Analysis of orthogonal cutting of biocomposites

The use of 100% biodegradable composites in the industry is increasing significantly over the years, mainly due to their excellent properties as well as to the growing ecologic concern. However, after their manufacture, the composite pieces do not always have the final shape, requiring subsequent processing operations, usually drilling and trimming. The performance of cutting processes on fully biodegradable composites are often limited by induced damage as fraying and delamination. This type of phenomena is related, among others, with the cutting parameters and geometries of the tool. Orthogonal cutting is a simplified process that could help in the understanding of damage mechanisms, it is a well-known technique in traditional composites but its use in biocomposites is an almost unexplored field. This work focuses on flax/PLA 100% biodegradable woven composites. The specimens have been manufactured with different angles of orientation, ranging from 0° to 60°, being subjected to orthogonal cutting in a special machine developed for that purpose that allows to develop cutting tests with linear displacement at high speeds. Damage extension, failure modes, and cutting forces are analyzed allowing the extraction of important experimental information.Authors gratefully acknowledges the financial support to the Ministry of Economy and Competitiveness of Spain and FEDER program through the project DPI2017-89197-C2-1-R

Sustainable high-speed finishing turning of haynes 282 using carbide tools in dry conditions

Nickel-based superalloys exhibit an exceptional combination of corrosion resistance, enhanced mechanical properties at high temperatures, and thermal stability. The mechanical behavior of nickel-based superalloys depends on the grain size and the precipitation state after aging. Haynes 282 was developed in order to improve the creep behavior, formability, and strain-age cracking of the other commonly used nickel-based superalloys. Nevertheless, taking into account the interest of the industry in the machinability of Haynes 282 because of its great mechanical properties, which is not found in other superalloys like Inconel 718 or Waspaloy, more research on this alloy is necessary. Cutting tools suffer extreme thermomechanical loading because of the high pressure and temperature localized in the cutting zone. The consequence is material adhesion during machining and strong abrasion due to the hard carbides included in the material. The main recommendations for finishing turning in Haynes 282 include the use of carbide tools, low cutting speeds, low depth of pass, and the use of cutting fluids. However, because of the growing interest in sustainable processes and cost reduction, dry machining is considered to be one of the best techniques for material removal. During the machining of Haynes 282, at both the finishing and roughing turning, cemented carbide inserts are most commonly used and are recommended all over the industry. This paper deals with the machining of Haynes 282 by means of coated carbide tools cutting fluids (dry condition). Different cutting speeds and feeds were tested to quantify the cutting forces, quality of surface, wear progression, and end of tool life. Tool life values similar to those obtained with a lubricant under similar conditions in other studies have been obtained for the most favorable conditions in dry environments.This research was funded by the Ministry of Economy, Industry, and Competitiveness, and the FEDER program, grant number DPI2017-89197-C2-1-R

Finishing Turning of Ni Superalloy Haynes 282

Nickel-based superalloys are widely used in the aeronautical industry, especially in components requiring excellent corrosion resistance, enhanced thermal fatigue properties, and thermal stability. Haynes 282 is a nickel-based superalloy that was developed to improve the low weldability, formability, and creep strength of other gamma'-strengthened Ni superalloys. Despite the industrial interest in Haynes 282, there is a lack of research that is focused on this alloy. Moreover, it is difficult to find studies dealing with the machinability of Haynes 282. Although Haynes 282 is considered an alloy with improved formability when compared with other nickel alloys, its machining performance should be analyzed. High pressure and temperature localized in the cutting zone, the abrasion generated by the hard carbides included in the material, and the tendency toward adhesion during machining are phenomena that generate extreme thermomechanical loading on the tool during the cutting process. Excessive wear results in reduced tool life, leading to frequent tool change, low productivity, and a high consumption of energy; consequentially, there are increased costs. With regard to tool materials, cemented carbide tools are widely used in different applications, and carbide is a recommended cutting material for turning Haynes 282, for both finishing and roughing operations. This work focuses on the finishing turning of Haynes 282 using coated carbide tools with conventional coolant. Machining forces, surface roughness, tool wear, and tool life were quantified for different cutting speeds and feeds.This research was funded by the Ministry of Economy, Industry and Competitiveness and the FEDER program, grant number DPI2014-56137-C2-2-R

High-pressure cooling in finishing turning of haynes 282 using carbide tools: Haynes 282 and inconel 718 comparison

