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Metal cutting experiments and modelling for improved determination of chip/tool contact temperature by infrared thermography
Get PDFTemperature measurement in metal cutting at the chip and work contact is of central importance due to temperature dependence of tool wear and surface integrity. Infrared thermography is commonly employed to determine the tool side face temperature in orthogonal cutting but temperature needs to be estimated at the tool chip contact area. This experimental and modelling study of AISI 4140 steel and Ti6Al4V titanium alloy cut respectively by P and K grade cemented carbide tools at practical cutting speeds and feeds shows the relationship between side face and in-contact temperature, for the more certain use of the infra-red thermography method
A Note on Interpreting Tool Temperature Measurements from Thermography
Get PDFThermography (thermal imaging) is a well-established experimental method for studying cutting tool temperature distributions. In one form, cutting edge temperatures within the chip / tool contact area are deduced from thermal images of tool faces normal to the cutting edge but offset from the contact region. In general practice, the offset is made as small as possible (<< 1 mm) and it is assumed that the observed temperature is the same as that within the contact. In this short communication an approximate analytical model is developed for the influence of the offset on the observed temperature. The predictions from the model are compared with previously unpublished existing results on the machining of Ti alloys (Ti6Al4V and Ti5Al4V) and on steel (AISI 4140). It is shown that ignoring the offset may introduce underestimates of cutting edge temperature of ≈ 30% or more. This is large compared to the usually considered uncertainties of ± 5% from camera and tool emissivity calibration. There is a need for a dedicated study of this effect
Hybrid ac/dc microgrids. Part II : Review and classification of control strategies
Get PDFMicrogrids are envisioned as one of the most suitable alternatives for the integration of distributed generation units in the utility grid, as they efficiently combine generation, energy storage and loads in the same distribution network. In this context, hybrid ac/dc microgrids are arising as an interesting approach as they combine the advantages of ac and dc networks and do not require excessive modifications in the distribution network. However, they require more complex control strategies as they need to control the ac and dc networks and the interface power converter simultaneously. This paper identifies and analyses the control strategies that can be implemented in hybrid microgrids for an adequate power management in grid-tied and islanded modes of operation. The review is focused on hierarchical controls as they are the most extended approach in the literature. A classification has been elaborated, which covers the three main levels of hierarchical control strategies (primary, secondary and tertiary). Each of the levels has been independently studied in order to provide a comprehensive analysis of the alternatives found in the literature. The future trends related to this topic show that a higher research effort is required regarding the control of the interface device and the ancillary services that the management strategy must provide—e.g. blackstart, transition between islanded and grid-connected modes of operation, interconnection of microgrids, etc
Gazteen ikus-entzunezkoen kontsumoa, interakzioa eta partekatzea: Mondragon Unibertsitateko ikasleen kasu-azterketa
Get PDFIkerketa honen helburua da ezagutzea zelan – eta zein neurritan- baliatzen dituzten gazteek
digitalizazioak ekarritako ikus-entzunezko kontsumo-modu berriak, arreta berezia jarrita ikusentzunezko edukien partekatzean. Doktorego-tesi hau Mondragon Unibertsitateko kasu-azterketa da,
eta galdetegia, egunerokoa eta sakoneko elkarrizketak baliatu dira. Galdetegiko emaitza kuantitatiboak
dira artikulu honetan azalduko direnak. Emaitzek erakusten digutenez, ohiko telebistak jarraitzen du
izaten telebistako edukiak kontsumitzeko biderik ohikoena. Bestalde, aipagarria da partekatzeak
hartzen duen garrantzia, gazteen ia %68k partekatzen baititu ikus-entzunezko edukiak interneten.The aim of this PhD research is to know how digitization has brought about new ways of television
and video consumption among youth, focusing on online video sharing. The study is carried out
among Mondragon University students to collect quantitative and qualitative data of their viewing and
sharing habits. It is as case study that comprises a survey, a media diary and in-depth interviews. This
article is focused on the quantitative results of the study. The findings show that the TV set is still the
