• Title, Summary, Keyword: Volume Fraction

Search Result 2,159, Processing Time 0.037 seconds

Effect of volume fraction on stability analysis of glass fibre reinforced composite plate

  • Mini, K.M.;Lakshmanan, Mahadevan;Mathew, Lubin;Kaimal, Girish
    • Steel and Composite Structures
    • /
    • v.12 no.2
    • /
    • pp.117-127
    • /
    • 2012
  • This paper deals with an experimental investigation to study the effect of fibre content on the stability of composite plates with various aspect ratios. Epoxy based glass fibre reinforced composite plates with aspect ratio varying from 0.4 to 1 and with volume fractions of 0.36, 0.4, 0.46, 0.49 and 0.55 are used for the investigation. From the study it is observed that for plate with aspect ratio of 0.5 and 0.4 there is no buckling and the plate got crushed at the middle. As the volume fraction increases the buckling load also increases to a limit and then began to reduce with further increase in fibre content. The optimum range of fibre content for maximum stability is found between 0.49 and 0.55. Polynomial expressions are developed for the study of buckling behaviour of composite plates with different volume fractions in terms of load and aspect ratio.

Effects of Volume Fraction & Particle Size of Alumina on Sintering Behaviors of the Glass-Alumina Composites for Low Firing Temperature (저온 소성용 유리-알루미나 복합체에서 알루미나의 부피분율과 입자크기에 따른 소결 거동)

  • 박덕훈;김봉철;김정주;박이순
    • Journal of the Korean Ceramic Society
    • /
    • v.37 no.7
    • /
    • pp.638-644
    • /
    • 2000
  • The sintering behaviors of the glass-alumina composites for low firing temperature were investigated as functiions of the volume fraction of alumina powder and the particle size with respect to porosity and pore shape. As the volume fraction of alumina powder was increased or the particle size of it was decreased, the sintering temperature of open pore-closing was raised. When the volume fractions of alumina which had 2.19$\mu\textrm{m}$ median diameter were increased with 20, 30, 40, and 50%, the sintering temperatures of open pore-closing were 425, 450, 475, and 500$^{\circ}C$. And when the median particle size of alumina was diminished from 2.19$\mu\textrm{m}$ to 0.38$\mu\textrm{m}$, the sintering temperature of open pore-closing was increased from 450$^{\circ}C$ to 475$^{\circ}C$. Especially, the sintering temperature, which showed maximum density, was corresponded with the stage of open pore-closing and after achieving maximum density over heating resulted in dedensification of specimen, so called, over-firing behavior.

  • PDF

Exchange Coupling in Massively Produced Nd2Fe14B+Fe3B Nanocomposite Powders

  • Yang, Choong Jin;Park, Eon Byung;Han, Jong Soo;Kim, Eung Chan
    • Journal of Magnetics
    • /
    • v.9 no.2
    • /
    • pp.27-33
    • /
    • 2004
  • Magnetic properties of $Nd_4Fe_{77.5}B_{18.5}$ compound in term of exchange coupling between $Nd_2Fe_{14}B$ and $Fe_3B$ magnetic nano crystals in melt spun powders were characterized by varying the quenching speed in mass production line. The exchange coupled phenomenon was characterized as functions of nano crystal size and volume fraction of each magnetic phase which was possible by employing Henkel plot (${\delta}M$) and refined Mossbauer spectroscopy. The optimized magnetic properties obtained from the present volume production line were: $B_r= 11.73 kG,{_i}H_c/ = 3.082 kOe$, and $(BH)_{max} = 12.28 MGOe.$ The volume fraction of each magnetic phase for those conditions giving the grain size of 10 nm were ${\alpha}-Fe; 4.2%, Fe_3B; 60.1 %$, and $Nd_2Fe_{14}B; 35.7%$. The superior magnetic properties in the $Nd_2Fe_{14}Fe_3B$ based nanocomposites were confirmed to be dependant on the volume fraction of $Fe_3B$.

