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Metal-based additive manufacturing (AM) technologies such as selective laser melting (SLM) have seen successful applications in the gas turbine industry over the past years. The rapidly growing demand in AM requires in-depth knowledge of the process, materials and design for additive manufacturing (DFAM). However, the material characterization and...
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... successfulness in this direction dictates the quality of "cause and effect," which is the realistic engineering response of the structure and is often to be observed through testing and validation.Based on the process chain model, we propose a DFAM framework that is tied to a generic design-to-AM process generalized from the Siemens gas turbine design process. As shown in Figure 3, the idea is to identify the gaps between AM and design, and to close the gaps by introducing ad-hoc DFAM solutions that meet the design needs in all design stages. Casting the closed loop design and AM process chain to the model in Figure 2, we can see that the framework embodies the performance-to-processing "goal/means" with five DFAM tasks, and integrates them seamlessly into the product development workflow. ...
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... next task is to parameterize the concepts in the CAD environment, and the results will be high-fidelity 3D models for later analyses. DFAM task b) in Figure 3 focuses on efficient ways of modelling AM designs. This is necessary in that the current B-rep based CAD modelling function- alities are not suitable for creating sophisticated AM structures, and the resulting CAD files becomes too cumbersome to be practical when the complexity of AM designs increases. ...
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... Magnetic effects Electric motors [6, 12, 18,48] Optical lenses [18,49] Sensors [50] 5 Shape memory effects 4D printing [51] •Self-assembly [52] •Multi-functionality or self-adaptability [52][53][54] •Self-repair [55] •Soft robotics [56] Civil engineering [57] High-load actuators [58] 6 Thermal effects Heat exchangers HX [17,[59][60][61][62] Injection nozzle [63] Injection molds [64] Die casting [65] Pistons [66] Heat sink for Nd: YAG laser crystals [67] Spark plug [68] Gas turbine [69,70] Actuator [47,71] Sensors [47] decided which properties would benefit the component most. Additive manufacturing enables this approach by locally setting elements into structural materials, powder dampeners [29][30][31], heat conductors (by filling media into cooling channels, creating isolating air pockets or manufacturing multi-material parts) [32], void or others and therefore setting local properties [4]. ...
With the help of effect-engineering, highly efficient additively manufactured products with a high-power density can be designed. The potential of product development lies in the conceptualization design and embodiment design phases, which have, however, only been methodically analyzed to a limited extent. Effect-engineering offers the possibility to resolve constructive contradictions and to influence disturbance variables. The research question answered in this article describes how a methodical procedure for effect-engineering must look to design highly efficient products for additive manufacturing. Simulation and multi-criteria optimization are particularly challenging in this context. For this purpose, a framework of effect engineering will be developed and the effects that offer significant added value for additive manufacturing will be shown. Furthermore, new system technologies in additive manufacturing are presented, which serve as enablers of the various effects. As a result of the contribution, the method of effect-engineering is successfully applied to two application examples.KeywordsEffect-engineeringDesign for additive manufacturing (DfAM)Laser powder bed fusion (LPBF)Particle dampingMulti-material components
... The numerical adjoint optimization enables irregular shape designs for the coolant nozzle which require advanced manufacturing processes. Additive manufacturing is capable of producing radically different designs from the conventional subtractive manufacturing processes and allows for novel solutions to highly challenging engineering problems (Fu et al., 2018). While some researchers (Snyder and Thole, 2020) have focused on studying the relation between the cooling performance and the surface roughness of additively manufactured cooling holes, others have begun investigating design concepts facilitated by the recent development in additive manufacturing. ...
