Search results for "Lamina"
showing 10 items of 439 documents
Adaptive control of a seven mode truncation of the Kolmogorov flow with drag
2009
Abstract We study a seven dimensional nonlinear dynamical system obtained by a truncation of the Navier–Stokes equations for a two dimensional incompressible fluid with the addition of a linear term modelling the drag friction. We show the bifurcation sequence leading from laminar steady states to chaotic solutions with increasing Reynolds number. Finally, we design an adaptive control which drives the state of the system to the equilibrium point representing the stationary solution.
On the mechanical behavior of BFRP to aluminum AA6086 mixed joints
2013
The aim of this work is to analyze the possibility to join aluminum alloy AA6086 and composite laminates reinforced with basalt fibers, an innovative material which use is growing in several applications as an alternative to glass fibers. To this goal, three joining techniques were investigated: mechanical by Self Piercing Riveting (in the next called SPR), adhesive by co-curing technique and mixed in which the joining techniques (i.e. adhesive and mechanical) were combined. Two manufacturing technologies (i.e. hand lay-up and vacuum bagging) were used both to produce composite substrates and to realize co-curing adhesion between the substrates to be joined. Mixed joints were realized by in…
Numerical simulation of fatigue-driven delamination using interface elements
2005
This paper presents a computational technique for the prediction of fatigue-driven delamination growth in composite materials. The interface element, which has been extensively applied to predict delamination growth due to static loading, has been modified to incorporate the effects of cyclic loading. Using a damage mechanics formulation, the constitutive law for the interface element has been extended by incorporating a modified version of a continuum fatigue damage model. The paper presents details of the fatigue degradation strategy and examples of the predicted fatigue delamination growth in mode I, mode II and mixed mode I/II are presented to demonstrate that the numerical model mimics…
Effet de l'orientation des fibres des plis adjacents sur la résistance au délaminage en mode I pur = Effect of the fibre's orientation of adjacent pl…
2009
National audience; Ce travail concerne l'étude de l'effet de l'orientation des fibres des plis adjacents à la fissure dans une éprouvette DCB (Double Cantilever Beam) sur la résistance au délaminage en mode I pur. Afin d'isoler l'influence de l'orientation l'étude porte sur des stratifiés particuliers ayant tous les mêmes matrices de comportement global A B D. Les résultats expérimentaux montrent une grande variation de résistance au délaminage GIC et des courbes R selon l'orientation des plis situés de part et d'autre du plan de fissure. Une modélisation par éléments finis permet de mettre en évidence l'importance de l'état de contraintes locales et donc de l'endommagement au voisinage du …
A Strain Sensing Structural Health Monitoring System for Delaminated Composite Structures
2012
Structural Health Monitoring (SHM) for composite materials is becoming a primary task due to their extended use in safety critical applications. Different methods, based on the use of piezoelectric transducers as well as of fiber optics, has been successfully proposed to detect and monitor damage in composite structural components with particular attention focused on delamination cracks.In the present paper a Structural Health Monitoring model, based on the use of piezoelectric sensors, already proposed by the authors for isotropic damaged components, is extended to delaminated composite structures. The dynamic behavior of the host damaged structure and the bonded piezoelectric sensors is m…
A Cohesive-frictional interface model subjected to mixed complex loading paths
2017
The paper presents a cohesive-frictional interface model based on surface damage mechanics. The proposed model is developed under the assumption that the fracture energies in mode I and in mode II are different values, as shown by several experimental evidences. At difference with the most spread available interface models, only one isotropic interface internalvariable is adopted for the constitutive model. The interface constitutive model is developed in a Thermodynamic consistent framework with an Helmholtz free energy potential and the fulfillment of the thermodynamic principles is obtained enforcing the Clausius-Duhem inequality. The damage/friction activation functions and dissipative …
Numerical analysis of delamination in through-thickness reinforced composite laminates
2009
Composite laminates show a high vulnerability to out-of-plane actions, responsible for localized damage between two adjacent laminae, i.e. delamination phenomenon. A recent technological solution to improve the strength of the composite laminates in the thickness direction consists in inserting through-thickness reinforcement. In this paper, the composite delamination is analyzed in the context of non-linear fracture mechanics by an original two-phase interface model able to describe the anisotropic elastic and post-elastic mechanical response given by the presence of the reinforcement fibres. The two phases (adhesive joint or matrix of the composite and the reinforcement) are characterized…
Choice of ceramic for use in treatments with porcelain laminate veneers.
2006
El tratamiento mediante Frentes Laminados de Porcelana (FLP) se utiliza desde hace más de dos décadas para el tratamiento de problemas estéticos y/o funcionales, particularmente en el grupo anterior de las arcadas dentarias (1,2,3). La actual oferta en el mercado de cerámicas dentales aptas para este tipo de tratamiento, pero muy distintas en cuanto a composición, características ópticas y sistema de elaboración, hace complicada la selección del material más adecuado a cada paciente en particular. Proponemos un sistema sencillo de elección de la cerámica teniendo en cuenta las dos variables que más influirán en el resultado estético final: de un lado las características propias del diente (…
A DIC-based study of flexural behaviour of roving/mat/roving pultruded composites
2015
Abstract This paper reports a study of the flexural behaviour and resultant failure modes in E-glass/polyester pultruded composites. The digital image correlation (DIC) method is used to estimate the effect of fibre orientation on failure behaviour in thick beams, taking into account the presence of continuous filament mat layer (CFM) in the stacking sequence. In particular, the tests were carried out for specimens with off-axis angle of 0°, 7.5°, 15°, 30°, 45° and 90°. The crack initiation and the failure mechanisms depend on the mutual interaction between the stiffness properties of different areas in the stacking sequence. An influence index (I) was introduced to evaluate the magnitude o…
Digital image correlation analysis of interfacial debonding properties and fracture behavior in concrete
2007
The use of digital image correlation (DIC) as a fracture mechanics tool is described, for two projects currently underway. The goal of the first project is to examine the bond between carbon fiber reinforced polymers (CFRP) and concrete substrates. The second project involves the interfacial transition zone (ITZ) of plain concrete, and the softening and fracture behavior of this region. For both projects, DIC allows for precise measurement of the surface displacements of the deforming materials. The resulting strain data are higher in resolution than is possible with other experimental techniques. For both projects, the DIC results are being used to determine bond constitutive laws, which w…