Studying of the influence of 3D wire deposition process parameters on the formation of residual deformations

Abstract

Additive technologies make it possible to manufacture products using a layer-by-layer synthesis, thus obtaining products of complex shapes. When solving a complex problem of numerical modeling of additive technological processes, it is necessary to describe various thermomechanical phenomena with high accuracy. The most effective in this regard is the use of a combination of capabilities of specialized software systems and the development of unique algorithms for them, taking into account the maximum possible number of process parameters. The paper considers the calculation algorithm of non-stationary temperature fields and stress-strain state of the structure in the process of its creation by 3D welding of wire materials developed and implemented using the ANSYS Mechanical package in the APDL language. In particular, this model takes into account the non-stationary radiant transfer of thermal energy of the welding arc to the surface of the product. The review highlights three of the most commonly used methods for modeling material deposition, i.e. the so-called element birth, sleeping element (quiet element) and hybrid activation (hybrid activation). It is shown that in order to ensure greater efficiency of calculations, it is necessary to use the principle in which successive steps of melting and even layers are grouped together for a subsequent simultaneous activationn. In the presented model, the task is divided into the boundary problem of non-stationary thermal conductivity and the boundary problem of thermomechanics of the stress-strain state, which are uncoupled. To solve them we applied the technology of killing and the subsequent birthing of a part of the material, implemented with the ANSYS package. Verification of the developed numerical algorithm aimed at solving the three-dimensional problem of the arc surfacing of wire materials was carried out by a comparison with the results of the experimental tests on D16 aluminum alloy samples. To describe the elastoplastic behavior of the alloy, the BISO model of bilinear isotropic plasticity with a temperature dependence of yield strength was used. A good consistency of the calculated data with the experiment was shown. The effect was studied on the level of the residual distortion of such process parameters as exposure time to the next layer, the motion path of the slicer, ambient temperatures. It is shown that the latter parameter is the most effective way to reduce residual shape deviations, but requires high thermal stability of equipment and accuracy of arc energy control.