Journal: Materials & Design

Abbreviation

Mater. des.

Publisher

Elsevier

Journal Volumes

ISSN

0264-1275
1873-4197

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2010 - 2019232020 - 202665
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Publications 1 - 10 of 88
  • Microstructural features of Sc- and Zr-modified Al-Mg alloys processed by selective laser melting
    Item type: Journal Article
    Spierings, Adriaan B.; Dawson, K.; Heeling, Thorsten; et al. (2017)
    Materials & Design
  • Towards the realization of composite metastructures: A failure analysis of connections
    Item type: Journal Article
    Gaultier, Victor; Pappas, Georgios A. (2024)
    Materials & Design
    Metastructures hold significant potential for applications such as adaptive structures and soft robotics. Architectures of fiber-reinforced polymer metastructures may relate to modular arrangement of straight and curved laminates, with their connections to resemble perfect cracks, thus susceptible to delamination. This study investigated geometrical effects on the load-carrying capabilities of these connections upon a global tensile deformation, as well as lean modeling tools to facilitate the development of architected composite metastructures. Numerical fracture mechanics approach on different connection geometries and thicknesses showed that connection delamination is a critical failure mode, but crack-driving-force has low dependence on connection shape for given ligament thickness (and stiffness). Adopted analytical models could capture either moment or force-driven delamination failure, while the intermediate regime necessitates numerical tools. First-ply failure may precede depending on shape and ligament stiffness. These trends were also verified on an exemplary rotating chiral composite geometry. Furthermore, interface load-carrying capability improvements were studied via design considerations including connection filler material and element variable thickness. Indicatively, the latter showed a 157 % increase in bending deflection (and global deformations), while reducing crack driving force by 38 % for a given load case. The conducted analysis offers valuable insights into the design of lightweight, load-carrying composite metastructures.
  • Influence of the strain-rate on the mechanical properties of mild carbon steel at elevated temperatures
    Item type: Journal Article
    Knobloch, Markus; Pauli, Jacqueline; Fontana, Mario (2013)
    Materials & Design
  • Mechanical characterization of 3D printed polymers for fiber reinforced polymers processing
    Item type: Journal Article
    Türk, Daniel; Brenni, Franco; Zogg, Markus; et al. (2017)
    Materials & Design
  • Structural investigations of Fe-Zr-Si-Cu metallic glass with low glass-forming ability produced in laser powder bed fusion technology
    Item type: Journal Article
    Szczepanski, Łukasz; Bambach, Markus; Jensch, Felix; et al. (2021)
    Materials & Design
    Fe-based metallic glasses (MG) have become the subject of extensive research in recent years due to their favorable mechanical and magnetic properties. In particular, the production of this type of materials in Laser Powder Bed Fusion (LPBF), also known as Selective Laser Melting (SLM) technology, is a kind of breakthrough, as it has become possible to produce elements of any shape. An important factor influencing the properties of the manufactured parts is their microstructure. For metallic glass Fe79Zr6Si14Cu1 with low glass-forming ability, produced in SLM technology, tests were carried out in the field of structural X-ray diffraction, Scanning Electron Microscopy, and Transmission Electron Microscopy. In addition, porosity analysis was compared with process parameters such as laser power and scanning speed. The paper shows that the fusion line comprises a solid solution α-Fe(Si) and low fraction of intermetallic Fe23Zr6 and FeZr2 phases. Furthermore, in the melt pool area, a nanometric α-Fe(Si) phase and an amorphous matrix was observed. The presented research results of the Fe79Zr6Si14Cu1 alloy produced for the first time in SLM technology will undoubtendly contribute to further optimization of parameters for elements produced in Additive Manufacturing technology using Fe-based MG.
  • Investigating anisotropic effects and optimizing parameters in ultra-short pulsed (USP) laser machining of single crystalline diamond (SCD)
    Item type: Journal Article
    Michael, Kiran; Greiner, Lukas; Putzer, Matthias; et al. (2024)
    Materials & Design
    This research investigates the anisotropic behavior of single crystalline diamonds (SCD) during ultra-short pulse (USP) laser machining. The ablation behavior of SCD synthesized by high-pressure high-temperature (HPHT) and chemical vapor deposition (CVD) methods is studied on their primary crystallographic planes: {100}, {110}, and {111}. The results show different ablation thresholds for each plane, with the {100} plane having the highest threshold for both SCD types. CVD diamonds exhibit higher ablation thresholds than HPHT diamonds, indicating synthesis methods influence USP laser machining. The anisotropy of material removal, breakouts, and cracks, dependent on the in-plane machining angle, is investigated by machining grooves on the {100}, {110}, and {111} planes. Each plane shows unique characteristics, with varying anisotropic behavior at different in-plane angles. The material removal rate (MRR) differs between planes and even between grooves at different in-plane angles on the same plane. Distinct cracking behaviors are also observed, emphasizing the relationship between the crystallographic plane and the in-plane angle. The ideal in-plane angle for stable and clean ablation on each plane is determined. Temporal beam shaping, with MHz burst pulses, effectively minimizes detrimental effects such as cracks during SCD processing, enhancing machining quality and expanding USP laser machining applicability.
