The Experts below are selected from a list of 120690 Experts worldwide ranked by ideXlab platform
G J Zarragoicoechea - One of the best experts on this subject based on the ideXlab platform.
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geometrical and physicochemical considerations of the pit membrane in relation to air seeding the pit membrane as a capillary valve
Tree Physiology, 2007Co-Authors: Ariel G Meyra, G J ZarragoicoecheaAbstract:A theoretical treatment of some of the factors influencing air seeding at the pit membranes of xylem vessels is given. Pit membrane structure, viewed as a three-dimensional mesh of intercrossing fibrils, and vulnerability to water-stress-induced air seeding are examined in the context of the Young-Laplace equation. Simple geometrical considerations of the porous membrane show that the vapor-liquid Interface curvature radius is a function of fiber-fiber distance, fiber radius, wetting angle and position of the wetting line. Air seeding (maximum pressure) occurs at the minimum curvature radius, therefore air seeding is not simply determined by the fiber-fiber distance but is a function of the geometry of the pit membrane and of physicochemical quantities like surface tension and wetting angle. As a consequence of considering a wetting angle different from zero, the minimum curvature radius becomes larger than half the fiber-fiber distance. The present model considers that, for a given pressure difference at the pit membrane, all Local Interface curvatures are the same. In this sense, pit membranes work as variable capillary valves that allow or prevent air seeding by adjusting Local curvatures and Interface positions relative to the pore-forming fibers, following the pressure differences across the membranes. The theoretical prediction for the air seeding threshold is consistent with recent experimental data for angiosperm trees.
J N Reddy - One of the best experts on this subject based on the ideXlab platform.
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interaction of anisotropic crack phase field with Interface cohesive zone model for fiber reinforced composites
Composite Structures, 2021Co-Authors: D Pranavi, Amirtham Rajagopal, J N ReddyAbstract:A new phase field model considering the interfacial damage for different configurations of a fiber reinforced composite is proposed and formulated. Crack and non Local Interface are considered to be diffused. A coupled traction separation law based on a potential function is adopted to represent the behavior of the Interface. Anisotropy is introduced into the elastic equilibrium by considering the distinct contributions of fiber and matrix in different modes. The present model captures the predominant failure phenomena in a composite such as matrix failure, delamination by considering the role of fiber orientation, Interface fracture properties and configuration of lamina. The proposed formulation is extended to a fiber reinforced composite lamina consisting of two fiber families oriented in different directions. Parametric studies are conducted to understand the effect of anisotropy parameter, length scales, fracture properties of fiber, matrix and Interface on crack propagation and mechanical response of the whole system. Numerical examples are performed to validate the proposed model, understand the anisotropic crack growth for unidirectional and woven fiber reinforced composites, study the interaction of anisotropic crack with composite-composite Interface and metal-composite Interface.
Hassan Ijaz - One of the best experts on this subject based on the ideXlab platform.
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prediction of delamination crack growth in carbon fiber epoxy composite laminates using non Local Interface damage model
Mechanics & Industry, 2014Co-Authors: Hassan Ijaz, Laurent Gornet, Muhammad Asad, Syed Yasir AlamAbstract:The use of composite laminates is increasing in these days due to desired directional properties and low densities in comparison of metals. Delamination is a major source of failure in composite laminates where a crack like entity can initiate and propagate between different layers of composite laminates under given loading conditions. Damage mechanics based theories are employed to simulate the delamination phenomena between composite laminates. These damage models are inherently Local and can cause the concentration of stresses around the crack tip. In the present study integral type non-Local damage formulation is proposed to avoid the Localization problem associated to damage formulation. A comprehensive study is carried out for the selection of different non-Local variables. Finite element simulations based on proposed non-Local damage models and classical Local damage model are performed and results are compared with available experimental data for UD IMS/924 Carbon/fiber epoxy composite laminate.