Film cooling is one of the essential approaches developed to protect gas turbine blades and vanes from high temperature gases. It does so by covering the surface with a film of coolant air. Experimental and numerical studies have identified the parameters affecting film cooling aerodynamic and thermal behaviours; one of the most important is the coolant nozzle geometry. In this study, the nozzle geometry is optimized to enhance film effectiveness and heat transfer while keeping the inlet area and pitch-to-hole-width ratio fixed. A Reynolds-Averaged Navier Stokes (RANS) model, developed and validated against experimental data, served as the baseline for further optimization. The model was used to design a “racetrack slot” which is rectangular slot with semi-circular lateral edges. The aspect ratio of the slot was varied and an aspect ratio of seven was found to have the best cooling performance. As such, it served as the starting point for further, irregular, shape optimization of the coolant nozzle utilizing the ANSYS Fluent Adjoint solver. This solver allows mesh morphing within specified constraints and yielded a highly irregular coolant hole which taps into the potential of using additive manufacturing to produce cooled parts. The irregular shape optimization increased adiabatic film effectiveness over the test surface from 0.24 (for optimum racetrack coolant hole) to 0.34 (for optimum, irregular, coolant nozzle geometry). The enhancement is remarkable, especially when compared to 0.1; the value for the round coolant hole under the same conditions.
... akustische [7] Emissionen. Jedoch werden dabei Effekte, die nach dem Auftrag stattfinden, wie thermische Verzüge durch Spannungen [8] oder Schmelzbadaktivitäten [9], nicht direkt berücksichtigt. Aus diesem Grund wird innerhalb dieser Arbeit der Weg zu einem neuartigen Ansatz erläutert: die Prüfung der jeweiligen erstarrten Bauteilschicht nach ihrer Fertigstellung im AM-Prozess Laser Powder Bed Fusion (L-PBF oder LPBF) mit aktiver Laserthermografie. ...
Die zerstörungsfreie Prüfung von metallischen Bauteilen hergestellt mit additiver Fertigung (Additive Manufacturing - AM) gewinnt zunehmend an industrieller Bedeutung. Grund dafür ist die Feststellung von Qualität, Reproduzierbarkeit und damit auch Sicherheit für Bauteile, die mittels AM gefertigt wurden. Jedoch wird noch immer ex-situ geprüft, wobei Defekte (z.B. Poren, Risse etc.) erst nach Prozessabschluss entdeckt werden. Übersteigen Anzahl und/oder Abmessung die vorgegebenen Grenzwerte für diese Defekte, so kommt es zu Ausschuss, was angesichts sehr langer Bauprozessdauern äußerst unrentabel ist. Eine Schwierigkeit ist dabei, dass manche Defekte sich erst zeitverzögert zum eigentlichen Materialauftrag bilden, z.B. durch thermische Spannungen oder Schmelzbadaktivitäten. Dementsprechend sind reine Monitoringansätze zur Detektion ggf. nicht ausreichend.
Daher wird in dieser Arbeit ein Verfahren zur aktiven Thermografie an dem AM-Prozess Laser Powder Bed Fusion (L-PBF) untersucht. Das Bauteil wird mit Hilfe des defokussierten Prozesslasers bei geringer Laserleistung zwischen den einzelnen gefertigten Lagen unabhängig vom eigentlichen Bauprozess erwärmt. Die entstehende Wärmesignatur wird ort- und zeitaufgelöst durch eine Infrarotkamera erfasst. Durch diese der Lagenfertigung nachgelagerte Prüfung werden auch zum Bauprozess zeitversetzte Defektbildungen nachweisbar.
In dieser Arbeit finden die Untersuchungen als Proof-of-Concept, losgelöst vom AM-Prozess, an einem typischen metallischen Testkörper statt. Dieser besitzt eine Nut als oberflächlichen Defekt. Die durchgeführten Messungen finden an einer eigens entwickelten L-PBF-Forschungsanlage innerhalb der Prozesskammer statt. Damit wird ein neuartiger Ansatz zur aktiven Thermografie für L-PBF erforscht, der eine größere Bandbreite an Defektarten auffindbar macht. Der Ansatz wird validiert und Genauigkeit sowie Auflösungsvermögen geprüft. Eine Anwendung am AM-Prozess wird damit direkt forciert und die dafür benötigten Zusammenhänge werden präsentiert.
... The technique can be used both for building new parts and for repairing damaged parts at worn areas, directly on the original parts [125]. Additive manufacturing is also used to address the challenges of fuelling gas turbines with hydrogen by the development of novel combustion technology with complex cooling profiles and fuel routing paths [126]. AM or 3D printing allows for the burner design to be adjusted on the inside without changing the exterior, which makes it easier to retrofit existing turbines to enable hydrogen operation. ...
