ON SHAKEDOWN OF 3-DIMENSIONAL ELASTOPLASTIC STRAIN-HARDENING STRUCTURES

The present article considers the shakedown problem of structures made of either kinematic or mixed strain-hardening materials. Some basic a nd useful shakedown properties of elastoplastic strain-hardening struc tures are proved mathematically. It is impossible for a kinematic stra in-hardening structure to be involved in incremental plastic collapse, and so its only possible failure mode is that of alternating plastici ty. A time-independent self-equilibrium stress field has no influence on the shakedown of a kinematic strain-hardening structure although it contributes to the magnitude of plastic deformation. The sufficient s hakedown conditions for either kinematic or mixed strain-hardening str uctures are deduced, from which the lower bound of shakedown load doma in can be obtained via a mathematical programming problem. It should b e pointed out that, to guarantee the safety of an elastoplastic strain -hardening structure, the damage analysis is also necessary to determi ne the maximum load factor the structure can bear. The shakedown analy sis of strain-hardening structures can be simplified by the conclusion s obtained in this article, as is illustrated by two simple examples. (C) 1997 Elsevier Science Ltd.