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prediction of delamination crack growth in carbon fiber epoxy composite laminates using a non Local cohesive zone modeling
Advanced Materials Research, 2012Co-Authors: Hassan Ijaz, Laurent Gornet, Waqas Saleem, K Nisar, S R ChaudryAbstract:The global behavior of composite materials is strongly influenced by the quality of adhesion between different components. A component can be single phase, like fibers or particles used as reinforcement in a homogenous matrix, or a multiphase material like a layer in long-fiber laminate. In the latter case the degradation of adhesion implies the separation of the layers, known as delamination. Among all different failure mechanisms, Delamination is considered to be the most prominent mode of failure in fiber-reinforced laminates as a result of their relatively weak inter-laminar strength. When laminated structures are subjected to static, dynamic or cyclic loadings, the inter-laminar adhesion strength between individual plies tends to deteriorate significantly and act as the origin of the final failure. Therefore, an efficient and reliable design tool capable of predicting delamination could improve the durability for composite laminates. There exist damage mechanics based formulations capable of simulating the delamination crack growth in carbon/glass fiber epoxy based composite laminates. The present study is focused on taking a step forward in this respect. At first, already existed Local Interface models effectiveness is tested and results are successfully compared with available experimental data for UD IMS/924 Carbon/fiber epoxy composite laminate. Next, a non-Local integral-type regularization scheme is introduced to overcome the spurious Localization problem associated to the existing Local model. Basic concepts and mathematical modeling of Non-Local damage evolution law are comprehensively studied and presented in this study. Finite Element simulation results based on proposed model are discussed in detail and are compared with experimental results.
Ariel G Meyra - One of the best experts on this subject based on the ideXlab platform.
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geometrical and physicochemical considerations of the pit membrane in relation to air seeding the pit membrane as a capillary valve
Tree Physiology, 2007Co-Authors: Ariel G Meyra, G J ZarragoicoecheaAbstract:A theoretical treatment of some of the factors influencing air seeding at the pit membranes of xylem vessels is given. Pit membrane structure, viewed as a three-dimensional mesh of intercrossing fibrils, and vulnerability to water-stress-induced air seeding are examined in the context of the Young-Laplace equation. Simple geometrical considerations of the porous membrane show that the vapor-liquid Interface curvature radius is a function of fiber-fiber distance, fiber radius, wetting angle and position of the wetting line. Air seeding (maximum pressure) occurs at the minimum curvature radius, therefore air seeding is not simply determined by the fiber-fiber distance but is a function of the geometry of the pit membrane and of physicochemical quantities like surface tension and wetting angle. As a consequence of considering a wetting angle different from zero, the minimum curvature radius becomes larger than half the fiber-fiber distance. The present model considers that, for a given pressure difference at the pit membrane, all Local Interface curvatures are the same. In this sense, pit membranes work as variable capillary valves that allow or prevent air seeding by adjusting Local curvatures and Interface positions relative to the pore-forming fibers, following the pressure differences across the membranes. The theoretical prediction for the air seeding threshold is consistent with recent experimental data for angiosperm trees.
D Pranavi - One of the best experts on this subject based on the ideXlab platform.
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interaction of anisotropic crack phase field with Interface cohesive zone model for fiber reinforced composites
Composite Structures, 2021Co-Authors: D Pranavi, Amirtham Rajagopal, J N ReddyAbstract:A new phase field model considering the interfacial damage for different configurations of a fiber reinforced composite is proposed and formulated. Crack and non Local Interface are considered to be diffused. A coupled traction separation law based on a potential function is adopted to represent the behavior of the Interface. Anisotropy is introduced into the elastic equilibrium by considering the distinct contributions of fiber and matrix in different modes. The present model captures the predominant failure phenomena in a composite such as matrix failure, delamination by considering the role of fiber orientation, Interface fracture properties and configuration of lamina. The proposed formulation is extended to a fiber reinforced composite lamina consisting of two fiber families oriented in different directions. Parametric studies are conducted to understand the effect of anisotropy parameter, length scales, fracture properties of fiber, matrix and Interface on crack propagation and mechanical response of the whole system. Numerical examples are performed to validate the proposed model, understand the anisotropic crack growth for unidirectional and woven fiber reinforced composites, study the interaction of anisotropic crack with composite-composite Interface and metal-composite Interface.