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    Compression and fatigue performance of additively manufactured NiTi architected shape memory alloys
    (IOP Publishing Ltd, 2025) Zwerink, B.B. ; Biffi, C.A. ; Fiocchi, J. ; Mehrpouya, M.
    Additive manufacturing of architected materials—particularly lattice or porous structures—has gained significant attention in recent years due to their enhanced strength-to-weight ratios, load-bearing capabilities, and energy absorption properties. The integration of these structures with shape memory alloys offers multifunctional performance for advanced engineering applications. This study investigates the compressive fatigue behavior of NiTi lattice structures fabricated by Laser powder bed fusion. Initial quasi-static compression tests, carried out to full structural collapse, were used to define load levels for subsequent fatigue experiments. Fatigue testing was then conducted at 40 °C to induce pseudoelastic behavior, and an S–N curve was generated to characterize fatigue performance. Results showed that the NiTi lattice could sustain cyclic loading at 8 kN for an average of approximately 86 000 cycles, and around 18 000 cycles at 11 kN. Post-mortem microstructural analyses revealed martensite accumulation near fracture regions, attributed to stress-induced phase transformation.
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    Multi-Scale Virtual Testing of an Automatic Fibre Placed Orthogrid Fuselage Panel
    (Scipedia, 2021) Vroon, J. ; Hoorn, N. van ; Brink, W.M. van den
    Virtual testing can be a viable solution to improve experimental testing and could in theory eliminate physical tests. In this work, a step-wise virtual testing approach of a large-scale fuselage panel is presented as part of the Advanced Concepts for Aero-Structures with Integrated Antennas and Sensors (ACASIAS) project. This grid-stiffened fuselage panel is manufactured using Automatic Fibre Placement (AFP). A glass fibre section allows for the integration of a phased array satellite communication antenna. Virtual testing is a concept with several attributes and can be considered as the simulation of structures using advanced non-linear Finite Element Analyses (FEA). At coupon level, the stiffness and cohesive failure behaviour at the grid-skin interface is calibrated by virtual testing of rib-peel coupons. These calibrated properties are validated by simulating a single grid section shear test. Both failure and (post-)buckling behaviour are predicted accurately. A virtual test of the most critical static ultimate load test of the panel was performed. At this stage, the panel contained an artificial manufacturing defect, Barely Visible Impact Damage (BVID), and Clearly Visible Impact Damage (CVID). A combined axial load and cabin pressure are applied at the testing facility at Royal NLR. All relevant features of this test set-up are modelled to increase the accuracy of the virtual test. Prior to the execution of the physical test the virtual test showed no failure at ultimate load. The predictions were compared with strain gauge readings and Digital Image Correlation (DIC) using ARAMIS deformation and showed good agreement.
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    Morphing concept based on thermoplastic fiber reinforced plastics
    (Eccomas Proceedia, 2023) Goozen, H. van ; Eijk, W. van der ; Pijlman, H.H. ; Docter, J.R.
    Over the last few decades, much effort has gone into developing compliance-based morphing solutions for reducing drag generated by slots in the wing surfaces required for movables to operate. The main components of these morphing solutions are generally a continuous skin supported by a compliant internal structure. These components should provide sufficient stiffness to resist the aerodynamic loads and, as a contradiction, sufficient flexibility to allow deformation. Against this background, it is investigated whether a novel morphing concept is suitable for a winglet application with a tabto be used for large passenger aircraft wing load alleviation. This concept achieves flexibility and stiffness by combining a carbon fiber-reinforced thermoplastic skin lay-up with glass fiber reinforced thermoplastic so-called shear resistant flexures.
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    Laser powder bed fusion of 3D metamaterials for energy absorption
    (Elsevier, 2025) Wits, W.W. ; Vos, C.J. de ; Montero Sistiaga, M.L. ; Smit, M.J. de
    Metamaterials with unique energy absorption properties are fabricated by additive manufacturing. Manufacturing limitations, imposed by Laser Powder Bed Fusion (LPBF), hamper the production of in particular 3D metamaterial structures, due to unsupported overhanging struts that are part of the unit cell design. This study analyses two types of 3D metamaterials, the auxetic re-entrant and octet truss. Optimal process parameters are determined experimentally for stainless steel 316L and unit cell design parameters are related to the overall performance of the metamaterial lattices. Drop-weight impact testing experiments are conducted on LPBF-fabricated metamaterial samples. Unique properties for energy absorption, directly related to the metamaterial’s unit cell design, are demonstrated.
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    General applicability of fatigue life assessment method for metal laser powder bed fusion parts : variation in material, shape and test conditions
    (Elsevier, 2025) Wits, W.W. ; Amsterdam, E.
    The general applicability of our formerly developed fatigue prediction and life assessment methodology for metal Laser Powder Bed Fusion (LPBF) parts is validated for a new commonly used feedstock material; AlSi7Mg. Moreover, another specimen geometry and surface finish, as well as another fatigue loading condition have been used. The fatigue life assessment method for additively fabricated metal parts uses both the size of LPBF-process inherent initial defects and a material- and process-specific pivot point to accurately predict the fatigue life. An experimental campaign was completed and confirmed that the method is indeed expandable to another material, shape and fatigue loading condition.