Relaxed incremental variational formulation for damage at large strains with application to fiber-reinforced materials and materials with truss-like microstructures

Authors

  • Daniel Balzani,

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    • Institute of Mechanics, University of Duisburg-Essen, Faculty of Engineering, Department of Civil Engineering Universitätsstr. 15, 45117 Essen, Germany
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  • Michael Ortiz

    1. Engineering and Applied Sciences Division, California Institute of Technology, Pasadena, CA, USA
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Daniel Balzani, Institute of Mechanics, University of Duisburg-Essen, Faculty of Engineering, Department of Civil Engineering, Universitätsstr. 15, 45117 Essen, Germany.

E-mail: daniel.balzani@uni-due.de

SUMMARY

In this paper, an incremental variational formulation for damage at finite strains is presented. The classical continuum damage mechanics serves as a basis where a stress-softening term depending on a scalar-valued damage function is prepended an effective hyperelastic strain energy function, which describes the virtually undamaged material. Because loss of convexity is obtained at some critical deformations, a relaxed incremental stress potential is constructed, which convexifies the original nonconvex problem. The resulting model can be interpreted as the homogenization of a microheterogeneous material bifurcated into a strongly and weakly damaged phase at the microscale. A one-dimensional relaxed formulation is derived, and a model for fiber-reinforced materials based thereon is given. Finally, numerical examples illustrate the performance of the model by showing mesh independency of the model in an extended truss, analyzing a numerically homogenized microtruss material and investigating a fiber-reinforced cantilever beam subject to bending and an overstretched arterial wall. Copyright © 2012 John Wiley & Sons, Ltd.

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