History Reduction by Lumping for Time-Efficient Simulation of Additive Manufacturing

Andreas Malmelöv,Andreas Lundbäck,Lars-Erik Lindgren

doi:10.3390/met10010058

Andreas Malmelöv, Andreas Lundbäck + Show 1 more

Open Access

https://doi.org/10.3390/met10010058

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Journal: Metals	Publication Date: Dec 29, 2019
Citations: 17	License type: CC BY 4.0

Affiliation: Luleå University of Technology

Abstract

Additive manufacturing is the process by which material is added layer by layer. In most cases, many layers are added, and the passes are lengthy relative to their thicknesses and widths. This makes finite element simulations of the process computationally demanding owing to the short time steps and large number of elements. The classical lumping approach in computational welding mechanics, popular in the 80s, is therefore, of renewed interest and is evaluated in this work. The method of lumping means that welds are merged. This allows fewer time steps and a coarser mesh. It was found that the computation time can be reduced considerably, with retained accuracy for the resulting temperatures and deformations. The residual stresses become, to a certain degree, smaller. The simulations were validated against a directed energy deposition (DED) experiment with alloy 625.

Highlights

Additive manufacturing (AM) is a process by which a product is built by adding the material layer by layer
The model with the fine mesh was validated with measurements and acts as a reference model for the lumped models
The simulation was compared with the temperature and displacement measurements from [26] for the cases with no dwell time and with 20 s dwell time between layers

Summary

Introduction

Additive manufacturing (AM) is a process by which a product is built by adding the material layer by layer. This method provides new opportunities from the design and manufacturing points of view. It is possible to create complex shapes, which can be utilized for the design of optimized geometries with the possibility of saving weight. It can be used to repair existing products. Other advantages are the reduced material waste and shorter component lead-time [1]. A challenge with AM is how to minimize the distortions and residual stresses of the final product

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