Despite the interest of industry in nickel-based superalloys and its main features (high temperatures resistance, hardness, low thermal conductivity, among others), even today they are still materials that are difficult to cut. Cutting tools withstand both high pressures and temperatures highly localized at the cutting area because of the elevated work hardening of the alloy and the problems for the cutting fluid to access the region, with the consequent strong tool wear. The use of cutting fluids at high pressures improves coolant access and heat removal. This paper analyzed the machining of Haynes 282 alloy by means of coated carbide tools under high-pressure cutting fluids at finishing conditions. Tests were developed at different cutting speeds and feeds quantifying the machining forces, surface roughness, tool wear, and tool life. Values of 45.9 min and Ra between 2 µm and 1 µm were obtained in this study for tool life and roughness, respectively, for the combination of cutting speed 50 m/min and feed 0.1 mm/rev. Likewise, a comparative analysis is included with the results obtained in previous works developed by the authors relating to the finishing turning of Haynes 282 and Inconel 718 under conventional pressure cooling. The comparative analysis with Inconel 718 is included in the study due to its importance within the nickel base superalloys being widely used in industry and widely analyzed in scientific literature.The authors gratefully acknowledge the funding support received from the Spanish Ministry of Science and Innovation and the FEDER program for funding the projects PID2020-112628RA-I00, PID2020-118480RB-C22 and PDC2021-121368-C21

Experimental analysis of the influence of drill point angle and wear on the drilling of woven CFRPs

This paper focuses on the effect of the drill geometry on the drilling of woven Carbon Fiber Reinforced Polymer composite (CFRPs). Although different geometrical effects can be considered in drilling CFRPs, the present work focuses on the influence of point angle and wear because they are the important factors influencing hole quality and machining forces. Surface quality was evaluated in terms of delamination and superficial defects. Three different point angles were tested representative of the geometries commonly used in the industry. Two wear modes were considered, being representative of the wear patterns commonly observed when drilling CFRPs: flank wear and honed cutting edge. It was found that the crossed influence of the point angle and wear were significant to the thrust force. Delamination at the hole entry and exit showed opposite trends with the change of geometry. Also, cutting parameters were checked showing the feed's dominant influence on surface damage.This work was supported by the Ministry of Economy and Competitiveness of Spain under the project DPI2011-25999Publicad

Experimental and numerical analysis of the influence of drill point angle when drilling biocomposites

Biocomposites are promising materials for traditional composites replacement in specific applications due to their interesting properties and sustainability. Although the composite components are manufactured near net shape, some machining operations, commonly drilling, are commonly required prior to mechanical joining of the components. Tool geometry, mainly the point angle of the drill, strongly affects the performance of the drilling process of composites in terms of machining induced damage. The aim of this work is analyzing the influence of the point angle of the drill on the damage generated during drilling of 100% biodegradable composite, using both numerical and experimental approaches. The novelty of the work relies on the lack of studies of drilling 100% biodegradable composites. The influence of the point angle on the thrust forces and hence in the machining induced damage was demonstrated.The authors acknowledge the financial support to the Ministry of Economy and Competitiveness of Spain and FEDER program through the projects DPI2017-89197-C2-1-R and DPI2017-89197-C2-2-R

Modelo adaptativo para la gestión ambiental y energética de inmuebles de uso residencial y terciario

Programa Oficial de Doutoramento en Tecnoloxías da Información e as Comunicacións. 508V01[Resumen] Desde la entrada en vigor de la Directiva Europea 91 del 2002, relativa a la eficiencia energética de los edificios, la cual obligaba a los Estados miembros de la Unión Europea a establecer una metodología para determinar la eficiencia energética de los edificios mediante su trasposición a la legislación local; la evaluación del comportamiento energético y ambiental de los edificios, especialmente los que integran en parque de edificios existentes, ha adquirido una gran relevancia. Para cumplir estos objetivos de aumento de la eficiencia energética y de reducción de emisiones de dióxido de carbono en el sector de la edificación, es necesario disponer de la mayor cantidad de información posible sobre el comportamiento energético y ambiental de los edificios existentes. En España, el proceso de implantación de esta metodología para evaluar la eficiencia energética de los edificios existentes se ha producido con un cierto retraso, dándose dos circunstancias que dificultan su aplicación; por un lado no hay acceso público a los resultados de la labor certificadora realizada hasta la fecha, no disponiendo de información referente al comportamiento energético de estos edificios, que son los que presentan el comportamiento energético y ambiental más desfavorable. Por otro lado, no se dispone de modelos específicos que permitan predecir su comportamiento energético y ambiental en las distintas zonas climáticas de España. Por tal motivo, ante este grave y complejo problema, el empleo de nuevas técnicas de estudio de simulación energética para establecer el comportamiento energético y ambiental de los distintos tipos de edificios, resultan indispensables; tales como la utilización de técnicas y procedimientos de Inteligencia Artificial (en adelante IA) como son las Redes de Neuronas Artificiales y la Programación Genética. La presente investigación tiene por objeto demostrar la aplicabilidad de las Redes de Neuronas Artificiales y la Programación Genética al estudio del comportamiento energético y ambiental del edificio, así como de su eficiencia energética, proporcionando una potente y eficaz herramienta de apoyo a la labor certificadora. En este caso, se realiza el estudio sobre una muestra representativa del parque de edificios existentes, compuesta por inmuebles situados en el Noroeste de España y con diferentes características constructivas

Siete películas para trabajar valores, desarrollo moral y prosocialidad en el medio penitenciario

