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2000 | Buch

Mechanics of Curved Composites

verfasst von: S. D. Akbarov, A. N. Guz

Verlag: Springer Netherlands

Buchreihe : Solid Mechanics and Its Applications

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SUCHEN

Über dieses Buch

This book is the frrst to focus on mechanical aspects of fibrous and layered composite material with curved structure. By mechanical aspects we mean statics, vibration, stability loss, elastic and fracture problems. By curved structures we mean that the reinforcing layers or fibres are not straight: they have some initial curvature, bending or distortion. This curvature may occur as a result of design, or as a consequence of some technological process. During the last two decades, we and our students have investigated problems relating to curved composites intensively. These investigations have allowed us to study stresses and strains in regions of a composite which are small compared to the curvature wavelength. These new, accurate, techniques were developed in the framework of continuum theories for piecewise homogeneous bodies. We use the exact equations of elasticity or viscoelasticity for anisotropic bodies, and consider linear and non-linear problems in the framework of this continuum theory as well as in the framework of the piecewise homogeneous model. For the latter the method of solution of related problems is proposed. We have focussed our attention on self-balanced stresses which arise from the curvature, but have provided sufficient information for the study of other effects. We assume that the reader is familiar with the theory of elasticity for anisotropic bodies, with partial differential equations and integral transformations, and also with the Finite Element Method.

