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Free Vibration Analysis of Fiber Metal Laminate Annular Plate by State-Space Based Differential Quadrature Method  [PDF]
G. H. Rahimi,M. S. Gazor,M. Hemmatnezhad,H. Toorani
Advances in Materials Science and Engineering , 2014, DOI: 10.1155/2014/602708
Abstract: A three-dimensional elasticity theory by means of a state-space based differential quadrature method is presented for free vibration analysis of fiber metal laminate annular plate. The kinds of composite material and metal layers are considered to be S2-glass and aluminum, respectively. A semianalytical approach which uses state-space in the thickness and differential quadrature in the radial direction is implemented for evaluating the nondimensional natural frequencies of the annular plates. The influences of changes in boundary condition, plate thickness, and lay-up direction on the natural frequencies are studied. A comparison is also made with the numerical results reported by ABAQUS software which shows an excellent agreement. 1. Introduction Recently, fiber metal laminates (FML), due to their excellent mechanical properties as well as low density, have gained much attention for aircraft structures. Till now, several research papers have been conducted on the vibrational behavior of these structures. Using the free vibration damping tests, Botelho et al. [1] obtained the elastic and viscous responses for aluminum 2024-T3 alloy, carbon fiber/epoxy composites, carbon fiber/aluminum 2024-T3/epoxy hybrid composites, and glass fiber/aluminum2024-T3/epoxy hybrid composites. They also compared the elastic and viscous responses of these new materials with those of conventional polymer composites. Reyes and Cantwell [2] investigated the quasistatic and impact properties of a novel fiber/metal laminate system based on a tough glass-fiber-reinforced polypropylene. Their testing showed that, by incorporating an interlayer based on a maleic-anhydride modified polypropylene copolymer at the interface between the composite and aluminum layers, one can reach to excellent adhesion properties. Based on the first-order shear deformation theory, Shooshtari and Razavi [3] solved the linear and nonlinear vibrations of FML plate using the multiple time scales method. Khalili et al. [4] studied the dynamic response of FML cylindrical shells subjected to initial combined axial load and internal pressure. They implemented the Galerkin method for solving the governing equations. They examined the influences of FML parameters and arrived at the point that the FML layup has a significant effect on the natural frequencies of vibration. In recent years, several researchers have implemented the differential quadrature method (DQM) for investigating the free vibration and static analyses of engineering structures. Using the three-dimensional theory of elasticity, Alibeigloo and
Strength Characterization of E-glass Fiber Reinforced Epoxy Composites with Filler Materials  [PDF]
K. Devendra, T. Rangaswamy
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2013, DOI: 10.4236/jmmce.2013.16054
Abstract: In this research work, an investigation was made on the mechanical properties of E-glass fiber reinforced epoxy composites filled by various filler materials. Composites filled with varying concentrations of fly ash, aluminum oxide (Al2O3), magnesium hydroxide (Mg(OH)2) and hematite powder were fabricated by standard method and the mechanical properties such as ultimate tensile strength, impact strength and hardness of the fabricated composites were studied. The test results show that composites filled by 10% volume Mg(OH)2 exhibited maximum ultimate tensile strength and hardness. Fly ash filled composites exhibited maximum impact strength.
Fracture of Aramid Fiber/Epoxy Resin Micro Composites
Xia WANG,Chunxin ZHANG,Shijiu JIN,Yunzhao YU,

材料科学技术学报 , 1995,
Abstract: Kevlar-49 fiber was modified through cold air plasma treatment and plasma grafting with acrylic monomers. Fracture of aramid fiber/epoxy resin micro composites has been studied by means of single fiber pull-out test. Tow types of pull-out curves are correlated with the different failure modes. A polyacrylic acid-co-ethyl acrylate graft layer can improve the adhesion and protect the fiber from damage caused by interfacial stresses.
Mechanical and morphological characterizations of carbon fiber fabric reinforced epoxy composites used in aeronautical field
Paiva, Jane Maria Faulstich de;Santos, Alexandre De Nadai dos;Rezende, Mirabel Cerqueira;
Materials Research , 2009, DOI: 10.1590/S1516-14392009000300019
Abstract: carbon fiber reinforced composites (cfrc) have been used in aeronautical industry in the manufacture of different aircraft components that must attend tight mechanical requirements. this paper shows a study involving mechanical (flexural, shear, tensile and compressive tests) and morphological characterizations of four different laminates based on 2 epoxy resin systems (8552tm and f584tm) and 2 carbon fiber fabric reinforcements (plain weave (pw) and eight harness satin (8hs)). all laminates were obtained by handing lay-up of prepregs plies (0o/90o) and consolidation in an autoclave following an appropriate curing cycle with vacuum and pressure. the results show that the f584-epoxy matrix laminates present better mechanical properties in the tensile and compressive tests than 8552 composites. it is also observed that pw laminates for both matrices show better flexural and interlaminar shear properties.
