• Journal of the Korean Society of Safety
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• v.34 no.2
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• pp.7-14
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• 2019

A palladium can adsorb hydrogen and detect leaking hydrogen through changes in color and electrical resistance. This study is to evaluate the structural behavior of carbon fiber adding palladium composite materials used in the hydrogen storage vessel. A multi-scale analysis technique was used to analyze accurately the behavior of each material in relation to the microscopic composition. The multi-scale analysis is more proper and precise for composite materials because of considering the individual microscopic structure and properties of each material for composite materials. Also the crack evaluation was performed by XFEM analysis to confirm the reinforcement performance of aluminum as a liner of the hydrogen vessel. The results show that the addition of the palladium material increased the macroscopic stress, but microscopically the carbon fiber stress was reduced. It means the performance improvement of the palladium added carbon fiber/Al composite.

• Advances in nano research
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• v.7 no.6
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• pp.419-429
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• 2019

The effect of an increasing percentage of nanofiller (glass cenosphere) with Glass/Epoxy hybrid composite curved panels modeled mathematically using the multiscale concept and subsequent numerical eigenvalues of different geometrical configurations (cylindrical, spherical, elliptical, hyperboloid and flat) predicted in this research article. The numerical model of Glass/Epoxy/Cenosphere is derived using the higher-order polynomial type of kinematic theory in association with isoparametric finite element technique. The multiscale mathematical model utilized for the customized computer code for the evaluation of the frequency data. The numerical model validation and consistency verified with experimental frequency data and convergence test including the experimental elastic properties. The experimental frequencies of the multiscale nano filler-reinforced composite are recorded through the impact hammer frequency test rig including CDAQ-9178 (National Instruments) and LABVIEW virtual programming. Finally, the nano cenosphere filler percentage and different design associated geometrical parameters on the natural frequency data of hybrid composite structural configurations are illustrated through a series of numerical examples.

• Interaction and multiscale mechanics
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• v.4 no.4
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• pp.321-336
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• 2011

This paper presents the results of static vertical load tests carried out on a model building frame supported by pile groups embedded in cohesionless soil (sand). The effect of soil interaction on displacements and rotation at the column base and also the shears and bending moments in the columns of the building frame were investigated. The experimental results have been compared with those obtained from the finite element analysis and conventional method of analysis. Soil nonlinearity in the lateral direction is characterized by the p-y curves and in the axial direction by nonlinear vertical springs along the length of the piles (${\tau}-z$ curves) at their tips (Q-z curves). The results reveal that the conventional method gives the shear force in the column by about 40-60%, the bending moment at the column top about 20-30% and at the column base about 75-100% more than those from the experimental results. The response of the frame from the experimental results is in good agreement with that obtained by the nonlinear finite element analysis.

• Interaction and multiscale mechanics
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• v.6 no.4
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• pp.357-375
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• 2013

In this paper, the forced vibration problem of an Euler-Bernoulli beam that is joined with a semi-infinite field of a compressible fluid is considered as a boundary value problem (BVP). This BVP includes two partial differential equations (PDE) and some boundary conditions (BC), which are introduced comprehensively. After that, the closed-form solution of this fluid-structure interaction problem is obtained in the frequency domain. Some mathematical techniques are utilized, and two unknown functions of the BVP, including the beam displacement at each section and the fluid dynamic pressure at all points, are attained. These functions are expressed as an infinite series and evaluated quantitatively for a real example in the results section. In addition, finite element analysis is carried out for comparison.

• Interaction and multiscale mechanics
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• v.4 no.2
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• pp.155-164
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• 2011

The lattice strain evolution within polycrystalline solids is influenced by the crystal orientation and grain interaction. For multi-phase polycrystals, due to potential large differences in properties of each phase, lattice strains are even more strongly influenced by grain interaction compared with single phase polycrystals. In this research, the effects of the grain interaction and crystal orientation on the lattice strain evolution in a two-phase polycrystals are investigated. Duplex steel of austenite and ferrite phases with equal volume fraction is selected for the analysis, of which grain arrangement sensitivity is confirmed in the literature through both experiment and simulation (Hedstr$\ddot{o}$m et al. 2010). Analysis on the grain interaction is performed using the results obtained from the finite element calculation based on the model of restricted slip within crystallographic planes. The dependence of lattice strain on grain interactions as well as crystal orientation is confirmed and motivated the need for more in-depth analysis.

