Defect Detection and Imaging in Composite Structures Using Magnetostrictive Patch Transducers

The use of thin magnetostrictive patches to generate and detect guided waves within the composite samples is investigated for defect detection. This approach has been implemented using SH0 shear horizontal guided waves in both CFRP and GFRP plates. A magnetostrictive patch transducer was able to generate SH0 waves with known directional characteristics. The synthetic aperture focusing technique (SAFT) was then used to reconstruct images of defects using multiple transmission and detection locations. The results for imaging defects in both types of material are presented.“NDTonAIR” Marie Skłodowska Curie Training Network in Non-Destructive Testing and Structural Health Monitoring of Aircraft structures (MSCA-ITN) under the action H2020-MSCA-ITN-2016- under Grant number 722134

Zigzag-shaped nickel nanowires via organometallic template-free route

In this manuscript, the formation of nickel nanowires (average size: several tens to hundreds of μm long and 1.0-1.5 μm wide) at low temperature is found to be driven by dewetting of liquid organometallic precursors during spin coating process and by self-assembly of Ni clusters. Elaboration of metallic thin films by low temperature deposition technique makes the preparation process compatible with most of the substrates. The use of iron and cobalt precursor shows that the process could be extended to other metallic systems. In this work, AFM and SEM are used to follow the assembly of Ni clusters into straight or zigzag lines. The formation of zigzag structure is specific to the Ni precursor at appropriate preparation parameters. This template free process allows a control of anisotropic structures with homogeneous sizes and angles on standard Si/SiO2 surface

Formation of octapod MnO nanoparticles with enhanced magnetic properties through kinetically-controlled thermal decomposition of polynuclear manganese complexes

Polynuclear manganese complexes are used as precursors for the synthesis of manganese oxide nanoparticles (MnO NPs). Altering the thermal decomposition conditions can shift the nanoparticle product from spherical, thermodynamically-driven NPs to unusual, kinetically-controlled octapod structures. The resulting increased surface area profoundly alters the NP's surface-dependent magnetism and may have applications in nanomedicine

The Effect of Changes in Magnetic Field and Frequency on the Vibration of a Thin Magnetostrictive Patch as a Tool for Generating Guided Ultrasonic Waves

Copyright: © 2022 by the authors. A set of experiments was designed and conducted to investigate the vibrational ultrasonic response of a thin magnetostrictive patch bonded to a glass plate, with changes in static and dynamic magnetic fields applied to the patch. Such arrangements are often used as a means of generating guided waves in pipes or plates, by attaching a patch to a sample’s surface. The effect of varying the applied static and dynamic magnetic field’s amplitudes and directions and the frequency of the dynamic magnetic field was studied. It was demonstrated that the vibration of the magnetostrictive patch could be controlled and enhanced by optimizing the magnetic fields. It was also shown that for low-amplitude dynamic magnetic fields, Lorentz forces generated within the patch and the resonant frequency of the patch could also contribute to the enhancement of the vibration of the patch for low-amplitude fields. For high-amplitude dynamic magnetic fields, the magnetostriction effect can be the main transduction mechanism, which can be optimized for non-destructive testing and inspection purposes.“NDTonAIR” Marie Skłodowska Curie Training Network in Non-Destructive Testing and Structural Health Monitoring of Aircraft structures (MSCAITN) under the action H2020-MSCA-ITN-2016- under Grant number 722134

Free surface flow : experiments in a hydraulic channel with the water at rest and a moving bottom

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.When considering the problem of water waves, induced by an obstacle, in a fluid domain of finite depth, the main assumption is generally to consider the water as an inviscid fluid, which means that the velocity profile is not sheared but constant upstream from the bottom up to the free-surface. The objective of the experiments presented in this paper is to produce a free-surface flow over an obstacle, in a hydraulic channel, with a constant velocity profile upstream. To achieve this, we carried out an original device. The channel, with an obstacle lying on its bottom, is filled with a quantity of water at rest. A drive system moves, at a constant adjustable velocity, the bottom of the channel generating then a relative movement of the water with respect to the obstacle. Measurements of the wavelengths are performed and compared with that given by the theory.dc201

Cu2+-induced self-assembly and amyloid formation of a cyclic d,l-α-peptide: Structure and function

In a wide spectrum of neurodegenerative diseases, self-assembly of pathogenic proteins to cytotoxic intermediates is accelerated by the presence of metal ions such as Cu2+. Only low concentrations of these early transient oligomeric intermediates are present in a mixture of species during fibril formation, and hence information on the extent of structuring of these oligomers is still largely unknown. Here, we investigate dimers as the first intermediates in the Cu2+-driven aggregation of a cyclic D,L-alpha-peptide architecture. The unique structural and functional properties of this model system recapitulate the self-assembling properties of amyloidogenic proteins including beta-sheet conformation and cross-interaction with pathogenic amyloids. We show that a histidine-rich cyclic D,L-alpha-octapeptide binds Cu2+ with high affinity and selectivity to generate amyloid-like cross-beta-sheet structures. By taking advantage of backbone amide methylation to arrest the self-assembly at the dimeric stage, we obtain structural information and characterize the degree of local order for the dimer. We found that, while catalytic amounts of Cu2+ promote aggregation of the peptide to fibrillar structures, higher concentrations dose-dependently reduce fibrillization and lead to formation of spherical particles, showing self-assembly to different polymorphs. For the initial self-assembly step to the dimers, we found that Cu2+ is coordinated on average by two histidines, similar to self-assembled peptides, indicating that a similar binding interface is perpetuated during Cu2+-driven oligomerization. The dimer itself is found in heterogeneous conformations that undergo dynamic exchange, leading to the formation of different polymorphs at the initial stage of the aggregation process

