Abstract:
To study the formation of residual stresses and distortions of structures created by wire-arc surfacing, Cranfield University performed surfacing on a fixed substrate of an aluminum alloy wall, including with a layer-by-layer roll-in with a different clamping force. In this paper, the deflection values of the released structure from this experiment are reproduced numerically, for which a mathematical model is constructed. The process was presented in the form of successively solved tasks: a) thermal — surfacing of 10-20 layers of material, b) thermo-elastic-plastic — formation of eigenstrains and residual stresses due to cooling of the created structure with an inhomogeneous temperature distribution, c) thermo-elastic-plastic — rolling of a stressed workpiece at elevated temperature (the stage may be absent) and d) elastic-plastic — the structure distortion and changes in the field of residual stresses when the structure is released. It is established that tensile residual stresses are formed in the deposited wall near its upper face, and use of layerby-layer roll-in allows to reduce longitudinal strains, distortion of the released specimen and inhomogeneity of the distribution of residual stresses by the wall height. The calculated deflection values correspond to the experimental data. A beam-rod model of the mechanics of a built-up multilayer wall has been developed, the results of which allow us to predict the evolution of the curvature of the structure and the distribution of residual stresses.
Fulltext:
PDF file (1010 kB)