Institute of Fundamental Technological Research
Polish Academy of Sciences


Ralf Denzer

Technische Universität Dortmund (DE)

Recent publications
1.  Stupkiewicz S., Denzer R., Piccolroaz A., Bigoni D., Implicit yield function formulation for granular and rock-like materials, COMPUTATIONAL MECHANICS, ISSN: 0178-7675, DOI: 10.1007/s00466-014-1047-8, Vol.54, pp.1163-1173, 2014

The constitutive modelling of granular, porous and quasi-brittle materials is based on yield (or damage) functions, which may exhibit features (for instance, lack of convexity, or branches where the values go to infinity, or ‘false elastic domains’) preventing the use of efficient return-mapping integration schemes. This problem is solved by proposing a general construction strategy to define an implicitly defined convex yield function starting from any convex yield surface. Based on this implicit definition of the yield function, a return-mapping integration scheme is implemented and tested for elastic–plastic (or -damaging) rate equations. The scheme is general and, although it introduces a numerical cost when compared to situations where the scheme is not needed, is demonstrated to perform correctly and accurately.

Plasticity, Return mapping algorithm, Automatic differentiation

Stupkiewicz S. - IPPT PAN
Denzer R. - Technische Universität Dortmund (DE)
Piccolroaz A. - University of Trento (IT)
Bigoni D. - University of Trento (IT)

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