• Title/Summary/Keyword: Hybrid Structures

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Impact Properties of Glass/Kevlar Hybrid Composites (유리/케블라 하이브리드 구조로 강화된 복합재료의 충격 거동)

  • Joo, Ki-Ho;Ryou, Han-Sun;Chung, Kwan-Soo;Kang, Tae-Jin
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2005.04a
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    • pp.191-194
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    • 2005
  • Impact properties of glass/Kevlar hybrid composites which have 3-D braided structures were studied. Results were compared to those of composites made of only glass fibers where the same epoxy resin were used as matrix. Absorbed impact energies evaluated through the combination of the data from the impact tester and high speed camera were compared to each other. In order to see the difference between the damaged area distribution CCD camera captures were performed.

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Self Diagnosis Monitoring System of Carbon and Glass Hybrid Fiber Materials for Concrete Structures (CFGFRP 복합재료를 이용한 콘크리트 자기진단 모니터링)

  • Park, Seok-Kyun;Kim, Dae-Hun
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.05a
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    • pp.359-362
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    • 2005
  • Self diagnosis monitoring system is defined as concrete structural carbon and glass hybrid fiber materials, in response to the change in external disturbance and environments, toward structural safety and serviceability as well as the extension of structural service life. In this study, carbon and glass hybrid fiber materials were investigated fundamentally for the applicability of self diagnosis in smart concrete structural system as embedded functions of sensors.

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Numerical Analysis of SMA Hybrid Composite Plate Subjected to Low-Velocity Impact

  • Kim, Eun-Ho;Roh, Jin-Ho;Lee, In
    • International Journal of Aeronautical and Space Sciences
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    • v.8 no.2
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    • pp.76-81
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    • 2007
  • The fiber reinforced laminated composite structures are very susceptible to be damaged when they are impacted by foreign objects. To increase the impact resistance of the laminated composite structures, shape memory alloy(SMA) thin film is embedded in the structure. For the numerical impact analysis of SMA hybrid composite structures, SMA modeling tool is developed to consider pseudoelastic effect of SMAs. Moreover, the damage analysis is considered using failure criteria and a simple damage model for reasonable impact analysis. The numerical results are verified with the experimental ones. Impact analyses for composite plate with pre-strained SMAs are numerically performed and the damage areas are investigated.

Effect of fiber content on flexural properties of fishnet/GFRP hybrid composites

  • Raj, F. Michael;Nagarajan, V.A.;Elsi, S. Sahaya;Jayaram, R.S.
    • Steel and Composite Structures
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    • v.22 no.1
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    • pp.13-24
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    • 2016
  • In the present paper, glass fibers are substituted partially with monofilament fishnet and polyester matrix for making the composites. The composite specimens were prepared in accordance with ASTM for analyzing the flexural strength and dynamic mechanical properties. Furthermore, machinability revealed the interaction of glass fiber and partial substituted monofilament fishnet fiber with the matrix. Fiber pullouts on the fractured specimen during the physical testing of the composites are also investigated by COSLAB microscope. The results reveal that the fishnet based composites have appreciably higher flexural properties. Furthermore, the glass fiber, woven roving and fishnet composite has more storage modulus and significant mechanical damping. The composite specimens were fabricated by hand lay-up method. Hence, these composites are the possible applications to develop the value added products. The results of this study are presented.

Maintenance And Reinforcement Design Of Olympic fencing Stadium (올림픽 펜싱경기장의 보수.보강설계)

  • HwangBo, Suk;Yoon, Kwang-Jae;Han, Sang-Eul
    • Proceeding of KASS Symposium
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    • 2005.05a
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    • pp.108-115
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    • 2005
  • Maintenance and reinforcement are very important especially in the case of the hybrid structures. In this paper, we introduce the maintenance and reinforcement design method of cable dome structures. In the case of the Olympic fencing stadium structural system has the stiffness in dependence of the initial tension force. Therefore, the verification of this phenomenon is very important. The result shows that the final tension force which is measured is almost reached to the calculated aim tension force after the maintenance ana reinforcement works is confirmed.

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Investigations on critical speed suppressing by using electromagnetic actuators

  • Mahfoud, Jarir;Der Hagopian, Johan
    • Smart Structures and Systems
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    • v.9 no.4
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    • pp.303-311
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    • 2012
  • The possibility of suppressing critical speeds by using electromagnetic actuators (EMAs) is assessed experimentally in this paper. The system studied is composed of a horizontal flexible shaft supported by two ball bearings at one end and one roller bearing that is located in a squirrel cage at the other end. Four identical EMAs supplied with constant current are utilized. The EMAs associated to the squirrel cage constitutes the hybrid bearing. Results obtained, show that the constant current, when applied to the EMAs, produces a shift of the first critical speed toward lower values. Moreover, the application of constant current for a speed interval around the critical speed enables a smooth run-up or run-down without crossing any resonance.

