• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.4
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• pp.96-100
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• 1997

Tensile properties of carbon fiber reinforce composite laminates with non-woven carbon mat are evaluated in this paper. Composite laminates are made by inserting non-wovon carbon mat between layers, The specimens were cut and polished according to ASTM standard . Longitudinal and Transverse Young's modulus are obtained by tensile test. Young's moduli without non-woven carbon mat are compared with those with non-woven carbon mat. Longitudinal and Transverse tensile strength are also investigated. Experimental results show that the transverse Young's modulus of composite materials with non-woven carbon mat is about 10% higher than that of composite materials without non-woven carbon mat. Longitudinal tensile strength of composite materials with non-woven carbon mat is about 24% higher than that of composite materials without non-woven carbon mat. Transverse tensile strength and torughness also increase by inserting non-woven carbon mat between layers.

• Journal of the Korean Wood Science and Technology
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• v.16 no.3
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• pp.48-64
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• 1988

This study was carried out to investigate the free vibrational properties of traditional and replaceable species for sounding board, using piezoelectrical accelerometer and signal analyzer. In the study, the frequency equations of free-free beam carrying a concentrated mass in the transverse vibration and of free-mass beam in the longitudinal vibration were used. The results obtained were as follows. 1. Average values of dynamic modulus of rigidity of Korean commercial species measured were as follows. Paulownia tomatosa (Thunb.) Steudel: $5.590\times10^9\;dyne/cm^2$ Tilia amurensis Rupr.: $5.414\times10^9\;dyne/cm^2$ Macckia amurensis Rupr.: $10.044\times10^9\;dyne/cm^2$ Fraxinus mandshurica Rupr.: $8.876\times10^9\;dyne/cm^2$ Ulmus davidiana var.japonica Nakai: $8.677\times10^9\;dyne/cm^2$ Pinus rigida Miller: $6.33\times10^9\;dyne/cm^2$ Fraxinus rhynchophylla Hance: $4.666\times10^9\;dyne/cm^2$ 2. The ratio of dynamic transverse Young's modulus to dynamic modulus of rigidity, $E_T/G_{LT}$, was 24.922 for Fraxinus rhynchophylla Hance, which was the highest, 7.317 for Paulownia tomentosa (Thunb.) Steudel, which was the lowest among Korean commercial species measured. 3. The value of longitudinal dynamic Young's modulus was about 3.7% and 19.8%, respectively, higher than those of transverse dynamic and static Young's modulus. The value of transverse dynamic Young's modulus was about 15.5% higher than that of static Young's modulus. 4. Predicted value of MOR in terms of correlation coefficient by transverse dynamic Young's modulus was slightly higher than that of static Young's modulus, but no significance was found out. 5. Transverse dynamic Youne's modulus was $(2.002\pm0.288)\times10^{11}\;dyne/cm^2$ for Fraxinus mandshurlca Rupr., which was the highest, $(0.601\pm0.100)\times10^{11}\;dyne/cm^2$ for Paulownia tomentosa (Thunb.) Steudel, which was the lowest among Korean commercial species measured. The sound velocity of sitka spruce was 5,685 m/sec, which was the highest. 6. Internal friction of Paulownia tomentosa (Thunb.) Steudel was shown the lowest value among Korean commercial species, $(8.795\pm1.795)\times10^{-3}$, but was higher than that of sitka spruce, $(7.331\pm0.991)\times10^{-3}$. Internal friction was shown negative correlation with density and dynamic Young's modulus, respectively. 7. K value was affected largely by internal friction and was the highest, $2.225\times10^8$ for Paulownia tomentosa (Thunb.) Steudel and was the lowest, $0.550\times10^8$ for Fraxinus rhynchophylla Hance. K value of Paulownia tomentosa (Thunb.) Steudel was higher than that of sitka spruce and K values of melapi and cottonwood, which have been considered to be replaceable species with sitka spruce in the piano industry, were lower than those of Paulownia tomentosa (Thunb.) Steudel and mill amurensis Rupr.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.04a
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• pp.45-52
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• 1997

The elastic deflection of thin ice sheets due In bending and shear deformation is considered. The in-plane Young's modulus and the transverse shear modulus are calculated by least squres fit of transverse plate deflection data. Results show that thin ice plates behave predominantly in shear. Previously, the Young's moduli were calaulated based on bending theory alone. The Young's moduli of thin model ice sheets, estimated using the bending and shear theory, are more than an order of magnitude greater than calculated previously, and hence are more realistic. Further, the previous ambiguity in the Young's modulus, arising from fitting the data at various distances from the point of loading, is removed by considering shear and bending deformation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.11
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• pp.1896-1911
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• 1997

Effects of fiber-matrix interphases on the micro-and macro-mechanical behaviors of unidirectionally fiber-reinforced composites subjected to transverse shear loading at remote distance have been studied. The interphases between fibers and matrix have been modeled by the spring-layer which accounts for continuity of tractions, but allows radial and circumferential displacement jumps across the interphase that are linearly related to the normal and tangential tractions. Numerical calculations for basic cells of the composites have been carried out using the boundary element method. For an undamaged composite the micro-level stresses at the matrix side of the interphase and effective shear stiffness have been computed as functions of fiber volume ratio $V_f$ and interphase stiffness k. Results are presented for various interphase stiffnesses from the perfect bonding to the case of total debonding. For a square array composite the results show that for a high interphase stiffness k>10, an increase of $V_f$ increases the effective transverse shear modulus G over bar of the composite. For a relatively low interphase stiffness k<1, it is shwon that an increase of $V_f$ slightly decreases the effective transverse shear modulus. For the perfect bonding case, G over bar for a hexagonal array composite is slightly larger than that for a square array composite. Also for a damaged composite partially debonded at the interphase, local stress fields and effective shear modulus are calculated and a decrease in G over bar has been observed.

