scholarly journals MODELING AND CONVERGENCE ANALYSIS OF DIRECTED ENERGY DEPOSITION SIMULATIONS WITH HYBRID IMPLICIT / EXPLICIT AND IMPLICIT SOLUTIONS

2019 ◽  
Vol 19 (3) ◽  
pp. 95-108 ◽  
Author(s):  
Johannes BUHL ◽  
Rameez ISRAR ◽  
Markus BAMBACH
Keyword(s):  
Residual Stresses ◽  
Young’S Modulus ◽  
Energy Deposition ◽  
Young's Modulus ◽  
Temperature History ◽  
Fatigue Properties ◽  
Time Step ◽  
Directed Energy Deposition ◽  
Directed Energy ◽  
Wire Arc Additive Manufacturing

Conventional metal manufacturing techniques are suitable for mass production. However, cheaper and faster alternatives are preferred for small batch sizes and individualized components. Directed energy deposition (DED) processes allow depositing metallic material in almost arbitrary shapes. They are characterized by cyclic heat input, hence heating and cooling every point in the workpiece several times. This temperature history leads to distribution of mechanical properties, distortions, residual stresses or even fatigue properties in the part. To avoid experimental trial-and-error optimization, different methods are available to simulate DED processes. Currently, the wire arc additive manufacturing (WAAM) is the most competitive DED process. In this work, a simulation method for the WAAM process is established and validated, which should be capable to calculate global effects (e.g. distortions, residual stresses) of real WAAM-processes with duration of hours and thousands of weld beads. The addition of beads and layers is simulated by the element birth and death technique. The elements are activated according to the movements of the heat source (arc). In this paper, the influence of the time step, the mesh size and the material properties of the inactive elements in hybrid implicit / explicit and fully implicit solutions are evaluated with respect to the computation time and stability. This investigation concludes several recommendations for AM-modelling. For example, a low Young’s modulus (100 N/mm²) for the inactive elements show nearly no influences on the welding simulation, but introduces numerical instabilities in case of multiple welding beads. The Young’s modulus should be increased to 1.000 N/mm² for small mesh-sizes, small step-sizes and many beads, even when it introduces unwanted stresses.

scholarly journals Substrate design to minimize residual stresses in Directed Energy Deposition AM processes

2021 ◽  
Vol 202 ◽  
pp. 109525
Author(s):  
Xufei Lu ◽  
Michele Chiumenti ◽  
Miguel Cervera ◽  
Junjie Li ◽  
Xin Lin ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Energy Deposition ◽  
Directed Energy Deposition ◽  
Directed Energy ◽  
Am Processes

scholarly journals Influence of High-Productivity Process Parameters on the Surface Quality and Residual Stress State of AISI 316L Components Produced by Directed Energy Deposition

2021 ◽  
Author(s):  
Gabriele Piscopo ◽  
Alessandro Salmi ◽  
Eleonora Atzeni
Keyword(s):  
Surface Roughness ◽  
Residual Stresses ◽  
Surface Quality ◽  
Process Parameters ◽  
Energy Deposition ◽  
Industrial Applications ◽  
High Productivity ◽  
Directed Energy Deposition ◽  
Productivity Process ◽  
Directed Energy

AbstractThe production of large components is one of the most powerful applications of laser powder-directed energy deposition (LP-DED) processes. High productivity could be achieved, when focusing on industrial applications, by selecting the proper process parameters. However, it is of crucial importance to understand the strategies that are necessary to increase productivity while maintaining the overall part quality and minimizing the need for post-processing. In this paper, an analysis of the dimensional deviations, surface roughness and subsurface residual stresses of samples produced by LP-DED is described as a function of the applied energy input. The aim of this work is to analyze the effects of high-productivity process parameters on the surface quality and the mechanical characteristics of the samples. The obtained results show that the analyzed process parameters affect the dimensional deviations and the residual stresses, but have a very little influence on surface roughness, which is instead dominated by the presence of unmelted particles.

scholarly journals Acoustic emissions in directed energy deposition processes

2022 ◽  
Author(s):  
Tobias Hauser ◽  
Raven T. Reisch ◽  
Tobias Kamps ◽  
Alexander F. H. Kaplan ◽  
Joerg Volpp
Keyword(s):  
Additive Manufacturing ◽  
Laser Beam ◽  
Energy Deposition ◽  
Process Analysis ◽  
Acoustic Emissions ◽  
Air Pressure ◽  
Directed Energy Deposition ◽  
Deposition Processes ◽  
Directed Energy ◽  
Wire Arc Additive Manufacturing

