Artículos (Ingeniería Mecánica y Fabricación)

URI permanente para esta colecciónhttps://hdl.handle.net/11441/11372

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Commissioning of the Power Supplies and Coils of the SMART Tokamak
(Institute of Electrical and Electronics Engineers (IEEE), 2026-06) Vicente Torres, P.; Sánchez Gamino, Juan; Cruz Zabala, Diego José; Salas Suárez-Barcena, Jesús; Erena Guardia, Diego; Peña Arévalo, David; Márquez Alcaide, Abraham; León Galván, José Ignacio; Garcia Muñoz, Cristina; Física Atómica, Molecular y Nuclear; Ingeniería Electrónica; Ingeniería Mecánica y Fabricación; European Union (UE)
The small aspect ratio tokamak (SMART) is a spherical tokamak (ST) that ffers unique capabilities for studying the potential of negative triangularity. It has been designed, constructed, and is currently being operated by the Plasma Science Fusion Technology (PSFT) Laboratory at the University of Seville. SMART has a total of 21 coils, organized into seven independent circuits and driven by five modular power supplies (PS). The PS operation relies on switching converter technology based on IGBT and supercapacitors (SCs). The PS delivers predefined current waveforms to the copper coil system consisting of the central solenoid (CS), 12 toroidal field (TF) coils, three series pairs of poloidal field (PF) coils, and two independent PF coils. This study details the commissioning and validation of the PS toroidal and solenoid coils, as well as the assembly of coils in SMART. The maximum rated current and slope were measured, along with the series impedance of the coils, the output current ripple, and the noise levels. The internal parameters of the SCs were measured, and optimized current profiles were proposed to enhance overall performance. A comparison has been made between the theoretical values and the experimental results, providing insight into the performance of the PS and areas for improvement.
Cross-validated neural network models for fretting fatigue life prediction across multiple materials and contact geometries
(Elsevier, 2026-08) Conde, Zacarías; García Vallejo, Daniel; Navarro Pintado, Carlos; Domínguez Abascal, Jaime; Ingeniería Mecánica y Fabricación; TEP111: Ingeniería Mecánica
Fretting fatigue is a complex mechanism of material damage and a common cause of failure in mechanical components, yet its life prediction remains challenging for traditional empirical models. These methods typically show significant scatter and are often limited to individual material alloys. This study develops, implements, and validates data-driven neural network models capable of accurately predicting fretting fatigue life across a wide spectrum of high-strength engineering alloys and varied contact geometries. The models are trained on an experimental dataset that includes eight distinct alloys (including Aluminum, Titanium, and Inconel) and both spherical and cylindrical contact geometries. A key methodological innovation is the systematic integration of k-fold cross-validation to mitigate the risk of overfitting, a common issue with limited fretting fatigue datasets. This validation protocol maximizes data utility. We compare two complementary NN architectures: NN1, which uses only readily measurable global experimental parameters for rapid, simple deployment; and NN2, which incorporates physics-based subsurface stress–strain descriptors as engineered inputs to evaluate whether they improve prediction vs global parameters. The resulting suite of cross-validated, multi-material neural network predictors provides a tool for the rapid estimation of fatigue life under fretting conditions, supporting informed material selection and guiding experimental design in high-performance applications.
A fast log-Euclidean one-point estimate for coupled electromechanical polycrystals: Spectral bounds, inversion consistency, and Loewner-order diagnostics
(Elsevier, 2026) Buroni, Julieta L.; Buroni Cuneo, Federico Carlos; Ingeniería Mecánica y Fabricación; Ministerio de Ciencia e Innovación (MICIN). España
We present a semi-analytical scheme to estimate the effective electromechanical properties of textured piezoelectric polycrystals, introducing the log–Euclidean geometric mean for the extended constitutive tensor into this context. The method combines closed-form orientation averages—derived for tetragonal crystals under arbitrary textures—with matrix logarithm and exponential maps applied to the extended constitutive tensor. This formulation incorporates both electromechanical coupling and inversion consistency (i.e., invariance under matrix inversion), addressing key limitations of classical Voigt–Reuss schemes. When benchmarked against self-consistent computations, the geometric-mean estimate captures the overall texture-driven trends while exhibiting component-dependent accuracy across the considered coefficients. In contrast to self-consistent schemes, it avoids any iterative fixed-point loop in the estimate itself; moreover, for