  • Hardening of Al-Mg-Si alloys: Effect of trace elements and prolonged natural aging
    Item type: Journal Article
    Werinos, Marion; Antrekowitsch, Helmut; Ebner, Thomas; et al. (2016)
    Materials & Design
  • 3D integration of pH-cleavable drug-hydrogel conjugates on magnetically driven smart microtransporters
    Item type: Journal Article
    Bernasconi, Roberto; Mauri, Emanuele; Rossetti, Arianna; et al. (2021)
    Materials & Design
    Targeted drug delivery is currently emerging as a promising approach to overcome the limits of currently employed administration techniques. The most convenient methodology to control drug delivery is the application of stimuli-responsive materials, which can release drugs only when required, to remotely controlled microdevices able to navigate human body. Thanks to this synergy, release can be controlled both spatially and temporally. Spatial control is guaranteed by the maneuverability of the devices, which can be precisely guided to release in targeted locations. Temporal control, conversely, is guaranteed by the functionalization introduced in the stimuli-responsive material. In this context, the present work describes the coating of magnetically controlled microdevices with functionalized alginate-based hydrogels able to release drugs at pH values lower than 4.5. Hydrogels are functionalized binding the drug with either an azidoethyl ester bond or an amidic bond, following an innovative synthesis route. After fabrication, release from hydrogel coated microdevices as a function of the environmental pH is characterized. Finally, devices are magnetically actuated and the possibility to achieve spatially and temporally controlled release is demonstrated. The functional microtransporters described in the present work are particularly promising for in-vivo applications in environments where pH differences are present, like the digestive apparatus.
  • Lightweight macroporous Co-Pt electrodeposited films with semi-hard-magnetic properties
    Item type: Journal Article
    Navarro-Senent, Cristina; Eiler, Konrad; Pané, Salvador; et al. (2022)
    Materials & Design
    Macroporous, partially L10-ordered Co-Pt films with nearly equiatomic composition were successfully synthesized by electrodeposition from an aqueous sulfate–chloride electrolyte on colloidal crystal-templated substrates, followed by annealing in vacuum. The colloids deposited on the substrate consisted of amidine-functionalized polystyrene spheres of 215 ± 13 nm in diameter, which were self-assembled by electrophoresis. As-deposited Co-Pt films obtained after the removal of the spheres showed a highly-packed arrangement of macropores. Structurally, the films showed the A1-disordered face-centered cubic (fcc) Co-Pt solid solution, accompanied by small amounts of fcc/hexagonal close-packed (hcp)–Co. Upon annealing at 600 °C, the A1-disordered phase partly transformed into the L10-ordered (face-centered tetragonal, fct) phase. As a result, the coercivity significantly increased from 148 Oe to 1328 Oe. Importantly, the porosity of the films was preserved after annealing. Optimum annealing temperature and time were selected on the basis of a prior parametric study with electroplated dense counterparts. This work demonstrates that the combination of colloidal crystal templating and electrodeposition is a very convenient pathway towards lightweight semi-hard magnets with potential technological applications in automotive and aerospace industries, portable sensors or spectrometers, magnetic levitation systems, or magnetoelectric devices, among others.
  • Additively manufactured mesh-type titanium structures for cranial implants: E-PBF vs. L-PBF
    Item type: Journal Article
    Lewin, Susanne; Fleps, Ingmar; Åberg, Jonas; et al. (2021)
    Materials & Design
    A patient-specific titanium-reinforced calcium phosphate (CaP–Ti) cranial implant has recently shown promising clinical results. Currently, its mesh-type titanium structure is additively manufactured using laser beam powder bed fusion (L-PBF). Nevertheless, an electron-beam (E-PBF) process could potentially be more time efficient. This study aimed to compare the geometrical accuracy and mechanical response of thin titanium structures manufactured by L-PBF (HIPed) and E-PBF (as-printed). Tensile test (ø = 1.2 mm) and implant specimens were manufactured. Measurements by μCT revealed a deviation in cross-sectional area as compared to the designed geometry: 13–35% for E-PBF and below 2% for L-PBF. A superior mechanical strength was obtained for the L-PBF specimens, both in the tensile test and the implant compression tests. The global peak load in the implant test was 457 ± 9 N and 846 ± 40 N for E-PBF and L-PBF, respectively. Numerical simulations demonstrated that geometrical deviation was the main factor in implant performance and enabled quantification of this effect: 34–39% reduction in initial peak force based on geometry, and only 11–16% reduction based on the material input. In summary, the study reveals an uncertainty in accuracy when structures of sizes relevant to mesh-type cranial implants are printed by the E-PBF method.
Publications 1 - 10 of 88