• Geomechanics and Engineering
• /
• v.16 no.2
• /
• pp.125-140
• /
• 2018

Tianjin, which is located on the west shore of the Bohai Sea, is part of China's Circum-Bohai-Sea Region, where very weak clay is deposited. From the 1970s to the early $21^{st}$ century, Tianjin marine clay deposits have been the subject of numerous geotechnical investigations. Because of these deposits' geological complexity, great depositional thickness, high water content, large void ratio, excessive settlement, and low shear strength, the geotechnical properties of Tianjin marine clay need to be summarized and evaluated based on various in situ and laboratory tests so that Tianjin can safely and economically sustain more infrastructure in the coming decades. In this study, the properties of Tianjin marine clay, especially its consolidation properties, are summarized, evaluated and discussed. The focus is on establishing correlations between the geotechnical property indexes and mechanical parameters of Tianjin marine clay. These correlations include the correlations between the water content and the void ratio, the depth and the undrained shear strength, the liquid limit and the compression index, the tip resistance and the constrained modulus, the plasticity index and the ratio of undrained shear strength and the preconsolidation pressure. In addition, the primary consolidation properties of Tianjin marine clay, such as the intrinsic compression line (ICL), sedimentation compression line (SCL), compression index, $C_c$, coefficient of consolidation, $C_v$, and hydraulic conductivity change index, $C_{kv}$, are evaluated and discussed. A secondary consolidation property, i.e., the secondary compression index, $C_a$, is also investigated, and the results show that the ratio of $C_a/C_c$ for Tianjin marine clay can be used to calculate $C_a$ in secondary consolidation settlement predictions.

• Macromolecular Research
• /
• v.12 no.1
• /
• pp.119-126
• /
• 2004

In this study, the influence of silane coupling agents, featuring different organo-functional groups on the interlaminar and thermal properties of woven glass fabric-reinforced nylon 6 composites, has been by means of short-beam shear tests, dynamic mechanical analysis, scanning electron microscopy, and thermogravimetric analysis. The results indicate that the fiber-matrix interfacial characteristics obtained using the different analytical methods agree well with each other. The interlaminar shear strengths (ILSS) of glass fabric/nylon 6 composites sized with various silane coupling agents are significantly improved in comparison with that of the composite sized commercially. ILSS of the composites increases in the order: Z-6076 with chloropropyl groups in the silanes > Z-6030 with methacrylate groups> Z-6020 with diamine groups; this trend is similar to that of results found in an earlier study of interfacial shear strength. The dynamic mechanical properties, the fracture surface observations, and the thermal stability also support the interfacial results. The improvement of the interfacial properties may be ascribed to the different chemical reactivities of the reactive amino end groups of nylon 6 and the organo-functional groups located at the ends of the silane chains, which results from the increased chemical reactivity in order chloropropyl > methacrylate > diamine.

• Korean Journal of Metals and Materials
• /
• v.50 no.1
• /
• pp.71-77
• /
• 2012

We studied the effect of heat treatment on the microstructures and mechanical strength of the solder joints in the Light Emitting Diode (LED) packages. The commercial LED packages were mounted on the a flame resistance-4 (FR4) Printed Circuit Board (PCB) in the reflow process, and then the joints were aged at $125^{\circ}C$ for 100, 200, 300, 500 and 1000 hours, respectively. After the heat treatment, we measured the shear strength of the solder joints between the PCB and the LED packages to evaluate their mechanical property. We used Pb-free Sn-3.0Ag-0.5Cu solder to bond between the LED packages and the PCBs using two different surface finishes, Electroless Nickel-Immersion Gold (ENIG) and Electroless Nickel-Electroless Palladium-Immersion Gold (ENEPIG). The microstructure of the solder joints was observed by a scanning electron microscope (SEM). (Cu,Ni)6Sn5 intermetallic compounds (IMCs) formed between the solder and the PCB, and the thickness of the IMCs was increased with increasing aging time. The shear strength for the ENIG finished LED package increased until aging for 300 h and then decreased with increasing aging time. On the other hand, in the case of an ENEPIG finished LED package, the shear strength decreased after aging for 500 h.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.18 no.5
• /
• pp.41-50
• /
• 2014

