Synthetic fibers made from nylon or polypropylene have gained application when loose and woven into geo textile form although no information on the matrix’s mechanical performance is obtained so that more understandi...Synthetic fibers made from nylon or polypropylene have gained application when loose and woven into geo textile form although no information on the matrix’s mechanical performance is obtained so that more understanding of their structural contribution to resist cracking can be determined. This paper presents the results of an experimental investigation to determine the performance characteristics of concrete reinforced with a polypropylene structural fiber. In this investigation “Fiber mesh” brand of fibers manufactured by SL Concrete System, Tennessee, USA and marketed by M/S Millennium Building System, Inc., Ban-galore, India are used. The lengths of the fibers used were 24 mm. Fiber dosages used were 0.9, 1.8, 2.7 kg/m3. A total of three mixtures, one for each fiber dosage were made. A standard slump cone test was conducted on the fresh concrete mix with and without fibers to determine the workability of the mix. The test program included the evaluation of hardened concrete properties such as compressive, split tensile, modulus of rupture and flexural strengths. The increase in compressive strength is about 36.25%, 26.20%, and 23.75% respectively that of plain concrete. This increase in strength was directly proportional to amount of fibers present in the mix. The increase in flexural strength for Mixes I^III is about 21%, 16.6%, and 23% respectively that of plain concrete specimens. An experimental investigation was also made to study the behaviors of reinforced fibers concrete beams (with longitudinal reinforcements) under two-point loading. The deflection and crack patterns were also studied. The improvements in strength and ductility characteristics were discussed.展开更多
This research presents a finite element formulation based on four-variable refined plate theory for bending analysis of cross-ply and angle-ply laminated composite plates integrated with a piezoelectric fiber-reinforc...This research presents a finite element formulation based on four-variable refined plate theory for bending analysis of cross-ply and angle-ply laminated composite plates integrated with a piezoelectric fiber-reinforced composite actuator under electromechanical loading. The four-variable refined plate theory is a simple and efficient higher-order shear deformation theory, which predicts parabolic variation of transverse shear stresses across the plate thickness and satisfies zero traction conditions on the plate free surfaces. The weak form of governing equations is derived using the principle of minimum potential energy, and a 4-node non-conforming rectangular plate element with 8 degrees of freedom per node is introduced for discretizing the domain. Several benchmark problems are solved by the developed MATLAB code and the obtained results are compared with those from exact and other numerical solutions, showing good agreement.展开更多
In the present literature,two types of piezoelectric fiber-reinforced composite(PFRC)based cylindrical models are considered to investigate the circumferential shear wave propagation on a cylinder.Model I consists of ...In the present literature,two types of piezoelectric fiber-reinforced composite(PFRC)based cylindrical models are considered to investigate the circumferential shear wave propagation on a cylinder.Model I consists of a pre-stressed PFRC layer imperfectly bonded to a pre-stressed piezoelectric cylinder of infinite length.Model II comprises a pre-stressed PFRC layer that is imperfectly bonded to a fiber-reinforced core cylinder.The dispersion equations have been derived for both models,assuming electrically open and short boundaries.The numerical simulations are carried out,and results are portrayed graphically to show the effects of various parameters.The radius ratio,pre-stress,mechanical imperfect bonding parameter,fiber reinforcement and fiber-matrix volume ratio exert considerable effects on the PFRC cylinder.Comparative analysis of the dispersion behavior reveals that the shear wave’s phase velocity varies differently for Model I and Model II,and the phase velocity for Model I is higher compared to Model II.The phase velocity reaches its minimum when the piezoelectric fiber is 0.5-0.6 by volume fraction in the PFRC layer.展开更多
文摘Synthetic fibers made from nylon or polypropylene have gained application when loose and woven into geo textile form although no information on the matrix’s mechanical performance is obtained so that more understanding of their structural contribution to resist cracking can be determined. This paper presents the results of an experimental investigation to determine the performance characteristics of concrete reinforced with a polypropylene structural fiber. In this investigation “Fiber mesh” brand of fibers manufactured by SL Concrete System, Tennessee, USA and marketed by M/S Millennium Building System, Inc., Ban-galore, India are used. The lengths of the fibers used were 24 mm. Fiber dosages used were 0.9, 1.8, 2.7 kg/m3. A total of three mixtures, one for each fiber dosage were made. A standard slump cone test was conducted on the fresh concrete mix with and without fibers to determine the workability of the mix. The test program included the evaluation of hardened concrete properties such as compressive, split tensile, modulus of rupture and flexural strengths. The increase in compressive strength is about 36.25%, 26.20%, and 23.75% respectively that of plain concrete. This increase in strength was directly proportional to amount of fibers present in the mix. The increase in flexural strength for Mixes I^III is about 21%, 16.6%, and 23% respectively that of plain concrete specimens. An experimental investigation was also made to study the behaviors of reinforced fibers concrete beams (with longitudinal reinforcements) under two-point loading. The deflection and crack patterns were also studied. The improvements in strength and ductility characteristics were discussed.
文摘This research presents a finite element formulation based on four-variable refined plate theory for bending analysis of cross-ply and angle-ply laminated composite plates integrated with a piezoelectric fiber-reinforced composite actuator under electromechanical loading. The four-variable refined plate theory is a simple and efficient higher-order shear deformation theory, which predicts parabolic variation of transverse shear stresses across the plate thickness and satisfies zero traction conditions on the plate free surfaces. The weak form of governing equations is derived using the principle of minimum potential energy, and a 4-node non-conforming rectangular plate element with 8 degrees of freedom per node is introduced for discretizing the domain. Several benchmark problems are solved by the developed MATLAB code and the obtained results are compared with those from exact and other numerical solutions, showing good agreement.
文摘In the present literature,two types of piezoelectric fiber-reinforced composite(PFRC)based cylindrical models are considered to investigate the circumferential shear wave propagation on a cylinder.Model I consists of a pre-stressed PFRC layer imperfectly bonded to a pre-stressed piezoelectric cylinder of infinite length.Model II comprises a pre-stressed PFRC layer that is imperfectly bonded to a fiber-reinforced core cylinder.The dispersion equations have been derived for both models,assuming electrically open and short boundaries.The numerical simulations are carried out,and results are portrayed graphically to show the effects of various parameters.The radius ratio,pre-stress,mechanical imperfect bonding parameter,fiber reinforcement and fiber-matrix volume ratio exert considerable effects on the PFRC cylinder.Comparative analysis of the dispersion behavior reveals that the shear wave’s phase velocity varies differently for Model I and Model II,and the phase velocity for Model I is higher compared to Model II.The phase velocity reaches its minimum when the piezoelectric fiber is 0.5-0.6 by volume fraction in the PFRC layer.
