• Steel and Composite Structures
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• v.22 no.5
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• pp.975-999
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• 2016

This work investigates a thermomechanical bending analysis of functionally graded sandwich plates by proposing a novel quasi-3D type higher order shear deformation theory (HSDT). The mathematical model introduces only 5 variables as the first order shear deformation theory (FSDT). Unlike the conventional HSDT, the present one presents a novel displacement field which includes undetermined integral variables. The mechanical properties of functionally graded layers of the plate are supposed to change in the thickness direction according to a power law distribution. The core layer is still homogeneous and made of an isotropic ceramic material. The governing equations for the thermomechanical bending investigation are obtained through the principle of virtual work and solved via Navier-type method. Interesting results are determined and compared with quasi-3D and 2D HSDTs. The influences of functionally graded material (FGM) layer thickness, power law index, layer thickness ratio, thickness ratio and aspect ratio on the deflections and stresses of functionally graded sandwich plates are discussed.

• Steel and Composite Structures
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• v.32 no.5
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• pp.611-632
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• 2019

In this work, a four-variable refined plate model is applied to study the thermomechanical bending of two kinds of functionally graded material (FGM) sandwich plates. The sandwich core of one kind is isotropic with the FGM face sheets whereas in the second kind, the sandwich core is FGM with the isotropic and homogeneous face sheets. By considering only four unknown variables, the governing equations are written based on the principle of virtual work and then Navier method is employed to solve these equations. Deflections and stresses of two kinds of FGM sandwich structures are analyzed and discussed. The validity and efficiency of the proposed model is checked by comparing it with various available solutions in the literature. The effects of volume fraction distribution, geometric ratio and thermal load on thermomechanical bending properties of FGM sandwich plate are investigated in detail.

• Journal of Adhesion and Interface
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• v.18 no.2
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• pp.68-74
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• 2017

Epoxy resins are widely used in various fields due to their excellent thermal, mechanical and chemical properties. In order to improve the mechanical properties of the epoxy composition after curing, various materials are mixed in the epoxy resin. Among the nano materials, CNT is the most widely used. However, CNT has limitations in terms of manufacturing process and manufacturing cost. Therefore, there is a growing interest in naturally occurring HNTs having similar structure to that of CNT. In this study, the thermal and mechanical properties of epoxy compositions containing HNTs treated with two types of silane compounds were investigated. The mechanical properties of silane-treated HNT were measured by using a universal testing machine. The differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), and thermomechanical analysis (TMA) were used to measure thermal properties. As a result of the above tests, when the HNT was surface-treated with aminosilane, the tensile strength of the epoxy composition containing the HNT was higher than that of the epoxy composition containing epoxy silane treated HNT. The linear thermal expansion coefficients (CTE) obtained from the thermomechanical analysis of the two epoxy compositions for the comparison of dimensional stability showed that the HNT composition treated with aminosilane showed a lower value of CTE than that of epoxy composition including the pristine HNT.

• The Korean Journal of Ceramics
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• v.2 no.4
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• pp.246-250
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• 1996

The thermomechanical properties of materials from the system Al2O3-SiO2-TiO2(Tialite-Mullite) were investigated by correlating the thermal expansion anisotroypy, flexural strength and Young's modulus with grain size and atructural microcracking during cooling. Microcracking temperatures were determined by measuring the hysteresis of the thermal expansion anisotropy with dilatometry. Single phase Aluminium Titanate is a low strength material, while composites with more than 10 vol% mullite as second phase enhance the Young's modulus, thermal expansion coefficient and room temperature strength.

• Fibers and Polymers
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• v.5 no.1
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• pp.19-24
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• 2004

PET yarns textured at different texturing conditions were treated with superheated steam or dry heat at different temperatures for different times. The effects of the treatment conditions on the thermomechanical and structural changes of the yarn were examined by shrinkage, X-ray diffraction and birefringence measurements. With increase in superheated steam temperature, the crystalline orientation factor and birefringence decreased, whereas crystal size increased. Dry heat treatment had a smaller effect on shrinkage and structural properties in comparison with superheated steam treatment. The additional shrinkage after texturing process was investigated. The effect of heat-setting in both media was more significant at $200^{\circ}C$. The time dependence of the properties was not linear.

• Journal of the Korean Society for Heat Treatment
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• v.3 no.1
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• pp.8-16
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• 1990

Effects of thermomechanical treatments(TMT) on the microstructures and mechanical properties in Al-2.27%, Li-1.28%, Cu-0.63%, Mg-0.12%, Zr alloy were investigated. The TMT process improved the tensile strength. Growth of ${\delta}^{\prime}$, S' and $T_1$ phases was restrained by TMT processes while the density of ${\delta}^{\prime}$, S' and $T_1$ phases was increased by TMT processes. The TMT treated specimens tend to fail in inter-subboundary mode. The increases of strength by the T-HA processes were compared to those of the T-AHA processes.

• Proceedings of the Materials Research Society of Korea Conference
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• 1994.11a
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• pp.182-182
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• 1994

• Proceedings of the Korean Nuclear Society Conference
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• 2005.05a
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• pp.455-456
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• 2005

• Proceedings of the Korean Fiber Society Conference
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• 2000.04a
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• pp.101-104
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• 2000

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.48 no.2
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• pp.28-33
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• 2016

This study was conducted to investigate the effects of deep eutectic solvent (DES) treatment on properties of TMP fibers and handsheets. DES was prepared by mixing of lactic acid and betaine (L and B), and the molar ratio of these two components mixtures was controlled to 2:1 (L:B=2:1) and 5:1 (L:B=5:1). As results, lignin was partly extracted from the TMP fibers. Especially, the delignification of TMP samples was promoted according to the increase of the molar ratio of lactic acid. Except for tear index, both tensile index and burst index of handsheets were increased when higher molar ratio of lactic acid was mixed for DES preparation. However, the LB DES treatment of TMP fibers didn't give any effect on the optical properties of TMP handsheets. The plausibility of TMP fiber was to be enhanced by LB DES treatment.