• 제목/요약/키워드: composite suitability

검색결과 60건 처리시간 0.024초

Shear behavior of a demountable bolted connector in steel-UHPC lightweight composite structures

  • Gu, Jin-Ben;Wang, Jun-Yan
    • Structural Engineering and Mechanics
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    • 제81권5호
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    • pp.551-563
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    • 2022
  • Bolted connector could be an alternative to replace the conventional welded headed stud in steel-ultra high performance concrete (UHPC) lightweight composite structures. In this paper, a novel demountable bolted shear connector, consisting of a high-strength bolt (HSB) and a specially-designed nut which is pre-embedded in a thin UHPC slab, is proposed, which may result in the quick installation and disassembly, due to the mountable, demountable and reusable features. In order to study the shear behavior of the new type of bolted shear connector, static push-out tests were conducted on five groups of the novel demountable bolted shear connector specimens and one group of conventional welded headed stud specimen for comparison. The effect of the bolt shank diameter and aspect ratio of bolt on failure mode, shear stiffness, peak slip at the steel-UHPC interface, shear strength and ductility of novel bolted connectors is investigated. Additionally, design formula for the shear strength is proposed to check the suitability for assessment of the novel demountable bolted shear connectors.

Transverse seismic response of continuous steel-concrete composite bridges exhibiting dual load path

  • Tubaldi, E.;Barbato, M.;Dall'Asta, A.
    • Earthquakes and Structures
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    • 제1권1호
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    • pp.21-41
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    • 2010
  • Multi-span steel-concrete composite (SCC) bridges are very sensitive to earthquake loading. Extensive damage may occur not only in the substructures (piers), which are expected to yield, but also in the other components (e.g., deck, abutments) involved in carrying the seismic loads. Current seismic codes allow the design of regular bridges by means of linear elastic analysis based on inelastic design spectra. In bridges with superstructure transverse motion restrained at the abutments, a dual load path behavior is observed. The sequential yielding of the piers can lead to a substantial change in the stiffness distribution. Thus, force distributions and displacement demand can significantly differ from linear elastic analysis predictions. The objectives of this study are assessing the influence of piers-deck stiffness ratio and of soil-structure interaction effects on the seismic behavior of continuous SCC bridges with dual load path, and evaluating the suitability of linear elastic analysis in predicting the actual seismic behavior of these bridges. Parametric analysis results are presented and discussed for a common bridge typology. The response dependence on the parameters is studied by nonlinear multi-record incremental dynamic analysis (IDA). Comparisons are made with linear time history analysis results. The results presented suggest that simplified linear elastic analysis based on inelastic design spectra could produce very inaccurate estimates of the structural behavior of SCC bridges with dual load path.

The Effects of Dielectric Coatings on Electron Emission from Tungsten

  • Al-Qudah, Ala'a M.;Alnawasreh, Shady S.;Madanat, Mazen A.;Trzaska, Oliwia;Matykiewicz, Danuta;Alrawshdeh, Saad S.;Hagmann, Mark J.;Mousa, Marwan S.
    • Applied Microscopy
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    • 제47권1호
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    • pp.36-42
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    • 2017
  • Field electron emission measurements were performed on dielectric-coated tungsten emitters, with apex radii in the nanometer and micrometer range, which were prepared by electrochemical etching in NaOH solution. Measurements were performed in a field electron microscopy (FEM) with a base pressure <$10^{-6}$ Pascal ($10^{-8}$ mbar). Four different types of dielectric were used, namely: (1) Clark Electromedical Instruments epoxylite resin, (2) Epidian 6 produced by Ciech Sarzyna S. A., (3) a Radionox solution of colloidal graphite; and (4) Molyslip 2001 E compound ($MoS_2$ and MoS). Current-voltage measurements and FEM images were used to investigate the characteristics of these composite emitters, and to assess how the different types of dielectric coating affect the suitability of the composite emitter as a potential electron source.

곡률반경을 갖는 CFRP 적층쉘의 충격손상 (Impact Damage of CFRP Laminated Shells with the Curvature)

  • 황재중;이길성;김영남;나승우;심재기;양인영
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2003년도 춘계학술대회 논문집
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    • pp.1341-1344
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    • 2003
  • Studies on impact damage of composite laminate shells were fewer compared with those on impact behaviors to analyze time-load, displacement-load and impact energy - energy absorption. Up to date the studies were not enough to demonstrate suitability of their results because they were dependent on theories and numerical analyses. In particular, it is a well-known fact that there was a correlation between initial peak load and damage resistance of composite material flat plates imposed with low-speed impact, but studies on composite material shells with curvature were also very few. Actually structures such as wings or moving bodies of airplanes, motor cases and pressure containers of rockets are circular. And as low-speed impact load is imposed for optimal design of take-off and landing, and containers of airplanes, it is very important to analyze evaluation of behaviors and damaged areas. Therefore, in this paper to evaluate the impact characteristics of the CFRP laminate shell according to size of curvature quantitatively, it was to identify energy absorption and impact damage instruments according to change of impact speed.

