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Applied Composite Materials: An International Journal for the Science and Application of Composite Materials (v.4, #3)
Experimental evaluation of thermal effects on the tensile mechanical properties of pultruded GFRP rods by F. Crea; G. Porco; R. Zinno (pp. 133-143).
This work represents a preliminary study of a more articulate research project whose aim is to show the possible applications of pultruded products in civil engineering and, in particular, the substitution of FRP rods in classic concrete structures. We present an experimental procedure to first degrade FRP rods with aligned continuous glass fibres through exposure to elevated temperature and then evaluate the changes in their tensile mechanical parameters. The procedure to expose the rods to heat is defined starting from the specifications contained in ASTM D794-68, while the evaluation of the tensile mechanical parameters was set up in a previous work for analogous undamaged FRP rods. From the observation of the experimental data obtained in this work, it is possible to show the strong effects of heat on the ultimate strength and on the Young's modulus of the material that constitutes the rods. In particular, the ultimate strength shows a constant degradation when the temperature increases. By contrast, the Young's modulus is subject to different changes at different temperature exposures.
Keywords: composite materials; pultrusion; thermal damage
Experimental Evaluation of Thermal Effects on the Tensile Mechanical Properties of Pultruded GFRP Rods by F. Crea; G. Porco; R. Zinno (pp. 133-143).
This work represents a preliminary study of a more articulate research project whose aim is to show the possible applications of pultruded products in civil engineering and, in particular, the substitution of FRP rods in classic concrete structures. We present an experimental procedure to first degrade FRP rods with aligned continuous glass fibres through exposure to elevated temperature and then evaluate the changes in their tensile mechanical parameters. The procedure to expose the rods to heat is defined starting from the specifications contained in ASTM D794-68, while the evaluation of the tensile mechanical parameters was set up in a previous work for analogous undamaged FRP rods. From the observation of the experimental data obtained in this work, it is possible to show the strong effects of heat on the ultimate strength and on the Young’s modulus of the material that constitutes the rods. In particular, the ultimate strength shows a constant degradation when the temperature increases. By contrast, the Young’s modulus is subject to different changes at different temperature exposures.
Keywords: composite materials; pultrusion; thermal damage
Fabrication of woven metal fibre reinforced glass matrix composites by Aldo R. Boccaccini; James Ovenstone; Paul A. Trusty (pp. 145-155).
A processing route has been developed for the fabrication of metallic fibre mat reinforced glass matrix composites. For the model experiments reported here, a commercially available satin woven stainless steel 316L fibre mat was used as the reinforcement and soda-lime glass as the matrix. The process involves two steps: (1) the infiltration of the intra- and inter-tows regions of the fibre mats with silica sol using electrophoretic deposition and (2) the fabrication of a composite by cold uniaxial pressing and pressureless sintering of impregnated fibre mats sandwiched between layers of the matrix glass powder. The sintering took place in air at 670°C, and composite materials of sufficient integrity could be obtained without damaging the fibres. The deposited silica remained amorphous at the processing temperature providing a porous interface between the glass matrix and the metallic reinforcement. Obervation of fracture surfaces revealed that both fibre pull-out and fibre deformation occur, which should lead to a significant toughness enhancement. The presence of the interfacial silica layer, deposited using electrophoresis, is thought to be responsible for this behaviour.
Keywords: glass matrix composites; woven metal fibre reinforcement; electrophoresis; processing
Fabrication of Woven Metal Fibre Reinforced Glass Matrix Composites by Aldo R. Boccaccini; James Ovenstone; Paul A. Trusty (pp. 145-155).
A processing route has been developed for the fabrication of metallic fibre mat reinforced glass matrix composites. For the model experiments reported here, a commercially available satin woven stainless steel 316L fibre mat was used as the reinforcement and soda-lime glass as the matrix. The process involves two steps: (1) the infiltration of the intra- and inter-tows regions of the fibre mats with silica sol using electrophoretic deposition and (2) the fabrication of a composite by cold uniaxial pressing and pressureless sintering of impregnated fibre mats sandwiched between layers of the matrix glass powder. The sintering took place in air at 670°, and composite materials of sufficient integrity could be obtained without damaging the fibres. The deposited silica remained amorphous at the processing temperature providing a porous interface between the glass matrix and the metallic reinforcement. Observation of fracture surfaces revealed that both fibre pull-out and fibre deformation occur, which should lead to a significant toughness enhancement. The presence of the interfacial silica layer, deposited using electrophoresis, is thought to be responsible for this behaviour.
Keywords: glass matrix composites; woven metal fibre reinforcement; electrophoresis; processing
Derived dynamic ply properties from test data on angle ply laminates by F. A. R. Al-Salehi; S. T. S. Al Hassani; N. M. Bastaki; M. J. Hinton (pp. 157-172).
