Now showing 1 - 10 of 39
  • Publication
    Open Access
    A practical toolpath planning method for cold spray additive manufacturing of rotational symmetry parts
    Rotational symmetry parts are common and essential in industrial applications. Cold spray additive manufacturing (CSAM) is an attractive and rapidly developing solid-state material deposition process, providing an efficient and convenient method for producing such parts, as it allows for the rapid formation of high-quality, large-volume 3D objects. Since there is no highly reactive liquid phase involved in this process, the deposited material is free of oxides. As compared to conventional additive manufacturing methods, cold spraying enables to reduce the production costs and times. In this work, a general implementation method for CSAM of rotating symmetry casing parts is presented. Here, the developed application can handle rotational symmetry parts of arbitrary geometry in the form of CAD files to generate precise toolpaths. Robot offline programming allows for process simulation, analysis, and optimization. Additionally, modelling of robot kinematics is employed to evaluate the effect of the planned toolpaths on the spraying process, ensuring efficient and precise manufacturing processes.
  • Publication
    Open Access
    Temperature and stress management in cold sprayed deposits
    Material deposition in cold spraying occurs in solid state and thus avoids undesired effects of melting and solidification. However, residual stress conditions in cold sprayed coatings could limit possible part performance. The temperature distribution and thermal history of the cold sprayed components has significant influence on stress distribution and thus deposition and part quality. The present study investigates the effect of substrate material and nozzle traverse speed (as a secondary parameter) on effective temperatures and residual stress distributions of titanium-grade 1 deposits. The results demonstrate that substrate material properties and nozzle traverse speeds have significant influence on residual stresses of the cold spray deposit. It is understood that coefficient of thermal expansion (CTE) difference of the coating and substrate materials has significant effect on residual stress state. On the other hand, the residual stresses change from more compressive to more tensile state as the temperature of the components increases by decreasing the nozzle traverse speed. These findings indicate that thermal parameters affect residual stresses substantially. Thus, by adjusting the kinematic parameters and reducing maximum reached local temperatures within the part, more favorable stress states of the finished component can be obtained. The attained knowledge is essential for the development of high-quality deposits and the selection of the best strategies for repair and additive manufacturing applications.
  • Publication
    Open Access
    Trajektorienplanung und -optimierung für die automatisierte Reparaturanwendung durch robotergeführtes Kaltgasspritzen
    Das Kaltgasspritzen entwickelt sich zu einem Verfahren mit großem Potenzial für die Reparatur metallischer Bauteile, insbesondere für das Aufbringen von hitze- und oxidationsempfindlichen Materialien. In diesem Zusammenhang ermöglicht der Einsatz von Automatisierung und Robotik eine flexible Steuerung des Reparaturprozesses. Um einen optimalen Reparaturprozess zu gewährleisten, müssen die verschiedenen Anforderungen des robotergeführten Kaltgasspritzens bereits in der simulativen Planungsphase berücksichtigt werden. Herkömmliche Trajektorien zum Materialauftrag berücksichtigen jedoch oft nicht die bei Reparaturen zu beachtenden geometrischen Randbedingungen des Materialaufbaus, den effizienten Materialeinsatz und die zugrundeliegenden Einschränkungen der Roboterkinematik. In dieser Arbeit wird daher ein Konzept zur automatisierten Trajektorienplanung und anschließenden Trajektorienoptimierung zur Reparatur durch robotergeführtes Kaltgasspritzen beschrieben. Das Ziel ist es, eine optimierte Trajektorie zu erzeugen, die die Anforderungen des Kaltgasspritzens und der Roboterkinematik berücksichtigt, um eine qualitativ hochwertige Reparatur und einen effizienten Materialeinsatz zu gewährleisten. Dazu gehören die Minimierung des überschüssigen Materials und die Minimierung des Rucks bei der Roboterbewegung. Die Ergebnisse zeigen die erfolgreiche Anwendung der initialen Trajektorienplanung und der anschließenden Trajektorienoptimierung für die Bauteilreparatur durch Kaltgasspritzen.