• Advances in nano research
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• v.9 no.2
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• pp.83-90
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• 2020

This research investigates the effect of single walled carbon nanotubes (SWCNTs) dimensions in terms of diameter on the mechanical properties (longitudinal and transverse Young's modulus) of the simulated nanocomposites by molecular dynamics (MDs) method. MDs utilized to create nanocomposite models consisting of five case studies of SWCNTs with different chiralities (5, 0), (10, 0), (15, 0), (20, 0) and (25, 0) as the reinforcement and using polymethyl methacrylate (PMMA) as the common matrix. The results show that with increasing of SWCNTs diameter, the mechanical and physical properties increase. It is important that with the increasing of SWCNTs diameter, density, longitudinal and transverse Young's modulus, shear modulus, poisson's ratio, and bulk modulus of simulated nanocomposite from (5, 0) to (25, 0) approximately becomes 1.54, 3, 2, 1.43, 1.11 and 1.75 times more than (5, 0), respectively. Then to validate the results, the stiffness matrix is obtained by Materials studio software.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.92-93
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• 2015

The main purpose of this paper is to present the dynamic test method developed for measuring the elastic modulus of sound insulating coat. The test setup was devised based on the theoretical natural frequency of a simply-supported beam subject to free transverse vibration. A stainless steel beam was tested and the result showed a good compliance with the standard value listed in literatures. The result indicates that the test set up can serve as a quick, economical and suitable scheme to test non self-supporting materials.

• Journal of Industrial Technology
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• v.19
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• pp.245-251
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• 1999

The joint in the concrete pavement provides a control against transverse or longitudinal cracking at slab, which may be caused by temperature or moisture variation during or after hydration. Without control of cracking, random crack may cause more serious distresses and result in structural or functional failure of pavement system. Sometimes, joint itself, purposed to control crack, may cause a distresses in joint due to its inherent weakness in structural integrity. Thus, the load transfer capacity in joint is very important for serviceability and durability. The purpose of this dissertation was to develop an evaluation system at joints of jointed concrete pavement using finite element analysis was performed using ILLI-SLAB program with a selected variables which might affect fairly to on the performance of transverse joints. The most significant variables were selected from precise analysis. It was concluded that the variables which most significantly affect to pavement deflections are the modulus of subgrade reaction(K) and the modulus of dowel/concrete interaction(G), and limiting criteria on the performance of joints at JCP at 300pci, 500,000 lb/in. respectively.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.6
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• pp.589-598
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• 2001

The fracture of acrylic resin dentures remains an unsolved problem. Therefore, many investigations have been performed and various approaches to strengthening acrylic resin, for example, the reinforcement of heat-cured PMMA resin using glass fibers, have been suggested over the years. The aim of the present study was to investigate the effect of short glass fibers treated with silane coupling agent on the transverse strength of heat-polymerized PMMA denture base resin. To avoid fiber bunching and achieve even fiber distribution, glass fiber bundles were mixed with PMMA powder in conventional mixer whose blade was modified to be blunt. Composite of glass fiber($11{\mu}m$ diameter, 3mm & 6mm length, silane treated) and PMMA resin was made. Transverse strength and Young's modulus were estimated. Glass fibers were incorporated with 1%, 3%, 6% and 9% by weight. Plasticity and workability of dough was evaluated. Fracture surface of specimens was investigated by SEM. The results of this study were as follows 1. 6% and 9% incorporation of 3mm glass fibers in the PMMA resin enhanced the transverse strength of the test specimens(p<0.05). 2. 6% incorporation of 6mm glass fibers in the PMMA resin increased transverse strength, but 9% incorporation of it decreased transverse strength(p<0.05). 3. When more than 3% of 3mm glass fibers and more than 6% of 6mm glass fibers were incorporated, Young's modulus increased significantly(p<0.05). 4. Workability decreased gradually as the percentage of the fibers increased. 5. Workability decreased gradually as the length of the fibers increased. 6. In SEM and LM, there was no bunching of fibers and no shortening of fibers.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.2
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• pp.407-412
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• 1990

Elastic modulus of unidirectional short fiber composite has theoretically derived with the consideration of Poisson's ratios of matrix and fiber. Unidirectional short fiber composite is modeled as an aggregate of grains developed by Kerner. Under the assumption of extra strain at fiber ends, the strain distribution along the fiber's length is determined, and the elastic modulus is derived from this distribution. For the consideration of effects of Poisson's ratio, Kerner's results for particulate composites are adapted as boundary conditions. The effect of differences in Poisson's ratio of fiber and matrix on elastic modulus is studied. Proposed equation shows a good agreement with experimental data of Halpin and Tock, et al.

• Composites Research
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• v.23 no.1
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• pp.17-22
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• 2010

The compressive and dynamic properties of magnetorheological elastomers were investigated as functions of magnetizable particle volume fraction, alignment of the embedded particle and magnetic force. The specimens consisted of pure and filled silicons with randomly dispersed, longitudinal and transverse aligned magnetizable particle chains. To align the embedded particles in the elastomer, the cross-linking of the elastomer composites took place in a magnetic field. The compression and dynamic tests in the absence and the presence of different magnetic forces were carried out. The modulus and loss factor of the elastomer composites increase with increasing volume fraction at the same magnetic force. The case of longitudinal alignment shows a high modulus and loss factor when compared to the case of transverse alignment or random dispersion.