Date

2018

Document Type

Thesis

Degree

Master of Science

Department

Mechanical Engineering

First Adviser

Nied, Herman F.

Abstract

Additive manufacturing represents a relatively newly developed technology with many rapidly changing innovations . One of the most important processes in additive manufacturing is 3D printing. For a couple of decades, polymers have dominated the materials used in 3D printing. In the last few years, 3D printing of metals has had a high impact on interest in this technology. One 3D printing process that uses metals is Wire Arc Additive Manufacturing (WAAM). This technique has some technical obstacles that may detract from its use in commercial applications. One of the crucial issues concerns the control of residual stresses and related distortions. The evolution of residual stresses can theoretically be simulated by using computational software for the WAAM process, in a manner similar to welding process modeling, using nonlinear finite element codes such as ABAQUS, ANSYS, SYSWELD, etc. This study focuses on using SYSWELD to model the WAAM process.In this thesis, the key reference problem is the simulation of the WAAM process for a vertical 3D printed plate. This “reference” problem was chosen because =WAAM printed plates have been fabricated at Lehigh University and thus, comparisons can easily be made between simulations and experimental measurements. The simulated WAAM parts examined in the study compare two types of steel alloys: 1) austenitic stainless-steel grade 316L and, 2) Low carbon steel S355J2G3. The residual stress components of particular interest were determined to be: 1) Longitudinal stresses across the width of the plate and, 2) the maximum principle stress. The distortion of the WAAM plate after the metal deposition processes are complete illustrate the difficulty in maintaining dimensional tolerances. The simulation process predicts higher residual stresses and lower distortion for the low carbon steel alloy, when compared with the austenitic stainless steel.

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