• Composites Research
• /
• v.31 no.6
• /
• pp.398-403
• /
• 2018

Recently, environmental pollution caused by plastic waste, ecosystem disturbance of micro-plastics and human body accumulation are becoming big problems. In order to replace the traditional plastic, eco-friendly resin and natural fiber-based composite materials have been developed, but they have a disadvantage that their mechanical properties are significantly lower than those of synthetic fiber-based composites. In this study, eco - friendly nanofiber was extracted from seaweed and used as an additive in order to improve the mechanical properties of jute fiber-reinforced composites. Through the hand lay-up process, the composites were fabricated, and it was confirmed that the nanofiber was effective in improving the mechanical properties of natural fiber composites through tensile, bending and drop weight impact tests.

• Journal of Bio-Environment Control
• /
• v.5 no.1
• /
• pp.23-33
• /
• 1996

This study was performed to induce a quality improvement and standardization of materials used for greenhouse. For this purpose, physical and mechanical properties of agricultural films for greenhouse were measured by kinds and thickness of the films. The properties are composed of impact, tensile, tear propagation strength and light transmittance. The results were summarized as follows. 1. At the impact test result of the falling dart, the thicker the film, the greater the impact strength of soft film. The impact weight at 50 percents is from 158g to 213g and the strength of low density polyethylene(LDPE) film is higher than the rest of any other films. 2. Seeing the leveling of the impact rupture, maximum impact weight which was ruptured very little ranges from 62g to 192g. The impact strength of 0.1mm films was higher than that of 0.05mm as from 1.8 to 3.2 times. 3. Tensile weight covers from 0.95kg to 2.22kg in the test materials, and the weight of lengthwise film is larger than that of width. LDPE film has high value of tensile weight. Elongation range is from 345 to 102 percent and lengthwise elongation is greater than width as much as from 1.4 to 2.7 times. 4. Tea. propagation strength ranges from 80.5kg/cm to 121.7kg/cm, and unlike which of LDPE film has high value, EVA film has low value in the films tested. The width strength is higher than the lengthwise. 5. The light transmittance of the soft film is about 78-92 percent in the range of ultraviolet ray, but has high value in the visible ray range.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.40 no.6
• /
• pp.573-579
• /
• 2016

Studies on the deformation behavior of materials subjected to impact loads have been carried out in various fields of engineering and industry. The deformation and fracture of members for these machines/structures are known to correspond to the intermediate strain-rate region. Therefore, for the structural design, it is necessary to consider the dynamic deformation behavior in these intermediate strain-rate ranges. However, there have been few reports with useful data about the deformation and fracture behavior at intermediate strain-rate ranges. Because the intermediate strain-rate region is located between quasi-static and high strain-rate regions, it is difficult to obtain the intermediate strain-rate using conventional reasonable test equipment. To solve this problem, in this study, the measurement reliability of the constructed drop-bar impact tensile test apparatus was established and the dynamic behavior at the intermediate strain-rate range of carbon steels was evaluated by utilizing the apparatus.