• Interaction and multiscale mechanics
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• v.1 no.4
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• pp.449-465
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• 2008

In this paper a general approach for studying the motion of a cantilever beam interacting with a 2D fluid flow is presented. The fluid is solved by a general purpose commercial computational fluid dynamics (CFD) package (FLUENT 6.2), while the structure is managed by means of a dedicated finite element method solver, coded in FLUENT as a user-defined function (UDF). A weak fluid structure interaction coupling scheme is adopted exchanging information at the end of each time step. An arbitrary cantilever beam can be introduced in the CFD mesh with its wetted boundaries specified; the cantilever can also interact with specified rigid and flexible walls through use of a non-linear contact algorithm. After a brief review of relevant scientific contributions, some test cases and application examples are presented.

• Interaction and multiscale mechanics
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• v.3 no.4
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• pp.299-308
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• 2010

The indirect approach for measuring the bridge frequencies from the dynamic responses of a passing vehicle is a highly potential method. In this study, the effect of road surface roughness on such an approach is studied through finite element simulations. A two-dimensional mathematical model with the vehicle simulated as a moving sprung mass and the bridge as a simply-supported beam is adopted. The dynamic responses of the passing vehicle are solved by the finite element method along with the Newmark ${\beta}$ method. Through the numerical examples studied, it is shown that the presence of surface roughness may have negative consequence on the extraction of bridge frequencies from the test vehicle. However, such a shortcoming can be overcome either by introducing multiple moving vehicles on the bridge, besides the test vehicle, or by raising the moving speed of the accompanying vehicles.

• Interaction and multiscale mechanics
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• v.3 no.4
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• pp.405-414
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• 2010

The performance of full-scale steel and composite bridge safety barriers under vehicle crash is evaluated by using the nonlinear explicit finite element code LS-DYNA. Two types of vehicles used in this study are passenger car and truck, and the performance criteria considered include structural strength and deformation, occupant protection, and post-crash vehicle behavior. It can be concluded that the composite safety barrier satisfies all performance criteria of vehicle crash. Although the steel safety barrier satisfies the performance criteria of occupant protection and post-crash vehicle behavior, it fails to satisfy the performance criterion of deformation. In all performance evaluations, the composite safety barrier exhibits a superior performance in comparing with the steel safety barrier.

• Interaction and multiscale mechanics
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• v.3 no.3
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• pp.277-298
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• 2010

The complex variable reproducing kernel particle method (CVRKPM) and the FEM are coupled in this paper to analyze the two-dimensional potential problems. The coupled method not only conveniently imposes the essential boundary conditions, but also exploits the advantages of the individual methods while avoiding their disadvantages, resulting in improved computational efficiency. A hybrid approximation function is applied to combine the CVRKPM with the FEM. Formulations of the coupled method are presented in detail. Three numerical examples of the two-dimensional potential problems are presented to demonstrate the effectiveness of the new method.

• Interaction and multiscale mechanics
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• v.2 no.3
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• pp.235-261
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• 2009

This study illustrates the differences between the elasto-plastic cap model and Lade's model with Cosserat rotation through the analyses of two large-scale geosynthetic-reinforced soil (GRS) retaining wall tests that were brought to failure using a monotonically increasing surcharge pressure. The finite element analyses with Lade's model were able to reasonably simulate the large-scale plane strain laboratory tests. On average, the finite element analyses gave reasonably good agreement with the experimental results in terms of global performances and shear band occurrences. In contrast, the cap model was not able to simulate the development of shear banding in the tests. In both test simulations the cap model predicted failure loads that were substantially less than the measured ones.