the texture families treated in closed form it requires no numerical integration over SO(3). This yields a fast estimator. Once the texture coefficients are specified, the remaining computation is limited to closed-form expressions and the matrix logarithm and exponential of the 9 × 9 extended constitutive operator. A spectral analysis shows that the log–Euclidean estimate is enclosed between the Reuss and Voigt spectra (eigenvalue-wise), but this does not imply energetic (Loewner) enclosure of the full operators. Accordingly, the inequality (...) does not hold in general. To rigorously delineate this limitation, we derive matrix inequalities showing that the geometric mean is Loewner-enclosed only between orthogonally similar transformations of the classical bounds, an algebraic consequence of the spectral ordering rather than a variational (physical) bound, valid even under strong anisotropy. We further propose a practical energetic-admissibility diagnostic based on the minimum eigenvalues of the Loewner differences, and quantify admissibility loss via Frobenius gaps to the similarity enclosures. Numerical tests on BaTiO3 polycrystals with fiber texture confirm that the geometric mean satisfies the spectral enclosure in all cases and that the entries of the extended stiffness constitutive tensor remain within the componentwise Voigt–Reuss bracket. When reported as extended compliances or engineering constants, the same behavior holds for the considered cases, with only minor departures for coupling-sensitive shear components. The log-Euclidean construction captures coupling-induced effects that are absent from blockwise (uncoupled) one-point treatments. In particular, neglecting coupling can lead to marked deviations in engineering constants. From a representational standpoint, the method applies both to continuous textures (via GSHM texture coefficients) and to discrete orientation sets (e.g. EBSD), in which case it reduces to an exact weighted orientation sum. For the Gaussian and von Mises–Fisher fiber families analyzed here, the required coefficients are provided in closed form, and the ensuing orientation averages are exact with respect to the supplied texture information. Compared to the Riemannian geometric mean, which lacks closed-form expressions and remains difficult to apply under general texture distributions, the log-Euclidean mean offers an analytically tractable and computationally efficient compromise. These features make it a promising tool for modeling anisotropic ferroic ceramics and for guiding texture-informed material design.
Evaluation of total alloplastic temporo-mandibular joint replacement with two different types of prostheses: A three-year prospective study
(Medicina Oral, S.L., 2016) González Pérez, Luis Miguel; Gonzalez Perez-Somarriba, Borja; Centeno Báez, Gabriel; Vallellano Martín, Carpóforo; Montes Carmona, Jose Francisco; Ingeniería Mecánica y Fabricación; Cirugía; TEP111: Ingeniería Mecánica
Background: Temporo-Mandibular Joint (TMJ) replacement has been used clinically for years. The objective of this study was to evaluate outcomes achieved in patients with two different categories of TMJ prostheses. Material and Methods: All patients who had a TMJ replacement (TMJR) implanted during the study period from 2006 through 2012 were included in this 3-year prospective study. All procedures were performed using the Biomet Microfixation TMJ Replacement System, and all involved replacing both the skull base component (glenoid fossa) and the mandibular condyle. Results: Fifty-seven patients (38 females and 19 males), involving 75 TMJs with severe disease requiring reconstruction (39 unilateral, 18 bilateral) were operated on consecutively, and 68 stock prostheses and 7 custom-made prostheses were implanted. The mean age at surgery was 52.6±11.5 years in the stock group and 51.8±11.7 years in the custom-made group. In the stock group, after three years of TMJR, results showed a reduction in pain intensity from 6.4±1.4 to 1.6±1.2 (p<0.001), and an improvement in jaw opening from 2.7±0.9 cm to 4.2±0.7 cm (p<0.001). In the custom-made group, after three years of TMJR, results showed a reduction in pain intensity from 6.0±1.6 to 2.2±0.4 (p<0.001), and an improvement in jaw opening from 1.5±0.5 cm to 4.3±0.6 cm (p<0.001). No statistically significant differences between two groups were detected. Conclusions: The results of this three-year prospective study support the surgical placement of TMJ prostheses (stock prosthetic, and custom-made systems), and show that the approach is efficacious and safe, reduces pain, and improves maximum mouth opening movement, with few complications. As such, TMJR represents a viable technique and a stable long-term solution for cranio-mandibular reconstruction in patients with irreversible endstage TMJ disease. Comparing stock and custom-made groups, no statistically significant differences were detected with respect to pain intensity reduction and maximum mouth opening improvement.
