• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 봄 학술발표회 논문집
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• pp.3-11
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• 2002

A moment-curvature relationship to simulate the behavior of reinforced concrete (RC) columns under cyclic loading is introduced. Unlike previous moment-curvature models and the layered section approach, the unposed model takes into account the bond-slip effect by using a monotonic moment-curvature relationship constructed on the basis of the bond-slip relation and corresponding equilibrium equation at each nodal point. In addition, the use of curved unloading and reloading branches inferred from the stress-strain relation of steel gives more exact numerical result. The pinching enact caused by axial force is considered with an assumption that the absorbing energy corresponding to any deformation level maintains constant regardless of the magnitude of applied axial force. The advantages of the proposed model, comparing tn layered section approach, may be on the reduction in calculation time and memory space in case of its application to large structures.. Finally, correlation studies between analytical results and experimental studies are conducted to establish the validity of the proposed mood.

• Steel and Composite Structures
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• 제44권4호
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• pp.473-488
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• 2022

A high-speed railway (HSR) bridge may undergo long-term deformation due to the degradation of material stiffness, or foundation settlement during its service cycle. In this study, an analytical model is set up to evaluate the influence of this long-term vertical bridge deformation on the track geometry. By analyzing the structural characteristics of the HSR track-bridge system, the energy variational principle is applied to build the energy functionals for major components of the track-bridge system. By further taking into account the interlayer's force balancing requirements, the mapping relationship between the deformation of the track and the one of the bridge is established. In order to consider the different behaviors of the interlayers in compression and tension, an iterative method is introduced to update the mapping relationship. As for the validation of the proposed mapping model, a finite element model is created to compare the numerical results with the analytical results, which show a good agreement. Thereafter, the effects of the interlayer's different properties of tension and compression on the mapping deformations are further evaluated and discussed.

• 대한토목학회논문집
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• 제31권3A호
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• pp.199-206
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• 2011

현재 국내에서 사용되고 있는 교량의 선박충돌력에 대한 설계기준은 Woisin의 실험으로부터 제안된 평균충돌력을 적용한 AASHTO LRFD에 기반을 두고 있다. 이러한 평균충돌력의 보수성을 평가하기 위하여, 본 연구에서는 비선형 유한요소해석을 토대로 선박의 질량-가속도의 관계, 선수의 변형-운동에너지의 관계를 이용하여 선수충돌시 발생하는 평균충돌력을 산정하고 이를 AASHTO 설계기준과 비교하였다. 그 결과, 선박의 크기에 따른 평균충돌력의 변화는 해석에서 얻어진 평균충돌력에 비해 매우 보수적이지만 경향은 일치하는 것으로 나타났다. 그러나 속도에 따른 평균충돌력의 변화는 충돌속도에 비례하는 설계기준의 값과는 달리 선수의 소성거동에 지배를 받는 것으로 나타났다.

• 한국식품과학회지
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• 제29권2호
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• pp.266-272
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• 1997

오이, 무우, 마늘 생강 및 감자의 가식부위를 일정크기$({\Phi}\;5\;mm{\times}H\;5\;mm)$로 만든 후, 힘을 가할 때와 제거할 때 발생하는 힘-변형 곡선의 관계로부터 압축 및 비압축 특성을 살펴보고 성분함량 및 세포특성과의 관계를 살펴보았다. 힘을 가하는 초기에 변형의 증가속도가 컸지만 그 이후에는 감소하였으며, 힘을 제거할 때는 압축시와 반대의 결과를 보였다. 9 N에 도달하는 시간과 변형은 감자가 컸으며 마늘이 작았다. 압축 및 비압축시 모든 시료가 분명한 이력현상을 보였으며, 힘(y)과 변형(x)은 y=exp(a+b log(x))의 관계가 있었다. 힘을 가할 때에는 감자가 $3.888{\sim}5.099{\times}10^{-3}\;J$의 많은 일을 하였으며, 그 다음으로는 오이, 무우 순이었으나 힘을 제거할 때에는 마늘이 $2.09{\times}10^{-3}\;J$로 많은 일을 하였다. 비회복성 일은 오이, 무우, 감자가 $76{\sim}96%$이었으며, 마늘이 $36{\sim}42%$로 작았다. 힘을 가할 때 변형은 감자가 컸으며, 마늘이 작았다. 탄성도는 마늘이 압축속도 별로 각각 0.777 및 0.756로 컸으며, 감자와 무우는 $0.301{\sim}0.465$로 작았다. 압축 및 비압축 특성치는 수분함량, 즙액의 점도, 세포의 크기, 조밀도 및 규칙성과 높은 상관이 있었다.

• 한국분무공학회지
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• 제5권2호
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• pp.53-60
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• 2000

An aerodynamically progressed model, which is called APTAB model. has been proposed for more accurate prediction of the deformation and breakup of a spray. Especially, the effects of the droplet deformation on the droplet aerodynamic external force are considered in this model, which was neglected in TAB model. It is found that the predicted droplet deformation using APTAB model shows better agreement with experimental data than those of other models for the droplets in both bag-type and shear-type breakup regimes. A new breakup criterion has been proposed to predict more reasonable breakup quantities, such as breakup deformation length, time and so on; i.e., it is defined that the breakup occurs when the internal liquid phase pressure of the deformed droplet at the equator is greater than that of the pole. The proposed breakup criterion shows more physical relationship between the degree of droplet deformation at breakup and the corresponding breakup Weber number as compared with the results with TAB and DDB models. Therefore, it provides better predictions of the experimental data than TAB and DDB models for the droplet deformation and time in both bag-type and shear-type breakup regimes.