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구리박막의 넓이와 간격에 따른 melt-blown 부직포의 전자파 차폐 효과 (Electromagnetic Shielding Effectiveness of Melt-blown Nonwoven Fabric with Width and Interval of Thin Copper Film)

  • 신현세;손준식;김영상;정진수
    • 한국염색가공학회지
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    • 제16권5호
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    • pp.42-47
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    • 2004
  • The main objective of this work is to develop melt-blown nonwoven fabric composite materials have electromagnetic shielding characteristics using thin copper film. Melt-blown nonwoven fabric is the matrix phase and thin copper films are the reinforcement of the composite materials. Thin copper films are incorporated as conductive fillers to provide the electromagnetic shielding property of the melt-blown nonwoven fabric. The width and interval of thin copper films in the nonwoven fabric are varied by changing 1, 3, 5 mm for thin copper film's width and 1, 3, 5 mm for thin copper film's interval. The shielding effectiveness(SE) of various melt-blown nonwoven fabrics is measured in the frequency range of 50 MHz to 1.8 GHz. The variations of SE of melt-blown nonwoven fabric with width and interval of thin copper films are described. Suitability of melt-blown nonwoven fabric for electromagnetic shielding applications is discussed. The results indicate that the melt-blown nonwoven fabric composite material using thin copper film can be used for the purpose of electromagnetic shielding.

Application of the full factorial design to modelling of Al2O3/SiC particle reinforced al-matrix composites

  • Altinkok, Necat
    • Steel and Composite Structures
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    • 제21권6호
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    • pp.1327-1345
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    • 2016
  • $Al_2O_3$/SiC particulate reinforced (Metal Matrix Composites) MMCs which were produced by using stir casting process, bending strength and hardening behaviour were obtained using an analysis of variance (ANOVA) technique that uses full factorial design. Factor variables and their ranges were: particle size $2-60{\mu}m$; the stirring speed 450 rpm, 500 rpm and the stirring temperature $620^{\circ}C$, $650^{\circ}C$. An empirical equation was derived from test results to describe the relationship between the test parameters. This model for the tensile strength of the hybrid composite materials with $R^2$ adj = 80% for the bending strength $R^2$ adj = 89% were generated from the data. The regression coefficients of this model quantify the tensile strength and bending strengths of the effects of each of the factors. The interactions of all three factors do not present significant percentage contributions on the tensile strength and bending strengths of hybrid composite materials. Analysis of the residuals versus was predicted the tensile strength and bending strengths show a normalized distribution and thereby confirms the suitability of this model. Particle size was found to have the strongest influence on the tensile strength and bending strength.

Research on safety assessment and application effect of nanomedical products in physical education

  • Zhuli Li;Song Peng;Gang Chen
    • Advances in nano research
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    • 제15권3호
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    • pp.253-261
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    • 2023
  • This study investigates the application of nano-composite materials in physical education, specifically focusing on improving the performance of sports hall flooring. The research centers on carbon nanotube reinforced polyvinyl chloride (PVC) composites, which offer enhanced mechanical properties and durability. The incorporation of carbon nanotubes as reinforcements in the PVC matrix provides notable benefits, including increased strength, improved thermal stability, electrical conductivity, and resistance to fatigue. The key parameters examined in this study are the weight percentage of carbon nanotubes and the temperature during the fabrication process. Through careful analysis, it is found that higher weight percentages of carbon nanotubes contribute to a more uniform dispersion within the PVC matrix, resulting in improved mechanical properties. Additionally, higher fabrication temperatures aid in repairing macroscopic defects, leading to enhanced overall performance. The findings of this study indicate that the utilization of carbon nanotube reinforced PVC composites can significantly enhance the strength and durability of sports hall flooring. By employing these advanced materials, the safety and suitability of physical education environments can be greatly improved. Furthermore, the insights gained from this research can contribute to the optimization of composite material design and fabrication techniques, not only in the field of physical education but also in various industries where composite materials find applications.

