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Full Description
This book contains results of more than a decade's effort on coupled deformation and diffusion obtained in research performed at the Institute of Fracture and Solid Mechanics, Lehigh University. Despite the overwhelming number of theories on this subject, little is known on the assessment of coupling effects because of the inherent difficulties associated with experimentation. A case in point is couple thermoelasticity, a theory that has remained virtually unused in practice. This is indicative of the inadequacy of conventional approaches. The interdependence of heat, moisture and deformation arises in many engineer ing problems of practical interest. Whether these effects are coupled or not depend on the transient character of the boundary conditions. Special attention is given to finding the coupling constants. Invoked is the assumption that the physical parameters should be independent of the specified boundary conditions. They can thus be extracted from known experimental data for situations where coupling effects are relatively weak and then applied to predict strong coupling effects as boundary conditions are altered. This is illustrated for the T300/5208 material commonly used in composites and permits a more reliable evaluation of material behaving under extreme environmental conditions. The lack of this knowledge can often be a major deterrent to the achievement of new technological advances. The reader will recognize that the material in this book does not follow the main stream of research on moisture-temperature diffusion and deformation.
Contents
1 Classical diffusion theories.- 1.1 Introduction.- 1.2 Thermal diffusion: heat conduction.- 1.3 Moisture diffusion.- 1.4 Appendix: Anisotropic character of diffusion coefficient in fiber reinforced composite.- References.- 2 Coupled diffusion of temperature and moisture.- 2.1 Introduction.- 2.2 Dufour and Soret effects.- 2.3 Linear dependence of moisture and temperature in two-phase system.- 2.4 Solution by normal coordinates.- 2.5 Evaluation of coupling constants.- 2.6 Temperature and moisture diffusion in T300/5208 graphite/epoxy system.- 2.7 Appendix A: Additional models of moisture and temperature coupling.- 2.8 Appendix B: Diffusion parameters for simultaneous moisture and temperature boundary conditions.- References.- 3 Analytical solutions of transient hygrothermal stresses in elastic bodies.- 3.1 Introduction.- 3.2 One-dimensional stress and strain expressions.- 3.3 Symmetric through thickness diffusion.- 3.4 Anti-symmetric through thickness diffusion.- 3.5 Spherical cavity in infinite solid.- 3.6 Appendix A: Elastic properties of T300/5208 graphite/epoxy laminate.- 3.7 Appendix B: General solution for coupled diffusion problems.- References.- 4 Time dependent finite element formulation of hygrothermal elasticity problems.- 4.1 Introduction.- 4.2 Finite element applied to coupled diffusion equations.- 4.3 Laplace transformation and eigenvalue formulation.- 4.4 Finite element hygrothermal stress formulation.- 4.5 Sudden localized heating of semi-infinite solid.- 4.6 Concentration of diffusion and stresses around a circular cavity.- 4.7 Redistribution of hygrothermal stresses around an elliptical opening.- 4.8 Appendix A: Variational procedure.- 4.9 Appendix B: Derivation of ?TI and ?CI.- 4.10 Appendix C: Modal decomposition.- References.- 5 Coupled theory ofheat, moisture and deformation.- 5.1 Introduction.- 5.2 General information.- 5.3 Plane hygrothermoelasticity.- 5.4 Method of hygrothermoelastic potential.- 5.5 Physical constants in deformation coupled theory.- 5.6 Uncoupled theories.- References.- 6 Complex variable formulation of hygrothermoelasticity problems.- 6.1 Introduction.- 6.2 Stress function.- 6.3 Complex formulation.- 6.4 Conformai transformation.- 6.5 Circular region subjected to diffusion and deformation.- 6.6 Remote extension of region with cavity.- References.- 7 Numerical analysis of coupled diffusion and deformation problems.- 7.1 Introduction.- 7.2 Basic formulation.- 7.3 Smooth slab subjected to sudden moisture change.- 7.4 Smooth slab subjected to sudden temperature change.- 7.5 Diffusion and stress boundary conditions applied to body with circular cavity.- 7.6 Hygrothermal stresses around narrow elliptical cavity.- References.- 8 The strain energy density function.- 8.1 Introduction.- 8.2 Energy per unit volume.- 8.3 Energy density decay near a crack.- 8.4 Failure criterion.- References.- Author index.
