• Journal of the Korean Electrochemical Society
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• v.25 no.3
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• pp.105-112
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• 2022

For the commercialization of all-solid-state batteries, it is essential to develop a solid electrolyte that can be operable at room temperature, and it is necessary to manufacture all-solid-state batteries by adopting materials with high ionic conductivity. Therefore, in order to increase the ionic conductivity of the existing oxide-based solid, Li₇La₃Zr₂O₁₂ (LLZO) doped with heterogeneous elements was used as a filler material (Al and Nb-LLZO). An electrolyte with garnet-type inorganic filler doped was prepared. The binary metal element and the polymer mixture of poly(ethylene oxide)/poly(propylene carbonate) (PEO/PPC) (1:1) are uniformly manufactured at a ratio of 1:2.4, The electrochemical performance was tested at room temperature and 60 ℃ to verify room temperature operability of the all-solid-state battery. The prepared composite electrolyte shows improved ionic conductivity derived from co-doping of the binary elements, and the PPC helps to improve the ionic conductivity, thereby increasing the capacity of all-solid-state batteries at room temperature as well as 60 ℃. It was confirmed that the capacity retention rate was improved.

• Structural Engineering and Mechanics
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• v.40 no.3
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• pp.393-410
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• 2011

The eight-node 3D solid element is one of the most extensively used elements in computational mechanics. This is due to its simple shape and easy of discretization. However, due to the parasitic shear locking, it should not be used to simulate the behaviour of structural members in bending dominant conditions. Previous researches have indicated that the introduction of incompatible mode into the displacement field of the solid element could significantly reduce the shear locking phenomenon. In this study, an incompatible mode eight-node solid element, which considers both geometric and material nonlinearities, is developed for modelling of structural members at elevated temperatures. An algorithm is developed to extend the state determination procedure at ambient temperature to elevated temperatures overcoming initially converged stress locking when the external load is kept constant. Numerical studies show that this incompatible element is superior in terms of convergence, mesh insensitivity and reducing shear locking. It is also showed that the solid element model developed in this paper can be used to model structural behaviour at both ambient and elevated temperatures.

• Computers and Concrete
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• v.1 no.3
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• pp.285-302
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• 2004

A FE-(FE-HE)-BE procedure is presented for dynamic analysis of concrete arch dams. In this technique, dam body is discretized by solid finite elements, while the reservoir domain is considered by a combination of fluid finite elements and a three-dimensional fluid hyper-element. Furthermore, foundation rock domain is handled by three-dimensional boundary element formulation. Based on this method, a previously developed program is modified, and the response of Morrow Point arch dam is studied for various conditions. Moreover, the effects of canyon shape on response of dam, is also discussed.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.780-783
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• 2004

The two-dimensional modeling of the non-stationary thermal state and voltage responsivity of the sensitive elements usually used in solid-state pyroelectric focal plane arrays are presented. Temperature distributions under periodical thermal excitation and the response of the thermal imaging device, which is composed of the pyroelectric sensitive elements mounted on a single silicon substrate, are numerically calculated. The sensitive element consists of a covering metal layer, infrared polymer absorber, front metal contact, sensitive pyroelectric element, the interconnecting column and the bulk silicon readout. The results of the numerical modeling show that the thermal crosstalk between sensitive elements to be critical especially at low frequency (f < 10Hz) of periodically modulated light. It is also shown that the use of our models gives the possibility to improve the design, operating regimes and sensitivity of the device.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.10
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• pp.1517-1525
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• 2004

Shell finite elements are widely used for the analysis of thin section objects such as sheet metal parts, automobile bodies and et al. due to their computational efficiency. Since many of input data for finite element analysis are given as solid models or triangulated surface models, one should extract midsurface information from these input data initially and then construct shell meshes on the extracted midsurfaces. In this paper, a method of generating shell elements on midsurfaces directly from input models has been proposed, in which midsurface generating process can be omitted. In order to construct shell meshes, the input models should be triangulated on surfaces first, and then tetrahedral elements are generated by using an advancing front method, and finally mid shell surfaces are obtained from tetrahedral meshes. Some examples are given to demonstrate the efficiency of the proposed method.

• Coupled systems mechanics
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• v.11 no.5
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• pp.439-458
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• 2022

Over-coating is one of the most popular engineering practices to strengthen Reinforced Concrete (RC) structures, due to the relative quickness and ease of construction. It consists of an external coat bonded to the outer surface of the structural RC element, either by the use of chemical adhesives, mechanical anchor bolts or simply mortar injection. In contrast to these constructive advantages, the numerical estimation of the bearing capacity of the strengthened reinforced concrete element is still complicated, not only for the complexity of modelling a flexible membrane or plate attached to a quasi-rigid solid, but also for the difficulties that raise of simulating any potential delamination between both materials. For these reasons, the standard engineering calculations used in the practice remain very approximated and clumsy. In this work, we propose the formulation of a new 2D solid-layer finite element capable to link a solid body with a flexible thin layer, as it were the "skin" of the body, allowing the potential delamination between both materials. In numerical terms, this "skin" element is intended to work as a transitional region between a solid body (modelled with a classical formulation of a standard quadrilateral four-nodes element) and a flexible coat layer (modelled with cubic beam element), dealing with the incompatibility of Degrees-Of-Freedom between them (two DOF for the solid and three DOF for the beam). The aim of the solid-layer element is to simplify the mesh construction of the strengthened RC element being aware of two aspects: a) to prevent the inappropriate use of very small solid elements to simulate the coat; b) to improve the numerical estimation of the real bearing capacity of the strengthened element when the coat is attached or detached from the solid body.

