• Structural Engineering and Mechanics
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• v.49 no.2
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• pp.273-283
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• 2014

According to deformation features of pre-twisted bar, its elastic bending and torsion buckling equation is developed in the paper. The equation indicates that the bending buckling deformations in two main bending directions are coupled with each other, bending and twist buckling deformations are coupled with each other as well. However, for pre-twisted bar with dual-axis symmetry cross-section, bending buckling deformations are independent to the twist buckling deformation. The research indicates that the elastic torsion buckling load is not related to the pre-twisted angle, and equals to the torsion buckling load of the straight bar. Finite element analysis to pre-twisted bar with different pre-twisted angle is performed, the prediction shows that the assumption of a plane elastic bending buckling deformation curve proposed in previous literature (Shadnam and Abbasnia 2002) may not be accurate, and the curve deviates more from a plane with increasing of the pre-twisting angle. Finally, the parameters analysis is carried out to obtain the relationships between elastic bending buckling critical capacity, the effect of different pre-twisted angles and bending rigidity ratios are studied. The numerical results show that the existence of the pre-twisted angle leads to "resistance" effect of the stronger axis on buckling deformation, and enhances the elastic bending buckling critical capacity. It is noted that the "resistance" is getting stronger and the elastic buckling capacity is higher as the cross section bending rigidity ratio increases.

• Proceedings of the Korean Fiber Society Conference
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• 1986.06a
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• pp.22-22
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• 1986

• Journal of Fashion Business
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• v.12 no.6
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• pp.61-72
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• 2008

The UV-protection effect of green-tea dyed fabrics was reported in our previous studies. The chitosan was used as a natural mordant of cellulose fiber for green tea extract because chitosan is a natural bio-polymer. The increase in the UV protection property of summer cellulose fabrics, cotton and linen, upon the repetition of chitosan mordanting and green tea dyeing was observed. However, the physical property change would be followed by this repeated wet processing of the cellulose fabric. Therefore, the physical changes of the chitosan mordanted and green tea dyed cotton and linen fabrics were evaluated by KES-FB system. Tensile, shear, bending, compression, and surface characteristics were tested upon the repetition of mordanting and dyeing treatments. Linearity of tensile force increased in the treated cotton and linen samples. Tensile energy and resilience decreased in all treated fabrics. Shear stiffness increased in the treated cotton and linen in general. Shear hysteresis was increased in all cotton samples and some linen samples. In cotton, the bending rigidity in all treated cottons increased except C3G3. As the chitosan mordanting numbers increased, the bending rigidity tended to decrease. In linen, the bending rigidity and hysteresis increased in all treated samples. Compressional energy and resilience increased as the number of chitosan mordanting increased both in cotton and linen. This could be the result of the increase in thickness upon chitosan mordanting. Surface coefficient of friction increased in the treated cotton and linen in general. Surface roughness tended to increase in cotton.

• Fashion & Textile Research Journal
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• v.6 no.5
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• pp.660-666
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• 2004

This article describes the change of hand value of chitosan crosslinked cotton fabrics. The chitosan crosslinked cotton fabrics were manufactured by mercerizing process using epichlorohydrin(ECH) as crosslinkins agent, 2% aqueous acetic acid as a solvent of chitosan and ECH, and 20% aqueous sodium hydroxide as a mercerizing agent and crosslinking catalyst. Cotton fabrics were dipped in the mixed solution of chitosan and ECH, picked up by mangle, mercerized and crosslinked in NaOH solution, and finally wash and dry. Mechanical and physical properties of the chitosan crosslinked fabric were investigated using Kawabata Evaluation System(KES) and other instruments. Tensile energy and tensile strain were decreased with the increase of the concentration of chitosan. Tensile resilience, compression resilience bending rigidity, bending hysteresis, shear stiffness, shear hysteresis, coefficient of friction, geometrical roughness, compression linearity, compressional energy, and thickness were increased with the increase of the concentration of chitosan. On the other hand, bending rigidity, bending hysteresis, coefficient of friction, geometrical roughness, compressional resilience, and thickness were increased with the increase of the concentration of crosslinking agent(epichlorohydrin).

• Journal of Fashion Business
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• v.8 no.5
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• pp.31-40
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• 2004

The purpose of this study is to investigate the change of the physical properties, bending and luster properties, which are related to the touch and appearance of silk fabrics modified by the degumming process. The silk has long been known as one of the most elegant and soft textile materials. The raw silk yarn, or cocoon bave, spun from the spinneret, is rather stiff due to the sericin covering the two fibroins together. The sericin can be removed during a degumming process. The removal of the sericin would result in remarkable change in the physical properties of the raw silk fabrics, including luster of the fabrics, which process parameters could possibly be utilized to adequately control the silk fabric properties. The KES(Kawabata Evaluation System) is a testing methodology that has been used with considerable success for predicting the hand and tailorability of apparel fabrics. This study uses one of the KES, bending tester, to measure the bending properties of the silk fabrics degummed for specified period to change the physical/mechanical properties of the fabric. The KES bending measurement revealed that the bending rigidity decreased for both the warp and weft direction of the silk fabrics with the increase of the degumming period. It has been shown in this study that the some of the hand-related physical properties, including the bending rigidity, drapability, and luster, could be modified with the change in the degumming period.