Assessment of cumulative damage by using ultrasonic C-scan on carbon fiber/epoxy composites under thermal cycling
Shiino, Marcos Yutaka;Faria, Maria Candida Magalh?es;Botelho, Edson Cocchieri;Oliveira, Pedro Carlos de;
Materials Research , 2012, DOI: 10.1590/S1516-14392012005000062
Abstract: in recent years, structural composites manufactured by carbon fiber/epoxy laminates have been employed in large scale in aircraft industries. these structures require high strength under severe temperature changes of -56° until 80 °c. regarding this scenario, the aim of this research was to reproduce thermal stress in the laminate plate developed by temperature changes and tracking possible cumulative damages on the laminate using ultrasonic c-scan inspection. the evaluation was based on attenuation signals and the c-scan map of the composite plate. the carbon fiber/epoxy plain weave laminate underwent temperatures of -60° to 80 °c, kept during 10 minutes and repeated for 1000, 2000, 3000 and 4000 times. after 1000 cycles, the specimens were inspected by c-scanning. a few changes in the laminate were observed using the inspection methodology only in specimens cycled 3000 times, or so. according to the found results, the used temperature range did not present enough conditions to cumulative damage in this type of laminate, which is in agreement with the macro - and micromechanical theory.
Fatigue behaviour study on repaired aramid fiber/epoxy composites  [PDF]
Edson Cocchieri Botelho,Rogério Lago Mazur,Michelle Leali Costa,Geraldo Maurício Candido
Journal of Aerospace Technology and Management , 2009,
Abstract: Aramid fiber reinforced polymer composites have been used in a wide variety of applications, such as aerospace, marine, sporting equipment and in the defense sector, due to their outstanding properties at low density. The most widely adopted procedure to investigate the repair of composites has been by repairing damages simulated in composite specimens. This work presents the structural repair influence on tensile and fatigue properties of a typical aramid fiber/epoxy composite used in the aerospace industry. According to this work, the aramid/epoxy composites with and without repair present tensile strength values of 618 and 680MPa, respectively, and tensile modulus of 26.5 and 30.1 GPa, respectively. Therefore, the fatigue results show that in loads higher than 170 MPa, both composites present a low life cycle (lower than 200,000 cycles) and the repaired aramid/epoxy composite presented low fatigue resistance in low and high cycle when compared with non-repaired composite. With these results, it is possible to observe a decrease of the measured mechanical properties of the repaired composites.
Bending investigation on carbon fiber/epoxy composites nano-modified by graphene
ávila, A. F.;Peixoto, L. G. Z. de O.;Silva Neto, A.;ávila Junior, J. de;Carvalho, M. G. R.;
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2012, DOI: 10.1590/S1678-58782012000300007
Abstract: an extreme conditions situation, e.g. pre-salt deep sea exploration, requires new materials with even better performance. nanotechnology is the new paradigm that can lead to the development of these new super materials. the effect of graphene pileups dispersion into carbon fiber/epoxy composites was investigated experimentally. the dispersion process was based on sonication and high shear mixing. xrd and sem indicate that although the dispersion process can lead to exfoliated nanostructures, there is a saturation limit for the epoxy system, around 0.5 wt. %. the addition of graphene to carbon/epoxy composites seems to have no influence into stiffness, as the slopes of the stress-strain curves were near constant for all specimen tested. the bending strength, however, was heavily influenced by formation of graphene pileups into epoxy matrix and its dispersion around the carbon fibers. the increase on bending strength from 623.01±70.16 mpa (control samples) to 1259.92±61.73 mpa for 0.5 wt. % graphene addition represents an average improvement of 102%. this can be attributed to changes on failure mechanism, moving from intra-laminar failure to a mix failure mode where inter- and intra-laminar failure are combined in a zigzag pattern. a possible explanation for such behavior is the formation of strong bonds at the fiber/matrix surroundings due to nanostructures formation.