This study evaluated the bonding property of fiber and flexural behavior of fiber reinforced concrete. Amorphous steel fiber, hooked steel fiber and polyamide fiber was used for evaluation of bonding property and flexural behavior. As a result, the hooked steel fiber was pulled out from matrix when peak stress. However amorphous steel fiber occurred shear failure because bonding strength between fiber and matrix was higher than tensile strength of fiber. Polyamide fibers occurred significantly displacement to peak stress because of elongation of fiber. After that peak stress, fiber was cut off. Amorphous steel fiber reinforced concrete had a greater maximum flexural load compared with hooked steel fiber reinforced concrete because bonding performance between fiber and matrix was high and mixed population of fiber was many. However flexural stress was rapidly reduced in load-deflection curve because of shear failure of fiber. Flexural stress of hooked steel fiber reinforced concrete was slowly reduced because fiber was pulled out from the matrix. In the case of polyamide fiber reinforced concrete, flexural stress was rapidly lowered because of elongation of fiber. However flexural stress was increased again because of bonding property between polyamide fiber and matrix. The pull-out properties of the fiber and matrix has effect on the deformation capacity and flexural strength of fiber reinforced concrete.

• Polymer(Korea)
• /
• v.39 no.3
• /
• pp.514-521
• /
• 2015

In this study, we would like to describe peel strength and dynamic shear property on various substrates of multi-layered structural double-sided adhesive tape with or without adhesive (AD) prepared by UV curing for an automobile, construction, and display junction. According to adapt the adhesive, the peel and dynamic shear strength of adhesion tape prepared with acrylic foam or various plastic substrates increased with increasing molecular weight, however, decreased over 650000 molecular weight. The adhesion property shows high value at the thin AD layer with decreasing temperature. The interface property shows highest at MW 615000 (AD-4), and the interface junction below MW 615000 resulted to divide from acrylic foam and adhesive layer. From this study, the multi-layered structural double-sided adhesive tapes seem to be a useful for industrial area such as a low surface energy plastic material and curved substrate.

• Korean Journal of Materials Research
• /
• v.24 no.11
• /
• pp.625-631
• /
• 2014

To investigate the deformation properties of TiC-(5-20) mol% Mo solid solution single crystals at high temperature by compression testing, single crystals of various compositions were grown by the radio frequency floating zone technique and were deformed by compression at temperature from 1250K to 2270K at strain rates from $5.1{\times}10^{-5}$ to $5.9{\times}10^{-3}/s$. The plastic flow property of solid solution single crystals was found to be clearly different among a three-temperature range (low, intermediate and high temperature ranges) whose boundaries were dependent on the strain rate. From the observed property, we conclude that the deformation in the low temperature range is controlled by the Peierls mechanism, in the intermediate temperature range by the dynamic strain aging and in the high temperature range by the solute atmosphere dragging mechanism. The work softening tends to become less evident with an increasing experimental temperature and with a decreasing strain rate. The temperature and strain rate dependence of the critical resolved shear stress is the strongest in the high temperature range. The curves are divided into three parts with different slopes by a transition temperature. The critical resolved shear stress (${\tau}_{0.2}$) at the high temperature range showed that Mo content dependence of ${\tau}_{0.2}$ with temperature and the dependence is very marked at lower temperature. In the higher temperature range, ${\tau}_{0.2}$ increases monotonously with an increasing Mo content.

