Validation of the Mechanical Behavior of an Aeronautical Fixing Turret Produced by a Design for Additive Manufacturing (DfAM)

The design of parts in such critical sectors as the manufacturing of aeronautical parts is awaiting a paradigm shift due to the introduction of additive manufacturing technologies. The manufacture of parts designed by means of the design-oriented additive manufacturing methodology (DfAM) has acquired great relevance in recent years. One of the major gaps in the application of these technologies is the lack of studies on the mechanical behavior of parts manufactured using this methodology. This paper focuses on the manufacture of a turret for the clamping of parts for the aeronautical industry. The design of the lightened turret by means of geometry optimization, the manufacture of the turret in polylactic acid (PLA) and 5XXX series aluminum alloy by means of Wire Arc Additive Manufacturing (WAAM) technology and the analysis by means of finite element analysis (FEA) with its validation by means of a tensile test are presented. The behavior of the part manufactured with both materials is compared. The conclusion allows to establish which are the limitations of the part manufactured in PLA for its orientation to the final application, whose advantages are its lower weight and cost. This paper is novel as it presents a holistic view that covers the process in an integrated way from the design and manufacture to the behaviour of the component in useThis project has received funding from the ELKARTEK program of the Basque Government (Project VIRTUA3D, under Contract nº KK-2022/00025) and HAZITEK (Project ADDHOC, under Contract nº ZL-2022/00665)

HiTZ@Antidote: Argumentation-driven Explainable Artificial Intelligence for Digital Medicine

Providing high quality explanations for AI predictions based on machine learning is a challenging and complex task. To work well it requires, among other factors: selecting a proper level of generality/specificity of the explanation; considering assumptions about the familiarity of the explanation beneficiary with the AI task under consideration; referring to specific elements that have contributed to the decision; making use of additional knowledge (e.g. expert evidence) which might not be part of the prediction process; and providing evidence supporting negative hypothesis. Finally, the system needs to formulate the explanation in a clearly interpretable, and possibly convincing, way. Given these considerations, ANTIDOTE fosters an integrated vision of explainable AI, where low-level characteristics of the deep learning process are combined with higher level schemes proper of the human argumentation capacity. ANTIDOTE will exploit cross-disciplinary competences in deep learning and argumentation to support a broader and innovative view of explainable AI, where the need for high-quality explanations for clinical cases deliberation is critical. As a first result of the project, we publish the Antidote CasiMedicos dataset to facilitate research on explainable AI in general, and argumentation in the medical domain in particular.Comment: To appear: In SEPLN 2023: 39th International Conference of the Spanish Society for Natural Language Processin

On the incubation effect on two thermoplastics when irradiated with ultrashort laser pulses: Broadening effects when machining microchannels

In the present work, the incubation effect on polycarbonate (PC) and poly(methyl methacrylate) (PMMA) foils has been investigated when irradiated with femtosecond pulses (400 nm in wavelength, 90 fs in pulse length and 1 kHz in pulse repetition rate). First, craters produced with different number of pulses (N = 1, 50, 100, 200 and 500) have been obtained and crater diameters measured by means of atomic force microscopy for single-shot craters (N = 1) and confocal optical microscopy for multi-shot craters. Taking into account the gaussian shape of the laser beam, the dependence of crater diameter with fluence has been well established according to a conventional description and, then, fluence thresholds extracted as function of the number of pulses. These values show a good agreement with the incubation model and the incubation coefficient, ξ, has been obtained for both materials (ξ = 0.68 for polycarbonate and ξ = 0.61 for poly(methyl methacrylate)). This result supports well the observed fact that the incubation effects play a more important role in some thermoplastics than in any other kind of material, where ξ usually lies between 0.8 and 0.95. In the second part of this work, these results have been considered in the machining of microchannels, since the number of pulses is directly connected to the relative motion of laser beam and the sample through the feedrate of the stages. So, the observed broadening of microchannels with feedrate for a given fluence can be successfully explained and widths predicted with an uncertainty below 2 μm. Finally, the channel depth is investigated and the well known transition between a gentle and a strong phase behaviour is showed in the case of polycarbonate.Authors acknowledge A. Juarros for AFM characterization and Basque Government for financial support.Peer reviewe