Investigation on the tensile properties of glass fiber reinforced polymer composite for its use as a structural component at cryogenic temperature

  • Shrabani Ghosh;Nathuram Chakrobarty;Swapan C. Sarkar
    • 한국초전도ㆍ저온공학회논문지
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    • 제25권3호
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    • pp.43-48
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    • 2023
  • Polymer composites, especially glass fiber reinforced polymer (GFRP) are finding ever-increasing applications in areas such as superconductivity, space technology, cryogenic rocket engines, and cryogenic storage vessels. Various components made of polymer composites are much lighter than their metallic counterparts but have equivalent strength for ultra-low temperature applications. In this paper, we have investigated the tensile properties of an indigenously prepared unidirectional cylindrical hollow composite tube for its use as a neck of the cryogenic vessel. XRD and SEM of the tube are completed before cryogenic conditioning to ascertain the fiber and resin distribution in the matrix. The result shows that for composites, after 15, 30, 45, and 60 minutes of cryogenic conditioning at 77K in a liquid nitrogen bath, the strength and modulus increase significantly with the increase of strain rate and reach the optimum value for 45 minutes of conditioning. The results are encouraging as they will be helpful in assessing the suitability of GFRP in the structural design of epoxy-based components for cryogenic applications.

자연유황 회복을 위한 댐 운영에 따른 금강의 물리서식처 변화 분석 (Investigation of the change in physical habitat in the Geum-gang River by modifying dam operations to natural flow regime)

  • 최병웅;장지연;최성욱
    • 한국수자원학회논문집
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    • 제54권11호
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    • pp.985-998
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    • 2021
  • 일반적으로 상류의 댐은 하류 유황을 자연 상태에서 발전방류 조건으로 심각하게 변화시킨다. 본 연구에서는 물리서식처모의를 통하여 국내 조절하천에서 자연유황 패턴이 하류의 어류 서식처에 미치는 영향을 조사하였다. 연구 대상하도는 금강의 용담댐 하류 13.4 km 구간으로 설정하였다. 현장조사 결과, 대상하도에서 피라미, 쉬리, 그리고 끄리가 우점하고 있는 것으로 나타났으며, 이들이 전체의 70%를 차지하고 있는 것으로 파악되었다. 이중 끄리는 금강에 서식하는 토착어종이다. 이들 3종을 물리서식처모의를 위한 대상어종으로 선정하였다. 수리해석과 서식처모의를 위하여 2차원 천수방정식에 기반한 Nays2D 모형과 HIS 모형을 각각 사용하였다. 자연 유황에 따른 영향을 검토하기 위하여, 본 연구에서는 댐 유입 유량과 발전유량을 이용하였다. 물리서식처모의 결과, 자연유황 조건에서 대상하도의 복합서식처지수가 크게 증가하는 것으로 나타났다. 그리고 BBA 방법을 이용하여 대상하도에 자연유황에 대한 댐 운영 시나리오를 제시하였다. 시나리오 1을 위하여 유입유량의 양과 지속기간을 고려하는 수문학적 방법을 이용하였고, 시나리오 2는 유입유량을 월별로 평균하여 구축하였다. 시나리오 1과 시나리오 2를 통해서 구현된 자연유황 조건이 발전방류에 비해 가중가용면적을 크게 증가시키는 것으로 나타났다. 결과적으로 댐 운영을 자연유황 조건으로 변환시켜 방류하였을 때 하류의 어류 서식처를 개선하는데 도움이 되는 것으로 확인되었다.

Stereo-digital image correlation in the behavior investigation of CFRP-steel composite members

  • Dai, Yun-Tong;Wang, Hai-Tao;Ge, Tian-Yuan;Wu, Gang;Wan, Jian-Xiao;Cao, Shuang-Yin;Yang, Fu-Jun;He, Xiao-Yuan
    • Steel and Composite Structures
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    • 제23권6호
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    • pp.727-736
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    • 2017
  • The application of carbon fiber reinforced polymer (CFRP) in steel structures primarily includes two categories, i.e., the bond-critical application and the contact-critical application. Debonding failure and buckling failure are the main failure modes for these two applications. Conventional electrometric techniques may not provide precise results because of the limitations associated with single-point contact measurements. A nondestructive full-field measurement technique is a valuable alternative to conventional methods. In this study, the digital image correlation (DIC) technique was adopted to investigate the bond behavior and buckling behavior of CFRP-steel composite members. The CFRP-to-steel bonded joint and the CFRP-strengthened square hollow section (SHS) steel column were tested to verify the suitability of the DIC technique. The stereo-DIC technique was utilized to measure continuous deformation. The bond-slip relationship of the CFRP-to-steel interface was derived using the DIC data. Additionally, a multi-camera DIC system consisting of four stereo-DIC subsystems was proposed and applied to the compressive test of CFRP-strengthened SHS steel column. The precise buckling location and CFRP delamination of the CFRP-strengthened SHS steel column were identified. The experimental results confirm that the stereo-DIC technique can provide effective measurements for investigating the behaviors of CFRP-steel composite members.