Damage mechanics

In the context of continuum mechanics, damage mechanics describes the material properties of a structure that have been changed as a result of material damage. The aim of damage mechanics is to record the damage processes occurring in the micro-range in the material model , while the cracks resulting therefrom in the macro-range are described by the fracture mechanics .

Building on this, the load-bearing capacity can be assessed or the service life can be predicted for technical constructions whose materials are subject to damage processes during the operating time.

Overview

Scheme for the formation, growth and coalescence of cavities in the material, which can lead to the initiation of macro cracks

In general, real materials already contain microscopic defects and inhomogeneities in the unloaded state , which can have a decisive influence on the macroscopic strength of the component in question. These microscopic material defects can, for. B. metals in the form of micro-cavities (z. B. voids ), micro-cracks , inclusions and precipitates occur. The number, size and distribution of these microdefects in the matrix material, the actual supporting structure, are significant for the micromechanical damage processes that occur. The corresponding cavity volume can be viewed as a measure of the material damage.

If the component is stressed by an external load , the micro-cavities and cracks continue to enlarge and ultimately grow together, while in areas with high stress concentrations, e.g. B. on inclusions, new micro-cavities can form. At the end of this structural damage in the material, there is a complete loss of the material bond; a macroscopic crack is formed through material separation.

The models of damage mechanics are able to describe these processes using phenomenologically or micromechanically based damage laws. Known material models are z. B. the Gurson model and the Rousselier model, which start from spherical cavities that are distributed in the matrix material.

literature

J. Lemaitre: Course on Damage Mechanics. Springer, 1996, ISBN 3-540-60980-6 .
D. Krajcinovic: Damage Mechanics. Elsevier. 1996, ISBN 0-444-82349-2 .
Local Approach to Fracture, Presses de l'Ecole des Mines. 2004, ISBN 2-911762-55-X .
Literature on damage mechanics in the catalog of the German National Library

Individual evidence

↑ Dieter Radaj: Fatigue Resistance . 2nd Edition. Springer, Berlin / Heidelberg / New York 2003, ISBN 978-3-540-44063-5 , chapter 5.3, p. 253–255 ( limited preview in Google Book search).
↑ Sumio Murakami: Continuum Damage Mechanics . A Continuum Mechanics Approach to the Analysis of Damage and Fracture (= Solid Mechanics and Its Applications . Volume 185 ). Springer, Dordrecht / Heidelberg / London / New York 2012, ISBN 978-94-007-2665-9 , Chapters 6.5.1–6.5.3 (English, limited preview in Google Book Search).

[1] Dieter Radaj: Fatigue Resistance . 2nd Edition. Springer, Berlin / Heidelberg / New York 2003, ISBN 978-3-540-44063-5 , chapter 5.3, p. 253–255 ( limited preview in Google Book search).

[2] Sumio Murakami: Continuum Damage Mechanics . A Continuum Mechanics Approach to the Analysis of Damage and Fracture (= Solid Mechanics and Its Applications . Volume 185 ). Springer, Dordrecht / Heidelberg / London / New York 2012, ISBN 978-94-007-2665-9 , Chapters 6.5.1–6.5.3 (English, limited preview in Google Book Search).