• 제목/요약/키워드: dynamic properties

검색결과 3,327건 처리시간 0.03초

Pulse Shaper를 이용한 SHPB 실험 응력파 제어 효과의 해석 및 실험적 검증 (Numerical and Experimental Verification of Stress Wave Control Effect in SHPB Experiment using Pulse Shaper)

  • 김용희;우민아;강범수;김정
    • 소성∙가공
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    • 제26권5호
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    • pp.314-322
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    • 2017
  • In the high-speed forming analysis, dynamic material properties considering a high strain rate are required. The split Hopkinson pressure bar (SHPB) experiment was performed for measuring dynamic material properties under high strain rate. The pulse shaping method was used to improve the accuracy of the SHPB experiment. A pulse shaper attached to the front of the incident bar was used for specimen dynamic stress equilibrium through stress wave control. Numerical analysis and SHPB test were performed to verify whether the pulse shaper affects the dynamic stress equilibrium in copper and Al6061 specimens. The results of SHPB test and numerical analysis show that the pulse shaper contributes to the dynamic stress equilibrium. Based on the improved stress equilibrium using a pulse shaper, the flow stress curves for copper and Al6061 materials were obtained at strain rates of 1344.4/sec and 1291.6/sec, respectively.

Prediction of the dynamic properties in rubberized concrete

  • Habib, Ahed;Yildirim, Umut
    • Computers and Concrete
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    • 제27권3호
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    • pp.185-197
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    • 2021
  • Throughout the previous years, many efforts focused on incorporating non-biodegradable wastes as a partial replacement and sustainable alternative for natural aggregates in cement-based materials. Currently, rubberized concrete is considered one of the most important green concrete materials produced by replacing natural aggregates with rubber particles from old tires in a concrete mixture. The main benefits of this material, in addition to its importance in sustainability and waste management, comes from the ability of rubber to considerably damp vibrations, which, when used in reinforced concrete structures, can significantly enhance its energy dissipation and vibration behavior. Nowadays, the literature has many experimental findings that provide an interesting view of rubberized concrete's dynamic behavior. On the other hand, it still lacks research that collects, interprets, and numerically investigates these findings to provide some correlations and construct reliable prediction models for rubberized concrete's dynamic properties. Therefore, this study is intended to propose prediction approaches for the dynamic properties of rubberized concrete. As a part of the study, multiple linear regression and artificial neural networks will be used to create prediction models for dynamic modulus of elasticity, damping ratio, and natural frequency.

에어컨 실내기 팬 모터용 방진고무의 동특성 측정에 관한 연구 (A Study on the Measurement of Dynamic Properties of the Rubber Mount in the Impeller Fan Motor of the Air-conditioner)

  • 최현;김준우;강태호
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2001년도 추계학술대회논문집 I
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    • pp.185-190
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    • 2001
  • The structure borne noise of the air-conditioner, which degrades the noise quality, is hardly reduced by the general noise treatments. It can be effectively reduced by eliminating the structural vibration which the noise originates from. The rubber vibration isolator prevents the dynamic force induced by the fan driving motor from exciting the chassis structure, which finally reduces the structure borne noise. The dynamic properties of the vibration isolation system such as the natural frequency of the vibration isolation and loss factor of the rubber isolator, need to be experimentally evaluated. In this paper, these dynamic properties were obtained by the resonant method using the impact hammer for 3 types of the isolator specimens. It is known that the isolation natural frequency of the axial direction of the rubber isolator is two times higher than that of the radial direction, and is proportional to the hardness of the rubber specimen.

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풍응답계측시 RD법에 의한 고층건물의 동적특성의 진폭의존성 (Amplitude Dependent Dynamic Properties of Tall Building under the Strong Wind)

  • 윤성원
    • 한국공간구조학회논문집
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    • 제4권1호
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    • pp.61-68
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    • 2004
  • 풍향풍속계와 구조 모니터링 시스템을 설치하여 강풍과 거물의 동적 특성을 계측하였다. 계측건물은 속초의 산기슭에 위치하고 있다. 감쇠율과 고유진동수의 진폭 의존성을 분석하였다. 감쇠율의 진폭의존성은 9%로서, 가속도진폭이 증가함에 따라서 감쇠율이 명료하게 증가하는 경향을 보였다. 계측데이터에서 얻은 동적 특성의 경향은 사용성 평가시 건물의 동적 특성을 평가하는데 유용하게 사용되리라 기대된다.

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Static and dynamic finite element analysis of honeycomb sandwich structures

  • Triplett, Matt H.;Schonberg, William P.
    • Structural Engineering and Mechanics
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    • 제6권1호
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    • pp.95-113
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    • 1998
  • The extensive use of honeycomb sandwich structures has led to the need to understand and analyze their low velocity impact response. Commercially available finite element software provides a possible analysis tool for this type of problem, but the validity of their material properties models for honeycomb materials must be investigated. Three different problems that focus on the effect of differences in honeycomb material properties on static and dynamic response are presented and discussed. The first problem considered is a linear elastic static analysis of honeycomb sandwich beams. The second is a nonlinear elastic-plastic analysis of a circular honeycomb sandwich plate. The final problem is a dynamic analysis of circular honeycomb sandwich plates impacted by low velocity projectiles. Results are obtained using the ABAQUS final element code and compared against experimental results. The comparison indicates that currently available material properties models for honeycomb materials can be used to obtain a good approximation of the behavior of honeycomb sandwich structures under static and dynamic loading conditions.

