• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1491-1494
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• 2003

A specific experimental method, the Split Hopkinson Pressure Bar (SHPB) technique has been widely used to determine the dynamic material properties under the impact compressive loading conditions with strain-rate of the order of 103/s∼104/s. This type of test procedure has been used to examine the dynamic response of materials in various modes of testing. In this paper, dynamic deformation behaviors of rubber materials widely used for the isolation of vibration from varying structures under dynamic loading are determined using a Split Hopkinson Pressure Bar technique.

• Earthquakes and Structures
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• 제13권3호
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• pp.299-307
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• 2017

High Damping Rubber bearings (HDR bearings) have been used in the seismic design of bridge structures widely in China. In earthquakes, structural natural periods will be extended, seismic energy will be dissipated by this kind of bearing. Previously, cyclic loading method was used mainly for test studies on mechanical properties of HDR bearings, which cannot simulate real seismic responses. In this paper, Real-Time Substructure (RTS) test study on mechanical properties of HDR bearings was conducted and it was found that the loading rate effect was not negligible. Then the influence of peak acceleration of ground motion was studied. At last test results were compared with a numerical simulation in the OpenSees software framework with the Kikuchi model. It is found that the Kikuchi model can simulate real mechanical properties of HDR bearings in earthquakes accurately.

• Geomechanics and Engineering
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• 제14권2호
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• pp.115-129
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• 2018

This paper presents a set of results of plate load tests that imposed incremental cyclic loading to a sandy soil bed containing multiple layers of granulated rubber-soil mixture (RSM) at large model scale. Loading and unloading cycles were applied with amplitudes incrementally increasing from 140 to 700 kPa in five steps. A thickness of the RSM layer of approximately 0.4 times the footing diameter was found to deliver the minimum total and residual settlements, irrespective of the level of applied cyclic load. Both the total and residual settlements decrease with increase in the number of RSM layers, regardless of the level of applied cyclic load, but the rate of reduction in both settlements reduces with increase in the number of RSM layers. When the thickness of the RSM layer is smaller, or larger, settlements increase and, at large thicknesses may even exceed those of untreated soil. Layers of the RSM reduced the vertical stress transferred through the foundation depth by distributing the load over a wider area. With the inclusion of RSM layers, the coefficient of elastic uniform compression decreases by a factor of around 3-4. A softer response was obtained when more RSM layers were included beneath the footing damping capacity improves appreciably when the sand bed incorporates RSM layers. Numerical modeling using "FLAC-3D" confirms that multiple RSM layers will improve the performance of a foundation under heavy loading.

• Earthquakes and Structures
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• 제7권6호
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• pp.1141-1169
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• 2014

This study is aimed to investigate the seismic performance of low-rise precast wall system with base isolation. Three types of High Damping Rubber Bearing (HDRB) were designed to provide effective isolation period of 2.5 s for three different kinds of structure in terms of vertical loading. The real size HDRB was manufactured and tested to obtain the characteristic stiffness as well as damping ratio. In the vertical stiffness test, it was revealed that the HDRB was not an ideal selection to be used in isolating lightweight structure. Time history analysis using 33 real earthquake records classified with respective peak ground acceleration-to-velocity (a/v) ratio was performed for the remaining two types of HDRB with relatively higher vertical loading. HDRB was observed to show significant reduction in terms of base shear and floor acceleration demand in ground excitations having a/v ratio above $0.5g/ms^{-1}$, very much lower than the current classification of $0.8g/ms^{-1}$. In addition, this study also revealed that increasing the damping ratio of base isolation system did not guarantee better seismic performance particularly in isolation of lightweight structure or when the ground excitation was having lower a/v ratio.

• 한국지진공학회논문집
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• 제5권6호
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• pp.1-10
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• 2001

본 연구에서는 수평전단시험을 통하여 LRB(lead-rubber hearing)의 동적 특성을 분석하였다. 10ton 및 200ton 용량의 LRB를 이용하여 수평전단시험을 수행한 결과 LRB의 동적 특성은 수평하중의 재하속도, 연직하중의 크기 및 전단변형률 등에 따라 크게 달라지는 것으로 나타났다. 세장비가 큰 면진장치에 과도한 변형을 가할 경우 내부 납심에 소성한지가 발생되어 납심이 파괴되는 것으로 나타났다. 따라서 면진구조물의 설계 및 해석 시에는 지진응답과 재하하중의 크기에 따라서 달라지는 LRB의 기계적 특성치를 적용하여 안전한 설계가 이루어질 수 있도록 하여야 한다.