Microstructure and Material Properties of Fibrous Al2O3-(m-ZrO2)/t-ZrO2 Composite Depending on the Volume Fraction of Core/Shell (코어/쉘 부피비에 따른 섬유상 Al2O3-(m-ZrO2)/t-ZrO2 복합재료의 미세조직 및 물성)

  • Kim Ki-Hyun;Lee Byong-Taek
    • Korean Journal of Materials Research
    • /
    • v.15 no.12
    • /
    • pp.751-755
    • /
    • 2005
  • Fibrous $Al_2O_3-(m-ZrO_2)/t-ZrO_2$ composites having core/shell structure were fabricated by multi-extrusion process. The effect o volume fraction between core ($Al_2O_3-(m-ZrO_2)$) and shell ($t-ZrO_2$ was investigated to understand the relationship between microstructure and material properites, in which the volume fractions of core and shell were varied as 40:60, 50:50 and 60:40. The material properties o hardness and bending strength were increased as the volume fraction of core was increased, and their maximum values were about 1320 Hv and 750MPa, respectively. However, as the volume fraction of core increased, the values of relative density and fracture toughness were decreased from 97.1 to $96.5\%$ and from $6.5MPa{\cdot}m^{1/2}$ to $5.7MPa{\cdot}m^{1/2}$, respectively.

A Study about Mechanical Properties of GFRP Laminates depending on Fiber Volume Fraction (섬유체적함유율의 영향에 따른 GFRP적층판의 기계적 특성에 관한 연구)

  • 국중석
    • Proceedings of the Korean Society For Composite Materials Conference
    • /
    • /
    • pp.225-230
    • /
    • 2003
  • Domestic small and medium ship companies have lack of leisure boat technologies and especially they have a problem about its low performance because of the overweight of boat hull. So it is necessary to have alternative manufacturing process to improve the mechanical properties of composite material. In this study, a vacuum curing system was developed as an alternative manufacturing process and then changed the fiber volume fractions of GFRP laminates. The properties of GFRP laminates such as void contents, Young's modulus and fracture toughness were determined for various fiber volume fractions.

  • PDF

Anisotropy Studies on Hot-forged $\gamma$-TiAl Alloys (열간단조된 $\gamma$-TiAl 합금의 이방성에 관한 연구)

  • Lee, Jae-Seung;Park, No-Jin;Kim, Seong-Jin;Kim, Seung-Eon;O, Myeong-Hun
    • Korean Journal of Materials Research
    • /
    • v.10 no.9
    • /
    • pp.629-635
    • /
    • 2000
  • The texture evolution during isothermal forging and subsequent heat treatment in Ti-48.5at%Al-0.6at%Mo alloy was investigated. Especially, in the present study, research interest was focused on the interrelation between lamellar volume fraction and textures varied with the change of heat-treated time and temperature. It was found that texture components having ND┴{302) and TD$\perp${100} with minor TD$\perp${111} were developed by isothermal forging. In addition, when the followed heat-treatment time and temperature increased from $1330^{\circ}C$/10h to $1350^{\circ}C$/20h respectively, both the lamellar volume fraction and the intensity of textures mentioned above also gradually increased. However, the tensile elongation at room temperature decreased oppositely, as the lamellar volume fraction increased. These results suggested that tensile properties of $\gamma$-TiAl with the nearly lamellar microstructure at room temperature were affected more strongly by the microstructural features such as lamellar volume fraction rather than by textures.

