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Deformation characteristics of composite laminates- Part II: An experimental/numerical study on equivalent single-layer theories
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Through-the-thickness distribution of strains in laminated composite plates subjected to bending
No full textIn this paper, the through-the-thickness deformation of laminated composite plates subjected to out-of-plane line and concentrated loads is studied experimentally and numerically using different span to depth ratios. Experimental inspection of the specimens is carried out by combining two different techniques: embedded fibre Bragg grating sensors for internal strain measurements and surface-mounted resistive strain gauges for surface strain measurements at selected locations. To eliminate the contribution due to the strain concentration in the vicinity of the loading point and highlight that due to shear effects, measurements are carried out at various distances from the load application by displacing the specimens in the loading frame. A departure from linearity in the through-the-thickness strain distribution is highlighted for small span to depth values. Results are compared to numerically calculated values from finite-element simulations using both laminated-shell and solid elements
Deformation characteristics of composite laminates- Part I: Speckle interferometry and embedded Bragg grating sensor measurements
No full textExperimental Analysis of Composite Laminates Subjected to Bending
No full textComposite materials are becoming increasingly important in many engineering domains. Often the estimation of their mechanical properties is not trivial and simulations need to be accompanied by experimental verification. In this paper, the use of optical methods to characterize the mechanical behaviour of composite laminated plates subjected to bending is described. Speckle Interferometry and fibre optic sensors are used in a combined manner to reach a full understanding of the specimen behaviour. In- and out-of-plane Speckle Interferometry is employed to measure full-field displacements on the free surfaces of the plates, while the strain distribution through the thickness is derived using embedded fibre Bragg grating sensors. Measurements are carried out in the "thin" and "thick" plate ranges and results are compared to analytical and numerical calculation
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Smart composites with embedded shape memory alloy actuators and fibre Bragg grating sensors: Activation and control
No full textThis paper describes the production of an adaptive composite by embedding thin pre-strained shape memory alloy actuators into a Kevlar-epoxy host material. In order to combine the activation and sensing capabilities, fibre Bragg grating sensors are also embedded into the specimens, and the strain measured in situ during activation. The effect of manufacturing conditions, and hence of the initial stress state in the composite before activation, on the magnitude of the measured strains is discussed. The results of stress and strain simulations are compared with experimental data, and guidelines are provided for the optimization of the composite. Finally, a pilot experiment is carried out to provide an example of how a strain-stabilizing feedback mechanism can be implemented in the smart structur
Characterization of the response of fibre Bragg grating sensors subjected to a two-dimensional strain field
No full textIn this paper, the behaviour of fibre Bragg grating sensors subjected to transversal as well as axial strains is characterized, both in the case of low-birefringent and polarization-maintaining single-mode optical fibres. Two configurations are considered. Firstly, diametrical compression is studied and the results compared to those previously obtained in the literature. Secondly, the sensors are embedded in an epoxy specimen and their response monitored when the latter is subjected to biaxial loading. In both cases, the experimental results are compared to those obtained by means of finite-element simulations and an appropriate analytical description of the opto-mechanical response of polarization-maintaining fibre
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