• Geomechanics and Engineering
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• 제31권5호
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• pp.489-503
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• 2022

A 1257-m-long irregular deep foundation pit located in the central of Nanjing, China was constructed using the combined full-width and half-width top-down method. Based on the long-term field monitoring data, this study analyzed the evolution characteristics of the vertical movement of the columns, internal force of the struts, and axial force of the structural beam and slab. The relevance of the three mentioned above and their relationship with the excavation process, structural system, and geological conditions were also investigated. The results showed that the column uplift was within the range of 0.08% to 0.22% of the excavation depth, and the embedded depth ratio of the diaphragm wall and the bottom heave affected significantly on the column uplift. The differential settlement between the column and diaphragm wall remained unchanged after the base slab was cast. The final settlement of the diaphragm wall was twice the column uplift. The internal force of the struts did not varied monotonically but was related to numerous factors such as the excavation depth, number of struts, and environmental conditions. Additionally, the dynamic force and deformation of the columns, beams, and slabs were analyzed to investigate the inherent relationship and variation patterns of the responses of different parts of the structure.

• 한국기계가공학회지
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• 제3권2호
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• pp.10-17
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• 2004

A real depth of cut in deformed zone has larger than an ideal depth of cut. So the heat generated during grinding operation makes the deformation of a workpiece surface as convex farm. Consequently the workpiece surface remains a geometric error as concave form after cooling In this study, the grinding force and the geometric error were examined in surface grinding. Through magnitude and mode of geometric error were evaluated according to grinding conditions, an optimal grinding condition was proposed to minimize the geometric error In addition, the relationship between the geometric error and the grinding force was examined. Due to least square regression, It was possible to predict the geometric error by using the grinding force.

• 한국공작기계학회논문집
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• 제13권2호
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• pp.9-16
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• 2004

Because a generated heat during grinding operation makes a serious deformation on a ground surface as a convex form, a real depth of cut in deformed zone has larger than an ideal depth of cut. Consequently, the ground surface has a geometric error as a concave form after cooling the workpiece. In this study, the force and the geometric error of surface grinding were examined. From evaluating magnitude and mode of the geometric error according to grinding conditions, an optimal grinding condition was proposed to minimize the geometric error. In addiction the relationship between the geometric error and the grinding force was found out. Due to least square regression it was able to predict the geometric error by using the grinding force.

• Structural Engineering and Mechanics
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• 제81권4호
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• pp.481-492
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• 2022

Cycloidal ball planetary transmission (CBPT) has many applications as precision reducer, such as precision machinery and automation drive systems etc. The traditional analytical model of CBPT cannot accurately describe the change of the normal force of meshing points, and thus cannot describe the precise transmission process of meshing pairs. In the paper, a method for deriving the normal force equation is put forward by using the non-linear relationship between force and deformation in elastic mechanics. The two-point contact analytical models of all the meshing pairs are established to obtain the micro-displacement analytical model of CBPT under axial pre-tightening. Then, the non-real-time two-point contact analytical models of all the meshing pairs are further constructed to obtain the normal force expression to determine the critical compression coefficients. Experimental investigations are performed to verify the analytical model using the critical compression coefficients.

• Journal of Biosystems Engineering
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• 제17권2호
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• pp.156-170
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• 1992

The force-deformation relationship gives the basic physical properties of the fruits such as the bioyield point, the rupture point, and the deformations at the bioyield point and the rupture point. These informations are very important to study the stress-strain relationships of the fruits. This study was conducted to analyze those physical properties according to the sampling position of the fruits, and to determine the bioyield point, the rupture point, and the deformations at the bioyield point and the rupture point of the fruits for two different storage conditions(low temperature and normal temperature) and the storage period, and to investigate the effect of loading rate on those physical properties, the hysteresis on the loading-unloading condition and the degree of elasticity of the fruits. The results of the study were as follows : 1. The physical properties(BS, US, BD, and RD) of the test specimen selected from the different sampling positions were quite different. The values of the physical properties were shown smallest ones at the cheek of the fruits, and the statistical test results of the physical properties between the cheek from the other two positions of the fruits showed that there were significant difference at the 1 % level between them. 2. The effect of loading rate on the physical properties of the fruits was relatively large, all the considered physical propertis of the fruits increased with the loading rate, but the hysteresis loss decreased with it. 3. The physical properties of the fruits according to the storage conditions and period showed different, and the bioyield deformation and the rupture deformation of the fruits increased with the storage period, but the bioyield strength and the ultimate strength of the fruits decreased with it. The effect of the storage conditions on the those physical properties showed that the normal temperature storage condition was a little higher than the low temperature storage condition. 4. As a whole, it was shown that the bioyield strength and the ultimate strength of the pear decreased a little faster than those of the apple, and the bioyield deformation and rupture deformation of the pear increased a little faster than those of apple at the two storage conditions.