DeustoTeka
DeustoTeka recoge la producción científica del personal docente e investigador de la Universidad de Deusto. Su propósito es reunir, archivar, preservar y aumentar la visibilidad en acceso abierto de los resultados de investigación.
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Effects of partial-contact tool tilt angle on friction stir welded AA1050 aluminum joint properties.
(MDPI, 2023-05-31) Abdullah, Mahmoud E.; Rohim, M. Nafea M.
; Mohammed, Moustafa M.
; Derazkola, Hamed Aghajani
This study aims to investigate the impact of partial-contact tool tilt angle (TTA) on the mechanical and microstructure properties of the AA1050 alloy friction stir weld (FSW). Three levels of partial-contact TTA were tested, 0°, 1.5°, and 3°, compared to previous studies on total-contact TTA. The weldments were evaluated using surface roughness, tensile tests, microhardness, microstructure, and fracture analysis. The results show that in partial-contact conditions, increasing TTA decreases the generated heat in the joint line and increases the possibility of FSW tool wear. This trend was the opposite of joints that were friction stir welded via total-contact TTA. The microstructure of the FSW sample was finer at higher partial-contact TTA, while the possibility of defect formation at the root of the stir zone in higher TTA was more than in lower TTA. The robust sample prepared at 0° TTA had 45% of AA1050 alloy strength. The maximum recorded heat in 0° TTA was 336 °C and the ultimate tensile strength of this sample was 33 MPa. The elongation of the 0° TTA welded sample was 75% base metal, and the average hardness of the stir zone was 25 Hv. The fracture surface analysis of the 0° TTA welded sample consisted of a small dimple, indicating the brittle fracture mode.
Detailed study of tube hot rolling process by means of FEM
(Association of American Publishers, 2023) García Gil, Eduardo
; Llamazares Duran, Gorka; Conde Fernández, Aintzane; Murillo Marrodán, Alberto; Barco Atutxa, Jon
In this paper seamless tubes hot manufacturing calibration rolling is studied by means of a finite element model, to improve product quality and process performance. Based on real data provided by an industrial partner, Tubos Reunidos Group, a finite element model of the process has been created and validated for the thermo-mechanical analysis of the process. The model has been used for the study of the wall thickness evolution and peripherical distribution during process, the eccentricity and the polygonization effects. Results show that the tube velocity in the process is one of the factors affecting wall thickness eccentricity, due to mass flow conservation. Regarding polygonization and eccentricity effect it has been found that both effects increase in the rolling stands with higher reduction ratio, and are corrected afterwards. These effects are mainly due to the ovality of the rolls. However, the effect the different sliding velocity along roll perimeter has implications in the local deformation of the material in contact with the roll, causing local compressive stress areas in addition to the predominant tension areas.
The role of IoT devices in sustainable car expenses in the context of the intelligent mobility: a comparative approach
(MDPI, 2022-01-20) Goikoetxea Gonzalez, Javier
; Casado Mansilla, Diego; López de Ipiña González de Artaza, Diego
Connected cars have often been defined as vehicles that can provide some services and information without human intervention. Several scholars have examined the factors that promote the purchase or adoption of such augmented vehicles. However, little emphasis has been placed on the determinants for reducing car expenditures when a driver owns a car with an Internet of Things (IoT) device or a smart assistant in the context of smart mobility. Therefore, this article analyzes whether emerging technology such as IoT plays a key factor for a driver concerning the expenses related to the car (e.g., insurance, maintenance, and repairs). To this extent, a methodology based on exploratory (i) and confirmatory analysis (ii) was carried out. The authors initially conducted an exploratory phase by means of a Delphi method in which a group of vehicle experts (n = 25) were recruited to give their opinions and reach an agreement defining the determinants that they believed affected vehicle expenditures the most. Secondly, and taking into consideration that the salient determinant from the Delphi method was the use of technology and the warnings and alerts it triggers, a questionnaire was delivered to 556 drivers to analyze the everyday spending on their cars. Specifically, the survey aimed to compare the responses of people who own connected cars or have any kind of built-in IoT infrastructure (n = 302) with those of people with non-connected cars (n = 254). The main conclusion obtained for this latter approach was that drivers with a connected car have remarkably lower car expenses than those driving a conventional car.
La imagen de Europa en el semanario vasco Euzko Deya
(PILAR (Presse, Imprimés, Lecture dans l’Aire Romane), 2023) Arrieta Alberdi, Leyre
Effects of a physical exercise intervention on pain in workplaces: a case study
(MDPI, 2022-01-25) Río de Frutos, Xabier; Sáez Gómez de Cadiñanos, Iker
; González Bravo, Javier; Besga Otxoa, Angel
; Santano Morentin, Eneko; Ruiz de Alegría, Natxo; Solabarrieta, Josu; Coca Núñez, Aitor
Interventions that promote physical activity and healthy habits in workplaces have proven to be effective in reducing risk factors associated with numerous pathologies. This study examines the effects of an individualized physical exercise program that lasts five minutes for 30 working days on the perceived pain of workers, as well as analyzing adherence to it within workplaces. Data were collected through a visual analog scale of 1–10 of the perception of pain by anatomical areas, and, thus, we could observe variations in the perceived pain of workers through a program of five individualized exercises for one minute each based on the analysis of the worker and the job position. Significant differences were observed in three of the four centers analyzed (1: p = 0.006; 2: p = 0.009; 3: p = 0.000; 4: p = 0.791). A five-minute exercise program in the work environment appears to be an effective tool in terms of time and an improvement in workers’ perception of pain.