Influence of the Erection Regime on the Stress State of a Viscoelastic Arched Structure Erected by an Additive Technology under the Force of Gravity

摘要

We study the influence of gravity forces on additively constructed objects of a viscoelastic aging material (in a special case, of a purely elastic material) in the absence of additional surface loads and prestresses in the accreted material elements. It is shown that the stress-strain state of such objects crucially depends on how the process of their gradual formation evolves in time. The main tendencies whose interaction determines the process of deformation of these objects under a given formation regime are revealed and analyzed. The general reasoning is illustrated by the results of numerous numerical experiments performed in the framework of the model of linear mechanics of accreted bodies, which was developed by the authors for studying the essentially two-dimensional engineering problem on the erection of a heavy circular arched structure (a semicircular vault) on a smooth horizontal base by the method of layer-by-layer thickening of a blank structure previously erected on the base. This problem is used as an example in the detailed studies of the influence of the erection regime of a viscoelastic aging structure on the development of its stress state. We show that it is very important to take into account the influence of gravity forces during the entire process of erection of heavy objects rather than in their final configuration. It is conclusively shown that, without considering this influence, one can arrive at completely false conclusions about the current and resulting states of the erected structures such as overestimation of their strength and stability at the stage of formation and of their bearing capacity in their operation. The possibilities of efficient control of the stress state of the considered arch structure by varying the rate of the additional material accretion to the structure are demonstrated.