• 한국소음진동공학회논문집
• /
• 제12권5호
• /
• pp.330-337
• /
• 2002

A frequency equation of beam subjected to the axial load and having ηthrough-the-width-splits is developed. The beam comprises of beam elements that are split into the upper and the lower part, and non-split beam elements. Equations of motion of each beam element are non-dimensionalized with respect to length. The frequency equation of beam is derived from that of each beam element, which satisfies the displacement of the longitudinal and transverse vibration and the boundary conditions between the beam elements. Numerical simulation and experimental work for the beam having several split beam elements are carried out to demonstrate the analytical development and its validity. The experimental results are in good agreement with those of the present frequency equation. The relationships between the split beam width and natural frequencies, and also the relationships between number of split and natural frequencies, in case that the total beam split length is same. are discussed.

• 대한기계학회논문집B
• /
• 제25권12호
• /
• pp.1905-1910
• /
• 2001

Pressure resonance frequency that is caused in the combustion chamber can be interpreted by acoustic analysis. Until now the pressure resonance has been assumed and calculated to a disc type combustion chamber that neglected the combustion chamber height because the knock occurs near the TDC(top dead center). In this research FEM(finite element method) has been used to calculate the pressure resonance frequency inside the experimental engine combustion. The error of the resonance frequency obtained by FEM has decreased about 50% compared to the calculation of Draper's equation. Due to the asymmetry in the shape of the combustion chamber that was neglected in Draper's equation we could find out that a new resonance frequency could be generated. To match the experimental results, the speed of sound that satisfies Draper's equation is selected 13% higher than the value for pent-roof type combustion chamber.

• 멤브레인
• /
• 제14권1호
• /
• pp.18-25
• /
• 2004

본 연구의 목적은 정맥 내 폐 보조장치 설계에 있어서 기체전달을 예측하기 위하여 혈관 내 폐 보조장치를 정맥 내에 삽입하기 전, 여러 가지 설계조건에서 실험적 모델링을 통하여 예측식을 찾고자 시도하였다. 실험결과 중공사 충진율의 함수에 따라 기체전달을 예측할 수 있었다. 실험에 의하여 얻어진 기체전달은 예측식에 의한 기체전달과 유사하여, 식에 대한 신뢰성을 얻을 수 있었다. 그러므로, 중공사의 충진율의 함수에 따라 기체전달을 예측할 수 있으며, 혈관 내 폐 보조장치의 기체전달을 예측하는데 매우 유용하였다.

• Elastomers and Composites
• /
• 제45권4호
• /
• pp.250-255
• /
• 2010

비뉴톤 점탄성 Maxwell 요소와 탄성 스프링으로 이루어진 3 요소 비뉴톤 모델로부터 응력완화 식을 유도하였다. 이 식을 응력완화 실험 결과에 적용하여 여러 가지 모델 파라메타를 계산하였다. 모델 파라메타로부터 계산한 이론 곡선은 실험적인 응력완화 곡선과 잘 일치하였다. 비선형 점탄성 모델 파라메타로부터 섬유고분자 물질의 홀부피, 미세구조, 점탄성성질, 역학적인 성질 등을 연구하였다. 응력완화 실험은 용매기를 부착한 인장 시험기를 사용하였으며, 시료는 두 종류의 polyacrylonitrile-polyvinylchloride 공중합체와 또 다른 두 종류의 PVC 모노 필라멘트 섬유를 여러 온도의 공기와 물속에서 응력완화 실험을 하였다.

• Structural Monitoring and Maintenance
• /
• 제9권1호
• /
• pp.81-105
• /
• 2022

The use of concrete filled steel tube (CFST) column is widely accepted due to its property of high axial load carrying capacity, more ductility and more resistant to earthquake specially using in bridges and high-rise buildings. The initial imperfection (δ) that produces during casting or fixing causes the reduction in load carrying capacity, this is the reason, experimental capacity is always less then theoretical one. In this research, the effect of δ on load carrying capacity and behavior of concrete filled steel tube (CFST) column have been investigated by numerically simulation of large number of models with different δ and other geometric parameters that include length (L), width (B), steel tube thickness (t), f'_c and f_y. Finite element analysis software ANSYS v18 is used to develop model of SCFST column to evaluate strength capacity, buckling and failure pattern of member which is applied during experimental study under cyclic axial loading. After validation of results, 42 models with different parameters are evaluated to develop empirical equation predicting axial load carrying capacity for different value of δ. Results indicate that empirical equation shows the 0 to 9% error for finite element analysis Forty-two models in comparison with ANSYS results, respectively. Empirical equation can be used for predicting the axial capacity of early estimating the axial capacity of SCFT column including 𝛿.

