David F. Parker – författare

This volume records the Symposium on 'Anisotropy, Inhomogeneity and Nonlinearity in Solid Mechanics', held at the University of Nottingham from 30th August to 3rd September 1994, sponsored by the International Union of Theoretical and Applied Mechanics and held in conjunction with the In- ternational Society for the Interaction of Mechanics and Mathematics. The advent of composite materials, together with their widespread use in recent years, has provided a powerful stimulus for advances in several somewhat ne- glected areas of solid mechanics. Exploitation of fibre-reinforced solids and laminates has rekindled interest in the theory and application of anisotropic elasticity and motivated study of many aspects of material inhomogeneity. The need to understand fibre-matrix interactions, especially in modelling metal- matrix composites and the forming of thermoplastic components has fostered advances in plasticity and viscoelasticity theory, to describe phenomena such as deformation-induced inhomogeneity and anisotropy.Plasticity and flow of granular media are also intrinsically nonlinear, giving rise, for example, to highly anisotropic and strongly localized effects, such as shear bands. Most materials contain impurities. These inclusions, even if microscopically isotropic, cause macroscopic anisotropy in an 'effective-medium' theory. Dy- namic behaviour is even more complex, since wave propagation reveals both attenuation and dispersion effects. Increased interest in finer-scaled compos- ites (nanotechnology and superlattices) and ultra-high frequency techniques continue to reveal new effects, due to inhomogeneity and microstructure. An example included here is lattice-induced dispersion for certain surface waves of relatively long wavelength.

Many phenomena in the physical and biological sciences involve the collective behaviour of (very large) numbers of individual objects. For example, the be­ haviour of gases ultimately concerns the interacting motions of uncountably many atoms and molecules, but to understand flow in nozzles, around aircraft and in meteorology it is best to treat velocity and density as continuous func­ tions of position and time and then to analyse the associated flows. Although modern electronics involves ever smaller components, even the semiconduc­ tor devices used widely in electronic communications and in digital processing involve collective phenomena, such as electric currents and fields, which are continuously varying functions of position and time. Diffusion and reaction between various chemical constituents, the growth and spread of biological or­ ganisms and the flow of traffic on major highways are all phenomena which may be described and analysed in terms of fields and flows, while sound, light and various other electromagnetic phenomena involve both fields and waves. Treating these using a continuum model, which does not attempt to trace the motion and evolution of individual objects, often gives good predictions. The mathematical concepts and techniques which underlie such treatments are the subject of this book. This book is designed as a first introduction to the use of mathematical techniques, within continuum theories.

Many phenomena in the physical and biological sciences involve the collective behaviour of (very large) numbers of individual objects. For example, the be­ haviour of gases ultimately concerns the interacting motions of uncountably many atoms and molecules, but to understand flow in nozzles, around aircraft and in meteorology it is best to treat velocity and density as continuous func­ tions of position and time and then to analyse the associated flows. Although modern electronics involves ever smaller components, even the semiconduc­ tor devices used widely in electronic communications and in digital processing involve collective phenomena, such as electric currents and fields, which are continuously varying functions of position and time. Diffusion and reaction between various chemical constituents, the growth and spread of biological or­ ganisms and the flow of traffic on major highways are all phenomena which may be described and analysed in terms of fields and flows, while sound, light and various other electromagnetic phenomena involve both fields and waves. Treating these using a continuum model, which does not attempt to trace the motion and evolution of individual objects, often gives good predictions. The mathematical concepts and techniques which underlie such treatments are the subject of this book. This book is designed as a first introduction to the use of mathematical techniques, within continuum theories.

The topic of surface waves lies at the interface between a number of disci­ plines - physics, theoretical and applied mechanics, electroacoustics, ap­ plied mathematics, surface science and seismology. This volume, based on papers delivered at European Mechanics Colloquium 226, reflects this diversity in approach and background, while showing strong links between phenomena arising from different fields. The emphasis is on recent de­ velopments such as nonlinear and other nonclassical effects,which have great importance for both pure science and for applications such as signal processing, nondestructive evaluation and seismic studies. In recent years there has been considerable progress in the mathe­ matical treatment of nonlinear effects, of viscoelastic and of more novel constitutive effects which modify the predictions of linear elastic and piezo­ electric theory for surface acoustic wave (SAW) propagation. A number of these themes serve to group the contents of this volume. Part I contains recent advances in the rigorous mathematical treatment of nonlinearity, together with a paper giving experimental results showing the need for further theoretical development. Part II deals with anisotropic elasticity, showing that even the linear theory presents many possible behaviours, which are still not fully categorized.

The topic of surface waves lies at the interface between a number of disci­ plines - physics, theoretical and applied mechanics, electroacoustics, ap­ plied mathematics, surface science and seismology. This volume, based on papers delivered at European Mechanics Colloquium 226, reflects this diversity in approach and background, while showing strong links between phenomena arising from different fields. The emphasis is on recent de­ velopments such as nonlinear and other nonclassical effects,which have great importance for both pure science and for applications such as signal processing, nondestructive evaluation and seismic studies. In recent years there has been considerable progress in the mathe­ matical treatment of nonlinear effects, of viscoelastic and of more novel constitutive effects which modify the predictions of linear elastic and piezo­ electric theory for surface acoustic wave (SAW) propagation. A number of these themes serve to group the contents of this volume. Part I contains recent advances in the rigorous mathematical treatment of nonlinearity, together with a paper giving experimental results showing the need for further theoretical development. Part II deals with anisotropic elasticity, showing that even the linear theory presents many possible behaviours, which are still not fully categorized.

This volume records the Symposium on 'Anisotropy, Inhomogeneity and Nonlinearity in Solid Mechanics', held at the University of Nottingham from 30th August to 3rd September 1994, sponsored by the International Union of Theoretical and Applied Mechanics and held in conjunction with the In- ternational Society for the Interaction of Mechanics and Mathematics. The advent of composite materials, together with their widespread use in recent years, has provided a powerful stimulus for advances in several somewhat ne- glected areas of solid mechanics. Exploitation of fibre-reinforced solids and laminates has rekindled interest in the theory and application of anisotropic elasticity and motivated study of many aspects of material inhomogeneity. The need to understand fibre-matrix interactions, especially in modelling metal- matrix composites and the forming of thermoplastic components has fostered advances in plasticity and viscoelasticity theory, to describe phenomena such as deformation-induced inhomogeneity and anisotropy.Plasticity and flow of granular media are also intrinsically nonlinear, giving rise, for example, to highly anisotropic and strongly localized effects, such as shear bands. Most materials contain impurities. These inclusions, even if microscopically isotropic, cause macroscopic anisotropy in an 'effective-medium' theory. Dy- namic behaviour is even more complex, since wave propagation reveals both attenuation and dispersion effects. Increased interest in finer-scaled compos- ites (nanotechnology and superlattices) and ultra-high frequency techniques continue to reveal new effects, due to inhomogeneity and microstructure. An example included here is lattice-induced dispersion for certain surface waves of relatively long wavelength.