... IN625, and Hastelloy X are commercially available for AM and have been studied to facilitate the understanding of processing, microstructure, and properties. Fu et al. [126] described the microstructure resulting from selective laser melting (SLM) processing as characterised by fine, elongated grains that can recrystallise during heat treatment to form equiaxed and isotropic structures. In case recrystallisation does not occur, the material remains anisotropic. ...
With the increased pressure to decarbonise the power generation sector several gas turbine manufacturers are working towards increasing the hydrogen-firing capabilities of their engines towards 100%. In this review, we discuss the potential materials challenges of gas turbines fuelled with hydrogen, provide an updated overview of the most promising alloys and coatings for this application, and highlight topics requiring further research and development. Particular focus is given to the high-temperature oxidation of gas turbine materials exposed to hydrogen and steam at elevated temperatures and to the corrosion challenges of parts fabricated by additive manufacturing. Other degradation mechanisms such as hot corrosion, the dual atmosphere effect and hydrogen diffusion in the base alloys are also discussed.
In the following chapter, the creative methods of “Design with Additive Manufacturing” are presented. The focus is on the use of the design freedoms and potentials for expanding the design space. To this end, in Sect. 4.1 requirements are specified in the form of a checklist, which must be taken into account in additive manufacturing. Subsequently, the design goals and constructive contradictions are presented in Sect. 4.2. It should be emphasised that by pursuing several design goals in the conceptual design phase, a clear added value can be realised compared to conventionally manufactured products. Based on design goals and contradictions, we address the general functional structure in Sect. 4.3, from which the necessity of effect engineering (Sect. 4.4) emerges. Subsequently, in Sect. 4.5, the product architecture is elaborated and approaches from bionics are presented. Based on this, methods for the embodiment design, such as design principles, the one-piece machine method and methods of structural optimisation, are considered in detail in Sect. 4.6. Finally, in Sect. 4.7 discusses the development environment.
Although numerous successful showcases demonstrated the technological readiness of Additive Manufacturing (AM), its adoption continues to pose a major challenge to industrial organizations. Firms are required to consider a wide range of implementation factors, including AM technology, supply chain, operations, organization, and strategy. This section provides an overview of the AM adoption process. A review of the varying levels of AM implementation is given for the different manufacturing industries. Typical challenges and pitfalls of AM adoption are presented along the AM value chain. Two examples of successful implementation pathways are described to show key factors that enable firms to overcome the hurdles of AM adoption more efficiently. This includes, for instance, a systematic overview of AM-related competences (typical AM learning curve) that firms need to master to fully industrialize AM applications. Within this context, the role of change management is discussed, as stakeholders may hold reservations against the fundamental transformations implicated by the adoption of AM.
Additive manufacturing (AM) typically promotes epitaxial growth of columnar grains with strong crystallographic texture (〈001〉 fibre or cube texture) in nickel-base superalloys, due to high temperature gradients during the building process. Understanding the mutual dependency between AM process parameters, the resulting microstructure and the effective mechanical properties of the material is of great importance to accelerate the development of the manufacturing process. In this work, a multi-scale micromechanical model is employed to gain deeper insight into the influence of various texture characteristics on the creep behavior of an IN738 superalloy. The creep response is characterized using a phenomenological crystal plasticity (CP) creep model that considers the characteristic γ-γ' microstructure and all active deformation mechanisms. The results reveal that the creep strength increases with decreasing texture intensities and reaches maximum when the 〈001〉 fibre and cube textures are misaligned to the specimen building direction by 45 degree. The simulations also predict that the uncommon 〈111〉 and 〈110〉 fibres offer significantly higher creep resistance than the typically observed 〈001〉 fibre, which provides a further incentive to investigate AM processing conditions that can produce these unique textures in the material. As the intensities and the alignment of 〈001〉 fibre and cube textures can be attributed to the laser energy density and the scan strategy employed, and as the formation of distinct fibre textures depends on the geometry of the resulting melt pool, the Laser powder bed fusion (L-PBF) process parameters can be optimized to obtain microstructures with features that improve the creep properties.
