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The contribution of microstructure and friction in broaching Ferrite–Pearlite steels
Get PDFFerrite-Pearlite (FP) steels are used in many automotive components. However, their machinability in low cutting speed processes appears to be highly dependent on their metallurgical state. An experimental approach combining broaching and tribological tests under machining-like conditions was developed to determine the key FP features driving machining performance. Fundamental tests were performed on fifteen variants so as to cover a wide range of microstructural properties under dry and lubricated conditions using both uncoated and TiN coated High Speed Steel (HSS) tools. The correlation between the microstructure, tri-bology and outputs such as machining forces and chip thickness ratio is presented
A review of the effects of cyclic contact loading on fretting fatigue behaviour
Get PDFA damage phenomenon called fretting fatigue frequently takes place when two contact bodies are clamped together under a normal contact load along with a small-scale oscillatory motion due to cyclic loading. In contrast to the constant contact loading, less attention has been paid to variable contact loading which was technically reviewed in this study.
Emphasis was placed on the efforts made over the past decade and the future challenges including nonlinear effects of contact loads, friction, frequency, slip amplitude, wear, and contact mechanic are discussed extensively. It was revealed a need for new fatigue and contact mechanics models by identifying the aforementioned missing parameters
La innovación de la innovación responsable: deliberación y anticipación
Get PDFEs una de las ponencias presentadas en las III Jornadas sobre Responsabilidad Social Universitaria (RSU) bajo el título «Transparencia e integridad en la institución universitaria» celebradas en la Universitat Jaume I los días 29 y 30 de noviembre de 2018
Europaren geroa: geldialdi sekularreko eskenatokia
Get PDFMundura gero eta irekiagoa dagoen herria gara. Alde
horretatik, euskalherrigintzari buruz gogoeta egin eta erronka
lorgarriak zehaztu ahal izateko, badakigu mundu zabaleko
dinamikei ere arreta ipini behar diegula; interdependentzia
ekonomiko, komertzial eta soziala dela eta, gure herri-
egitasmoetan eskala globala kontuan hartzea ezinbestekoa
da. Egin kontu, gainera, mundu globalean sakonera handiko
transformazioak gertatzen ari direla. Hori dela eta, LANKI
Ikertegian “Euskalherrigintza mundu globalean” izeneko lan-
egitasmoa martxan dugu.
Egitasmo horren baitan, liburuaren helburu orokorra da
Europaren agertoki ekonomiko berria ulertzea. Izan ere,
Mendebaldeko herrialdeetan ekonomiaren hazkunde motela
eta geldialdi sekularra igarri daiteke, aktibazioko tresna
konbentzionalen gaitasuna agortua dago, eta merkatuaren
kontzentrazioak, desoreka makroekonomikoek eta proiekzio
demografikoek ere berresten dute agertoki berriak antz txikia
izango duela hamarkadetan normaltzat jotako ideia, praxia eta
espektatibekin. Europa galtzaile netoa den bitartean, errenta-
maila ezohiko erritmoetan hazten ari da populazio handieneko
munduko erregioan. Zalantzarik gabe, euskal gizartearen eta
ekonomiaren aukerak eta erronkak ere, neurri handi batean,
agertoki berri horretan argitu eta garatu beharko ditugu
Influence of lubrication condition on the surface integrity induced during drag finishing
Get PDFTribofinishing is one of the most popular polishing process in industry. The action of small abrasive media around parts enables to reduce significantly surface roughness and at the same time, to induce compressive residual stresses in the external surface layer. However, few scientific investigations have been made about this process. Whereas most of the previous works were focused on the effect of abrasive grains, the influence of lubrication and especially the filtering of the lubricant on the surface integrity have never been investigated before. This paper aims to study the influence of the presence of debris coming from the part and the media in the polishing process. For that purpose, rough surface parts (Ra~15 µm) have been tribofinished without and with lubrication filtering. Roughness parameters (Ra, RSm and Rsk), the offset between surface profiles and residual stresses have been compared. It is revealed that the lack of filtering leads to the presence of debris coming from the part and the media. This modifies tremendously the action of the media and prevent the surface from being polished properly. The reduction of roughness is saturated and the material is excessively deformed as a consequence of debris incrustations in the surface
Surface integrity of additive manufacturing parts: a comparison between optical topography measuring techniques
Get PDFAdditive Manufacturing (AM) presents significant industry-specific advantages allowing the creation of complex geometries and internal features that cannot be produced using conventional manufacturing processes. However, a current limitation of AM is the degraded dimensional control and surface integrity of specific surfaces. The parts are constructed through layer-by-layer approach, each layer presenting a characteristic ‘fingerprint’. The functional performance of the final part is influenced by the morphology of the outer surface as well as by the surface quality introduced at intermediate layers. Surface texture metrology therefore can play an enabling role in AM-related manufacture and research. The use of optical topography measurement instrumentation allows for a high level of detail in the acquisition of topographic information. Some of the most commonly used optical measuring instruments are Vertical Scanning Interferometry (CSI), Imaging Confocal Microscopy (CONF), and Focus Variation (FV), each one has benefits and drawbacks in terms of acquisition time and measurement resolution.