Impact of microstructural alterations to collagen networks on their mechanical behavior: a fiber in silico study of the articular cartilage surface
(Elsevier, 2026-10-01) Núñez Ortega, Elías; Sanz Herrera, José Antonio; Gaffney, Eamonn A.; Brown, Cameron P.; Reina Romo, Esther; Mecánica de Medios Continuos y Teoría de Estructuras; Ingeniería Mecánica y Fabricación; TEP245: Ingeniería de las Estructuras; TEP111: Ingeniería Mecánica
Background The collagen fibril network is a primary structural component of articular cartilage, ensuring its mechanical integrity; however, during osteoarthritis, this network undergoes pronounced structural changes. Hence, this in silico study investigates the non-linear mechanical behavior of collagen fibril networks representing the superficial zone of cartilage, examining normal and osteoarthritic conditions. Methods A previously validated in silico multiscale three-dimensional fiber network model has been extended by incorporating fibril interconnections (crosslinks) to represent the collagen network. This was first analyzed under normal conditions, followed by systematic modifications of key parameters—fibril Young’s modulus, crosslink density, and fibril orientation—to simulate degenerative microstructural changes characteristic of osteoarthritic cartilage in the superficial zone. Subsequently, computational transverse tensile tests, with uniaxial tension applied perpendicular to the preferential fibril orientation, were conducted to evaluate network integrity. These simulations predicted macroscopic mechanical responses, including energy and stress distributions in fibrils and crosslinks, providing insight into the transverse mechanical behavior of the collagen network under normal and pathological conditions. Results In the normal configuration, fibril interconnections appear to contribute to a more linear macroscopic mechanical response. Axial and bending energies are comparable in fibrils, and a limited set of fibrils and crosslinks act as stress concentrators. For degenerated configurations, stresses and energies increase significantly when fibrils are close to randomly oriented. Moreover, a case of mechanical compensation is found, where reduced interconnectivity does not decrease network stiffness after loading. Conclusions The proposed framework provides a virtual platform for investigating the mechanical behavior of normal and degenerated articular cartilage based on collagen microstructure. This may be combined with microstructural information from medical imaging to enable quantitative in silico explorations of how collagen network alterations influence tissue-scale mechanics.
Characterization of the I-phase regime at TCV
(IOP Publishing, 2024-12-06) Griener, M.; Wüthrich, C.; Wang, Y.; Brida, D.; Faitsch, M.; Offeddu, N.; Theiler, C.; EUROfusion Tokamak Exploitation Team; García Muñoz, Manuel; Ayllón Guerola, Juan Manuel; Cruz Zabala, Diego José; Domínguez-Palacios Durán, Jesús José; Doyle, Scott James; Galdón Quiroga, Joaquín; Hidalgo Salaverri, Javier; Van Vuuren, Anton Jansen; Viezzer, Eleonora; Física Atómica, Molecular y Nuclear; Ingeniería Mecánica y Fabricación; EUROfusion Consortium
The I-phase is an H-mode confinement regime of tokamaks characterized by limit cycle oscillations, the so-called LCOs or bursts. These bursts are the manifestation of a periodic flattening of the plasma edge pressure profile. The profile flattening is caused by increased radial transport, driven by a high-frequency plasma edge mode that periodically appears. This short-living mode is intrinsically connected to each burst. It vanishes once the profiles are fully flattened, and it reestablishes during profile recovery once critical gradients are reached and a new cycle begins. In this paper, we describe for the first time the unambiguous presence of the I-phase at the tokamak à configuration variable (TCV). As the I-phase confinement regime is found in the parameter regime between the L-mode and the fully developed H-mode, it is often confused with dithers between H-mode and L-mode. Therefore, we are highlighting the differences between these two phenomena. Furthermore, we show the two-dimensional dynamics of the I-phase mode and bursts and the associated filamentary transport, enabled by the outstanding capabilities of the 2D TCV Gas Puff Imaging diagnostics.
Formability and fracture of SLM-printed Ti6Al4V sheets
(Elsevier, 2026-09) López Fernández, José Andrés; Rosa-Sainz, Ana; Centeno Báez, Gabriel; Ferrer Real, Inés; García Romeu, María Luisa; Vallellano Martín, Carpóforo; Ingeniería Mecánica y Fabricación; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Agencia Estatal de Investigación. España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER)
Additive manufacturing (AM) allows the production of thin metallic sheet blanks with customised geometry and thickness, which can later be shaped by conventional or advanced forming processes, such as incremental forming. These techniques enable hybrid manufacturing processes in which printing and forming are combined, allowing applications such as components with a tailored distribution of thickness or porosity, as might be the case of customised biomedical implants. However, the formability and fracture behaviour of those printed sheet materials are still largely unknown. This work presents an experimental characterisation of fracture-controlled forming limits in selective laser melting (SLM) Ti6Al4V sheets under proportional loading. Uniaxial, plane strain and equi-biaxial tests were carried out on as-built and heat-treated material, using test geometries specifically selected to minimise material consumption and combining strain measurements with finite element simulations. The as-built condition shows very limited ductility and fractures shortly after yielding, whereas heat treatment leads to an increase in fracture strain with only a moderate reduction in strength. In all the tests, failure is controlled by fracture rather than by macroscopic necking, so the forming limits are described in terms of a fracture forming limit (FFL). Fracture results are represented in stress triaxiality versus equivalent strain space, leading to the assessment of a fracture locus that is physically consistent with triaxiality-sensitive fracture mechanisms commonly associated with porosity-assisted damage and void growth in SLM materials. Classical uncoupled fracture criteria are evaluated and calibrated using a minimum number of experimental points, highlighting the strengths and limitations of triaxiality-based approaches. The main novelty of the work lies in establishing a systematic fracture-controlled formability framework for Ti6Al4V sheets 3D-printed via SLM, intended as a practical basis for future hybrid AM-forming simulations.