• Journal of the Korean Home Economics Association
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• v.26 no.1
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• pp.11-19
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• 1988

Bending properties of 168 commercial silk fabrics and polyester fabrics for korean women's clothes were tested by KES-F system. Samples were classified into for summer, fall & winter fabrics. In this study, bending regidity(B) and bending hysteresis(2HB) were measured, then 2HB/W, {{{{ SQRT { 2HB/W} }}}}, 2HB/B which are concerning to formation of weared clothes and transformation behavior were investigated. fabrics for korean women's silk clothes for fall & winter were compared with fabrics for japanese kimono clothes on the bending properties. The results were as follows : 1. The bending regidity of silk fabrics were higher than polyester fabrics and bending hysteresis of fall & winter fabrics were higher than summer fabrics. 2. The 2HB/W and {{{{ SQRT { 2HB/W} }}}} of polyester fabrics were lower than silk fabrics. 3. the silk fabrics for summer clothes were the least in 2HB/B. 4. Silk fabrics for korean women's clothes were almost the same in bending rigidity, bending hysteresis and thickness of fabrics for japanese kimono clothes, but weight of the silk fabrics were lower to fabrics for jpanese kimono clothes.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.11
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• pp.95-99
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• 2008

Applications of composite materials in various engineering fields have been extended significantly. For being useful composite materials, we could modify the rigidity and strength characteristics of composite material according to structures and material direction. In this study, CFRP, which has been widely used in space leisure and general structural applications due to the weight, elasticity coefficient, high fatigue strength and lower thermal transformation ect, was selected. As the CFRP is an anisotropic material whose mechanical properties change with its stacking sequence or angle, special attention was given to the effects of the fiber orientation angle on the bending characteristics of CFRP fiat and CFEP square members. It's different on the each result of strength and rigidity of CFRP flat and CFRP square members.

• Journal of the Korean Society of Clothing and Textiles
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• v.21 no.6
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• pp.1041-1050
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• 1997

This study was carried out to improve the thermal insulation properties of wool and wool- like fabrics by treating the fabrics with polyethylene glycol, to evaluate the fabric hand of PEG treated wool and wool-like fabrics and to grade up the fabric hand of the treated fabrics by treating with softening agents. Wool and wool-like fabrics were treated with high molecular PEG-8,000 by PDC. The thermal release/storage properties were measured on a DSC. Hand of specimens were evaluated by KES-FB system. The results were as follows; 1. PEG-treated fabrics showed thermal storage and thermal release properties by DSC and the heat contents were generally proportional to the add-ons. 2. PEG-treated fabrics showed higher Koshi and lower Numeri and Sofutosa values due to lower tensile energy and recovery and higher bending rigidity and shear stiffness as the add- ons increased. 3. PEG-treated fabrics showed much lower bending rigidity after softening agents treatment.

• Advances in concrete construction
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• v.9 no.3
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• pp.301-312
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• 2020

This research deals with the study of the orthotropic vibrational features of single-walled carbon nanotubes according to Kelvin's model and to check the accuracy of the models, the results have been compared with earlier modeling/simulations. Obtaining rough approximations of the natural frequencies of CNTs using continuum equations are still a common procedure, even at high harmonics. The effects of different physical and material parameters on the fundamental frequencies are investigated for zigzag and chiral single-walled carbon nanotubes invoking Kelvin's theory. By using nonlocal Kelvin's model, the fundamental natural frequency spectra for two forms of single-walled carbon nanotubes (SWCNTs) have been calculated. The influence of frequencies with nonlocal parameters and bending rigidity are investigated in detail for these tubes. Computer software MATLAB is utilized for the frequencies of SWCNTs and current results shows a good stability with comparison of other studies.

• Textile Coloration and Finishing
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• v.10 no.2
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• pp.1-7
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• 1998

In this study, PET fabric was hydrolyzed with NaOH using the Tank m/c and Liquor-flow m/c to determine the alkali hydrolysis properties of PET fabrics. The results were as follows ： The weft density and tensile strength of PET fabrics hydrolyzed with Liquor-flow m/c were higher than those hydrolyzed with Tank m/c in case of less than 10％ of weight loss. However, above 10％ of weight loss, reverse phenomenon was showed. K/S value of hydrolyzed PET with Liquor-flow m/c was higher than that with Tank m/c above 10％ of weight loss. It was observed that the micropores of PET surface were collapsed due to physical force(abrasion and collision) during hydrolysis. Bending rigidity of hydrolyzed PET fabric was about 32％ and 40％ of bending rigidity of warp and weft direction of untreated fabric at 7％ of weight loss, respectively. Above 7％ of weight loss, decrease rate was decreased.