• Elastomers and Composites
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• 제53권3호
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• pp.168-174
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• 2018

Natural rubber (NR) and bromo-isobutylene-isoprene rubber (BIIR) were compounded with other formulation chemicals through polymer blending via a mechanical mixing method. After rubber vulcanization by hot-press compression molding, the cure characteristics, mechanical properties, and ozone resistance of the NR/BIIR blends were measured. As the BIIR content increased, the maximum torque of the blends decreased, while the optimum cure time and scorch time tended to increase. Furthermore, the hardness of the blends increased with increasing BIIR content, reaching the maximum value at 75 wt% BIIR, and decreased with a further increase in the BIIR loading. The tensile strength and elongation at break decreased with an increase in the BIIR content, reaching the minimum value at 75 wt% BIIR, and increased with a further increase in the BIIR content. In the ozone resistance test, cracks were not generated when the BIIR content was more than 75 wt%.

• Elastomers and Composites
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• 제31권2호
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• pp.111-121
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• 1996

The characteristic of silicone rubber can be seen from its resistance to both low and high temperature, whereas HNBR is resistant only in high temperature moderatly although it can be compounded to give good tensile properties, good oil resistance while silicone rubber severely lacks in these qualities. This study was initiated a balance of properties by blending HNBR and silicone rubber which is not considered for commercial blending; blends of HNBR with silicone rubber tend to show immiscible due to dissimilar nature of silicone and HNBR, the possibility of phase separation cannot be ruled out, in unfilled system after vulcanisation leading to premature failure. Attempt has been made to improve compatibility and minimise the layer seperation by the use of compatibilizer. Both filled and unfilled systems, in presence and absence of compatibilizer have been studied. Improvement in tensile properties of the blends or are observed as compared to the non-blended rubber. Different ratios of HNBR and silicone rubber are represented in this study. Blends of HNBR with silicone rubber were immiscible system. The tensile strength increased with filler loading.

• Smart Structures and Systems
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• 제20권6호
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• pp.739-757
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• 2017

The main goal of this study is to investigate the hysteretic behavior of polyurethane rubber springs in compression with and without precompression. The precompression is introduced to provide rigid force in the behavior, and thereby a precompressed rubber spring can be used for a restoring element. For the goal, this study prepares nine rubber springs for three suites which are all cylindrical in shape with a hole at the center. The rubber springs in each suite have different dimensions of diameter and length but have similar shape factors; thus, they are designed to have a similar compressive stiffness. Three rubber springs from the nine are tested with increasing compressive strain up to 30% strain to investigate the behavior of the rubber springs without precompression as well as the effect of the loading strain. The nine springs are compressed up to 30% strain with increasing precompressive strain from 0 to 20% at increments of 5%. The study analyzes the effective stiffness and damping ratio of the rubber springs with and without precompression, and the rigid force of the precompressed rubber springs is discussed. Finally, this study suggests a regression method to determine the minimum required precompression to eliminate residual strain after unloading.

• Advances in concrete construction
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• 제9권5호
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• pp.479-489
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• 2020

Studies have proved that the mechanical properties of concrete, suddenly is dropped off with employing waste materials as replacements. The effectiveness of fibre addition on the structural stability of concrete has been indicated in recent investigations. There are different waste aggregates and fibres as plastic, rubber tire, coconut, and other natural wastes, which have been evaluated throughout the last decades. The fibres incorporation has a substantial effect on the properties of concrete mix subjected to different loading scenarios. This paper has reviewed different types of wastes and the effect of typical fibres including Poly Ethylene Terephthalate (PET), rubber tire, and waste glass. Furthermore, waste plastic and waste rubber has been especially studied in this review. Although concretes containing PET fibre revealed a reduction in compressive strength at low fibre fractions, using PET is resulted to micro-cracking decrement and increasing flexibility and flexural strength. Finally, according to the reviews, the conventional waste fibres are well-suited to mitigated time-induced damages of concrete and waste fibres and aggregates could be a reliable replacement for concrete.

• 반도체디스플레이기술학회지
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• 제16권1호
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• pp.52-58
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• 2017

Graphene oxide (GO)/carboxylated styrene-butadiene rubber (XSBR) nanocomposites with various contents of GO were prepared by a latex compounding method. It has been confirmed that the functional groups of GO and the hydrogen bonds between GO and XSBR are existed. It can be seen that the scorch time ($t_{s2}$), which is the measurement of incipient vulcanization of rubber, showed a delay after the addition of GO. Field emission scanning electron microscopy was employed to confirm the uniform dispersion of filler in the matrix. Indeed, with increasing fillers loading, the torque, tensile strength, thermal stability and crosslink density of obtained nanocomposites were improved. These results were correlated to the better dispersion of fillers through the rubber matrix.