Nonlinear excitation of energetic particle driven geodesic acoustic mode by resonance overlap with Alfvén instability in ASDEX Upgrade
(Nature Portfolio, 2025-01-07) Wang, Hao; Lauber, Philipp; Todo, Yasushi; Suzuki, Yasuhiro; Li, Hanzheng; Idouakass, Malik; Wang, Jialei; Adulsiriswad, Panith; ASDEX Upgrade Team; Viezzer, Eleonora; Cruz Zabala, Diego José; García Muñoz, Manuel; Cano Megías, Pilar; Domínguez-Palacios Durán, Jesús José; Galdón Quiroga, Joaquín; Rivero Rodríguez, Juan Francisco; Sanchis Sánchez, Lucía; Física Atómica, Molecular y Nuclear; Ingeniería Mecánica y Fabricación; Japan Society for the Promotion of Science; Promoting Research by Networking among Institutions; EUROfusion Consortium
The Alfvén instability nonlinearly excited the energetic-particle-driven geodesic acoustic mode on the ASDEX-Upgrade tokamak, as demonstrated experimentally. The mechanism of the energetic-particle-driven geodesic acoustic mode excitation and the mode nonlinear evolution is not yet fully understood. In the present work, a first-principles simulation using the MEGA code investigated the mode properties in both the linear growth and nonlinear saturated phases. Here we show that the simulation successfully reproduced the excitation and coexistence of these two modes, and agreed with the experimental results well. Conclusive evidence showed that the resonance overlap is the excitation mechanism of the energetic-particle-driven geodesic acoustic mode. In the linear growth phase, energetic particles that satisfied different resonance conditions excited the Alfvén instability, which then caused energetic particle redistribution in phase space. These redistributed energetic particles caused resonance overlap, exciting the energetic-particle-driven geodesic acoustic mode in the nonlinear phase.
Observation of magnetic islands in tokamak plasmas during the suppression of edge-localized modes
(Nature Portfolio, 2024-10-28) Willensdorfer, Matthias; Mitterauer, Verena; Hoelzl, Matthias; Suttrop, Wolfgang; Cianciosa, Mark; Dunne, Mike; Fischer, Rainer; Leuthold, Nils; Puchmayr, Jonas; Samoylov, Oleg; Suárez López, Guillermo; Wendler, Daniel; ASDEX Upgrade Team; Viezzer, Eleonora; Cruz Zabala, Diego José; Domínguez-Palacios Durán, Jesús José; Galdón Quiroga, Joaquín; García Muñoz, Manuel; González Martín, Javier; Van Vuuren, Anton Jansen; Oyola Domínguez, Pablo; Rivero Rodríguez, Juan Francisco; Sanchis Sánchez, Lucía; Física Atómica, Molecular y Nuclear; Ingeniería Mecánica y Fabricación; Department of Energy. United States; EUROfusion Consortium
In tokamaks, a leading platform for fusion energy, periodic filamentary plasma eruptions known as edge-localized modes occur in plasmas with high-energy confinement and steep pressure profiles at the plasma edge. These edge-localized modes could damage the tokamak wall but can be suppressed using small three-dimensional magnetic perturbations. Here we demonstrate that these magnetic perturbations can change the magnetic topology just inside the steep gradient region of the plasma edge. We identify signatures of a magnetic island, and their observation is linked to the suppression of edge-localized modes. We compare high-resolution measurements of perturbed magnetic surfaces with predictions from ideal magnetohydrodynamic theory where the magnetic topology is preserved. Although ideal magnetohydrodynamics adequately describes the measurements in plasmas exhibiting edge-localized modes, it proves insufficient for plasmas where these modes are suppressed. Nonlinear resistive magnetohydrodynamic modelling supports this observation. Our study experimentally confirms the predicted role of magnetic islands in inhibiting the occurrence of edge-localized modes. This will be beneficial for physics-based predictions in future fusion devices to control these modes.
