WHEN metals are submitted to stress, the stress/swain relation is generally regarded as consisting of two parts, the elastic region and the region bfsplastiwin which a permanent set remains upon the remova of the stress. In the elastic region the absence of a permanent set does not necessarily imply that the relation between stress and strain is linear of even single-valued. Prof. Zener uses the term ‘anelasticity’ to describe the properties of solids, as a result of which stress and strain are not uniquely related. Examples are the elastic after-effect, the dependence of elastic constants on the method of measurement, and the dissipation of energy during vibration, which is often referred to as the damping capacity or internal friction of a solid. These effects have aroused much interest in recent years, largely owing to Prof. Zener's own work, and a good book on the subject is much to be desired. Elasticity and Anelasticity of Metals By Clarence Zener. Pp. x + 170. (Chicago: University of Chicago Press, London: Cambridge University Press, 1948.) 4 dollars.

Elasticity and Anelasticity of Metals

A hypoplastic constitutive model and hypoplasticity are described briefly.A procedure for the determination of its parameters is described in detail.This model is based on nonlinear tensorial functions and is developed without recourse to concepts of elastoplasticity theory such as yield surface,plastic potential,flow and hardening rules and decomposition of deformation into elastic and plastic parts.The paper also presents the hypoplastic model that is capable of capturing the salient features of granular materials,in particular,for problems involving extremely low stress levels or extremely high stress.

Introduction of hypoplasticity

Thermo-mechanical finite element prediction of the structural long-term response of asphalt pavements subjected to periodic traffic load: Tire-pavement interaction and rutting

The present thesis deals with modelling and simulation of the deformation behaviour of municipal solid waste. Municipal solid waste is a porous medium, in which landfill gas and leachate can move freely in the pore space. The Theory of Porous Media is the continuum mechanical framework for the model development. The applied kinematics are nonlinear because large displacements and deformations have to be described. The solid material consists of a basic matrix with properties similar to granular materials, in which fibrous constituents are embedded. Constitutive relations for the two solid phases include spontaneous as well as time-dependent inelastic behaviour. Effects from the anisotropic orientation of the fibres are considered, too. A generalised DARCY model for multiphase transport describes the motion of the pore fluids. Numerical simulations of laboratory experiments validate and verify the model. Structural analyses using the finite element method identify risks concerning the stability of landfill structures. The transport equations are simultaneously solved by the box method, a special case of the finite volume method.

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Stability of Municipal Solid Waste Landfills

A continuum mechanical model for asphalt based on the particle size distribution: Numerical formulation for large deformations and experimental validation

In der vorliegenden Arbeit wird ein Verbundmodell zur Beschreibung des thermo-mechanischen Verhaltens von Asphaltmischungen entwickelt und validiert. Das Modell beschreibt das Materialverhalten von Asphalt als Verbundwerkstoff auf Basis der Mischungstheorie. Hierfur ist das
Verformungsverhalten der Bindemittelkomponente mit einem fraktionalen rheologischen Modell beschrieben. Die Mineralstoffkomponente wird mit einem Modell der Hypoplastizitat erfasst. Mit Hilfe einer Evolutionsstrategie erfolgt die Identifikation der Modellparameter der Einzelkomponenten auf der Grundlage experimenteller Untersuchungen. Fur die Validierung des Verbundmodells liegt ein umfangreiches experimentelles Programm vor, bei dem zwei ausgewahlte Asphaltmischungen in einaxialen Versuchen untersucht werden. Der Vergleich der Versuche mit Ergebnissen numerischer Simulationen bedingt physikalisch begrundete Modifikationen am Verbundmodell. Das modifizierte Modell ermoglicht die Analyse des Verformungsverhaltens realer Strukturen aus Asphaltmaterialien in numerischen Berechnungen mit der Finite-Element-Methode.

Brodersen, Björn, Olov

Papers

Modellierung des thermo-mechanischen Verbundverhaltens von Asphalt in Straßenaufbauten