Comparison of Foliar Ultrastructure of 3 Dubautia species (Dubautia속(屬) 3종(種) 식물(植物)의 엽육조직(葉肉組織) 미세구조(微細構造) 비교연구(比較硏究))

  • Kim, In-Sun
    • Applied Microscopy
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    • v.24 no.4
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    • pp.13-31
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    • 1994
  • The fine structure of palisade chloroplasts has been studied in the mature leaves of 3 Dubautia species (D. scabra var. leiophylla, D. knudsenii and D. scabra var. leiophylla${\times}$D. knudsenii) to explore variation at the ultrastructural level, since the parental species exhibit quite different morphological and anatomical features. Types of thylakoidal membrane systems, occurrence and distribution of phytoferritin-like structures, lipid droplets, starch grains, mitochondria and microbodies were examined. Four different types of thylakoidal membranes were found in D. scabra var. leiophylla, 2 rather uniform types in D. knudsenii and 3 intermediate types in their hybrid. D. scabra var. leiophylla and the hybrid were marked by statistically significant differences in mean numbers of thylakoids per granum, while no significant difference was found between D. knudsenii and the hybrid. Phytoferritin-like structures which were about $100-120{\AA}$ in diameter as a whole particle each were found in all 3 species. The amount and distribution of particles varied by species. Lipid droplets, plastoglobuli, and starch grains occurred in all 3 species, but the frequency of starch grains also varied with the species. More frequent and larger starch grains were observed in D. knudsenii than in the other two species. Microbodies, or peroxisome, were observed throughout all species. They occurred, either with or without crystalline inclusions, around the chloroplasts.

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Mechanical Properties of Hybrid FRP Rebar (하이브리드 FRP 리바의 역학적 특성)

  • 박찬기;원종필
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.45 no.2
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    • pp.58-67
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    • 2003
  • Over the last decade fiber-reinforced polymer (FRP) reinforcement consisting of glass, carbon, or aramid fibers embedded in a resin such as vinyl ester, epoxy, or polyester has emerged as one of the most promising and affordable solutions to the corrosion problems of steel reinforcement in structural concrete. But reinforcing rebar for concrete made of FRP rebar has linear elastic behavior up to tensile failure. For safety a certain plastic strain and an elongation greater than 3% at maximum load is usually required for steel reinforcement in concrete structures. The same should be required for FRP rebar. Thus, the main object of this study was to develop new type of hybrid FRP rebar Also, this study was evaluated to the mechanical properties of Hybrid FRP rebar. The Manufacture of the hybrid FRP rebar was achieved by pultrusion, and braiding and filament winding techniques. Tensile and interlaminar shear test results of Hybrid FRP rebar can provide its excellent tensile strength-strain behavior and interlaminar stress-strain behavior.

Enabling role of hybrid simulation across NEES in advancing earthquake engineering

  • Gomez, Daniel;Dyke, Shirley J.;Maghareh, Amin
    • Smart Structures and Systems
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    • v.15 no.3
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    • pp.913-929
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    • 2015
  • Hybrid simulation is increasingly being recognized as a powerful technique for laboratory testing. It offers the opportunity for global system evaluation of civil infrastructure systems subject to extreme dynamic loading, often with a significant reduction in time and cost. In this approach, a reference structure/system is partitioned into two or more substructures. The portion of the structural system designated as 'physical' or 'experimental' is tested in the laboratory, while other portions are replaced with a computational model. Many researchers have quite effectively used hybrid simulation (HS) and real-time hybrid simulation (RTHS) methods for examination and verification of existing and new design concepts and proposed structural systems or devices. This paper provides a detailed perspective of the enabling role that HS and RTHS methods have played in advancing the practice of earthquake engineering. Herein, our focus is on investigations related to earthquake engineering, those with CURATED data available in their entirety in the NEES Data Repository.

Feedforward actuator controller development using the backward-difference method for real-time hybrid simulation

  • Phillips, Brian M.;Takada, Shuta;Spencer, B.F. Jr.;Fujino, Yozo
    • Smart Structures and Systems
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    • v.14 no.6
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    • pp.1081-1103
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    • 2014
  • Real-time hybrid simulation (RTHS) has emerged as an important tool for testing large and complex structures with a focus on rate-dependent specimen behavior. Due to the real-time constraints, accurate dynamic control of servo-hydraulic actuators is required. These actuators are necessary to realize the desired displacements of the specimen, however they introduce unwanted dynamics into the RTHS loop. Model-based actuator control strategies are based on linearized models of the servo-hydraulic system, where the controller is taken as the model inverse to effectively cancel out the servo-hydraulic dynamics (i.e., model-based feedforward control). An accurate model of a servo-hydraulic system generally contains more poles than zeros, leading to an improper inverse (i.e., more zeros than poles). Rather than introduce additional poles to create a proper inverse controller, the higher order derivatives necessary for implementing the improper inverse can be calculated from available information. The backward-difference method is proposed as an alternative to discretize an improper continuous time model for use as a feedforward controller in RTHS. This method is flexible in that derivatives of any order can be explicitly calculated such that controllers can be developed for models of any order. Using model-based feedforward control with the backward-difference method, accurate actuator control and stable RTHS are demonstrated using a nine-story steel building model implemented with an MR damper.