• Title, Summary, Keyword: softening

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Softening Analysis of Reinforced Concrete Frames (철근콘크리트 골조의 연성화 해석)

  • 나유성;홍성걸
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.438-443
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    • 1998
  • Softening os the name used for decreasing bending moment at advanced flexural deformation. To accommodate softening deformation in analysis, it is assumed that a hinge has finite length. The softening analysis of R/C frames relies on the primary assumption that softening occurs over a finite hinge length and that the moment-curvature relationship for any section may be closely described by a trilinear approximation. A stiffness matrix for elastic element with softening regions are derived and the stiffness matrix allows extension of the capability of an existing computer program for elastic-plastic analysis to the softening situation. The effect of softening on the collapse load of R/C frame is evaluated.

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Rate of softening and sensitivity for weakly cemented sensitive clays

  • Park, DongSoon
    • Geomechanics and Engineering
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    • v.10 no.6
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    • pp.827-836
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    • 2016
  • The rate of softening is an important factor to determine whether the failure occurs along localized shear band or in a more diffused manner. In this paper, strength loss and softening rate effect depending on sensitivity are investigated for weakly cemented clays, for both artificially cemented high plasticity San Francisco Bay Mud and low plasticity Yolo Loam. Destructuration and softening behavior for weakly cemented sensitive clays are demonstrated and discussed through multiple vane shear tests. Artificial sensitive clays are prepared in the laboratory for physical modeling or constitutive modeling using a small amount of cement (2 to 5%) with controlled initial water content and curing period. Through test results, shear band thickness is theoretically computed and the rate of softening is represented as a newly introduced parameter, ${\omega}_{80%}$. Consequently, it is found that the softening rate increases with sensitivity for weakly cemented sensitive clays. Increased softening rate represents faster strength loss to residual state and faster minimizing of shear band thickness. Uncemented clay has very low softening rate to 80% strength drop. Also, it is found that higher brittleness index ($I_b$) relatively shows faster softening rate. The result would be beneficial to study of physical modeling for sensitive clays in that artificially constructed high sensitivity (up to $S_t=23$) clay exhibits faster strain softening, which results in localized shear band failure once it is remolded.

Changes in Cell Wall Components and Cell Wall-degrading enzymes during Softening of Fruits (과실의 연화중에 세포벽 성분과 세포벽분해효소의 변화)

  • 신승렬;김광수
    • Korean Journal of Food Preservation
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    • v.3 no.1
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    • pp.93-104
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    • 1996
  • The cell wall components of fruit include cellulose. hemicellulose, pectin, glycoprotein etc., and the cell wall composition differs according to the kind of fruit. Fruit softening occurs as a result of a change in the cell wall polysaccharides : the middle lamella which links primary cell walls is composed of pectin. and primary cell walls are decomposed by a solution of middle lamella caused due to a result of pectin degradation by pectin degrading enzymes during ripening and softening, During fruit ripening and softening, contents of arabinose and galactose among non-cellulosic neutral sugars are notably decreased, and this occurs as a result of the degradation of pectin during fruit repening and softening since they are side-chained with pectin in the form of arabinogalactan and galactan Enzymes involved in the degradation of the cell wall include polygalacturonase, cellulose, pectinmethylesterase, glycosidase, etc., and various studies have been done on the change in enzyme activities during the ripening and softning of fruit. Among cell wall-degrading enzymes, polygalacturonase has the greatest effect on fruit softening, and its activity Increases during the maturating and softening of fruit. This softening leads to the textural change of fruit as a result of the degradation of cell wall polysaccharides by a cell wall degrading enzyme which exists in fruit.

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A softening hyperelastic model and simulation of the failure of granular materials

  • Chang, Jiangfang;Chu, Xihua;Xu, Yuanjie
    • Geomechanics and Engineering
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    • v.7 no.4
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    • pp.335-353
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    • 2014
  • The softening hyperelastic model based on the strain energy limitation is of clear concepts and simple forms to describe the failure of materials. In this study, a linear and a nonlinear softening hyperelastic model are proposed to characterize the deformation and the failure in granular materials by introducing a softening function into the shear part of the strain energy. A method to determine material parameters introduced in the models is suggested. Based on the proposed models the numerical examples focus on bearing capacity and strain localization of granular materials. Compared with Volokh softening hyperelasticity and classical Mohr-Coulomb plasticity, our proposed models are able to capture the typical characters of granular materials such as the strain softening and the critical state. In addition, the issue of mesh dependency of the proposed models is investigated.

