Sommario
Si usa il metodo degli elementi finiti per formulare problemi di analisi relativi a strutture elasto-plastiche soggette a prescritti programmi di carico, sotto le ipotesi restrittive:a) le superfici di plasticizzazione sono linearizzate a tratti, eb) la legge del flusso plastico è olonoma all'interno del singolo intervallo di tempo “finito”. Si danno formulazioni come problemi di complementarità lineare e come problemi di programmazione quadratica: due formulazioni sono in termini di storia delle velocità e dei coefficienti di attivazione plastica, altre due sono in termini di storia dei coefficienti di attivazione plastica soltanto. Si dimostra che le soluzioni sono caratterizzate da due principi di minimo per la storia delle velocità di deformazione. Dopo alcune osservazioni generali sui procedimenti di calcolo, il lavoro si conclude con dei suggerimenti per futuri sviluppi.
Summary
The finite element method approach is used to obtain formulations of analysis problems relative to elastic-plastic structures when subjected to prescribed programmes of loads, and under the restrictive hypotheses:a) the yielding surfaces are piecewise linearized, andb) the plastic flow-laws are supposed to be of holonomic type within a single “finite” time interval. For mulations are given as linear complementarity problems and quadratic programming problems: one pair of formulations in terms of velocity and plastic multiplier rate histories, and another pair in terms of plastic multiplier rate histories only. The solutions are shown to be characterized by two minimum principles for displacement and plastic strain rate histories. After some general remarks about computational procedures, the paper is concluded with some suggestions for future developments.
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Polizzotto, C. Minimum theorems for displacement and plastic strain rate histories in structural elastoplasticity. Meccanica 10, 99–106 (1975). https://doi.org/10.1007/BF02314747
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DOI: https://doi.org/10.1007/BF02314747