• Structural Engineering and Mechanics
• /
• v.91 no.1
• /
• pp.75-86
• /
• 2024

In this paper, the porous metal PM-35 is proposed as the filler material of filled thin-walled tubes (FTTs), and a series of experimental study is conducted to investigate the dynamic behavior and energy absorption performance of PM-35 filled thin-walled tubes under impact loading. Firstly, cylinder solid specimens of PM-35 steel are tested to investigate the impact mechanical behavior by using the Split Hopkinson pressure bar set (SHP); Secondly, the filled thin-walled tube specimens with different geometric parameters are designed and tested to investigate the feasibility of PM-35 steel applied in FTTs by the orthogonal test. According to the results of this research, it is concluded that PM-35 steel is with the excellent characteristics of high energy absorption capacity and low yield strength, which make it a potential filler material for FTTs. The micron-sizes pore structure of PM-35 is the main reason for the macroscopic mechanical behavior of PM-35 steel under impact loading, which makes the material to exhibit greater deformation when subjected to external forces and obviously improve the toughness of the material. In addition, PM-35 steel core-filled thin-wall tube has excellent energy absorption ability under high-speed impact, which shows great application potential in the anti-collision structure facilities of high-speed railway and maglev train. The parameter V0 is most sensitive to the energy absorption of FTT specimens under impact loading, and the sensitivity order of different variations to the energy absorption is loading speed V0>D/t>D/L. The loading efficiency of the FTT is affected by its different geometry, which is mainly determined by the sleeve material and the filling material, which are not sensitive to changes in loading speed V0, D/t and D/L parameters.

• Steel and Composite Structures
• /
• v.13 no.5
• /
• pp.423-436
• /
• 2012

In this study total of six buckling-restrained braces (BRBs) were manufactured using a square steel rod as a load-resisting core member and a hollow steel tube as restrainer to prevent global buckling of the core. The gap between the core and the tube was filled with steel rods as filler material. The performances of the proposed BRB from uniaxial and subassemblage tests were compared with those of the specimens filled with mortar. The test results showed that the performance of the BRB with discontinuous steel rods as filler material was not satisfactory, whereas the BRBs with continuous steel rods as filler material showed good performance when the external tubes were strong enough against buckling. It was observed that the buckling strength of the external tube of the BRBs filled with steel rods needs to be at least twice as high as that of the BRBs filled with mortar to ensure high cumulative plastic deformation of the BRB.

• Advanced Composite Materials
• /
• v.17 no.3
• /
• pp.259-275
• /
• 2008

This study aims to optimize the mechanical and electrical properties of electrically conductive polymer composites (CPCs) for use as a material of bipolar plates for PEM fuel cells. The thin CPCs consisting of conductive fillers and polymer resin were fabricated by a preform molding technique. Expanded graphite (EG), flake-type graphite (FG) and carbon fiber (CF) were used as conductive fillers. This study tested two types of CPCs, EG/FG filled CPCs and EG/CF filled CPCs, to optimize the material properties. First, the characteristics of EG/FG filled CPCs were investigated according to the FG ratio for 7 and $100{\mu}m$ sized FG. CPCs using $100{\mu}m$ FG showed optimal material properties at 60 wt% FG ratio, which were an electrical conductivity of 390 S/cm and flexural strength of 51 MPa. The particle size was an important parameter to change the mechanical and electrical behaviors. The flexural strength was sensitive to the particle size due to the different levels of densification. The electrical conductivity also showed size-dependent behavior because of the different contributions to the conductive network. Meanwhile, the material properties of EG/CF filled CPCs was also optimized according to the CF ratio, and the optimized electrical conductivity and flexural strength were 290 S/cm and 58 MPa, respectively. The electrical conductivity of this case decreased similarly to the EG/FG filled case. On the other hand, the behavior of the flexural strength was more complicated than the EG/FG filled case, and the reason was attributed to the interaction between the strengthening effect of CF and the deterioration of voids.

• Particle and aerosol research
• /
• v.19 no.4
• /
• pp.145-154
• /
• 2023

Granular bed filters are widely used to remove particulate matter in flue gas and are filled with various shapes of packing material. The packing material plays an important role in determining the overall collection performance, such as pressure drop and collection efficiency. The pressure drop of a granular bed filter has been calculated using the Ergun equation, while the collection efficiency has been predicted using the log-penetration equation based on the single sphere theory. However, a prediction equation of collection efficiency for a granular bed filter filled with non-spherical packing materials has not been suggested yet. Therefore, in this study, three different shapes of packing materials (sphere, cylinder, and irregular) were prepared to propose a prediction equation. The pressure drop and collection efficiency in a granular bed filter filled with each shape of packing material were measured experimentally and compared with theoretically predicted values. We found that experimentally measured pressure drops matched well with values theoretically predicted using the Ergun equation considering the shape factor. However, experimental collection efficiencies were higher than theoretical ones predicted by the log-penetration equation using the single sphere theory. We modified the log-penetration equation by employing a shape factor and found a good relationship between experimental and theoretical collection efficiencies.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1997.04a
• /
• pp.301-304
• /
• 1997

