The increasing use of advanced composite materials in modem structures of high performance calls for a detailed knowledge of their properties. On the other hand, these materials possessing intense anisotropy, and in some cases non homogeneity, require complicated theories based on homogeneous anisotropic elasticity. Typically, such materials either involve fiber-reinforced composites, which are stacked in layers and form laminates, or particulate composites, containing a second phase in powder form. However, each case must be separately analyzed in terms of the particular characteristics of the materials involved and the process of preparation of the com posite systems. Composite materials consisting of more than one destinct phase are in general use in modem industrial applications. Machine parts, structural components and others may be manufactured from such materials. Epoxy resins are suitable matrices for this class of materials. This is due not only to their general-properties such as linear mechanical behavior, transparency, etc., but also to the possibility of modifying their mechanical and optical properties in a very wide range by using suitable modifiers. Their rheological behavior, as well as their dynamic properties have been extensively investigated.

Klappentext

The increasing use of advanced composite materials in modern structures of high performance in automotive and aircraft structures calls for a deeper and more thorough knowledge of their properties. This book aims to provide such knowledge. Among the topics presented are models for composites, the evaluation of the extent of the mesophase and the influence of the mesophase on the mechanical, thermal and fracture behaviour of the composite system. The topics have been treated either theoretically or experimentally. The basic experimental method was the optical method of caustics, which are particularly convenient for the analysis of stress concentrations and intensities. Such concentrations are very common in the mesophases formed in composite materials. The monograph is oriented towards the mechanical aspect of the study of composites, with less coverage of the physiochemical part, in order to meet current scientific demands.

Inhalt
II Introduction.- III Models for Composite Materials.- III.1 General Aspects.- III.2 The Three-Layer Model for Particulates.- III.3 The Three-Cylinder Model for Short Fibres.- III.4 The Unfolding Models for Particulates.- III.5 The Unfolding Models for Fiber-Reinforced Composites.- IV Retardation Spectra of Composites Indicating the Existence of a Mesophase.- V Static and Dynamic Properties of Composites as Influenced by the Mesophase.- V.1 Static and Dynamic Moduli in Fiber Composites.- V.2 Influence of the Mesophase on the Loss Tangent of Fiber Composites.- V.3 Dynamic Properties of Particulates.- V.4 Mechanical Properties of Particulates.- V.5 Evaluation of Static and Dynamic Moduli in Particulates.- VI The Influence of the Mesophase on the Thermal Behavior of Composites.- VI.1 Thermal Properties of Fiber-Reinforced Composites.- VI.2 Thermal Properties of Particulates and Volume-Fraction of the Mesophase.- VII The Glas Transition of Composites and Influence of the Mesophase.- VII.1 Variation of the Glass-Transition Temperature with Direction of Fibers in Composites.- VII.2 Influence of the Mesophase on the Glass Transition of Particulates.- VIII Mechanisms of Moisture Absorption in Composites.- IX Shrinkage Stress at the Mesophase Developed During Casting.- IX.1 Shrinkage Stress in Fiber-Reinforced Composites.- IX.2 Shrinkage Stress in Particulates.- IX.3 Shrinkage Stress Distribution Along a Fiber.- X Stress Singularities at the Mesophase due to the Geometry of Inclusions.- X.l General Aspects.- X.2 Effect of Singularities at the Extremities of Fibers.- X.3 Effect of Stress Raisers.- XI Stress Singularities in Cracked Phases.- XI.1 Order of Singularities at the Apices of Multiwedges.- XI.2 The Optical Method of Caustics for the Study of Singularities.- XI.3 Singularities at Crack Tips of General Curvilinear Interfaces.- References.- Author Index.