Demonstration of Super-X divertor exhaust control for transient heat load management in compact fusion reactors
(Nature Portfolio, 2025-09-05) Kool, B.; Verhaegh, K.; Derks, G. L.; Wijkamp, T. A.; Koenders, J. T.W.; Lonigro, N.; McArdle, G.; Vincent, C.; Lovell, J.; Henderson, S. S.; Federici, F.; Brida, D.; Reimerdes, H.; Osborne, N.; van Berkel, M.; The EUROfusion Tokamak Exploitation Team; The MAST-U team; Ayllón Guerola, Juan Manuel; Cruz Zabala, Diego José; Chen, H.; Domínguez-Palacios Duran, Jesús José; Doyle, Scott James; Galdón Quiroga, Joaquín; García Muñoz, Manuel; Hidalgo Salaverri, Javier; Van Vuuren, Anton Jansen; Mancini, Alessio; Mckay, Kiera Anne; Oyola Domínguez, Pablo; Rivero Rodríguez, Juan Francisco; Romero Madrid, Carlos Francisco; Rueda Rueda, José; Toscano Jiménez, Manuel; Velarde Gallardo, Lina; Viezzer, Eleonora; Física Atómica, Molecular y Nuclear; Física Aplicada III; Ingeniería Mecánica y Fabricación; EUROfusion Consortium; Engineering and Physical Sciences Research Council (EPSRC); Department of Energy. United States
Nuclear fusion could offer clean, abundant energy. However, managing the power exhausted from the core fusion plasma towards the reactor wall remains a major challenge. This is compounded in emerging compact reactor designs promising more cost-effective pathways towards commercial fusion energy. Alternative Divertor Configurations (ADCs) are a potential solution. In this work, we demonstrate exhaust control in ADCs, employing a novel method to diagnose the neutral gas buffer, which shields the target. Our work on the Mega Ampere Spherical Tokamak Upgrade shows that ADCs tackle key risks and uncertainties for fusion energy. Their highly reduced sensitivity to perturbations enables active exhaust control in otherwise unfeasible situations and facilitates an increased passive absorption of transients, which would otherwise damage the divertor. We observe a strong decoupling of each divertor from other reactor regions, enabling near-independent control of the divertors and core plasma. Our work showcases the real-world benefits of ADCs for effective heat load management in fusion power reactors.
Overview of ASDEX Upgrade results in view of ITER and DEMO
(Institute of Physics Publishing (IOP), 2024-08-19) Zohm, Hartmut; EUROfusion Tokamak Exploitation Team; ASDEX Upgrade Team; Cruz Zabala, Diego José; Domínguez-Palacios Durán, Jesús José; Galdón Quiroga, Joaquín; García Muñoz, Manuel; González Martín, Javier; Van Vuuren, Anton Jansen; Oyola Domínguez, Pablo; Rivero Rodríguez, Juan Francisco; Sanchis Sánchez, Lucía; Viezzer, Eleonora; Física Atómica, Molecular y Nuclear; Ingeniería Mecánica y Fabricación; EUROfusion Consortium
Experiments on ASDEX Upgrade (AUG) in 2021 and 2022 have addressed a number of critical issues for ITER and EU DEMO. A major objective of the AUG programme is to shed light on the underlying physics of confinement, stability, and plasma exhaust in order to allow reliable extrapolation of results obtained on present day machines to these reactor-grade devices. Concerning pedestal physics, the mitigation of edge localised modes (ELMs) using resonant magnetic perturbations (RMPs) was found to be consistent with a reduction of the linear peeling-ballooning stability threshold due to the helical deformation of the plasma. Conversely, ELM suppression by RMPs is ascribed to an increased pedestal transport that keeps the plasma away from this boundary. Candidates for this increased transport are locally enhanced turbulence and a locked magnetic island in the pedestal. The enhanced D-alpha (EDA) and quasi-continuous exhaust (QCE) regimes have been established as promising ELM-free scenarios. Here, the pressure gradient at the foot of the H-mode pedestal is reduced by a quasi-coherent mode, consistent with violation of the high-n ballooning mode stability limit there. This is suggestive that the EDA and QCE regimes have a common underlying physics origin. In the area of transport physics, full radius models for both L- and H-modes have been developed. These models predict energy confinement in AUG better than the commonly used global scaling laws, representing a large step towards the goal of predictive capability. A new momentum transport analysis framework has been developed that provides access to the intrinsic torque in the plasma core. In the field of exhaust, the X-Point Radiator (XPR), a cold and dense plasma region on closed flux surfaces close to the X-point, was described by an analytical model that provides an understanding of its formation as well as its stability, i.e., the conditions under which it transitions into a deleterious MARFE with the potential to result in a disruptive termination. With the XPR close to the divertor target, a new detached divertor concept, the compact radiative divertor, was developed. Here, the exhaust power is radiated before reaching the target, allowing close proximity of the X-point to the target. No limitations by the shallow field line angle due to the large flux expansion were observed, and sufficient compression of neutral density was demonstrated. With respect to the pumping of non-recycling impurities, the divertor enrichment was found to mainly depend on the ionisation energy of the impurity under consideration. In the area of MHD physics, analysis of the hot plasma core motion in sawtooth crashes showed good agreement with nonlinear 2-fluid simulations. This indicates that the fast reconnection observed in these events is adequately described including the pressure gradient and the electron inertia in the parallel Ohm’s law. Concerning disruption physics, a shattered pellet injection system was installed in collaboration with the ITER International Organisation. Thanks to the ability to vary the shard size distribution independently of the injection velocity, as well as its impurity admixture, it was possible to tailor the current quench rate, which is an important requirement for future large devices such as ITER. Progress was also made modelling the force reduction of VDEs induced by massive gas injection on AUG. The H-mode density limit was characterised in terms of safe operational space with a newly developed active feedback control method that allowed the stability boundary to be probed several times within a single discharge without inducing a disruptive termination. Regarding integrated operation scenarios, the role of density peaking in the confinement of the ITER baseline scenario (high plasma current) was clarified. The usual energy confinement scaling ITER98(p,y) does not capture this effect, but the more recent H20 scaling does, highlighting again the importance of developing adequate physics based models. Advanced tokamak scenarios, aiming at large non-inductive current fraction due to non-standard profiles of the safety factor in combination with high normalised plasma pressure were studied with a focus on their access conditions. A method to guide the approach of the targeted safety factor profiles was developed, and the conditions for achieving good confinement were clarified. Based on this, two types of advanced scenarios (‘hybrid’ and ‘elevated’ q-profile) were established on AUG and characterised concerning their plasma performance.