Dynamic unidirectional tensile ply properties were extracted from the results of burst tests on angle ply filament wound GRP and KRP tubes under internal hoop loading. The extracted longitudinal and transverse tensile strengths as well as transverse tensile moduli exhibited strainrate sensitivities. Shear properties were derived from test results on 55° and 65° tube angles. Derived shear stress-strain curves and shear strength values are presented at different strain rates; again clearly demonstrating rate effects on these properties. Complete sets of strain rate dependent lamina tensile properties are presented for GRP and KRP covering the strain rate regime of 1 to 102 sec−1.
Keywords: ply properties; angle ply laminates; GRP and KRP tubes; strain rate; transverse and longitudinal strength; transverse and longitudinal moduli; shear strength; residual thermal stress
Derived Dynamic Ply Properties from Test Data on Angle Ply Laminates by F. A. R. Al-Salehi; S. T. S. Al Hassani; N. M. Bastaki; M. J. Hinton (pp. 157-172).
Dynamic unidirectional tensile ply properties were extracted from the results of burst tests on angle ply filament wound GRP and KRP tubes under internal hoop loading. The extracted longitudinal and transverse tensile strengths as well as transverse tensile moduli exhibited strain-rate sensitivities. Shear properties were derived from test results on 55° and 65° tube angles. Derived shear stress-strain curves and shear strength values are presented at different strain rates; again clearly demonstrating rate effects on these properties. Complete sets of strain rate dependent lamina tensile properties are presented for GRP and KRP covering the strain rate regime of 1 to 102 sec-1.
Keywords: ply properties; angle ply laminates; GRP and KRP tubes; strain rate; transverse and longitudinal strength; transverse and longitudinal moduli; shear strength; residual thermal stress
Mechanical and Impact Behaviour of (Al2O3)p/2014 and (Al2O3)p/6061 Al Metal Matrix Composites in the 25–200°C Range by F. Bonollo; L. Ceschini; G. L. Garagnani (pp. 173-185).
The present work is aimed at studying the impact behaviour of commercially available Aluminium matrix composites, in a temperature interval ranging from 25C° to 200°C. The results of instrumented impact tests and of microstructural and fractographic observations are correlated with the tensile properties of these materials. A description of the phenomena involved (particles cracking, interfacial failure associated to matrix-reinforcement reaction layers, ductile behaviour of the matrix) is given. The effect of testing temperature as well as that of the matrix characteristics are presented and discussed.
Keywords: aluminum matrix composites; impact strength; tensile strength; high temperature testing; fractography
Mechanical and impact behaviour of (Al2O3) p /2014 and (Al2O3) p /6061 Al metal matrix composites in the 25–200°C range by F. Bonollo; L. Ceschini; G. L. Garagnani (pp. 173-185).
The present work is aimed at studying the impact behaviour of commercially available Aluminium matrix composites, in a temperature interval ranging from 25°C to 200°C. The results of instrumented impact tests and of microstructural and fractographic observations are correlated with the tensile properties of these materials. A description of the phenomena involved (particles cracking, interfacial failure associated to matrix-reinforcement reaction layers, ductile behaviour of the matrix) is given. The effect of testing temperature as well as that of the matrix characteristics are presented and discussed.
Keywords: aluminum matrix composites; impact strength; tensile strength; high temperature testing; fractography
Fiber Optic Bend Sensor for In-Process Monitoring of Polymeric Composites by W. P. Wang; T. H. Hwang; E. Y. Shu; M. H. Vartanian; R. A. Ridilla (pp. 187-195).
Wrinkles, porosity, delaminations and other defects introduced during the manufacturing processing can compromise mechanical performance of advanced composites. This paper describes a method of using fiber optic sensors for monitoring the formation of graphite fiber bending in real time during manufacturing process. Theoretical formulation of the sensor behavior and experimental results are presented. The response of the sensor to composite fiber bending is characterized. The application to analyzing the formation of wrinkles in compression molding of graphite/epoxy composites is demonstrated.
Keywords: fiber optic; monitoring; wrinkle; polymeric composites; bend sensor; molding; on-line quality assurance
Fiber optic bend sensor for in-process monitoring of polymeric composites by W. P. Wang; T. H. Hwang; E. Y. Shu; M. H. Vartanian; R. A. Ridilla (pp. 187-195).
Wrinkles, porosity, delaminations and other defects introduced during the manufacturing processing can compromise mechanical performance of advanced composites. This paper describes a method of using fiber optic sensors for monitoring the formation of graphite fiber bending in real time during manufacturing process. Theoretical formulation of the sensor behavior and experimental results are presented. The response of the sensor to composite fiber bending is characterized. The application to analyzing the formation of wrinkles in compression molding of graphite/epoxy composites is demonstrated.
Keywords: fiber optic; monitoring; wrinkle; polymeric composites; bend sensor; molding; on-line quality assurance