preferred format for television viewing. In contrast, the importance of the online sharing is
highlighted, since almost %68 of the youth share video content on the web
Langileen pertzepzioak eta nahiak barne komunikazioari buruz kooperatibetan. Kasu azterketa
Get PDFIkerlan honen helburu nagusia da ezagutzea zelako pertzepzioak eta nahiak dituzten langileek barne
komunikazioari buruz kooperatibetan. Horretarako, besteak beste, aztertu da zer pertzepzio duten
langileek kooperatibak ematen dien informazioei buruz. Era berean, eta ezberdintasunik dagoen jakite
aldera, pertzepzio horiek guztiak ikertu dira kontuan izanik ondorengo aldagaiak: organoetako
partaide, esku lan mota, lan egoera eta egoitza.The main objective of this research is to explore the perceptions and expectations of the members of
the worker cooperative concerning Internal Communication. To that end, among others, have been
researched members´ perceptions of the information transmitted by cooperative. Additionally, in order
to examine the possibility of group differences, perceptions have been analyzed taking into account
following variables: membership on different governing bodies, type of workforce, labour status and
location
Numerical Simulation of Surface Modification During Machining of Nickel-based Superalloy
Get PDFThe main objective of this study is to implement a reliable FE model of the orthogonal machining of a Nickel based superalloy for the prediction of microstructural changes occurring during the process. A FE numerical model was properly calibrated using an iterative procedure based on the comparison between simulated and experimental results. A user subroutine was implemented in the FE code to simulate the dynamic recrystallization and consequently the grain refinement and hardness variation when orthogonal cutting of Nickel based superalloy is performed. Thus, Zener-Hollomon and Hall-Petch equations were implemented to predict the grain size and micro hardness, respectively. In addition, the depth of the affected layer was predicted using the critical strain equation. The obtained results proved the adequacy of the proposed model showing a good agreement between the simulated and the experimental results
Elastic behaviour characterisation of TRIP 700 steel by means of loading-unloading tests
Get PDFThe elastic behaviour of TRIP 700 steel under plastic deformation is analysed. The analysis is carried out by means of classical tensile test and loading–unloading cyclic tests. These tests have been performed using high deformation strain gages, which enable an accurate and continuous measurement of strain.
An elastic modulus reduction of 20% is observed for 12% plastic deformation. Furthermore, non-linear unloading and loading paths have been found in this work. This is an important difference with respect to other authors and opens new possibilities for the development of new material models to improve the prediction of the post-forming springback of industrial parts, which is an important issue for the automotive industry
EraLan ikerketa-proiektua 3 : Euskararen erabilera lan munduan
No full textEraLan ikerketa-proiektua da, izaera ezberdineko erakundeen arteko lankidetzaren bitartez gauzatzen
dena. Lan-arloan ematen den hizkuntzen erabilera da proiektuaren aztergai nagusia, eta gai horren inguruan Soziolinguistika Klusterraren baitan ikerketa aplikatua eta haren gaineko hausnarketa elkarrekin
egiten duten erakunde ezberdinen emaitza da EraLan.
Gehiago zehaztuz, EraLan proiektuaren helburua da hizkuntza normalizaziorako planak onartuta dituzten lan munduko erakundeetan –publiko zein pribatuetan– euskararen eta beste hizkuntzen erabileran
eragiten duten aldagaiak identifikatzea, eta horietan positiboki eragiteko metodologiak eta dinamikak
diseinatzeko eta inplementatzeko ezagutzan aurreratzea. Ezagutza praktikoan eta ezagutza teorikoan.
Eta ezagutza hori lankidetzan ari diren erakundeetako kideen artean partekatzea eta zirkulazioan jartzea.
Hizkuntza normalizazioaren kontzeptualizazioa, batetik, eraldaketa-prozesu gisa egiten dugu; bestetik,
hizkuntza normalizazioa organizazio batean gauzatzen denez, sistema konplexu gisa kontzeptualizatzen
dugu. Beraz, eraldaketa eta konplexutasun testuinguru horretan kokatzen dugu ikerketa-proiektua
Finding correlations between tool life and fundamental dry cutting tests in finishing turning of steel
Get PDFTool life is usually measured by end tool life tests, however, such experiments are costly and time consuming. Establishing correlation between these tests and shorter and cheaper tests is consequently of great interest. Experimental results from dry orthogonal cutting tests are reported and a good correlation between temperature reached at the tool and tool life test is shown