• Composites Research
• /
• v.34 no.5
• /
• pp.305-310
• /
• 2021

Mechanical properties of fiber reinforced composites were affected to fiber volume fractions (FVF) and interfacial property by sizing agent conditions. An optimum interface can relieve stress concentration by transferring the mechanical stress from the matrix resin to the reinforcements effectively, and thus can result in the performance of the composites. The interfacial properties and wettability between the epoxy resin and glass fiber (GF) were evaluated for different sizing agent conditions and FVFs. The surface energies of epoxy resin and different sizing agent treated GFs were calculated using dynamic and static contact angle measurements. The work of adhesion, W_a was calculated by using surface energies of epoxy matrix and GFs. The wettability was evaluated via the GF tow capillary test. The interfacial shear strength (IFSS) was evaluated by microdroplet pull-out test. Finally, the optimized GFRP manufacturing conditions could be obtained by using wettability and interfacial property.

• The Korean Fashion and Textile Research Journal
• /
• v.16 no.6
• /
• pp.1008-1016
• /
• 2014

This study aims to analyze the changes in the mechanical properties of woven fabrics(cotton, linen, wool, silk, and polyester) by bonding fusible interlinings with varying deniers(10D, 20D, and 30D) for a 3D virtual try-on system(one that a user to try garments through screens using Avatar) developed over the last decade. We experimented with four mechanical properties and thicknesses of twenty-three specimens of interlining bonded fabrics including face fabrics and interlinings by using the KES-FB-AUTO system. The results showed that the tensile property increased(LT and RT increased and WT decreased) as the denier of the interlining increased; however, the change was slight. In contrast, the bending and shear properties increased significantly as the denier of the interlining increased on both the warp and the weft. This showed evidence that the interlining gives the fabrics size stability. The compression property was slight changed as the tensile property varies depending on the fibers and the denier of interlining. As expected, the thickness increased by bonding the interlining as the denier of interlining increased. From these results, we conclude that 3D users need to reflect these changes of woven fabrics by bonding interlinings when they try screen fittings to accurately express the fabric reality of manufactured garment.

• The Korean Fashion and Textile Research Journal
• /
• v.19 no.2
• /
• pp.240-248
• /
• 2017

This study compares general jacquard fabrics and jacquard fabrics with optical fiber on mechanical properties, sensibility and preference evaluation of fabric for the blind. The analysis also assesses the effect of optical fiber in the evaluation and identifies those best suited for consumers. The mechanical properties of jacquard fabrics were measured by the KES-FB system. Sensibility and the preference of the jacquard fabric for the blind were rated on tactile sensation by women experts in their 20's and 30's. It was found that the optical fiber in jacquard fabric affected the change of mechanical properties as well as sensibility and preference. Jacquard fabric with optical fiber were softer and more transformable, while the fabrics had lower recover property by shear force and compression as well as more violent unevenness. Jacquard fabrics were also classified into three hand factors of surface property, resilience and weightiness. There were significant differences on surface property perceptions and weightiness, hand and blind preferences by optical fiber. Jacquard fabrics that contained optical fiber were not preferred by the blind because they were perceived to be uneven and heavy. Those, that were smooth and light, were preferred for jacquard fabric; in addition, fabrics preferred by the blind had good compression.

• Journal of Adhesion and Interface
• /
• v.6 no.4
• /
• pp.12-17
• /
• 2005

Natural fiber/phenolic biocomposites with chopped henequen fibers treated at various levels of electron beam irradiation (EBI) were made by means of a matched-die compression molding method. The interfacial property was explored in terms of interfacial shear strength measured by a single fiber microbonding test. The thermal properties were studied in terms of storage modulus, tan ${\delta}$, thermal expansion and thermal stability measured by dynamic mechanical analysis, thermomechanical analysis and thermogravimetric analysis, respectively. The result showed that the interfacial and thermal properties depend on the treatment level of EBI done to the henequen fiber surfaces. The present result also demonstrates that 10 kGy EBI is most preferable to physically modify the henequen fiber surfaces and then to improve the interfacial property of the biocomposite, supporting earlier results studied with henequen/poly (butylene succinate) and henequen/unsaturated polyester biocomposites.