Rafael Barea

Shape variation and deformation play a central role in computer animation, digital content creation and geometry processing, a domain that has undergone significant advances in the past decade owing to deep‐learning emergence. Most methods typically rely on large datasets or intermediate representations defined on Euclidean domains or grid‐like structures. As a result, learning expressive deformation models directly from surface‐based representations with limited data remains challenging. In this article, we present an unconditional learning‐based framework that captures the internal geometric statistics of a single 3D triangle mesh to generate smooth deformations ranging from local variations to larger‐scale shape changes across multiple spatial resolutions. The proposed Multiscale Graph‐based Generative Adversarial Network (MGGAN) consists of a pyramid of generators and discriminators built using spectral and spatial graph operators, trained directly on the input mesh and its downsampled versions with Gaussian noise injected at each scale. By operating directly on the input mesh, the method produces visually coherent, smooth and topology‐preserving deformed instances that are well suited for shape variation and asset exploration in animation and graphics pipelines.

Low-carbon steels, such as ER70S-6, are typically considered resistant to phase transformations due to their high critical cooling rate. However, this study investigates how the manufacturing process and specimen geometry influence heat dissipation, potentially leading to localized grain size variations that impact mechanical properties. To analyze these effects, samples were fabricated using Laser Wire-Feed Additive Manufacturing (LWAM) with different geometries, and their hardness and microstructural characteristics were evaluated. Vickers microhardness tests were performed along the specimens to assess local variations, while dilatometry measurements were conducted to determine thermal expansion coefficients for future integration into finite element models (FEMs) of residual stress distribution. The results reveal that differences in heat dissipation during fabrication lead to grain size heterogeneity, affecting hardness at a microscopic scale and overall mechanical performance. These findings highlight the importance of considering thermal history and geometry in LWAM-fabricated components to ensure consistent material properties.

The compressive deformation of the extruded binary Mg-Gd with gadolinium in solid solution has been studied in situ by combining synchrotron diffraction and acoustic emission techniques during compression tests. These two techniques are useful in investigating the evolution of twinning in all its stages. The extruded bars develop a fiber texture with the basal plane parallel to the extrusion direction. Moreover, the quenching of the magnesium bars immediately after the extrusion process ensured the production of the solid solution of gadolinium in the magnesium matrix. The solid solution of gadolinium solute atoms is the main strengthening mechanism of alloys and has a strong influence in plastic deformation. Tensile twinning controls the macroscopic yielding under compressive modes, although the activation of basal and non-basal dislocation systems has been also detected by in situ techniques. The presence of gadolinium atoms in solid solution tends to inhibit tensile twinning and, therefore, the twin volume fraction decreases with the increase in the gadolinium content. The compressive work hardening curve shows a maximum peak at intermediate plastic strain which is related to the interaction of dislocations within twins. The maximum value and the position of the peak decreases with the increase in the gadolinium content.

A suitable heat treatment in the Mg₉₇Gd₂Zn₁ (at.%) alloy in the as-cast condition results, after extrusion at high temperature, in a two-phase lamellar microstructure consisting of magnesium grains with thin lamellar shape precipitates and long fibers of the 14H-Long-Period Stacking Ordered (LPSO) phase elongated in the extrusion direction. The magnesium matrix is not fully recrystallized and highly oriented coarse non-dynamically recrystallized (non-DRXed) grains (17% volume fraction) elongated along the extrusion direction remain in the material. The deformation mechanisms of the extruded alloy have been studied measuring the evolution of the internal strains during in situ tension and compression tests using synchrotron diffraction radiation. The data demonstrate that the macroscopic yield stress is governed by the activation of the basal slip system in the randomly oriented equiaxed dynamic recrystallized (DRXed) grains. Non-DRXed grains, due to their strong texture, are favored oriented for the activation of tensile twinning. However, the presence of lamellar-shape precipitates strongly delays the propagation of lenticular thin twins through these highly oriented grains and they have no effect on the onset of the plastic deformation. Therefore, the tension–compression asymmetry is low since the plasticity mechanism is independent of the stress mode.

Tres aleaciones Mg-Gd ensayadas a compresión a temperaturas intermedias muestran un fenómeno de serrado dependiente de la velocidad de deformación y de la temperatura de ensayo. La aparición de este fenómeno se relaciona con la segregación de átomos de soluto en las dislocaciones móviles y/o en las fronteras de macla. Los ensayos de compresión se han realizado en un intervalo de temperaturas comprendido entre 25 y 300 °C y a velocidades de deformación comprendidas entre 4×10⁻⁵ y 8×10⁻³ s⁻¹ con el fin de analizar el fenómeno de serrado, e implícitamente, el proceso de envejecimiento dinámico por deformación. Experimentalmente se ha comprobado que el aumento de la concentración de gadolinio en solución sólida disminuye la energía de activación del proceso.

The Mg₉₀Y_6.5Ni_3.5 alloy composed almost completely of the Long-Period-Stacking-Ordered (LPSO) phase has been prepared by casting and extrusion at high temperature. An elongated microstructure is obtained where the LPSO phase with 18R crystal structure is oriented with its basal plane parallel to the extrusion direction. Islands of α-magnesium are located between the LPSO grains. The mechanical properties of the alloy are highly anisotropic and depend on the stress sign as well as the relative orientation between the stress and the extrusion axes. The alloy is stronger when it is compressed along the extrusion direction. Under this configuration, the slip of dislocations in the basal plane is highly limited. However, the activation of kinking induces an increase in the plastic deformation. In the transversal extrusion direction, some grains deform by the activation of basal slip. The difference in the yield stress between the different stress configurations decreases with the increase in the test temperature. The evolution of internal strains obtained during in-situ compressive experiments reveals that tensile twinning is not activated in the LPSO phase.