El Taller de cine, valores y desarrollo de la prosocialidad busca el objetivo de favorecer en los internos el desarrollo de un conjunto de habilidades éticas necesarias para el ejercicio de la ciudadanía, así como estimular su desarrollo moral. Este artículo es el resultado de analizar y evaluar esta experiencia que se viene implementando en la prisión de El Dueso (España) desde el año 2010. El desarrollo del taller se concentra en obtener un ambiente de intercambio cooperativo de grupo, y en el desarrollo individual a partir del conocimiento de las diferentes habilidades éticas y de los esquemas del desarrollo moral existentes. Se trata de una propuesta enriquecida por la reflexión crítica sobre las experiencias realizadas, la orientación práctica y la atención a procesos de aprendizaje. Fundamentado en la Teoría del Desarrollo Moral de Lawrence Kohlberg, el Taller se desarrolla en 16 sesiones de 2 horas. El artículo ofrece una herramienta práctica para potenciar el desarrollo moral en adultos penados

From transpressional to transtensional tectonics in Northern Central America

The Central American Volcanic Arc (CAVA) is located at the western margin of the Caribbean plate, over the Chortís Block, spanning from Guatemala to Costa Rica. The CAVA is associated to the subduction of the Cocos plate under the Caribbean plate at the Middle America Trench. Our study is focused in the Salvadorian CAVA segment, which is tectonically characterized by the presence of the El Salvador Fault Zone (ESFZ), part of the western boundary of a major block forming the Caribbean plate (the Chortis Block). The structural evolution of the western boundary of the Chortis Block, particularly in the CAVA crossing El Salvador remains unknown. We have done a kinematic analysis from seismic and fault slip data and combined our results with a review of regional previous studies. This approach allowed us to constrain the tectonic evolution and the forces that control the deformation in northern Central America. Along the active volcanic arc we identified active transtensional deformation. On the other hand, we have identified two deformation phases in the back arc region: A first one of transpressional wrenching close to simple shearing (Miocene); and a second one characterized by almost E-W extension. Our results reveal a change from transpressional to transtensional shearing coeval with a migration of the volcanism towards the trench in Late Miocene times. This strain change could be related with a coupled to decoupled transition on the Cocos – Caribbean subduction interface, which could be related to a slab roll-back of the Cocos Plate beneath the Chortis Block. The combination of different degrees of coupling on the subduction interface, together with a constant relative eastward drift of the Caribbean Plate, control the deformation style along the western boundary of the Chortis Block

Estimation of slip rates and seismic hazard parameters using conventional techniques of structural geology in a slow-moving fault: Alhama de Murcia – Alcantarilla segment of the Alhama de Murcia Fault (Murcia, SE Spain)

The convergence between Nubian and Eurasian plates in the Western Mediterranean is being accommodated by the Eastern Betic Shear Zone, located in Southeastern Iberia. This is a low strain region whose faults show low slip rates and long recurrence periods of their maximum earthquakes, so they do not provide clear evidence of their seismogenic activity. The Alhama de Murcia - Alcantarilla segment, defined as the NE end of the Alhama de Murcia Fault, is one of the structures of the Eastern Betic Shear Zone and there are few in-depth studies about its seismic potential. In order to assess the seismogenic potential and slip-rate of this segment we have carried out a structural analysis. We have built a 3D geological model of the area where the fault is currently bounding the Neogene Fortuna basin. The structural model is based on seismic reflection profiles which have been later input in MOVE, structural modelling and analysis software. The analysis of the model has revealed several structural features related to positive inversion tectonics in Fortuna basin, specifically a typical "harpoon" structure whose deformation is estimated to have begun since Upper Miocene (Messinian). Geometric models and area balance methods (e.g. depth-to-detachment method) applied to the previously mentioned structure have allowed to estimate the heave of the fault, representing the amount of shortening observed in the fault section during its recent activity. The horizontal shortening rate estimated is between 0.09 and 0.26 mm/yr during the last 5.3 - 2.6 Ma. Projecting the obtained shortening onto the fault plane and considering the present regional tectonic shortening it has been possible to obtain a net slip rate between 0.13 and 0.37 mm/yr. Such parameters suggest that the Alhama de Murcia - Alcantarilla segment has less activity than other segments of the fault. The result obtained is consistent with the fact that the Carrascoy Fault, oriented parallel and located to the south of the Alhama de Murcia - Alcantarilla segment, seems to absorb part of the regional tectonic shortening. That is why the relief uplifted by the Alhama de Murcia - Alcantarilla segment during the Quaternary is significantly less prominent than the mountains fronts generated by the Carrascoy Fault. Even so, Alhama de Murcia - Alcantarilla segment should be considered as an active structure with implications for seismic hazard. The maximum size of earthquake is calculated to be Mw 6.3 - 6.6 according to magnitude-area and magnitude-length scaling relationships, with a mean recurrence interval lower than 10.000 years for the slip rate obtained. In the same way, Mw 5.0 earthquakes, such as those recorded in the historical seismic catalog, are estimated to have a recurrence interval lower than 50 years. These earthquakes could be very destructive in densely populated areas, as is the case of SE Spain, so they should be considered in seismic-hazard analysis