scholarly journals Fatigue assessment of additively manufactured AlSi10Mg structures using effective stress concepts based on the critical distance approach

2021 ◽  
Author(s):  
Kai Schnabel ◽  
Jörg Baumgartner ◽  
Benjamin Möller ◽  
Matilde Scurria
Keyword(s):  
Critical Distance ◽  
Powder Bed Fusion ◽  
Powder Bed ◽  
Linear Elastic ◽  
Notched Specimens ◽  
Different Types ◽  
Reliable Design ◽  
End Use ◽  
Metallic Parts ◽  
Distance Approach

AbstractIn the last decade, Additive Manufacturing (AM) technologies have been considered by both the automotive and aerospace industries for the production of end-use metallic parts, with a main focus on Powder Bed Fusion – Laser Beam / metallic (PBF-LB/M) technologies. However, AM parts present features that are deleterious to their cyclic properties. For a reliable design in terms of fatigue strength, existing influencing variables must be identified and transferred to a numerical model. In particular, different types of defects, as well as their distribution, should be taken into account. In addition to the identification of relevant parameters based on literature data, an AlSi10Mg component-like structure is assessed based on results from notched specimens and a linear-elastic assessment concept using effective stresses.

scholarly journals Powder Surface Roughness as Proxy for Bed Density in Powder Bed Fusion of Polymers

Polymers ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 81
Author(s):  
Francesco Sillani ◽  
Ramis Schiegg ◽  
Manfred Schmid ◽  
Eric MacDonald ◽  
Konrad Wegener
Keyword(s):  
Manufacturing Industry ◽  
Thermoplastic Elastomer ◽  
Powder Bed Fusion ◽  
Polyamide 11 ◽  
Powder Bed ◽  
Polyamide 12 ◽  
End Use ◽  
High Standards ◽  
Laser Line Scan ◽  
Part Density

Powder bed fusion of polymers is becoming increasingly adopted by a variety of industries to tailor the strength, weight and functionality of end-use products. To meet the high standards of the modern manufacturing industry, parts built with powder bed fusion require consistent properties and to be free of defects, which is intrinsically connected to the quality of the powder bed prior to melting. The hypothesis of this work is that the roughness of the top surface of an unmelted powder bed can serve as a proxy for the powder bed density, which is known to correlate with final part density. In this study, a laser line scan profilometer is integrated onto the recoater arm of a custom powder test bench, which is able to automatically create layers of powder. A diverse group of polymers was investigated including polyamide 12 (PA12), polyamide 11 (PA11), polypropylene (PP), and a thermoplastic elastomer (TPU) under different recoating speed in order to increase the variance of the dataset. Data analytics were employed to compare roughness to measured powder bed density and a statically significant correlation was established between them.

Scalable Thermal Simulation of Powder Bed Fusion

2021 ◽  
pp. 1-17
Author(s):  
Yaqi Zhang ◽  
Vadim Shapiro ◽  
Paul Witherell
Keyword(s):  
Spatial Data ◽  
Manufacturing Process ◽  
Thermal Simulation ◽  
Powder Bed Fusion ◽  
Time Step ◽  
Powder Bed ◽  
Melt Pool ◽  
Scan Path ◽  
History Of ◽  
Metallic Parts

Abstract Powder bed fusion (PBF) has become a widely used additive manufacturing technology to produce metallic parts. In PBF, thermal field evolution during the manufacturing process plays an important role in determining both geometric and mechanical properties of the fabricated parts. Thermal simulation of the PBF process is computationally challenging due to the geometric complexity of the manufacturing process and the inherent computational complexity that requires a numerical solution at every time increment of the process. We propose a new thermal simulation of the PBF process based on the laser scan path. Our approach is unique in that it simulates the thermal history of the process on the discretization of the geometry implied by the process plan, as opposed to voxelization or meshing of the design geometry. The discretization is based on the laser scan path, and the thermal model is formulated directly in terms of the manufacturing primitives. An element growth mechanism is introduced to simulate the evolution of the melt pool during the manufacturing process. A spatial data structure, called contact graph, is used to represent the discretized domain and capture all thermal interactions. The simulation is localized through exploiting spatial and temporal locality. This limits the need to update to at most a constant number of elements at each time step, which implies that the proposed simulation not only scales to handle 3D components of arbitrary complexity but also can achieve real-time performance. The simulation is fully implemented and validated against experimental data and other simulation results.