• Coupled systems mechanics
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• v.12 no.6
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• pp.481-501
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• 2023

Over-coating is one of the most popular engineering practices to strengthen Reinforced Concrete (RC) structures, due to the relative quickness and ease of construction. It consists of an external coat bonded to the outer surface of the structural RC element, either by the use of chemical adhesives, mechanical anchor bolts or simply mortar injection. In contrast to these constructive advantages, the numerical estimation of the bearing capacity of the strengthened reinforced concrete element is still complicated, not only for the complexity of modelling a flexible membrane or plate attached to a quasi-rigid solid, but also for the difficulties that raise of simulating any potential delamination between both materials. For these reasons, the standard engineering calculations used in the practice remain very approximated and clumsy. In this work, we propose the formulation of a new 2D solid-layer finite element capable to link a solid body with a flexible thin layer, as it were the "skin" of the body, allowing the potential delamination between both materials. In numerical terms, this "skin" element is intended to work as a transitional region between a solid body (modelled with a classical formulation of a standard quadrilateral four-nodes element) and a flexible coat layer (modelled with cubic beam element), dealing with the incompatibility of Degrees-OfFreedom between them (two DOF for the solid and three DOF for the beam). The aim of the solid-layer element is to simplify the mesh construction of the strengthened RC element being aware of two aspects: a) to prevent the inappropriate use of very small solid elements to simulate the coat; b) to improve the numerical estimation of the real bearing capacity of the strengthened element when the coat is attached or detached from the solid body.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.3
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• pp.281-288
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• 2016

The ballistic performance data of composite materials is distributed due to material inhomogeneity. In this paper, the uncertainty in residual velocity is obtained experimentally, and a method of predicting it is established numerically for the high-speed impact of a bullet into laminated composites. First, the failure strain distribution was obtained by conducting a tensile test using 10 specimens. Next, a ballistic impact test was carried out for the impact of a fragment-simulating projectile (FSP) bullet with 4ply ([0/90]s) and 8ply ([0/90/0/90]s) glass fiber reinforced plastic (GFRP) plates. Eighteen shots were made at the same impact velocity and the residual velocities were obtained. Finally, simulations were conducted to predict the residual velocities by using the failure strain distributions that were obtained from the tensile test. For this simulation, two impact velocities were chosen at 411.7m/s (4ply) and 592.5m/s (8ply). The simulation results show that the predicted residual velocities are in close agreement with test results. Additionally, the modeling of a composite plate with layered solid elements requires less calculation time than modeling with solid elements.

• The Korean Journal of Ceramics
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• v.6 no.1
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• pp.47-52
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• 2000

Lanthanides such as La, Gd and Ce have recognized as elements of high level radioactive wastes immobilized by forming solid solution with $CaTiO_3$. For easy forming solid solution between $CaTiO_3$and lanthanides, the combustion synthesis process was applied and the powder characteristics and sinterability were investigated. The proper selection of the type and the composition of fuels are important to get the crystalline solid solution of $CaTiO_3$and lanthanides. When glycine or the mixtures of urea and citric acid with stoichiometric composition was used as a fuel, the solid solution of $CaTiO_3$with $La_2O_3$or $Gd_2O_3$or $CeO_2$was produced very well by the combustion process. The combustion synthesized powder seemed to have a good sinterability with the linear shrinkage of more than 25% up to $1500^{\circ}C$, while that of the solid state reacted powder was less than 10% at the same condition.

• Journal of Korea Foundry Society
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• v.33 no.3
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• pp.122-126
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• 2013

Recently, heat-resistant aluminum alloy has been re-focused as a downsizing materials for the internal combustion engines. Heat-resistant Al alloy development and many researches are still ongoing for the purpose of improving thermal stability, high-temperature mechanical strength and fatigue properties. The conventional principle of heat-resistant Al alloy is the precipitation of intermetallic compounds by adding a variety of elements is generally used to improve the mechanical properties of Al alloys. Heat resistant aluminum alloys have been produced by CrW homogeneous solid solution to overcome the limit of conventional heat resistant aluminum alloy. From EPMA, it is found that CrW homogeneous soild solution phases with the size of $50-100{\mu}m$ have been dispersed uniformly, and there is no reaction between aluminum and CrW alloy. In addition, after maintaining at high temperature of 573 K, there is no growth of hardening phase, nor desolved, but CrW still exists as a homogeneous solid solution.