• 소성∙가공
• /
• 제31권4호
• /
• pp.200-206
• /
• 2022

The finite element analysis is one of the representative methods for predicting the materials behavior for experiments that are difficult to perform empirically. Constitutive equations are essential for reducing computation time and sharing data because they enable finite element analysis simulations through simple formulae. However, it is difficult to derive accurate flow curves for all materials as most constitutive equations are not formulated based on their physical meaning. Also, even if the constitutive equation is a good representation of the flow curve to the experimental results, some fundamental issues remain unresolved, such as the effect of mesh size on the calculation results. In this study, a new constitutive equation was proposed to predict various materials by modifying the combined Swift-Voce model, and the calculation results with various mesh sizes were compared to better simulate the experimental results.

• Geomechanics and Engineering
• /
• 제35권1호
• /
• pp.55-65
• /
• 2023

Soft clay is widely spread in nature and encountered in geotechnical engineering applications. The creep property of soft clay greatly affects the long-term performance of its upper structures. Therefore, it is vital to establish a reasonable and practical creep constitutive model. In the study, two updated hyperbolic equations based on the volumetric creep and deviatoric creep are respectively proposed. Subsequently, three creep constitutive models based on different creep behavior, i.e., V-model (use volumetric creep equation), D-model (use deviatoric creep equation) and VD-model (use both volumetric and deviatoric creep equations) are developed and compared. From the aspect of prediction accuracy, both V-model and D-model show good agreements with experimental results, while the predictions of the VD-model are smaller than the experimental results. In terms of the parametric sensitivity, D-model and VD-model are lower sensitive to parameter M (the slope of the critical state line) than V-model. Therefore, the D-model which is developed by incorporating the updated deviatoric creep equation is suggested in engineering applications.

• 한국수산과학회지
• /
• 제21권6호
• /
• pp.366-370
• /
• 1988

In Previous paper, an experimental equation for prediction of thermal diffusivity of white muscled fish meat paste products was suggested. In this paper, another experimental equation for red muscled fish meat paste products was derived. The thermal diffusivities of products with water contents of 44.74 to $82.83\%$ and lipid contents of 0.35 to $23.38\%$ could be deduced as following equations ; $$\alpha_{80.39^{\circ}C}=0.0759{\cdot}10^{-6}{\cdot}X_w+0.0836{\cdot}10^{-6},\;m^2{\cdot}s^{-1}$$ $$\alpha_{100.63^{\circ}C}=0.0820{\cdot}10^{-6}{\cdot}X_w+0.0853{\cdot}10^{-6},\;m^2{\cdot}s^{-1}$$ $$\alpha_{120.09^{\circ}C}=0.0830{\cdot}10^{-6}{\cdot}X_w+0.09140{\cdot}10^{-6},\;m^2{\cdot}s^{-1}$$ The experimental equation derived from these equations was ; $$\alpha=(0.9795+.8996{\cdot}X_w){\cdot}\alpha_w-0.0709{\cdot}10^{-6}{\cdot}X_w-0.0779{\cdot}10^{-6},\;m^2{\cdot}s^{-1}$$ The errors of the thermal diffusivities of red muscled fish meat paste products predicted with this equation were less than ${\pm}\;0.52\%$ compared with those measured. A new experimental equation for products of white and red muscled fish meat paste could be discribed as follow ; $$\alpha=(1.096+0.5318{\cdot}X_w){\cdot}\alpha_w-0.0057{\cdot}10^{-6}{\cdot}X_w-0.0992{\cdot}10^{-6},\;m^2{\cdot}s^{-1}$$ The errors of the thermal diffusivities predicted with this equation were less than ${\pm}\;0.13\%$ compared with those measured.

• 한국생산제조학회지
• /
• 제22권3호
• /
• pp.380-387
• /
• 2013

In this study, two finite element (FE) models were developed to evaluate the thermal characteristics of a feeding axis of a CNC lathe. One was used for analysis of heat transfer to identify the temperature distribution of the feeding axis and then, the other was used for analysis of thermal deformation to evaluate its structural behavior based on the temperature distribution. The FE models were based on the test standard for the axial thermal displacement. The feeding velocity was composed of three steps: the ascending, constant, and descending velocities. Therefore, the heat generation and convection coefficient were calculated for each velocity and applied to the thermal FE model. The convection coefficient for the ball screw rotation was based on an experimental equation. The result of the analytical thermal displacement was compared with that of the experimental displacement to verify the finite element models.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2007년도 춘계학술대회
• /
• pp.13-19
• /
• 2007

To find out the optimum design of hydrogen storage and supply tank using Metal Hydride (briefly MH) and to make clear the performance characteristics under various conditions are our research purpose. In order to use the low-temperature exhaust heat, $LaNi_{4.7}Al_{0.3}$ which operates under the low pressure of 1 MPa is chosen, and we measure the basic properties, namely density, specific heat, PCT(Pressure-Concentration-Temperature) characteristics, and effective thermal conductivity. Then, a numerical calculation model of hydrogen storage using MH alloy is suggested and this thermal diffusion equation of model is solved by the backward difference method. This calculation results are compared with the experimental results of the systems which installed 1kg MH alloy and, it is found out that our calculation model can well predict the experimental results. By the experimental using MH alloy, it is recognized that the hydrogen flow rate can control by the step adjustment of brine temperature.