scholarly journals On the fatigue notch sensitivity of Ti6Al4V specimens with α+β microstructure produced by laser powder bed fusion

2021 ◽  
Author(s):  
Antonio Cutolo ◽  
Chola Elangeswaran ◽  
Gokula Krishna Muralidharan ◽  
Brecht Van Hooreweder
Keyword(s):  
Fatigue Behaviour ◽  
Critical Distance ◽  
Notch Sensitivity ◽  
Fatigue Properties ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Specific Strength ◽  
Industrial Sectors ◽  
Stress Relieving

Laser powder bed fusion (L-PBF) is an additive manufacturing (AM) process which offers several advantages over conventional manufacturing techniques, including material savings and design possibilities. For these reasons several industrial sectors such as biomedical, aerospace and automotive, are considering L-PBF for customized parts production. Among the processable material palette, Ti6Al4V gained increasing interest due to the high specific strength, and stiffness, and excellent bio-compatibility, and corrosion resistance. However, to include L-PBF Ti6Al4V parts in load bearing applications it is important to properly understand the mechanical properties of AM’ed materials with a specific focus on fatigue behaviour. In this study the fatigue notch sensitivity of Ti6Al4V L-PBF manufactured specimens is investigated in depth. Samples with different notches were subjected to stress relieving heat treatment to generate a fine α+β microstructure. The results were used to define a relation between the perturbed stress field generated by the geometrical discontinuity, the microstructure size and the notch sensitivity. Moreover, the critical distance has been calculated using the theory of critical distance formulated with the line method (LM). The estimated value were adopted to predict fatigue properties of notched components with different notch radii.

Grain Morphology and Texture Development in a Co-Cr-Mo Alloy Fabricated by Powder Bed Fusion with an Electron Beam

2019 ◽  
Author(s):  
Yufan Zhao ◽  
Yuichiro Koizumi ◽  
Kenta Aoyagi ◽  
Daixiu Wei ◽  
Kenta Yamanaka ◽  
...  
Keyword(s):  
Electron Beam ◽  
Grain Morphology ◽  
Texture Development ◽  
Powder Bed Fusion ◽  
Powder Bed

scholarly journals On the Relevance of Volumetric Energy Density in the Investigation of Inconel 718 Laser Powder Bed Fusion

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 538 ◽  
Author(s):  
Fabrizia Caiazzo ◽  
Vittorio Alfieri ◽  
Giuseppe Casalino
Keyword(s):  
Surface Roughness ◽  
Energy Density ◽  
Process Parameters ◽  
Vickers Hardness ◽  
Powder Bed Fusion ◽  
Processing Conditions ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Fractional Density ◽  
Experimental Variation

Laser powder bed fusion (LPBF) can fabricate products with tailored mechanical and surface properties. In fact, surface texture, roughness, pore size, the resulting fractional density, and microhardness highly depend on the processing conditions, which are very difficult to deal with. Therefore, this paper aims at investigating the relevance of the volumetric energy density (VED) that is a concise index of some governing factors with a potential operational use. This paper proves the fact that the observed experimental variation in the surface roughness, number and size of pores, the fractional density, and Vickers hardness can be explained in terms of VED that can help the investigator in dealing with several process parameters at once.

Heat source model calibration for thermal analysis of laser powder-bed fusion

2020 ◽  
Vol 106 (7-8) ◽  
pp. 3367-3379 ◽  
Author(s):  
Shahriar Imani Shahabad ◽  
Zhidong Zhang ◽  
Ali Keshavarzkermani ◽  
Usman Ali ◽  
Yahya Mahmoodkhani ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Heat Source ◽  
Model Calibration ◽  
Source Model ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Heat Source Model ◽  
Powder Bed
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