Remaining life prediction of concrete structural components accounting for tension softening and size effects under fatigue loading

  • Murthy, A. Rama Chandra;Palani, G.S.;Iyer, Nagesh R.
    • Structural Engineering and Mechanics
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    • v.32 no.3
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    • pp.459-475
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    • 2009
  • This paper presents analytical methodologies for remaining life prediction of plain concrete structural components considering tension softening and size effects. Non-linear fracture mechanics principles (NLFM) have been used for crack growth analysis and remaining life prediction. Various tension softening models such as linear, bi-linear, tri-linear, exponential and power curve have been presented with appropriate expressions. Size effect has been accounted for by modifying the Paris law, leading to a size adjusted Paris law, which gives crack length increment per cycle as a power function of the amplitude of a size adjusted stress intensity factor (SIF). Details of tension softening effects and size effect in the computation of SIF and remaining life prediction have been presented. Numerical studies have been conducted on three point bending concrete beams under constant amplitude loading. The predicted remaining life values with the combination of tension softening & size effects are in close agreement with the corresponding experimental values available in the literature for all the tension softening models.

Ultimate Compressive Strength Analysis of TMCP High Tensile Steel Plates with HAZ Softening(2nd Report) (HAZ 연화부를 가진 TMCP형 고장력강판의 압축최종강도에 관한 연구 - 제 2 보)

  • 백점기;고재용
    • Journal of Welding and Joining
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    • v.9 no.2
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    • pp.44-50
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    • 1991
  • The use of high tensile steel plates is increasing in the fabrication of ship and offshore structures. The softening region which has lower yield stress than base metal is located to prevent cracking in the conventional high tensile steel. Also, thermo mechanical control process(TMCP) steel with low carbon equivalent has the softening region which occurs in the heat affected zone when high heat input weld is carried out. The softening region in the high tensile steel gives rise to serious effect on structural strength such as tensile strength, fatigue strength and ultimate strength. In order to make a reliable structural design using high tensile steel plates, the influence of the softening on plate strength should be evaluated in advance. In the previous paper, the authors discussed the ultimate compressive strength of 50HT steel square plates with softening region. In this paper, the ultimate compressive strength with varying the yield stress of softening region and the aspect ratio of the plate is investigated by using the elasto-plastic large deformation finite element method.

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Softening Studies of Raw Sea Tangle Texture for Improvement of Its Processing Compatibility (가공적성 향상을 위한 다시마 조직의 연화에 관한 연구)

  • 송재철;신완철;박현정
    • The Korean Journal of Food And Nutrition
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    • v.17 no.2
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    • pp.186-192
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    • 2004
  • This study was performed to investigate softening methods of raw sea tangle for development of sea tangle processing products and intermediate materials. In examination of various softening agents, it was revealed that 0.3% sodium triphosphate was best effective on softening with heat treatment. Softerness and spreadability of sea tangle treated with sodium triphosphate and heat treatment were indicated to be better than the others. In blanching studies, microwave was extremely effective on softening and the effect was as follows: microwave>steaming>boiling water in softening order. In the case of adding 0.3% sodium triphosphate in blanching treatment, there was synergy effectiveness on softening. The color change of treated sea tangle was significantly different at p<0.05 depending on blanching method and addition amount of the agent.

Flow Softening Behavior during the High Temperature Deformation of AZ31 Mg alloy (AZ31 Mg 합금의 고온 변형 시의 동적 연화 현상)

  • Lee, Byoung-Ho;Reddy, N.S.;Yeom, Jong-Teak;Lee, Chong-Soo
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.70-73
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    • 2006
  • In the present study, the flow-softening behavior occurring during high temperature deformation of AZ31 Mg alloy was investigated. Flow softening of AZ31 Mg alloy was attributed to (1) thermal softening by deformation heating and (2) microstructural softening by dynamic recrystallization. Artificial neural networks method was used to derive the accurate amounts of thermal softening by deformation heating. A series of mechanical tests (High temperature compression and load relaxation tests) was conducted at various temperatures ($250^{\circ}C{\sim}500^{\circ}C$) and strain rates ($10^{-4}/s{\sim}100/s$) to formulate the recrystallization kinetics and grain size relation. The effect of DRX kinetics on microstructure evolution (fraction of recrystallization) was evaluated by the unified SRX/DRX (static recrystallization/dynamic recrystallization) approaches

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The Effect of the Injection Molding Conditions of Plastics on the Stress Relaxation (플라스틱의 사출성형조건이 응력완화에 미치는 영향)

  • 정석주;황봉갑
    • Journal of the Korean Society of Safety
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    • v.13 no.1
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    • pp.19-25
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    • 1998
  • In this study, proper injection molding condition has been studied through stress relaxation tests in order to experimentally investigate the effect of the condition on softening of mold product, using specimens produced under the different conditions according to the recommendation of resin manufactures. As a result, softening of the specimens was found to be strongly influenced by material melting temperature. The specimen with higher material melting temperature is found to have lower softening. However, softening of the specimen with lower mold temperature has an decrement, compared with other specimens. In particular, specimen with notch is influenced by mold temperature. The softening increase with higher injection speed and pressure. Finally in order to improve softening, material melting temperature, injection speed and injection pressure were found to be increased with low mold temperature.

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