AM surfaces overall present complex topographical features, requiring the acquisition of large surface areas and large z-scans which considerably increases the acquisition time. Speed is a key factor in industrial practice, and time optimization is required for quality control and surface analysis before down-stream processes. This paper reports on the measurement and characterisation of the surface texture of metal powder bed fusion AM parts. All measurements were performed in the same SENSOFAR S-NEOX instrument using the commonly used optical technologies (CSI, CONF, and FV) and the latest step in confocal measurement technology called Continuous Confocal (C-CONF). The resolution and acquisition time of each technique is analysed in order to check the suitability of each method to characterize and describe the AM surface microstructures in a time-efficient way
Effects of manufacturing tolerances of permanent magnets in fractional slot permanent magnet synchronous machines
Get PDFThe fractional slot permanent magnet synchronous machines are well-known for their low torque ripple. However, in mass-production machines, not all the permanent magnets are identical due to the manufacturing tolerances and new torque harmonics could appear. In addition, the magnetic field is modified and unbalanced magnetic pull (UMP) could happen. Apart from that it is important to study the effect on vibrations since the magnetic field is no longer ideal. So, here, a study of the effect of unevenly magnetised permanent magnet distribution on torque ripples, unbalance magnetic pull, and vibrations is proposed. Apart from that, the tolerance grade sensitivity is studied. Finally, experimental tests show good agreement with finite element
analysis
Enpresa kooperatiboaren bereizgarria
No full textArtikulu honetan enpresa kooperatiboaren ereduan jarriko dugu arreta. Zertan da enpresa kooperatiboa? Zeintzuk dira haren ezaugarri eta bereizgarri nagusiak? Edo, bestela esanda, zerk bereizten du enpresa kooperatiboa beste enpresa motetatik? Zein zailtasun eta erronkari egiten die aurre kooperatiba ereduak? Formula zaharkitua da ala proiekzio handiko formula? Horra hor geure gogoetaren ardatz diren galderetako batzuk
Classification of human-centered design tools to innovate in healthcare
Get PDFLas herramientas de diseño centrado en las personas nos ayudan a entender mejor al usuario que estamos analizando y así, poder dar soluciones pensadas en el usuario para problemas reales. En el contexto sociosanitario, la experiencia de paciente está cobrando importancia en el sector como manera de poner al paciente en el centro del sistema. La experiencia del paciente se caracteriza por (a) ser una experiencia continua en el tiempo de carácter especialmente emocional donde (b) aparecen diversos agentes que operan en sistemas complejos y (c) constituirse como la suma de todas las interacciones concretas que vive el paciente a lo largo de su viaje. En este contexto, este artículo presenta una identificación y clasificación de herramientas de diseño centrado en las personas que permita comprender en profundidad información relativa a la experiencia de paciente y a sus tres características clave de cara a poder proponer nuevassoluciones tecnológicas en el sector socio-sanitario
La comunicación interna en las cooperativas: la percepción de las personas trabajadoras sobre la escucha y la información
Get PDFEl objetivo principal de este trabajo de investigación es conocer las percepciones y expectativas de las personas trabajadoras de una cooperativa del Grupo MONDRAGON sobre la comunicación interna. Se ha puesto especial interés en conocer: por un lado, las percepciones de las personas trabajadoras sobre la información transmitida por la cooperativa; por otro lado, sus percepciones sobre cómo realizan la escucha los directivos y mandos intermedios cuando les trasladan sus preocupaciones y expectativas. Asimismo, con la intención de conocer si existen diferencias, se han analizado las percepciones indicadas teniendo en cuenta las siguientes variables: ser miembro de algún órgano, tipo de mano de obra, situación laboral y sede. Para la realización de este estudio de caso se han combinado la metodología cualitativa y cuantitativa: se ha llevado a cabo una recogida de datos cuantitativos a través de un cuestionario propio y datos cualitativos a través de la realización de entrevistas semiestructuradas. Los resultados de la investigación sugieren que por lo general, aunque las personas trabajadoras de la cooperativa se sienten informadas, tienen la percepción de que se les escucha poco a la hora de trasladar sus preocupaciones y expectativas; al mismo tiempo, encontramos diferencias estadísticas significativas al analizar esos mismos datos por variables