Tomographic reconstructions of the MAST-U fast ion loss detector using iterative algorithms
(IOP Publishing, 2025-12-05) Jiménez-Comez, Marina; Schmidt, B.; Rueda Rueda, José; Velarde Gallardo, Lina; Rivero Rodríguez, Juan Francisco; Reyner-Vinolas, A.; García Muñoz, Manuel; González Martín, Javier; Viezzer, Eleonora; Física Atómica, Molecular y Nuclear; Ingeniería Energética; Ingeniería Mecánica y Fabricación; European Union (UE); Engineering and Physical Sciences Research Council (EPSRC); Department of Energy. United States; Junta de Andalucía
In this work, we evaluate the Kaczmarz, Coordinate descent, and Cimmino algorithms together with the resolution principle as stopping criteria, using a synthetic signal model for the MAST-U fast-ion loss detector (FILD), complementing the efforts recently done for the ASDEX Upgrade FILD. The performance of these algorithms is assessed by analyzing the evolution of the reconstruction error as well as the computation time. To further assess the reliability of the reconstructions, a ‘fidelity map’ that reconstructs signals at each grid point is introduced to visualize reconstruction accuracy across velocity space. The Kaczmarz algorithm, which shows better performance in terms of accuracy, is also applied to experimental MAST-U FILD measurements of prompt fast-ion losses in an L-mode plasma heated by an on-axis neutral beam injector with 1.5 MW of input power. This algorithm demonstrates improved performance compared to 0th-order Tikhonov regularization.
Optimized collimator design and synthetic signals for the ITER Fast Ion Loss Detector*
(IOP Publishing, 2026-03-31) Reyner-Viñolas, A; González Martín, Javier; Galdón Quiroga, Joaquín; Snicker, A.; Marques, R.; Hyvärinen, O; Rueda Rueda, José; Rueda Rueda, José; García Muñoz, Manuel; Kocan, M.; the EUROfusion WPPrIO Team; Física Atómica, Molecular y Nuclear; Ingeniería Mecánica y Fabricación; European Union (UE)
An improved geometry for the ITER Fast Ion Loss Detector (FILD) (i.e. Lost Alpha Monitor) collimator has been optimized to maximize the signal-to-noise ratio and resolution for the lost 3.5 MeV fusion-born alpha particles. A new optimization method has been developed to be able to study a broad range of geometries and ensure the best performance through the entire velocity-space of interest. The collimator now presents advanced shaping, fitting the helical trajectories of the ions. Synthetic diagnostic simulations have been conducted with the FILDSIM code to evaluate its performance. These simulations provide the main parameters of the diagnostic, including the gyroradius and pitch angle resolutions, and the collimator factor. Synthetic signals are computed from ASCOT ion distributions to evaluate the optic and data acquisition system of ITER. A scan of the FILD insertion has been performed to evaluate the ion flux at different measuring positions. The synthetic signals in this work show that the new collimator geometry enhances both collimation and resolution, ultimately improving the signal to noise ratio by . These simulations incorporate the latest update on the optical system and multiple sources of noise: scintillator noise generated by gamma and neutron fluxes, camera-induced noise, neutronic noise on the camera sensor, optic transmission and field of view, and distortion due to the optical system.
The legacy of José Domínguez: Contributions to boundary element formulations in fracture mechanics
(Elsevier, 2026) Sáez Pérez, Andrés; Rodríguez de Tembleque Solano, Luis; García Sánchez, Felipe; Buroni Cuneo, Federico Carlos; Mecánica de Medios Continuos y Teoría de Estructuras; Ingeniería Mecánica y Fabricación
This work reviews and critically assesses the scientific legacy of José Domínguez in the development of boundary element formulations for fracture mechanics. The review focuses on methodological advances that shaped the modern use of the boundary element method (BEM) for crack problems, with emphasis on: (i) crack-tip element technology – including singular quarter-point and discontinuous quarter-point elements – that enables direct extraction of fracture parameters from boundary integral equations; (ii) regularization procedures for singular and hypersingular kernels that preserve standard BEM infrastructure; and (iii) extensions from linear elastostatics to coupled-field solids and to dynamic fracture via frequency- and time-domain formulations. The scope is restricted to linear fracture formulations under the assumptions of pre-existing sharp cracks and small-scale yielding, both in classical elasticity and in linear coupled-field settings. The discussion covers quasi-static and dynamic fracture analyses, three-dimensional extensions, and the systematic generalization to anisotropic, piezoelectric, and magnetoelectroelastic solids, where multifield coupling introduces additional theoretical and numerical challenges. Rather than aiming at an exhaustive survey, the paper traces the coherent research line initiated by Domínguez and continued by his collaborators, highlighting how these contributions established a unified framework for fracture analysis that remains foundational in current boundary element research.
