Search results for " Laminates"
showing 10 items of 65 documents
Layer-wise and equivalent single layer models for smart multilayered plates
2014
Layer-wise and equivalent single layer plate models for magneto-electro-elastic multiphysics laminates are presented in a unified framework. They are based on variable kinematics and quasi-static behavior of the electromagnetic fields. The electromagnetic state of each single layer is preliminary determined by solving the corresponding governing equations coupled with the proper interface continuity and external boundary conditions. By so doing, the electromagnetic state is condensed into the plate kinematics and the layer governing equations are inferred by the principle of virtual displacements. This approach identifies effective mechanical layers, which are kinematically equivalent to th…
Concrete columns confined with fibre reinforced cementitious mortars: Experimentation and modelling
2014
Abstract The structural behaviour of concrete columns strengthened with a system made up of fibre nets embedded in an inorganic stabilized cementitious matrix under an uniaxial load was investigated. Medium size specimens with circular and square cross-section were cast and subjected to monotonic uniaxial compression, to investigate the efficiency of a p-Phenylene BenzobisOxazole (PBO) Fibre Reinforced Cementitious Mortar (FRCM) system in increasing both strength and ductility. The experimental results show that the confinement system adopted produced a noticeable increment in strength and ductility, though the low mechanical ratios of fibre considered were not always able to ensure hardeni…
An analysis of interface delamination mechanisms in orthotropic and hybrid fiber-metal composite laminates
2007
Abstract The onset and propagation of interlaminar defects is one of the main damage mechanisms in composite materials. This is even more the case when considering layered materials comprising metallic laminae (typically Aluminium) and FRP laminae. Propagation of delamination mainly depends on the initial crack extension and its loading mode. This work presents some results of a combined analytical–numerical–experimental study on the onset and propagation mechanisms regarding interlaminar defects. Two cases have been analysed in particular, the first consisting of a glass-fibre reinforced epoxy resin laminate, and the second consisting of a hybrid laminate where a lamina of aluminium is lay…
Dependence of fracture toughness of composite laminates on interface ply orientations and delamination growth direction
2004
A critical review has been performed of the published experimental research concerning delamination onset and growth in composite laminate interfaces of different lay-ups under single-mode loadings. It was found that, depending on the loading mode and interface lay-up, the traditional fracture toughness characterization by unidirectionally reinforced composite tests can lead to marked under- or overestimation of material resistance to crack growth. Empirical models of fracture toughness as a function of delamination front orientation with respect to reinforcement directions of the adjacent laminae have been validated and their applicability range established.
Delamination study of through-thickness reinforced composite laminates via two-phase interface model
2007
A technique to enhance the strength of the composite laminates in the thickness direction consists in inserting through-thickness reinforcement, by which the potential delamination crack faces are bridged in order to increase the interlaminar fracture strength. In this paper, the composite delamination is analyzed in the context of non-linear fracture mechanics making use of the interface concept. The presence of the reinforcement fibres provides an anisotropic elastic and post-elastic mechanical response, which herein is described by an original two-phase interface model. The two phases, namely the adhesive joint (or matrix of the composite) and the reinforcement, are characterized by thei…
Finite elements for nonlinear free vibrations analysis of smart laminates subjected to in-plane loadings
2015
Advanced composites, able to provide multi-functional capabilities besides the traditional structural functions, has been gaining attention in many technological fields. This inherent coupling of different physical fields can be exploited in transducer applications, structural health monitoring, vibration control, energy harvesting and other applications. Magneto-electro-elastic (MEE) composite materials are attracting increasing consideration as they couple mechanical, electrical and magnetic fields and this makes them particularly suitable for smart applications. Generally, single-phase materials exhibit either piezoelectric or piezomagnetic behavior and no direct magneto-electric couplin…
A quantitative investigation on the thermoelastic effect of CFRP laminates
2009
The thermoelastic effect on CFRP laminates with various lay-ups is investigated. A thick low crimp unidirectional fabric reinforcement is adopted. The measured thermoelastic signal is compared with predictions from two analytical models based on the meso-mechanical bulk properties of the lamina and on assuming a strain witness behaviour of the surface resin rich layer.
Experimental design of the bearing performances of flax fiber reinforced epoxy composites by a failure map
2018
Abstract This paper represents the first effort aimed to the investigation of the pin/hole contact stress and failure mechanisms of epoxy composites reinforced with woven flax fabrics, underwent to tensile bearing tests. In particular, the maximum loads and failure modes are evaluated at varying the laminate geometrical configuration. In order to optimize the use of polymer composites reinforced with flax fibers in structural applications, an experimental failure map, identifying main failure modes of mechanically fastened joints, is obtained as function of hole diameter, distance of the hole from the free edge of the laminate and laminate width. Moreover, a theoretical approach based on th…
Effect of areal weight and chemical treatment on the mechanical properties of bidirectional flax fabrics reinforced composites
2010
Abstract In this paper several bidirectional flax fibers, usually used to made curtains, were employed as reinforcement of an epoxy matrix. Four different laminates were made by a vacuum bagging process, with varying both the areal weight and the treatment of the fabric. These structures were mechanically investigated carrying out both tensile and three point flexural tests. In order to evaluate the effect of the identified variables on the mechanical parameters (i.e. Young modulus and maximum stress) a statistical analysis was performed. Finally, by comparing the flax composite with a glass one, the convenience of the replacement of glass fiber was investigated in term of cost, weight and …
Moisture Absorption Effects on the Resistance to Interlaminar Fracture of Woven Glass/Epoxy Composite Laminates
2012
The influence of moisture absorption on the interlaminar fracture behaviour of 8/8 harness satin weave glass/epoxy composite was investigated. Two series of specimens with 0°/0° and 90°/90° predominant interfaces immersed in water for different duration were tested under double cantilever beam (DCB mode I), single leg bending (SLB mode I + II) and end notched flexural (ENF mode II) loadings. In general, the apparent flexural modulus: E, and the fracture toughness: G C, decrease with increasing moisture content. This effect is more remarkable if mode II participation is bigger. The value of G C measured on 90°/90° specimens reveals higher than that on 0°/0° ones, but the variation in G C is …