Ratcheting and strain ranges in the shakedown state with stress stiffening using the Simplified Theory of Plastic Zones

The behavior of elastic-plastic structures under cyclic loading can be determined by incremental elastic-plastic analyses where a given load histogram is analysed cycle-by-cycle until shakedown is achieved. Many cycles may be required for this, if a ratchet mechanism is causing plastic strains to ac...

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Veröffentlicht in:The International journal of pressure vessels and piping 2022-10, Vol.199, p.104727, Article 104727
Hauptverfasser: Hübel, Hartwig, Vollrath, Bastian
Format: Artikel
Sprache:eng
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Zusammenfassung:The behavior of elastic-plastic structures under cyclic loading can be determined by incremental elastic-plastic analyses where a given load histogram is analysed cycle-by-cycle until shakedown is achieved. Many cycles may be required for this, if a ratchet mechanism is causing plastic strains to accumulate in each cycle until either elastic or plastic shakedown is achieved. The complexity of the elastic-plastic response of a structure is further increased if geometric effects are present. It may be very costly to get the accumulated strains and strain ranges in the state of shakedown by incremental analyses so that simplified or direct methods have been developed as an alternative. The Simplified Theory of Plastic Zones (STPZ) has proven itself for estimating the required quantities in the state of elastic and plastic shakedown within the framework of the 1st order theory, i.e., if the equilibrium conditions are satisfied for the undeformed structure. It is shown in this paper, how the STPZ can be expanded to capture 2nd order effects introduced by the equilibrium of the deformed structure. Some examples are used to demonstrate its applicability and the quality of the results, but also its limitations with respect to determining the accumulated strains and elastic-plastic strain ranges. •Stress stiffening may increase the elastic-plastic strain range.•The Simplified Theory of Plastic Zones (STPZ) is suited to capture stress stiffening.•The STPZ may be used to estimate cyclic accumulated strains and strain ranges.
ISSN:0308-0161
1879-3541
DOI:10.1016/j.ijpvp.2022.104727