An affordable open-source 3D force platform and a wide force range calibration method
(Elsevier, 2026) Poyatos Bakker, Aarón Raúl; López Martínez, Javier; García Vallejo, Daniel; Muyor, José M.; Blanco Claraco, José Luis; Ingeniería Mecánica y Fabricación; Junta de Andalucía
This work introduces a novel 3D force platform design grounded on the use of planar uniaxial load cells and ball wheels, easy to manufacture from off-the-self components leading to an affordable and accurate system. An accompanying open-sourced software allows an easy use of the force platforms. A novel calibration method for 3D force platforms is proposed, whose setup uses a Smith-type bodybuilding machine, a triaxial load cell and a pole, allowing in-situ calibration and the application of multidirectional loads, including those exceeding body weight. The calibration matrix is obtained by applying least squares and cross-validation methodology. Experimental results show good accuracy for the vertical force and COP position, with average relative errors in the vertical and horizontal forces under 0.2 % and 2.5 %, respectively. The mean absolute error in the COP position is 0.32 mm in the x-axis and 0.27 mm in the y-axis. Additionally, the good performance of the force platform is demonstrated through its practical application in gait analysis.
Full-field elastic solution reconstruction of mechanical tests using a physics-based inverse method
(Elsevier, 2026-05) Sanz Herrera, José Antonio; Serna Moreno, M.C.; Horta Muñoz, S.; Chamorro Moreno, Rosario; Mecánica de Medios Continuos y Teoría de Estructuras; Ingeniería Mecánica y Fabricación; Ministerio de Ciencia e Innovación (MICIN). España; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Agencia Estatal de Investigación. España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER)
Accurate determination of the mechanical properties of materials is a technological necessity across a wide range of engineering applications. In this context, mixed numerical–experimental techniques aim to estimate anisotropic elastic constants by using measured displacement fields and loads as inputs. Although these methods seek to reduce the complexity of experimental campaigns, they still present some challenges. This paper introduces a novel inverse approach which addresses existing limitations by utilizing displacement and load data from a reduced region of the domain, thereby eliminating the need for a known distribution of boundary conditions. The developed algorithm was validated through two examples of application based on the Iosipescu test. In the first example, the approach demonstrated exceptional accuracy with synthetically generated data, achieving reconstruction errors of 0.55% and 1.49% for the elastic constants and strain field of a baseline case, respectively, even when a highly noisy input strain field is employed. Its practical viability was further confirmed in a second example using real test measurements. Beyond the recovery of elastic constants, the methodology also provides a physically consistent stress field across the full domain of the specimen, suggesting its broader utility for computing realistic stresses in structures from minimal data without pre-established deterministic hypotheses.
Can physical activity augment drug efficacy in PMO treatments - Insights from in-silico simulations of PTH and denosumab treatments
(Elsevier, 2026-03) Ruiz Lozano, Rocío; Calvo Gallego, José Luis; Pivonka, Peter; Martínez Reina, Francisco Javier; Ingeniería Mecánica y Fabricación; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; Australian Research Council (ARC)
The aetiology of osteoporosis (OP) is diverse, with ageing and the oestrogen decline after menopause being the main causes of the most prevalent type, primary OP. The concurrence of other diseases (such as chronic kidney disease or hyperparathyroidism), the use of certain medications (glucocorticoids) or an inadequate diet or a sedentary lifestyle may also cause or accelerate the appearance of OP. To counteract the sedentary lifestyle, physical exercise is often recommended as a preventive therapy or even as a complement to pharmacological treatments. In this work, we use a mathematical model of bone remodelling based on cell populations that implements bone mechanical feedback as a function of the strain level and the number of cycles of daily activities. We coupled this bone remodelling model with PK-PD models of denosumab and teriparatide to study the joint effect of drug treatments and exercise on bone density of postmenopausal women. Our results show that low-intensity exercise alone could slow down bone loss and prevent OP, particularly if started at a young age, and it could improve the efficacy of drug treatments, increasing bone density and reducing fracture risk. The incremental benefit of physical activity is greater in denosumab treatments, where the anabolic effect of exercise complements the anticatabolic effect of denosumab. However, the bone density gain and the reduction in fracture risk is greater, in absolute terms, in teriparatide treatments. In any case, disuse and sedentary lifestyle are detrimental to bone density and compromises the efficacy of drug treatments.
