee, Ho-Eon 대한기계학회 2001 大韓機械學會論文集A Vol.25 No.9
The objective of this work was to characterize mechanical properties of thermoplastic composites with various forming conditions in compression molding. Randomly oriented long glass fiber reinforced polypropylene(PP) was used in this work. The composite materials contained 20%, 30%, and 40% glass fiber by weight. Compression molding was conducted at various mold temperatures and charge sizes. The temperatures on the mold surface and at the material in the mid-plain were monitored during the molding. Differential Scanning Calorimeter was used to measure crystallinity at both in-side and out-side of the sheet material. Crystallinity at each temperature was also measured by X-ray diffractometer. Dimensional stability was studied at various conditions with the spring forward angle. Among the processing parameters, the crystallization time at the temperature above 130$^{\circ}C$, was found to be the most effective. Spring-forward angle was reduced and the tensile modulus was increased as the mold temperature increased.
고상성형된 열가소성 복합재료의 성형 변형률이 기계적 특성에 미치는 영향
이중희,조현철,이경엽,Lee, Jung-Hui,Jo, Hyeon-Cheol,Lee, Gyeong-Yeop 대한기계학회 2001 大韓機械學會論文集A Vol.25 No.8
This study investigates the effects of the pre-strain level on mechanical properties of the solid-phase formed thermoplastic composite. A uniaxial solid-phase forming was performed at the temperature of 125$\^{C}$ and at the constant cross-head speed of 3mm/sec. The composite sheet was formed to various pre-strain levels of 10%, 20%, and 30%. Tension, flexural, and impact tests were carried out to characterize the material properties of a solid-phase formed part. Tensile and flexural strengths decreased with increasing the pre-strain level, while impact strength increased. Various microstructures of the formed part explained the above material behavior.