Electrical and Mechanical Behaviour of Copper Tufted CFRP Composite Joints

Electrical continuity of dissimilar joints controls the current and thermal pathways during lightning strike. Tufting using carbon, glass or Kevlar fibres is a primary to introduce through thickness reinforcement for composite structures and assemblies. Replacing the conventional tuft thread material with metallic conductive wire presents an opportunity for enhancing current dissipation and deal with electrical bottlenecks across dissimilar joints. Simulation of the electro-thermo-mechanical behaviour of joints was carried out to assess the influence of metallic tufting. The finite element solver MSC.Marc was utilised. Mechanical models incorporate continuum damage mechanics (CDM) to capture progressive damage in both composite and aluminium components of the joint. The mechanical models were coupled with electrical and thermal simulations of reference and copper tufted carbon fibre epoxy composite joints to assess both the lightning strike response and mechanical robustness of the assembly as well as the improvements offered by tufting. Validation of the model is based on electrical conduction and temperature measurements alongside delamination tests.Clean Sky 2 Joint Undertaking under the European Union’s Horizon 2020 research and innovation programme under grant agreement No 887042, D-JOINTS

Triggers for displaced decays of long-lived neutral particles in the ATLAS detector

A set of three dedicated triggers designed to detect long-lived neutral particles decaying throughout the ATLAS detector to a pair of hadronic jets is described. The efficiencies of the triggers for selecting displaced decays as a function of the decay position are presented for simulated events. The effect of pile-up interactions on the trigger efficiencies and the dependence of the trigger rate on instantaneous luminosity during the 2012 data-taking period at the LHC are discussedFil: Aad, G.. Albert Ludwigs Universität; AlemaniaFil: Abajyan, T.. Universitaet Bonn; AlemaniaFil: Abbott, B.. University of Oklahoma; Estados UnidosFil: Abdallah, J.. Universitat Autònoma de Barcelona; EspañaFil: Abdel Khalek, S.. Universite Paris Sud; FranciaFil: Alconada Verzini, María Josefina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Alonso, Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Anduaga, Xabier Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Dova, Maria Teresa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: González Silva, María Laura. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Monticelli, Fernando Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Otero y Garzon, Gustavo Javier. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Piegaia, Ricardo Nestor. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Romeo, Gaston Leonardo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Tripiana, Martin Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Zhuang, X.. Ludwig Maximilians Universitat; AlemaniaFil: Zhuravlov, V.. Max-Planck Institut für Physik; AlemaniaFil: Zieminska, D.. Indiana University; Estados UnidosFil: Zimin, N. I.. Joint Institute for Nuclear Research; RusiaFil: Zimmermann, R.. Universitaet Bonn; AlemaniaFil: Zimmermann, S.. Universitaet Bonn; AlemaniaFil: Zimmermann, S.. Albert Ludwigs Universität; AlemaniaFil: Ziolkowski, M.. Universität Siegen; AlemaniaFil: Zitoun, R.. Université de Savoie; FranciaFil: Živković, L.. Columbia University; Estados UnidosFil: Zmouchko, V. V.. State Research Center Institute for High Energy Physics; RusiaFil: Zobernig, G.. University of Wisconsin; Estados UnidosFil: Zoccoli, A.. Università di Bologna; ItaliaFil: zur Nedden, M.. Humboldt University; AlemaniaFil: Zutshi, V.. Northern Illinois University; Estados Unido

Electrical and mechanical behaviour of copper tufted CFRP composite joints

Electrical continuity of dissimilar joints controls the current and thermal pathways during lightning strike. Tufting using carbon, glass or Kevlar fibres is a primary to introduce through thickness reinforcement for composite structures and assemblies. Replacing the conventional tuft thread material with metallic conductive wire presents an opportunity for enhancing current dissipation and deal with electrical bottlenecks across dissimilar joints. Simulation of the electro-thermo-mechanical behaviour of joints was carried out to assess the influence of metallic tufting. The finite element solver MSC.Marc was utilised. Mechanical models incorporate continuum damage mechanics (CDM) to capture progressive damage in both composite and aluminium components of the joint. The mechanical models were coupled with electrical and thermal simulations of reference and copper tufted carbon fibre epoxy composite joints to assess both the lightning strike response and mechanical robustness of the assembly as well as the improvements offered by tufting. Validation of the model is based on electrical conduction and temperature measurements alongside delamination tests.European Union funding: 88704