• 항공우주시스템공학회지
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• 제3권1호
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• pp.12-16
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• 2009

The laminated sequence and thickness of a composite structure is an important design parameter which affect the strength and impact damage. In this study, it was investigated the residual strength of carbon fiber laminate after impact damage by the experimental investigation. The tensile strength test and compressive strength test were used to find the mechanical properties, previously. Impact test was performed using low-velocity drop-weight test equipment. The impact damages were finally assessed by the compressive strength test. The investigation results revealed the residual strength of the damaged specimens due to the impact damage.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.564-569
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• 2005

Recently, from the viewpoint of global wanning, natural gas CO2 is considered as a main refrigerant for hot water system. The characteristics of CO2 is not toxic, not flammable, high pressure, and high refrigerating capacity. Also it is widely available as a byproduct of industrial processes. This paper describes the performance analysis program of the swash plate type compressor using CO2 refrigerant. Estimates of the refrigerant flow rate, compression work, discharge temperature and volumetric, compressor efficiencies of the CO2 swash plate type compressor are obtained from the various design parameter such as the inclination angle of the swash plate, discharge hole area and suction hole area.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1998년도 봄 학술발표회 논문집
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• pp.449-456
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• 1998

A consistent finite element formation and analytic solutions are presented for spatial stability of thin-walled circular arch. The total potential energy is derived by applying the principle of linearized virtual work and including second order terms of finite semitangential rotations. As a result the energy functional corresponding to the semitangential rotation is obtained, in which the elastic strain energy terms are considered restrained warping effects. We have obtained analytic solution for the lateral buckling of monosymmetric thin-walled curved beam subjected to pure bending or uniform compression and it's boundary conditions are simply supported. For finite element analysis, the two node cubic Hermitian polynomials are utilized as shape Auctions. In order to illustrate the accuracy of this study, parameter studies for lateral buckling problems of circular arch are presented and compared with available solutions and numerical results analyzed by the FEM using straight beam element.

• 소성∙가공
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• 제9권1호
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• pp.59-65
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• 2000

Most studies of failure analysis in ductile metals have been based on the classical plasticity theory using the local constitutive relations. These frequently yields a physically unrealistic solution, in which a numerical prediction of the onset of a deformation localization shows an inherent mesh-size sensitivity. A one way to remedy the spurious mesh sensitivity resulted in the unreasonable results is to incorporate the non-local plasticity into the simulation model, which introduce an internal (material) length-scale parameter into the classical constitutive relations. In this paper, a non-local version of the modified Gurson constitutive relation has been introduced into the finite element formulation of the simulation for plane strain compression of the visco elastic-plastic void material. By introducing the non-local constitutive relations we could successfully removed the inherent mesh-size sensitivity for the prediction of the deformation localization. The effects of non-local constitutive relation are discussed in terms of the load-stroke curve and the strain distributions accross the shear band.

• Advanced Composite Materials
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• 제18권3호
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• pp.251-264
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• 2009

Nonlinear mechanical behaviors of unidirectional carbon fiber-reinforced plastic (CFRP) laminates using cup-stacked carbon nanotubes (CSCNTs) dispersed epoxy are evaluated and compared with those of CFRP laminates without CSCNTs. Off-axis compression tests are performed to obtain the stress-strain relations. One-parameter plasticity model is applied to characterize the nonlinear response of unidirectional laminates, and nonlinear behaviors of laminates with and without CSCNTs are compared. Clear improvement in stiffness of off-axis specimens by using CSCNTs is demonstrated, which is considered to contribute the enhancement of the longitudinal compressive strength of unidirectional laminates and compressive strength of multidirectional laminates. Finally, longitudinal compressive strengths are predicted based on a kink band model including the nonlinear responses in order to demonstrate the improvement in longitudinal strength of CFRP by dispersing CSCNTs.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.75-78
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• 2005