Micromecanizado mediante láseres de femtosegundos de cerámicas LTCC: Fabricación de microcalentadores para un sensor de monóxido de carbono

El presente trabajo pretende mostrar la procesabilidad de cerámicas de baja temperatura de sinterizado, LTCC (Low Temperature Co-fired Ceramics) mediante ablación láser con pulsos ultracortos (femtosegundos). Este tipo de material, de indudable interés tecnológico en el desarrollo de microsensores, presenta una alta fragilidad en el estado sinterizado, por lo que la utilización de métodos de contacto (fresado, torneado, etc.) para su mecanizado conduce a la fractura o la aparición de microgrietas y desconchamientos. El trabajo ha sido dividido en dos partes bien diferenciadas. Primeramente, se ha realizado un estudio del proceso, obteniéndose los parámetros fundamentales (el umbral de ablación y el coeficiente de incubación) y se ha procedido a una parametrización de la anchura y altura de microcanales en función de la densidad de energía y el avance relativo en el movimiento muestra-láser. Posteriormente, estos resultados han permitido el micromecanizado de estructuras sencillas, como cajeras, orificios y estructuras en ¿V¿. Finalmente, se presenta una aplicación práctica que muestra el interés tecnológico del proceso. Así, se han realizado microcalentadores en LTCC como etapa inicial en el desarrollo de un sensor de monóxido de carbono químico-resistivo. Estos permiten el calentamiento de un área de 1mm x 1mm hasta una temperatura de 490ºC sin apenas disipación de calor al área circundante

Micromecanizado mediante láseres de femtosegundos de cerámicas LTCC. Fabricación de microcalentadores para un sensor de monóxido de carbono

In present work, the processability of LTCC (Low Temperature Co-fired Ceramics) by means of femtosecond laser ablation is shown. This kind of material, with a clear technological interest in the development of microsensors, possesses a high mechanical fragility in the sintered state and, consequently, contact methods for micromaching (micromilling, microgrinding, etc.) lead to fracture or the appearance of microcracks. The paper has been structured in two different parts. Firstly, a detailed study of the process has been performed, obtaining the fundamental parameters, as ablation threshold and incubation factor and a parametrization of width and height of microchannels as a function of fluence and feedrate. Afterwards, these results have allowed the fabrication of simple structures as boxes, passing-through holes and 21/2D structures. Finally, the technological interest of the material and the process is shown. This way, microheaters in LTCC have been fabricated as initial stage of a carbon monoxide chemoresistive sensor. The system allows the heating of a 1mm x 1mm area up to 490ºC with almost no heat dissipation to the surrounding area.<br><br>El presente trabajo pretende mostrar la procesabilidad de cerámicas de baja temperatura de sinterizado, LTCC (Low Temperature Co-fired Ceramics) mediante ablación láser con pulsos ultracortos (femtosegundos). Este tipo de material, de indudable interés tecnológico en el desarrollo de microsensores, presenta una alta fragilidad en el estado sinterizado, por lo que la utilización de métodos de contacto (fresado, torneado, etc.) para su mecanizado conduce a la fractura o la aparición de microgrietas y desconchamientos. El trabajo ha sido dividido en dos partes bien diferenciadas. Primeramente, se ha realizado un estudio del proceso, obteniéndose los parámetros fundamentales (el umbral de ablación y el coeficiente de incubación) y se ha procedido a una parametrización de la anchura y altura de microcanales en función de la densidad de energía y el avance relativo en el movimiento muestra-láser. Posteriormente, estos resultados han permitido el micromecanizado de estructuras sencillas, como cajeras, orificios y estructuras en “V”. Finalmente, se presenta una aplicación práctica que muestra el interés tecnológico del proceso. Así, se han realizado microcalentadores en LTCC como etapa inicial en el desarrollo de un sensor de monóxido de carbono químico-resistivo. Estos permiten el calentamiento de un área de 1mm x 1mm hasta una temperatura de 490ºC sin apenas disipación de calor al área circundante