INFLUENCE OF FIBER LENGTH IN THE WEAR BEHAVIOUR OF BORASSUS FRUIT FIBER REINFORCED EPOXY COMPOSITES  [PDF]
L. BOOPATHI,P.S. SAMPATH,K. MYLSAMY
International Journal of Engineering Science and Technology , 2012,
Abstract: In this paper, the wear behavior of Borassus fruit fiber reinforced epoxy composites has been explored. The composites were prepared with raw and 5% alkali treated Borassus fruit fibers of three different fiber lengths 3 mm, 5 mm and 7 mm respectively. The wear tests were made on a pin-on-disc machine when sliding against stainless steel disc by varying loads from 15N – 30 N under dry conditions and the speed of the disc from 300 – 500 rpm. It was observed that the alkali treatment to the fibers improved the wear properties. The influence of fiber length is a key factor in the reinforcement of composites and the results revealed that the 5 mm length alkali treated fiber reinforced composites exhibited superior wear properties than that of others. The Scanning Electron Microscopy image revealed that the 5 mm length alkali treated fiber had better bonding with the epoxy matrix.
Designing of epoxy composites reinforced with carbon nanotubes grown carbon fiber fabric for improved electromagnetic interference shielding
B. P. Singh,Veena Choudhary,Parveen Saini,R. B. Mathur
AIP Advances , 2012, DOI: 10.1063/1.4730043
Abstract: In this letter, we report preparation of strongly anchored multiwall carbon nanotubes (MWCNTs) carbon fiber (CF) fabric preforms. These preforms were reinforced in epoxy resin to make multi scale composites for microwave absorption in the X-band (8.2-12.4GHz). The incorporation of MWCNTs on the carbon fabric produced a significant enhancement in the electromagnetic interference shielding effectiveness (EMI-SE) from 29.4 dB for CF/epoxy-composite to 51.1 dB for CF-MWCNT/epoxy multiscale composites of 2 mm thickness. In addition to enhanced EMI-SE, interlaminar shear strength improved from 23 MPa for CF/epoxy-composites to 50 MPa for multiscale composites indicating their usefulness for making structurally strong microwave shields.
Effect of Red Mud and Copper Slag Particles on Physical and Mechanical Properties of Bamboo-Fiber-Reinforced Epoxy Composites  [PDF]
Sandhyarani Biswas,Amar Patnaik,Ritesh Kaundal
Advances in Mechanical Engineering , 2012, DOI: 10.1155/2012/141248
Abstract: In the present work, a series of bamboo-fiber-reinforced epoxy composites are fabricated by using red mud and copper slag particles as filler materials. A filler plays an important role in determining the properties and behavior of particulate composites. The effects of these two fillers on the mechanical properties of bamboo-epoxy composites are investigated. Comparative analysis shows that with the incorporation of these fillers, the tensile strength of the composites increases significantly, whereas the flexural strength and impact strength decrease with increase in filler content (red mud and copper slag fillers) in the epoxy-bamboo fiber composites. The density and hardness are also affected by the type and content of filler particles. It is found that the addition of copper slag filler improves the hardness of the bamboo-epoxy composites, whereas the addition of red mud filler reduces the hardness value of bamboo-epoxy composites. The study reveals that the addition of copper slag filler in bamboo-epoxy composites shows better physical and mechanical properties as compared to the red-mud-filled composites. 1. Introduction In the recent years, for making the low-cost engineering materials the use of natural fibers in polymers composites has brought forth a lot of interest. The new environmental legislation as well as consumer demands has pressured manufacturing industries (especially automotive, packaging and construction) to search new materials that can replace the conventional nonrenewable reinforcing materials such as glass fibre, carbon fiber, and so forth [1]. The advantages of natural fibers over the traditional glass fibers are low density, good specific strength and modulus, economical viability, enhanced energy recovery, and good biodegradability [2]. There are also some disadvantages of natural fiber-reinforced polymer composites such as the incompatibility between the hydrophilic natural fibres and hydrophobic thermoplastic and thermoset matrices requiring appropriate use of physical and chemical treatments to enhance the adhesion between fibre and the matrix [3]. Generally the cellulosic fibers, like henequen, sisal, coconut fiber (coir), jute, palm, bamboo, wood, paper in their natural condition, and several waste cellulosic products such as shell flour, wood flour, and pulp have been used as reinforcement materials in different thermosetting and thermoplastic resins [4–11]. Being a conventional construction material since ancient times, bamboo fiber is a good campaigner for use as a natural fiber in composite materials. The reason
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