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Functionally Graded Materials (FGMs) can outperform their homogeneous counterparts. Advances in digitalization technologies, mainly additive manufacturing, have enabled the synthesis of materials with tailored properties and functionalities. Joining dissimilar metals to attain compositional grading is a relatively unexplored research area and holds great promise for engineering applications. Metallurgical challenges may arise; thus, a theoretical critical analysis is presented in this paper. A multidisciplinary methodology is proposed here to unify optimal design, multi-feed Wire-Arc Additive Manufacturing (WAAM), and image-based characterization methods to create structure-specific oriented FGM parts. Topology optimization is used to design FGMs. A beam under pure bending is used to explore the layer-wise FGM concept, which is also analytically validated. The challenges, limitations, and role of WAAM in creating FGM parts are discussed, along with the importance of numerical validation using full-field deformation data. As a result, a conceptual FGM engineering workflow is proposed at this stage, enabling digital data conversion regarding geometry and compositional grading. This is a step forward in processing in silico data, with a view to experimentally producing parts in future. An optimized FGM beam, revealing an optimal layout and a property gradient from iron to copper along the build direction (bottom–up) that significantly reduces the normal pure bending stresses (by 26%), is used as a case study to validate the proposed digital workflow.

This work aimed to evaluate whether the established scientific knowledge for machining homogeneous and isotropic materials remains valid for machining additively manufactured parts. The machinability of thin-walled structures produced through two different variants of wire and arc additive manufacturing (WAAM) was studied, namely conventional MIG deposition and the innovative hot forging variant (HF-WAAM). Cutting operations were carried out varying the undeformed chip thickness (UCT) and the cutting speed, using a tool rake angle of 25°. A systematic comparison was made between the existing theoretical principles and the obtained practical results of the orthogonal cutting process, where the relation between the material properties (hardness, grain size, yield strength) and important machining outcomes (cutting forces, specific cutting energy, friction, shear stress, chip formation and surface roughness) is addressed. Additionally, high-speed camera records were used to evaluate the generated shear angle and chip formation process during the experimental tests. The machinability indicators shown that, through the appropriate selection of the cutting parameters, machining forces and energy consumption can be reduced up to 12%, when machining the mechanical improved additive manufactured material. Therefore, it has been confirmed the feasibility of machining such materials following the traditional machining principles, without compromising the surface quality requirements.

This work focuses on the influence of post-deposited heat treatments (PDHT) on the properties and machinability of high-strength low-alloy steel (HSLA) samples, produced by WAAM and the forged (HF-WAAM) variant. An adequate combination of deposition parameters was established, and the manufactured specimens were 3D scanned to evaluate the surface quality. Effects of normalizing and quenching & tempering (Q&T) heat treatments on the microstructure were assessed through optical microscopy and SEM, and the influence on the material hardness and electrical conductivity was evaluated. Orthogonal cutting experiments were conducted to determine the specific cutting energy (SCE), a crucial indicator of the cutting performance and machinability characteristics of the work material. The results revealed a significant SCE decrease when cutting the WAAM and HF-WAAM samples subjected to PDHT, with 8% and 38% decreases for pot-normalization, and 22% and 27% reductions after Q&T, compared to the as-built condition. No significant differences were registered when machining between the WAAM and HF-WAAM variants. HF-WAAM samples after PDHT show superior hardness, without compromising the cutting energy consumption. However, the geometrical features, namely the significant increase of the surface waviness of the hot-forged parts (≈70%) must be considered, being a critical factor to avoid possible undesirable machining effects.

We present a viable prototype of a simple mechanical ventilator intended as a last resort to ventilate COVID-19 patients. The prototype implements the pressure-controlled continuous mandatory ventilation mode (PC-CMV) with settable breathing rates, inspiration/expiration time ratios and FiO2 modulation. Although safe, the design aims to minimize the use of technical components and those used are common in industry, so its construction may be possible in times of logistical shortage or disruption or in areas with reduced access to technical materials and at a moderate cost, affordable to lower income countries. Most of the device can be manufactured by modest technical means and construction plans are provided.

  Continuando con nuestras sagradas tradiciones políticas, el Presidente Enrique Peña Nieto, como buen técnico futbolero, sacó a importantes figuras del escenario nacional, como el caso de Emilio Chuayffet de la Secretaría de Educación Pública, antes de rendir su Tercer Informe de Gobierno. El Gobernador electo, Jaime \"El Bronco\" Rodríguez, en reunión con el Rector electo de la UANL, Rogelio \"El Ranchero\" Garza, le pidió a este último apoyo para capacitar y profesionalizar a la burocracia estatal a través de la Universidad, según reportó EL NORTE. Investigar a la Tesorería, a la Secretaría de Obras Públicas -es un decir- y a los asesores, tan callados ellos, por mencionar algunos, se hace indispensable, ya que las coladeras por donde se esfumó el dinero también están ahí.