This study reports on the structural characteristics of slab-column connections using an ultra-high-strength-fiber-reinforced concrete. Compression tests were performed on two slab-column and four isolated column specimens. During the column load tests were performing on the slab-column specimens, the slab loads were also applied to consider actual confinement condition at the slab-column joint. The main parameter investigated was the ' puddling ' of ultra-high-strength-fiber-reinforced concrete. This paper also investigates the effects of some parameters on slab-column specimens and isolated column specimens without the surrounding slab for their ability to transmit axial loads from the ultra-high-strength concrete columns through slab-column connections. The beneficial effects of the ultra-high-strength-fiber-reinforced concrete puddling on the transmission of column loads through slab-column connections are demonstrated.

• 한국공간구조학회논문집
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• 제13권4호
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• pp.49-56
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• 2013

Beam string structures(BSS) are one kind of efficient structure system because the bending moment in the beams is reduced greatly through the struts and the strings. As the struts in BSS are used as middle supports to the beam and always in compression, the buckling of the struts should be avoided. This paper investigates the lateral buckling of the struts in BSS. Firstly, the strut of a one-strut BSS is simplified into an analytical model by considering load is formulated and some special cases of the model are analyzed. Finally, the lateral buckling load of the strut is numerically examined by means of parameter studies. It is known that, because on end of the struts is jointed to the beam while the other end is connected to the strings, the buckling of the struts not only depends on the length of the struts and the stiffness of the joints, but also depends on the rise and the lateral stiffness of the beam, the layout of the strings and the number of the struts.

• 한국자동차공학회논문집
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• 제7권7호
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• pp.122-128
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• 1999

CARS(Coherent anti-Stokes Raman Spectroscopy) temperature measurement under engine-like condition was validated by measuring unburned gas temperatures of premixed propane-air flame in a constant volume combustion chamber. The measured temperatures were compared with predictions of 2 zone flame propagation model. End-gas temperatures were measured were measured by CARS technique in a conventional 4 cylinder DOHC spark-ignition engine fueled with PRF 80. Cylinder pressure was measured simultaneously with CARS signal and used as a parameter on fitting CARS spectrum to library of theoretical spectra. There was a good agreement between the measured temperature and adiabatic core temperature calculated from measured cylinder pressure. Significant heating by pre-flame reaction in the gas was observed in the late part of compression stroke.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1996년도 추계학술대회논문집; 한국과학기술회관, 8 Nov. 1996
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• pp.217-223
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• 1996

A structure's vibration characteristic is determined by modal property of the system. Through proper vibration analysis or experiments, the structure can be modified to reduce of vibration and noise. This paper is concerned with the natural frequency and modal loss factor of sandwich plates with viscoelastic core. The effects of shear and normal strain in the viscoelastic layer are investigated on modal properties, natural frequency and modal loss factor, by changing geometry parameter and viscoelastic material property of sandwich plates. The errors of modal parameters resulting from neglecting the extension or compression in the core material for simply supported(S-S-S-S) case are compared with those for clamped(C-C-C-C) boundary condition. Finite difference method(FDM) is utilized as numerical analysis technique of square sandwich plates for fixed boundary conditions. In order to reduce computation time and increase accuracy, improved finite difference expression with fourth order truncation error was used.

• 대한금속재료학회지
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• 제47권11호
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• pp.773-785
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• 2009

Studies of a number of Cu-Zr amorphous alloys have demonstrated that those exhibiting greater plastic strain during homogeneous deformation at room temperature show lower global plasticity associated with inhomogeneous deformation in a typical compression test. Using a combination of experiments and molecular dynamics simulations, we clarify this seeming paradox between the homogeneous and inhomogeneous deformation by exploring the microstructural aspects in view of the structural disordering, disorder-induced softening, and shear localization and relate these findings to the global plasticity of bulk amorphous alloys. Additional analyses were conducted to derive a simple structural parameter that allows the prediction of the global plasticity of bulk amorphous alloys.