면외전단하중이 작용하는 기능경사재료 접합면 균열의 동적전파에 관한 연구 (Dynamic Propagation of a Interface Crack in Functionally Graded Layers under Anti-plane Shear)

  • 신정우;이영신;김성찬
    • 한국전산구조공학회:학술대회논문집
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    • 한국전산구조공학회 2010년도 정기 학술대회
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    • pp.459-464
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    • 2010
  • The dynamic propagation of an interface crack between two dissimilar functionally graded layers under anti-plane shear is analyzed using the integral transform method. The properties of the functionally graded layers vary continuously along the thickness. A constant velocity Yoffe-type moving crack is considered. Fourier transform is used to reduce the problem to a dual integral equation, which is then expressed to a Fredholm integral equation of the second kind. Numerical values on the dynamic energy release rate (DERR) are presented. Followings are helpful to increase of the resistance of the interface crack propagation of FGM: a) increase of the gradient of material properties; b) increase of the material properties from the interface to the upper and lower free surface; c) increase of the thickness of FGM layer. The DERR increases or decreases with increase of the crack moving velocity.

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임프린트 공법적용을 위한 절연재료의 열적, 기계적 성질 (Thermal stabilities and dynamic mechanical properties of dielectric materials for thermal imprint lithography)

  • 조재춘;나승현
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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    • pp.220-221
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    • 2007
  • Recently, imprint lithography have received significant attention due to an alternative technology for photolithography on high performance microelectronic devices. In this work, we investigated thermal stabilities and dynamic mechanical properties of dielectric materials for thermal imprint lithography. Curing behaviours, thermal stabilities, and dynamic mechanical properties of the dielectric materials cured with various curing agent and spherical filler were studied using dynamic differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), rheometer and universal test machine(UTM).

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Dynamic Rheological Invest igation of Hot Pepper-soybean Paste Mixed with Acetylated Starch: Effect of Storage Time and Temperature

  • Yoo, Byoung-Seung
    • Food Science and Biotechnology
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    • 제17권5호
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    • pp.1119-1121
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    • 2008
  • The effects of storage time (0, 1, and 2 month) and temperature (5, 15, and $25^{\circ}C$) on the dynamic rheological properties of hot pepper-soybean paste (HPSP) mixed with acetylated starches (AS) were studied by small-deformation oscillatory measurements. Dynamic moduli (G', G", and $\eta^*$) values of HPSP-AS mixtures increased with an increase in storage time and also decreased with increasing storage temperature. However, dynamic moduli values of the control (no added AS) were independent on storage time and temperature. Tan $\delta$ values (ratio of G"/G') in all HPSP samples did not change much with an increase in storage time and temperature. After 2 months of storage, the dynamic moduli of the HPSP-AS mixture samples were much lower than those of the control, indicating that the addition of AS can inhibit the retrogradation that developed over a long period of storage. Structural and rheological properties of HPSP samples seem to be stabilized by the presence of AS.

할인구매옵션을 고려한 동적 재생산계획문제 (A Dynamic Remanufacturing Planning Problem with Discount Purchasing Options)

  • 이운식
    • 한국경영과학회지
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    • 제34권3호
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    • pp.71-84
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    • 2009
  • This paper considers a remanufacturing and purchasing planning problem, in which either used products(or wastes) are remanufactured or remanufactured products(or final products) are purchased to satisfy dynamic demands of remanufactured products over a discrete and finite time horizon. Also, as remanufactured products are purchased more than or equal to a special quantity Q, a discount price policy is applied. The problem assumes that the related cost(remanufacturing and inventory holding costs of used products, and the purchasing and inventory holding costs of remanufactured products) functions are concave and backlogging is not allowed. The objective of this paper is to determine the optimal remanufacturing and purchasing policy that minimizes the total cost to satisfy dynamic demands of remanufactured products. This paper characterizes the properties of the optimal policy and then, based on these properties, presents a dynamic programming algorithm to find the optimal policy. Also, a network-based procedure is proposed for the case of a large quantity of low cost used products. A numerical example is then presented to demonstrate the procedure of the proposed algorithm.

압축된 고무재료의 정적 변형 해석과 동특성 예측 (Static Deformation Analysis and Dynamic Characteristics Predicton of Compressed Rubber Materials)

  • 김국원;임종락;손희기;안태길
    • 소음진동
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    • 제9권3호
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    • pp.472-476
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    • 1999
  • The effect of static preload on the dynamic properties of rubber materials is rather important, especially when good isolation characteristics are required at high frequencies. However, there are still few papers for dynamic characteristics of compressed rubber components. It was demonstrated in reference (4) that for bonded rubber material of a cylindrical shape, a simplified theory equation between linear dynamic and nonlinear static behavior of rubber material was useful to predict their combined effects. This paper presents the second part of the study. It is confirmed that for the compressed rubber material, the stress can be factored into a function of frequency and a function of strain(stretch). The finite element methodis applied to analyze non-linear large deformation of rubber material and its results are compared with those of a simplified theory equation. The predicted dynamic material properties based on non-linear static finite element analyses have a good agreement of experimental results and those based on simplified theory equation.

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