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Item type:Publication, Access status: with files , Design guidelines for laser powder bed fusion in Inconel 718(Laser Inst. of America, 2022-02-01); ; ; ; Additive manufacturing (AM) has been leveraged across various industries to potentially open design spaces allowing the design of parts to reduce the weight, cost, and integrated design. Over the past decade, AM has sped up fast enough to penetrate various industry offering potential solutions for multiple materials, such as metals, alloys, plastics, polymers, etc. However, challenges lie to best utilize the opened design spaces as current generation engineers are trained to design parts for the conventional manufacturing process. With this lack of design guidelines for the AM process, users are limiting themselves to best utilize the offering made by advanced manufacturing. For aerospace parts, the design freedom of additive manufacturing is attractive mainly for two purposes: for weight reduction through lighter, integrated design concepts as well as for functional optimization of parts aiming at an increase of performance, e.g., by optimizing flow paths. For both purposes, it is vital to understand the material-specific and manufacturing process design limits. In AM, combination of each material and manufacturing process defines the design space by influencing minimum thickness, angle, roughness, etc. This paper outlines a design guideline for the laser powder bed fusion (also DMLM, direct metal laser melting) AM process with Inconel 718 material. Inconel 718 is a superalloy with superior mechanical properties and corrosion resistance at elevated temperatures up to 700 °C and is, therefore, used in several applications including aerospace engine parts. Due to its weldability, the alloy has also been extensively investigated in laser powder bed fusion and other additive manufacturing processes. A comprehensive study is provided both analytically and experimentally suggesting how parts can be designed having critical design features, manufacturing direction/orientation to meet design requirements, design accuracy, and quality. Design features presented include walls, overhangs, bore holes, and teardrop shapes, with their minimal feature sizes and effects on accuracy and roughness of the build parts. For the light-weight design of parts, different concepts such as lattices and stiffener structures are discussed. For gas or liquid carrying flow channels, the geometrical form and size are highlighted. Based on an approach by Kranz et al., design guidelines for Inconel 718 are derived from the experiments and provided in the form of a catalog for easy application.Publicationtype: Journal ArticleScopus© Citations 14 113 446 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Structural health monitoring of fibre metal laminates under mode I and II loading(2018-04); ; Delamination is one of the most common defects in FRP and occurs due to low interlaminar strength. Such defects are difficult to detect and lead often to catastrophic failure of the composite. In this work a new approach of a multi-functional FML for structural applications is investigated. The interlaminar fracture toughness is determined and the capacitance change between the metal plies during crack propagation is measured in-situ. The metal sheet component undergoes a chemical pre-treatment by nanoscale sculpturing before manufacturing by resin transfer moulding, to prevent adhesive failure of the interfacial metal/matrix bond. The experimental test results show high potential for detecting defects in FMLs. Delamination, which occurs between the glass fibre/matrix interface, can be electrically detected using the capacitance measurement. The fracture surface of the pre-treated metal sheet demonstrates that the adhesive bond between the cubical hook-like surface structure of the aluminium and the matrix remains intact.Publicationtype: Journal Article130 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Structural health monitoring of multifunctional fibre metal laminates under mode i loadingDelamination is one of the most common degradation mechanisms in fibre reinforced polymer (FRP) composites and occurs due to low interlaminar strength. Such defects are difficult to detect and yield often to catastrophic failure of the composite. In this work a new approach for structural health monitoring (SHM) of fibre metal laminates (FML) for structural applications is investigated, which does not require additional sensors. Therefore, FMLs consisting of glass fibre reinforced polymer (GFRP) with different metal plies are manufactured by the resin transfer moulding process. The interlaminar fracture toughness GIc(Mode I) is determined and the capacitance change between the metal plies during crack propagation is measured insitu. Within one FML configuration, a metal sheet is applied additionally, which undergo a pre-treatment before application, to improve the mechanical adhesion of the metal/matrix interface bond. Metal sheets are conventionally used in FMLs to improve the mechanical performance such as the bearing behaviour. The experimental test results show a high potential detecting defects in FMLs. Delamination, which occurs between the fibre/matrix interface, can be electrically detected using the capacitance measurement. The FML with the surface structured metal sheet demonstrates promising results for designing tough composites for structural applications. The fractography demonstrates a higher interfacial bonding between the metal sheet and matrix compared to the glass fibre/matrix interface. Consequently, the pre-treated metal leads to higher resistance against delamination in comparison with the GFRP layers.Publicationtype: Conference Paper190