  • Publication
    Open Access
    Computerized Refurbishment
    (2022) ; ; ; ; ; ; ;
    Huang, Chunjie
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    ; ; ;
    Rashikbhai Gabani, Dhruvit
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    Gibmeier, Jens
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    Pundt, Astrid
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    Werner, Tiago
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    Hilgenberg, Kai
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    Madia, Marco
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    Böllinghaus, Thomas
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    Holzgaßner, Leonhard
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    Richter, Peter
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    Clausing, Nils
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    Loitz, Henry
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    Keuter, Philipp
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    Baben, Moritz to
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    Steierl, Markus
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    Schimbäck, David Erich
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    Rösler, Thorsten
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    Debuch, Holger
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    Gartner, Thomas
  • Publication
    Metadata only
    Knowledge-based optimization of cold spray for aircraft component repair
    In recent years, cold spraying (CS) has emerged as a promising technology for repair applications, particularly for oxidation-sensitive materials. In order to obtain an optimum repair result that fulfills the highest requirements regarding material properties, simple geometric shape restoration is not sufficient. Any additive manufacturing process results in particular features in microstructure, possible defects and respective – potentially even anisotropic – mechanical properties. To systematically tailor these microstructures and properties to the specific component and geometry requires complex routines. This work proposes the design of a knowledge-based cold spray repair system that facilitates a complete individual repair procedure for aircraft components. This system includes the elements of (i) reverse engineering to analyze, classify and generate digital data of the damaged component, (ii) pre-processing to obtain the ideal conditions for the CS process, (iii) toolpath planning to optimize robotics for the CS process, (iv) on-line monitoring to ensure process quality, (v) post-processing and (vi) performance testing of the material properties to meet the challenging requirements of the aerospace industry. By using an industrial robot and computer-aided planning of the trajectories, components are to be repaired under cold spray and geometrical conditions for ideal material deposition. The goal is to obtain repaired components that fulfill the required property profile equally well as respective new parts.
  • Publication
    Metadata only
    Size Effects of Brittle Particles in Aerosol Deposition - Molecular Dynamics Simulation
    (Springer, 2021-03-05) ; ;
    Assadi, Hamid
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    Höche, Daniel
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    © 2021, The Author(s). Up to now, the role of particle sizes on the impact behavior of ceramic particles in aerosol deposition not yet fully understood. Hence, with the aim to supply a more general understanding, modeling series of low strain rate compression and high-speed impact were performed by molecular dynamics on single-crystalline particles in sizes of 10-300 nm that are tuned to match mechanical properties of TiO2-anatase. The modeling results reveal that particles with original diameter of 25-75 nm exhibit three different impact behaviors that could be distinguished as (i) rebounding, (ii) bonding and (iii) fragmentation, depending on their initial impact velocity. In contrast, particles larger than 75 nm do not exhibit the bonding behavior. Detailed stress and strain field distributions reveal that combination of “localized inelastic deformation” along the slip systems and “shear localization” cause bonding of the small and large particles to the substrate. The analyses of associated temperature rise by the inelastic deformation revealed that heat diffusion at these small scales depend on size. Whereas small particles could reach a rather homogeneous temperature distribution, the evolved heat in the larger ones keeps rather localized to areas of highest deformation and may support deformation and the formation of dense layers in aerosol deposition.
  • Publication
    Metadata only
    Molecular Dynamics Simulations of Titanium Dioxide as Model System for Size Effects in Aerosol Deposition
    (2021) ; ; ; ;
    Assadi, Hamid
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    Höche, Daniel
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    Azarmi, F.
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    Chen, X.
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    Cizek, J.
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    Cojocaru, C.
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    Jodoin, B.
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    Koivuluoto, H.
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    Lau, Y.C.
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    Fernandez, R.
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    Ozdemir, O.
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    Salimi Jazi, H.
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    Toma, F.
  • Publication
    Metadata only
    Influence of MAX-Phase Deformability on Coating Formation by Cold Spraying
    (Springer, 2020-11-08)
    Busato, Marco
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    Bruera, Alessia
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    Bolelli, Giovanni
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    Lusvarghi, Luca
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  • Publication
    Metadata only
    Solid-state additive manufacturing of porous Ti-6Al-4V by supersonic impact
    (Elsevier, 2020)
    Moridi, Atieh
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    Stewart, Elizabeth J.
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    Wakai, Akane
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    Assadi, Hamid
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    Guagliano, Mario
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    Dao, Ming