1.Introduction to Composite Materials 2. Macrochemical Behavior of a Lamina 3.Micromechanical Behavior of a Lamina 4.Macromechanical Behavior of a Laminate 5.Bending, Buckling, and Vibration of Laminated Plates 6.Other Analysis and Behavior Topics 7.Introduction to Design of Composite Structures Appendix A.Matrices and Tensors Appendix B.Maxima and Minima of Functions of a Single Variable Appendix C.Typical Stress-Strain Curves Appendix D.Governing Equations for Beam Equilibrium and Plate Equilibrium, Buckling, and Vibration Index

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Mechanics of composite materials

Because heterogeneous materials can be designed to
exhibit the best characteristics of their individual
constituents, they are ideally suited to modern
technologies that require materials with an unusual
combination of properties. The study presented in
the current work is aimed to approach effective
electrical conductivity of various random
heterogeneous materials. It starts with the
description of a type of modern material with
specific morphology. Percolation theory and finite
element analysis are used in computations and
comparison with experimental results is provided. To
understand difficulties with classical approaches,
next a two-component composite material on a lattice
is studied, followed by discoveries in the
electrical field properties. Finally, a new
algorithm is suggested, which can be used to find
effective properties for any arbitrary morphology.
Material covered in this book will be of interest to
graduate students and researchers who work on the
front edge of physics, materials science,
engineering and applied mathematics. All necessary
derivations and definitions are included to make the
book self-contained and approachable.

Random Heterogeneous Materials

Composite materials parts manufacturing

The paper recognizes that the introduction of polymers and advanced polymer composites in the civil engineering world has been a comparatively rapid process vis-s-vis other civil engineering materials when they were first introduced. Aerospace and marine industries have been first to utilize advanced polymer compounds, but recently there has been a growing interest among civil/structural engineers in the importance of the unique mechanical and in-service properties of these materials together with their customized fabrication technologies. The paper outlines the development stages of this exciting material and provides a look into the future prospects for it.

The evolution of and the way forward for advanced polymer composites in the civil infrastructure

Sustainable thermal insulation biocomposites from rice husk, wheat husk, wood fibers and textile waste fibers: Elaboration and performances evaluation

The present work is devoted to damaging process in carbon–fiber reinforced laminated composites. An original experimental approach combining three optical measurement techniques is presented. Image stereo-correlation and infrared thermography, that respectively provide the kinematic and thermal fields on the surface of the composites, are used in live recording during axis and off-axis tensile tests. Special attention is paid to simultaneously conduct these two techniques while avoiding their respective influence. On the other hand, X-ray tomography allows a post-failure analysis of the degradation patterns within the laminates volume. All these techniques are non-destructive (without contact) and offer an interesting full-field investigation of the material response. Their combination allows a coupled analysis of different demonstrations of same degradation mechanisms. For instance, thermal events and densimetric fields show a random location of damage in the early stages of testing. The influence of the material initial anisotropy on damage growth, localization and failure mode can also be clearly put in evidence through various data. In addition to such characterization, this study illustrates at the same time the capabilities of the different full-field techniques and the damage features they can best capture respectively.

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Damage investigation in CFRP composites using full-field measurement techniques: Combination of digital image stereo-correlation, infrared thermography and X-ray tomography

Acoustic emission (AE) and infrared thermography (IT) are simultaneously combined to identify damage evolution in carbon fibre reinforced composites. Samples are subjected to tensile static loads while acoustic emission sensors and an infrared camera record the acoustic signals and the temperature variations respectively. Unsupervised pattern recognition procedure is applied to identify damage mechanisms from acoustic signals. Thermodynamic arguments are introduced to estimate global heat source fields from thermal measurements and anisotropic heat conduction behavior is taken into account by means of homogenization technique. A spatial and time analysis of acoustic events and heat sources is developed and some correlation range in the AE and IT events amplitude are identified.

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Damage detection in CFRP by coupling acoustic emission and infrared thermography

A critical review of some damage models with unilateral effect

This study deals with the macroscopic modelling of the mechanical behaviour of microcracked materials and particularly with the unilateral aspect of such damage which leads, at the closure of microcracks, to a partial damage deactivation. By means of a micromechanical analysis, the aim of this article is first to point out the influence of the opening-closure of microdefects on the effective elastic properties of a microcracked medium. According to these considerations, a new elastic moduli recovery condition at damage deactivation is proposed. The introduction of this condition within the anisotropic damage model proposed by Halm and Dragon, 1996 allows to extend its micromechanical background while preserving its main advantages, in particular the continuity of the stress-strain response and the symmetry of the stiffness tensor.

Some Remarks on the Damage Unilateral Effect Modelling for Microcracked Materials

Microcracking is one of the basic mechanisms of inelastic deformation for a large class of anisotropic materials such as brittle matrix composites. Even at fixed microcracks density, the macroscopic behavior of these materials is very complex due to the combination of two specific features of such deteriorating phenomenon. First, the oriented nature of microcracks induces an evolution of the material symmetry (interaction between the initial anisotropy and the microcracks induced one). Secondly, a change in the elastic response of the material is expected, based on whether microcracks are open or closed in response to specific loading situations (the so-called “unilateral effect”). The present paper is devoted to a continuum micromechanics-based investigation of the resulting – generally fully – anisotropic multilinear response of orthotropic materials containing microcracks. The procedure leads to the proposal of a closed-form expression of the macroscopic free energy corresponding to 2D initially orthotropic materials weakened by arbitrarily oriented microcracks systems. The established results provide a complete quantification of both coupling effects of anisotropies and elastic moduli recovery phenomena induced by microcracks closure. A particular emphasis is put on the importance of Hill lemma for the derivation of these results which constitute a basis to the micro-macro modeling of damage process in initially orthotropic media.

https://oatao.univ-toulouse.fr/6573/1/Goidescu_6573.pdf

Hélène Welemane

Papers

Damage investigation in CFRP composites using full-field measurement techniques: Combination of digital image stereo-correlation, infrared thermography and X-ray tomography

Damage detection in CFRP by coupling acoustic emission and infrared thermography

A critical review of some damage models with unilateral effect

Some Remarks on the Damage Unilateral Effect Modelling for Microcracked Materials

Microcracks closure effects in initially orthotropic materials