Effects of volatile impurities on deterioration characteristics of XLPE were investigated. Block type plate with needle-plane electrode and artificial void filled with $N_2$gas or humidity was subjected under high electric field. The dyed region by oxidation reaction around the artificial void filled with humidity was detected before tee initiation. Electrical tree was started from the tip of void filled with $N_2$gas earlier than humidity.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2007.04a
• /
• pp.688-693
• /
• 2007

Nowadays various studies related with superstructure of bridges are developed and they pursuit more effective section of bridges superstructure, material and economical application of composite materials. CFT structure(Concrete Filled Steel Tubular Structure) is developed type of composite structure that concrete is filled with steel box, and the deformation of the member, stiffness and internal force will be improved by confinement effect of steel box and concrete. This paper introduces new type of girder, CFTA girder( Concrete- Filled and Tied Steel Tubular Arch Girder) which is combined with traditional CFT structure,arch effect and prestress through carrying out the structural analysis by computer programs. The computer programs which is used are ABAQCS and MIDAS, and the 12.2m girder which is applied same load and prestresses is analyzed and compared the results respectively.

• Journal of Electrical Engineering and Technology
• /
• v.8 no.2
• /
• pp.345-353
• /
• 2013

This paper discusses the experimental results in an effort to understand the tracking and erosion resistance of the micro and nano size $Al_2O_3$ filled silicone rubber (SIR) material which has been studied under the AC voltages, with ammonium chloride as a contaminant, as per IEC 60587 test procedures. The characteristic changes in the tracking resistance of the micro and nano size filled specimens were analyzed through leakage current measurement and the eroded masses were used to evaluate the relative erosion and tracking resistance of the composites. The fundamental, third and fifth harmonic of the leakage current during the tracking study were analyzed using moving average current technique. It was observed that the harmonic components of leakage current show good correlation with the tracking and erosion resistance of the material. The thermogravimetry-derivative thermo gravimetric (TG-DTG) studies were performed to understand the thermal degradation of the composites. The physical and chemical studies were carried out by using scanning electron microscope (SEM), Energy Dispersive X-ray analysis (EDAX) and Fourier Transform Infra-red (FTIR) Spectroscopy. The obtained result indicated that the performance of nano filled SIR was better than the micro filled SIR material when the % wt. of filler increased.

• Tunnel and Underground Space
• /
• v.14 no.5
• /
• pp.318-326
• /
• 2004

In this study, a new direct shear apparatus was developed to investigate the shear characteristics of the rock joints at various conditions. Using the developed apparatus, various experiments on filled rock joints were carried out considering the asperity angle, the normal stress, the type and thickness of filling material and to investigated the basic shear characteristics of filled rock joints were analyzed. According to the experiments performed under the constant normal stress condition by varying the asperity angle, the type and thickness of filling material, it was shown that the behavior and strength of filled rock joint could be defined by the type and thickness of the filling material. The dilation angle of the filled joints was found to be smaller than that of unfilled rock joint, and thereby, the effect of roughness was also reduced due to the filling material. And critical thickness ratio varied according to stress level and roughness as well as the type of filing materials.

• Proceedings of the KSME Conference
• /
• 2004.11a
• /
• pp.238-243
• /
• 2004

A new sandwich composite was investigated in this paper. The honeycomb core of this composite was filled with viscoelastic material in order to obtain an improved damping performance. The viscoelastic fillings in the honeycomb cells was hoped to act as dampers and provide the function of energy dissipation in this combined material system. Dynamic test was set up to the specimens with various stacked carbon/epoxy laminate facesheets, $[0/90]_{4s}$, $[0/45/-45/90]_{2s}$, $[45/-45]_{4s}$. Frequency response, displacement response and damping ratio were checked and compared for the both groups of specimens, with and without rubber fillings. The experimental results provided a good agreement with our material design concept.

• Proceedings of the KSR Conference
• /
• 1998.11a
• /
• pp.30-38
• /
• 1998

Nowadays, the environmental vibration criteria has been severely restricted from the viewpoint of recipient. The vibration created by urban transit systems can be an important source of community discontent, and can have influence on high technology equipments. This has led to a desire of transit system operators to reduce vibration and to minimize community exposure to vibration. Recent research in this area has significantly increased for transit system engineers to reduce vibration. Unlike other material, soil has a complicated characteristic and it is very difficult to prevent vibration from transmitting. Generally, the trench can use to breaking propagation of vibration on passing way but needs much too maintenance. Therefore, the filled materials for trench had successfully developed and the characteristic test for the filled material had conducted during this term. Finally, we had executed analyses of real characteristic through the propagation test of ground vibration.