G. Hofstetter, R.L. Taylor:
"Treatment of the Corner Region for Drucker-Prager Type Plasticity";
ZAMM - Zeitschrift für Angewandte Mathematik und Mechanik, 71 (1991), S. 589 - 591.
Originally the return mapping algorithm was developed for J_2-plasticity. Recently the method also has been applied for Drucker-Prager type flow theories [2, 3] and non-smooth multi-surface plasticity [4, 5, 6]. In a recent paper  dealing, among various other yield criteria, with a return mapping algorithm for non-associative Drucker-Prager plasticity, it is not mentioned that for Drucker-Prager type plasticity and a certain range of elastic trial stresses the return mapping algorithm leads to physically meaningless results. Thus, the algorithm must be modified appropriately to treat this region and is necessary for both associative and non-associative forms of the Drucker-Prager model. The paper to be presented addresses appropriate modifications.
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