Wire Arc Additive Manufacturing Process for Topologically Optimized Aeronautical Fixtures

Publisher Copyright: © Copyright 2023, Mary Ann Liebert, Inc., publishers 2023.Additive manufacturing (AM) technologies in metallic materials have experienced significant growth over recent decades. Concepts such as design for additive manufacturing have gained great relevance, due to their flexibility and capacity to generate complex geometries with AM technologies. These new design paradigms make it possible to save on material costs oriented toward more sustainable and green manufacturing. On the one hand, the high deposition rates of wire arc additive manufacturing (WAAM) stand out among the AM technologies, but on the other hand, WAAM is not as flexible when it comes to generating complex geometries. A methodology is presented in this study for the topological optimization of an aeronautical part and its adaptation, by means of computer aided manufacturing, for WAAM manufacturing of aeronautical tooling with the objective of producing a lighter part in a more sustainable manner.Peer reviewe

Novel sensorized additive manufacturing-based enlighted tooling concepts for aeronautical parts

Publisher Copyright: © The Author(s) 2024.This paper presents lightweight tooling concepts based on additive manufacturing, with the aim of developing advanced tooling systems as well as installing sensors for real-time monitoring and control during the anchoring and manufacturing of aeronautical parts. Leveraging additive manufacturing techniques in the production of tooling yields benefits in manufacturing flexibility and material usage. These concepts transform traditional tooling systems into active, intelligent tools, improving the manufacturing process and part quality. Integrated sensors measure variables such as displacement, humidity and temperature allowing data analysis and correlation with process quality variables such as accuracy errors, tolerances achieved and surface finish. In addition to sensor integration, additive manufacturing by directed energy arc and wire deposition (DED-arc) has been selected for part manufacturing. The research includes the mechanical characterisation of the material and the microstructure of the material once manufactured by DED-arc. Design for additive manufacturing" principles guide the design process to effectively exploit the capabilities of DED-arc. These turrets, equipped with sensors, allow real-time monitoring and control of turret deformation during clamping and manufacturing of aeronautical parts. As a first step, deformation monitoring is carried out within the defined tolerance of ± 0.15, which allows a control point to be established in the turret. Future analysis of the sensor data will allow correlations with process quality variables to be established. Remarkably, the optimised version of the turret after applying DED technology weighed only 2.2 kg, significantly lighter than the original 6 kg version. Additive manufacturing and the use of lightweight structures for fixture fabrication, followed by the addition of sensors, provide valuable information and control, improving process efficiency and part quality. This research contributes to the development of intelligent and efficient tool systems for aeronautical applications.Peer reviewe

End-effector for automatic shimming of composites

Gaps in composite structures are a risky factor in aeronautical assemblies. For mechanically joined composite components, the geometrical conformance of the part can be problematic due to undesired or unknown re-distribution of loads within a composite component, with these unknowns being potentially destructive. To prevent unnecessary preloading of a metallic structure, and the possibility of cracking and delamination in a composite structure, it is important to measure all gaps and then shim any gaps greater than 127 microns. A strategy to overcome the high relative tolerances for assemblies lies in the automated manufacturing of shims for the gaps previously predicted through the evaluation of their volumes via a simulation tool. This paper deals with the development of a special end-effector prototype to enable the shimming of gaps in composites structures using a pre-processed geometry. The aim of this end-effector is to provide movement to a temperature controlled hot-end in order to generate a solid shim of ABS on the target composite surface. This process is defined according to the trajectories and velocities marked by the 3D printing process using standard G-code. The geometry and material volume to be printed are indicated by the simulated gap volume which is based on previous metrological measurements. The final objective will be to attach this end-effector to an anthropomorphic robot to enable autonomous manufacturing. This work is part of the EU FP7 funded LOCOMACHS project, under grant agreement n◦314003.European Union Seventh Framework Programme FP7/2007-2013 under grant agreement n° 314003; Basque program Elkartek Basqtech 201