  • PDF

Composite Structures of $SiC_p$/6063 Aluminum Alloy by Rheo-Compocasting. (Rheo-Compocasting에 의한 $SiC_p$/6063 Al합금의 복합조직)

  • Choe, Jeong-Cheol
    • Journal of Korea Foundry Society
    • /
    • v.10 no.4
    • /
    • pp.309-315
    • /
    • 1990
  • Aluminum alloy matrix composites reinforced by SiC particles were prepared by rheocompocasting, a process which consists of the incoporation and distribution of reinforcement by stirring within a semi-solid alloy. When the volume fraction of SiCp and stirring speed were fixed, the dispersion of SiCp in Al-matrix alloy depended on stirring time and solid volume fraction in slurry. The results were as follows : 1) As a dispersed SiCp during stirring at $647^{\circ}C$ in 6063-Al alloy, SiC was better dispersed than that other temperature, where solid volume fraction was 43% in slurry. 2) When increased solid fraction in slurry, rate of dispersing SiC increased during stirring and porosities decreased in matrix alloy after casting. 3) Inspite of stirring with 800rpm, since solid particles of matrix alloy in slurry joined each other and occured joining growth, so that SiC was not dispersed into solid particle.

  • PDF

Performance Analysis of Solar Heating System for High Solar Fraction using TRNSYS (태양열 온수급탕 시스템의 TRNSYS 열성능 분석)

  • Sohn, Jin-Gug
    • Journal of the Korean Solar Energy Society
    • /
    • v.32 no.3
    • /
    • pp.59-67
    • /
    • 2012
  • In this paper, performances of solar hot water supply systems are parametrically analyzed with the variations of solar collector area, slope of collector and volume of storage. All simulations are conducted by using TRNSYS computer program. Average solar fractions, collector efficiencies and temperatures of storage are investigated monthly as well as annually. For system analysis, the maximum value of monthly average solar fractions has a limitation of 90 percent. As a result, the designed solar thermal system with $6m^2$ collector area, $50^{\circ}$ slope and $0.36m^2$ storage volume could provide almost an annual average solar fraction of 72 percent. By increasing the storage volume to $0.42m^2$, the annual solar fraction of system increases up to 73 percent.

High Temperature Thermo-mechanical Properties of HfC Reinforced Tungsten Matrix Composites

  • Umer, Malik Adeel;Lee, Dong Ju;Ryu, Ho Jin;Hong, Soon Hyung
    • Composites Research
    • /
    • v.28 no.6
    • /
    • pp.366-371
    • /
    • 2015
  • In order to improve the mechanical properties of tungsten at room and elevated temperature, hafnium carbide (HfC) reinforced tungsten matrix composites were prepared using the spark plasma sintering technique. The effect of HfC content on the compressive strength and flexural strength of the tungsten composites was investigated. Mechanical properties of the composites were also measured at elevated temperatures and their trends, with varying reinforcement volume fraction, were studied. The effect of reinforcement fraction on the thermal properties of the composites was investigated. The thermal conductivity and diffusivity of the composites decreased with increasing temperature and reinforcement volume fraction. An inherently low thermal conductivity of the reinforcement as well as interfacial losses was responsible for lower values of thermal conductivity of the composites. Values of coefficient of thermal expansion of the composites were observed to increase with HfC volume fraction.

Material Topology Optimization of FGMs using Homogenization and Linear Interpolation Methods (균질화 및 선형보간법을 이용한 기능경사 내열복합재의 물성분포 최적설계)

  • 조진래;박형종
    • Journal of the Computational Structural Engineering Institute of Korea
    • /
    • v.14 no.4
    • /
    • pp.495-503
    • /
    • 2001
  • In a functionally graded materials(FGM), two constituent material particles are mixed up according to a specific volume fraction distribution so that its thermoelastic behavior is definitely characterized by such a material composition distribution. Therefore, the designer should determine the most suitable volume fraction distribution in order to design a FGM that optimally meets the desired performance against the given constraints. In this paper, we address a numerical optimization procedure, with employing interior penalty function method(IPFM) and FDM, for optimizing 2D volume fractions of heat-resisting FGMs composed of metal and ceramic. We discretize a FGM domain into finite number of homogenized rectangular cells of single design variable in order for the optimization efficiency. However, after the optimization process, we interpolate the discontinuous volume fraction with globally continuous bilinear function in order to enforce the continuity of volume fraction distributions.

  • PDF