Predictive analysis of wrinkling in shrink flanging using conventional versus incremental forming
(Elsevier, 2026-03) López Fernández, José Andrés; Centeno Báez, Gabriel; Silva, Maria Beatriz; Vallellano Martín, Carpóforo; Ingeniería Mecánica y Fabricación; Ministerio de Ciencia e Innovación (MICIN). España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Agencia Estatal de Investigación. España; European Union (UE); Fundação para a Ciência e a Tecnologia (FCT)
This work presents an experimental and numerical investigation of shrink flanging using Conventional Press Forming (CPF) and Single Point Incremental Forming (SPIF). Tests were carried out on aluminium AA2024-T3 sheets to identify failure modes, process windows, and formability limits under compressive loading. Finite Element simulations were developed for both processes, focusing on the evolution of in-plane stresses at the flange edge. A stress-based wrinkling criterion is stablished, and a process window is defined as a function of flange geometry. Results show that SPIF enhances formability and delays wrinkling compared to CPF. However, while CPF exhibits earlier wrinkling, certain cases allow wrinkle ironing, improving the final surface quality. A numerical criterion is introduced to detect wrinkling based on strain differences between the inner and outer surfaces of the sheet, enabling consistent identification of the wrinkling onset across geometries. A stress-based analysis reveals that the critical compressive stress required to initiate wrinkling is significantly lower in CPF and strongly dependent on flange length. Conversely, SPIF maintains a nearly constant wrinkling limit. Based on these findings, a process window was developed to support the selection of the most suitable forming strategy.
Effect of energetic ions on edge-localized modes in tokamak plasmas
(Nature Publishing, 2025-01-06) Domínguez-Palacios, J.; Futatani, S.; García Muñoz, Manuel; Jansen van Vuuren, A.; Viezzer, Eleonora; Gonzalez-Martin, J.; Toscano Jiménez, Manuel; Olaya Domínguez, Pablo; Todo, Y.; Suzuki, Y.; Sanchis, L.; Rueda Rueda, José; Galdón Quiroga, Joaquín; Hidalgo-Salaverri, J.; Chen, H.; Rivero Rodríguez, Juan Francisco; Velarde, L.; the ASDEX Upgrade Team; the EuroFUSION MST1 Team; Cruz Zabala, Diego José; Física Atómica, Molecular y Nuclear; Física Aplicada III; Ingeniería Mecánica y Fabricación
The most efficient and promising operational regime for the International Thermonuclear Experimental Reactor tokamak is the high-confinement mode. In this regime, however, periodic relaxations of the plasma edge can occur. These edge-localized modes pose a threat to the integrity of the fusion device. Here we reveal the strong impact of energetic ions on the spatio-temporal structure of edge-localized modes in tokamaks using nonlinear hybrid kinetic–magnetohydrodynamic simulations. A resonant interaction between the fast ions at the plasma edge and the electromagnetic perturbations from the edge-localized mode leads to an energy and momentum exchange. Energetic ions modify, for example, the amplitude, frequency spectrum and crash timing of edge-localized modes. The simulations reproduce some observations that feature abrupt and large edge-localized mode crashes. The results indicate that, in the International Thermonuclear Experimental Reactor, a strong interaction between the fusion-born alpha particles and ions from neutral beam injection, a main heating and fast particle source, is expected with predicted edge-localized mode perturbations. This work advances the understanding of the physics underlying edge-localized mode crashes in the presence of energetic particles and highlights the importance of including energetic ion kinetic effects in the optimization of edge-localized mode control techniques and regimes that are free of such modes.
Optimal planning and tracking for E-sail transition between steady-states
(Elsevier, 2025-03) Pacheco Ramos, Guillermo; Vázquez Valenzuela, Rafael; García Vallejo, Daniel; Ingeniería Aeroespacial y Mecánica de Fluidos; Ingeniería Mecánica y Fabricación; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER)
The E-sail technology employs the repulsive force of solar wind protons on positively charged tethers for continuous propulsion. Mission research highlights the necessity to modulate thrust, while dynamics studies reveal a tendency for oscillation. This study explores achieving stable transitions between different E-sail steady-states, each associated to varying voltages and thrust levels. By creating a simplified multibody model with straight, rigid tethers, controlled transitions are investigated, considering the system's underactuated nature. An optimal control perspective is adopted to minimize a cost function for optimal planning. Additionally, the system's response to open-loop control actions is examined, underscoring the need for feedback to ensure precise trajectory tracking. Consequently, a procedure for deriving a feedback control law using Model Predictive Control is proposed. The results suggest the feasibility of stable transitions using underactuated control and advocate for applying these methods to more complex and realistic scenarios.

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