Inhaltsverzeichnis

Frontmatter
Introduction
Abstract
According to [70, 73, 74] the classification of composite materials is based on the following principles: structural-design, i.e., by the type of the reinforcing elements and their disposition in the matrix; material, i.e., by the type of the fiber and matrix material and their properties; technology, i.e., by the production process. Here we consider the first classification only.
S. D. Akbarov, A. N. Guz
Chapter 1. Plane-Curved Composites
Abstract
In this chapter we present a simple new version of continuum theory for composite materials with periodic plane-curved structure. We suppose that the curves are small-scale, in other words, the period of the curvature of the reinforcing elements in the structure of the composite materials is significantly less than the size of the elements of objects fabricated from these composite materials. First we give some preliminary remarks on classical continuum approaches. Then we present the three-dimensional exact equations of motion, geometrical relations and boundary conditions in both geometrically linear and non-linear statements, for deformable solid body mechanics. After these preparatory procedures we detail the basic assumptions and relations of the simple new version of continuum theory for composite materials with periodic plane-curved structures. We give a solution procedure for the continuum problems, and then investigate some dynamic and static problems where we study the influence of the periodic plane curving in the structure of the constituent materials on the mechanical behaviour of the composite.
S. D. Akbarov, A. N. Guz
Chapter 2. General Curved Composites
Abstract
In this chapter we discuss a continuum theory for composite materials with general periodic or locally curved structures; this generalizes the analysis given in the previous chapter. Again we use tensor notation and sum repeated indices over their ranges, but do not sum underlined repeated indices.
S. D. Akbarov, A. N. Guz
Chapter 3. Problems for Curved Composites
Abstract
In this chapter we combine the theory developed in Chapter 2 with the finite element method (FEM) to solve some two and three dimensional static and dynamic problems for strips and rectangular plates. We discuss the influence of the parameters defining the curved composite on the stress distribution, and on the natural frequencies of the plates.
S. D. Akbarov, A. N. Guz
Chapter 4. Plane-Strain State in Periodically Curved Composites
Abstract
It is evident that any continuum approach is an approximate one and the most accurate information on the stress distribution in the curved composites can be obtained only in the framework of the piecewise-homogeneous body model with the use of the exact equations of deformable solid body mechanics. Therefore, from now on, we begin study the problems of curved composites in the framework of the piecewise homogeneous body model. In this chapter we consider plane strain problems of periodically plane-curved composites. First, the method for investigation of the stress distribution in these composites is presented. Then this method is developed for cases in which the materials of the layers are: l)viscoelastic; 2)rectilinearly anisotropic; 3) curvilinearly anisotropic. Many numerical results and their analyses are given for stress distributions in such composites.
S. D. Akbarov, A. N. Guz
Chapter 5. Composites with Spatially Periodic Curved Layers
Abstract
In this chapter the problem formulation and solution method presented in the previous chapter are developed for three-dimensional problems, namely, for composites with spatially curved layers. The solution method is detailed for periodic curving. Many numerical results are given for the stress distribution in such composites; all investigations are carried out for a piecewise-homogeneous body model.
S. D. Akbarov, A. N. Guz
Chapter 6. Locally-Curved Composites
Abstract
In this chapter we investigate the stress state in composite material with locally plane-curved layers. All investigations are carried out for plane-strain state with the use of the relations and assumptions given in Chapter 4. For various local curving form the distribution of the self-balanced stresses on the inter-layer surfaces are studied in detail.
S. D. Akbarov, A. N. Guz
Chapter 7. Fibrous Composites
Abstract
In this chapter the problem formulation and solution methods presented in the previous chapters are developed for fibrous composites with curved structures, and various concrete problems are investigated.
S. D. Akbarov, A. N. Guz
Chapter 8. Geometrically Non-Linear Problems
Abstract
In some combinations of geometric and curvature parameters of the filler layers (or fibers) and of the values of the external force intensities it is necessary to investigate of problems using the geometrically non-linear statement. Using the results of these investigations, we can determine the limit of the intensity of the external forces for which the results obtained in the linear statement are acceptable. Furthermore, we can determine the character of the influence of the geometrical non-linearity on the mechanical behaviour of the composites. We will also derive relations which will be very important for investigations of the fracture of unidirectional composites with curved structure in compression.
S. D. Akbarov, A. N. Guz
Chapter 9. Normalized Modulus of Elasticity
Abstract
Many researchers have investigated the influence of the reinforcing layers and fibers curvature on the values of the normalized moduli of elasticity, for example [56, 62, 64, 82, 112, 127, 128, 130, 140, 149]. These investigations used various approximate theories and different hypotheses. We will use the analyses developed in Chapters 3–8 and apply it to various particular problems.
S. D. Akbarov, A. N. Guz
Chapter 10. Fracture Problems
Abstract
The fracture of composite materials has different peculiarities depending on the structure of the composite, the type of loading and other factors. The following is one of these peculiarities.
S. D. Akbarov, A. N. Guz
Supplement 1. Viscoelastic Unidirectional Composites in Compression
Abstract
Up to now some attempts, which are cited in [54, 102, 105], had been made for investigations of fracture of viscoelastic unidirected composites in compression with the use of TDLT of stability. However, in these investigations the critical time is found by employing of the critical deformation method [86]. In the present supplement the composite with initial insignificant imperfection is used as a model for investigation of these problems and the approach proposed in section 10.3 is developed for viscoelastic composites.
S. D. Akbarov, A. N. Guz
Supplement 2. Geometrical Non-Linear and Stability Problems
Abstract
We will consider some plane deformation problems for the continuum theory presented in Chapter 2. It will be assumed that the plane deformation takes place in the Ox1x2 plane for the rectangular region shown in Fig.3.1.1 where Ox1x2 are the Lagrangian coordinates which in their natural state coincide with Cartesian coordinates. We will only consider the rigid edge conditions for this region-strip and use the geometrical non-linear exact equations of the theory of elasticity. All results will be obtained numerically by employing FEM.
S. D. Akbarov, A. N. Guz
Backmatter
Metadaten
Titel
Mechanics of Curved Composites
verfasst von
S. D. Akbarov
A. N. Guz
Copyright-Jahr
2000
Verlag
Springer Netherlands
Electronic ISBN
978-94-010-9504-4
Print ISBN
978-1-4020-0383-7
DOI
https://doi.org/10.1007/978-94-010-9504-4