• Elastomers and Composites
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• v.47 no.3
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• pp.201-209
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• 2012

Grommet is one of the Automotive rubber components and is made from EPDM(Ethylene Propylene Diene monomer M-class) rubber and the nonlinear hyperelastic material properties of rubber are important to predict the behavior of rubber product. In this study, the stable stress-strain relations were obtained from the uni-axial tension test and the equi-biaxial tension test. Finite element analysis for grommet was carried out and heat aging test for the lifetime prediction of grommet was introduced.

• Computational Structural Engineering
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• v.4 no.1
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• pp.73-82
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• 1991

Recently, the finite element method has been sucessfully extended to treat the rather complex phenomena such as nonlinear buckling problems which are of considerable practical interest. In this study, a finite element program to evaluate the elasto-plastic buckling stress is developed. The Stowell's deformation theory for the plastic buckling of flat plates, which is in good agreement with experimental results, is used to evaluate bending stiffness matrix. A bifurcation analysis is performed to compute the elasto-plastic buckling stress. The subspace iteration method is employed to find the eigenvalues. The results are compared with corresponding exact solutions to the governing equations presented by Stowell and also with experimental data due to Pride. The developed program is applied to obtain elastic and elasto-plastic buckling stresses for various loading cases. The effect of different plate aspect ratio is also investigated.

• Bulletin of the Society of Naval Architects of Korea
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• v.8 no.1
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• pp.53-66
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• 1971

The effect of reinforced circular hole in a flat plate under general biaxial loading conditions is considered. The reinforcement is achieved by attaching a circular ring of uniform rectangular cross section along the boundary of the hole. This investigation includes a theoretical solution and an experimental conformation. In the theoretical analysis, Gurney's method is used to obtain a solution for the stress distribution and the solution is expressed in a general form, so that it can be applicable to the case of general biaxial loading and general values of Poisson's ratios. In the experimental work a systematic series of photoelastic models, as shown in Fig.5 and Table 1, were analyzed on polariscope. The experimental results were in good agreement with the theoretical ones, as shown in Fig.8 and 9. The conclusions derived are as follows: 1) The theoretical results, given in Eq. $(1){\sim}(5)$, are sufficient in accuracy for the engineering design purpose. 2) The stress concentration factor decreases as the ratio n increases, but not significant beyond n=3. 3) The stress concentration factor increase as the ratio m increases, but not significant below m=0.7.

• Elastomers and Composites
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• v.36 no.2
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• pp.86-93
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• 2001

For solving the environmental problem of the waste EPDM and for new TPE blend materials, we developed a new kind of TPE material using a co-rotating twin screw extruder. To improve the mechanical properties of TPE material such as tensile strength, elongation at break, and modulus of the blend, PP and waste EPDM powder were blended with different screw configurations. The mechanical properties of the blends and morphology of the TPE were investigated. As the number of kneading disc and left-handed screw element increased, dynamic vulcanization of the material was increased because the shear stress and residence time of blends increased.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.281-284
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• 2006

ASCE-ACI Committee 426 and 445, on Shear and Torsion, well noted in their report that recent research work regarding shear and torsion had been devoted primarily to members. But it was not logical approach of PSC members applied by axial force based on the shear deformation in web element. And it was not included that the effect of axial is to shift the shear strain(or crack width) in the web element versus the applied shear curve up or down by the amount by which the biaxial tension-compression state varies. The shear strength also increases or decreases, so that the change in shear strain at service load due to the presence of axial load is to some extent changed. Generally, in corresponding beams the shear strain at service load is less in the beam subject to axial compression and greater in the beam subject to axial tension, than in the beam without axial load. In particular, however, no research were available on the shear deformation in shear of PSC members with web reinforcement, subject to axial force in addition to shear and bending. Therefore, this study was basically performed to develop the program for the calculation of the shear deformation based on the shear effect of axial force in prestressed concrete members.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.1
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• pp.223-231
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• 2002