AbstractAcoustic emissions in directed energy deposition processes such as wire arc additive manufacturing and directed energy deposition with laser beam/metal are investigated within this work, as many insights about the process can be gained from this. In both processes, experienced operators can hear whether a process is running stable or not. Therefore, different experiments for stable and unstable processes with common process anomalies were carried out, and the acoustic emissions as well as process camera images were captured. Thereby, it was found that stable processes show a consistent mean intensity in the acoustic emissions for both processes. For wire arc additive manufacturing, it was found that by the Mel spectrum, a specific spectrum adapted to human hearing, the occurrence of different process anomalies can be detected. The main acoustic source in wire arc additive manufacturing is the plasma expansion of the arc. The acoustic emissions and the occurring process anomalies are mainly correlating with the size of the arc because that is essentially the ionized volume leading to the air pressure which causes the acoustic emissions. For directed energy deposition with laser beam/metal, it was found that by the Mel spectrum, the occurrence of an unstable process can also be detected. The main acoustic emissions are created by the interaction between the powder and the laser beam because the powder particles create an air pressure through the expansion of the particles from the solid state to the liquid state when these particles are melted. These findings can be used to achieve an in situ quality assurance by an in-process analysis of the acoustic emissions.

scholarly journals An Extended Lumped-Parameter Model of Melt–Pool Geometry to Predict Part Height for Directed Energy Deposition

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Jianyi Li ◽  
Qian Wang ◽  
Panagiotis (Pan) Michaleris ◽  
Edward W. Reutzel ◽  
Abdalla R. Nassar
Keyword(s):  
Energy Deposition ◽  
Temperature Fields ◽  
Temperature History ◽  
Extended Model ◽  
Thin Wall ◽  
Melt Pool ◽  
Directed Energy Deposition ◽  
Lumped Parameter ◽  
Single Bead ◽  
Directed Energy

There is a need for the development of lumped-parameter models that can be used for real-time control design and optimization for laser-based additive manufacturing (AM) processes. Our prior work developed a physics-based multivariable model for melt–pool geometry and temperature dynamics in a single-bead deposition for a directed energy deposition process and then validated the model using experimental data from deposition of single-bead Ti–6AL–4V (or Inconel®718) tracks on an Optomec® Laser Engineering Net Shaping (LENS™) system. In this paper, we extend such model for melt–pool geometry in a single-bead deposition to a multibead multilayer deposition and then use the extended model on melt–pool height dynamics to predict part height of a three-dimensional build. Specifically, the extended model incorporates temperature history during the build process, which is approximated by super-positioning the temperature fields generated from Rosenthal's solution of point heat sources, with one heat source corresponding to one bead built before. The proposed model for part height prediction is then validated using builds with a variety of shapes, including single-bead thin wall structures, a patch build, and L-shaped structures, all built with Ti–6AL–4V using an Optomec® LENSTM MR-7 system. The model predictions on average part height show reasonable agreement with the measured average part height, with error rate less than 15%.

scholarly journals Fatigue Assessment of Inconel 625 Produced by Directed Energy Deposition from Miniaturized Specimens

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 156
Author(s):  
Felipe Klein Fiorentin ◽  
Duarte Maciel ◽  
Jorge Gil ◽  
Miguel Figueiredo ◽  
Filippo Berto ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Energy Deposition ◽  
High Cycle Fatigue ◽  
Fatigue Performance ◽  
Fatigue Properties ◽  
Inconel 625 ◽  
Cycle Fatigue ◽  
Directed Energy Deposition ◽  
Metallic Additive ◽  
Directed Energy

In recent years, the industrial application of Inconel 625 has grown significantly. This material is a nickel-base alloy, which is well known for its chemical resistance and mechanical properties, especially in high-temperature environments. The fatigue performance of parts produced via Metallic Additive Manufacturing (MAM) heavily rely on their manufacturing parameters. Therefore, it is important to characterize the properties of alloys produced by a given set of parameters. The present work proposes a methodology for characterization of the mechanical properties of MAM parts, including the material production parametrization by Laser Directed Energy Deposition (DED). The methodology consists of the testing of miniaturized specimens, after their production in DED, supported by a numerical model developed and validated by experimental data for stress calculation. An extensive mechanical characterization, with emphasis on high-cycle fatigue, of Inconel 625 produced via DED is herein discussed. The results obtained using miniaturized specimens were in good agreement with standard-sized specimens, therefore validating the applied methodology even in the case of some plastic effects. Regarding the high-cycle fatigue properties, the samples produced via DED presented good fatigue performance, comparable with other competing Metallic Additive Manufactured (MAMed) and conventionally manufactured materials.

Sign in / Sign up

Export Citation Format

Share Document