The pilot tests for the development of biaxial failure envelope of high strength concrete of reactor containments were performed. To apply biaxial loads to concrete, the plate specimens were used. The technical difficulties encountered on the development of a suitable biaxial test setup were discussed. To decide the optimum thickness of plate specimen, the nonlinear finite element analyses using ABAQUS were performed for a 1/8 model of cylindrical specimen(${\Phi}150{\times}300$) and four 1/4 models of plate Specimens ($200{\times}200{\times}T$(=30, 50, 60, 70)mm) under uniaxial compression. Analytical values and test data of relative strength ratio between those specimens with different geometric shapes were also compared. The various test data were obtained under uniaxial compression, uniaxial tension, and biaxial compression and then the stress-strain responses were plotted. The test data indicated that the strength of concrete under biaxial compression, $f_1/f_2=-1/-1$, is 15 percent larger than that under uniaxial compression and the poisson's ratio of concrete is 0.16. Teflon pads employed to eliminate friction between test specimen and loading platens showed an excellent effect under biaxial compression.

• Polymer(Korea)
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• v.24 no.3
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• pp.366-373
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• 2000

In this study, the PPS/ABS blend system was investigated in order to collectively identify the relationship among blend morphology, chemical compatibilization and thermal property. ABS resin was chemically modified by the incorporation of maleic anhydride through reactive extrusion for enhanced compatibilization, and PPS, ABS and the modified ABS were blend by a sing twin screw extruder. The effect of chemical modification of ABS on the morphological, mechanical, and thermal properities of the resulting blend was examined. A strong interaction was observed between PPS and MABS by optical microsopy as well as scanning electron microscopy, exhibiting a well-dispersed morphological feature. The PPS/MABS blend showing a single glass transition temperature was observed in dynamic mechanical analysis, demonstrating a pseudo-homogeneous phase morphology induced by chemical compatibilization. PPS/MABS blend also exhibited an enhanced thermal stability and heat distortion temperature compared with modified PPS/ABS blend.

• Elastomers and Composites
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• v.40 no.2
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• pp.119-127
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• 2005

Material characteristics and lifetime evaluation are very important in design procedure to assure the safety and reliability of the rubber components. In this paper, the material test and accelerated heat aging test were carried out to predict the useful life of NBR and EPDM rubber mount for a compression motor which is used in a refrigerator. In order to investigate the effects of heat-aging on the material properties, crosslink density, modulus at 100% strain, stress-strain curves were obtained from uniaxial and equi-biaxial tensile tests. The change of compression set were used for assessment of the useful life and the time to threshold value were plotted against the reciprocal of absolute temperature to give the Arrhenius plot. The useful life at variable temperatures are obtained in the Arrhenius relationship.

• Applied Chemistry for Engineering
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• v.33 no.3
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• pp.284-288
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• 2022

Polypropylene (PP) powder/cellulose nanofibers (CNF) 1 wt% slurry composites were prepared by filtering their suspension under reduced pressure and dried them in an oven followed by the use of a twin screw extruder. PP modified with side branches and polar groups was used. The side branches and polar groups were introduced into PP by using divinylbenzene and maleic anhydride (MAH), respectively. As a result of examining the dispersibility of CNF and the physical properties of the composite, it was confirmed that the composite prepared from PP powder/CNF 1 wt% slurry showed equal or higher levels in tensile and flexural strength as compared with those using the composite prepared from CNF powder.

• Progress in Superconductivity and Cryogenics
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• v.8 no.1
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• pp.19-22
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• 2006

Desirable substrates for $YBa_2Cu_3O_{7-\delta}$ coated conductor are highly cube textured Ni or Ni-alloy tapes, which can be produced by cold rolling and recrystallization annealing. We have fabricated hi-axially textured pure Ni tapes for the application of coated conductors. The sintered Ni rod was cold-rolled into the thin tapes of $50{\mu}m$ thickness and the tapes were heat-treated for texture development with line-focused infrared heater. The temperature was maintained at $800\sim1050^{\circ}C$, using 1kW double ended linear halogen lamp in $96%Ar-4%H_2$ atmosphere The biaxially tortured Ni tapes were successfully formed by line-focused infrared heat treatment The texture of the annealed Ni tapes was analysed using the GADDS (general area detector diffraction system). The full width at half maximum values of phi and omega scan for the Ni tapes were less than $10^{\circ}$ and the grain size was $20-50{\mu}m$.