Wear model for describing the time dependence of the material degradation mechanisms of the AISI 316L in a NaCl solution

[EN] The tribo-electrochemical behavior of AISI 316L has been investigated under tribocorrosion conditions in a 3% NaCl solution and the material damage evolution with time has been analyzed. A numerical contact model based on a Boundary Element Method (BEM) has been developed in order to determine the contact pressure distribution and to quantify the worn material as a function of time. The time dependence of the tribological behavior of the material has been described. At the initial state, the high contact pressures generate a material flow causing an increase in the worn area. After around 300 cycles, the Archard wear model linearly describes the wear evolution with time. The proposed model describes the evolution with time of the wear profiles of the tested material and takes into account the plastic behavior of the material during the first cycles.This work has been funded by the Spanish Ministry of Economy and Competitiveness under the Ref. MAT2014-53764-C3-3-R and the Generalitat Valenciana under the PROMETEO program Ref. 2016/040.Dalmau-Borrás, A.; Roda Buch, A.; Rovira, A.; Navarro-Laboulais, J.; Igual Muñoz, AN. (2018). Wear model for describing the time dependence of the material degradation mechanisms of the AISI 316L in a NaCl solution. Wear. 394-395:166-175. https://doi.org/10.1016/j.wear.2017.10.015S166175394-39

Chemo-mechanical effects on the tribocorrosion behavior of titanium/ceramic dental implant pairs in artificial saliva

[EN] In this paper, the degradation mechanisms of the ceramic and the metal in Titanium/Zirconia pairs for biomedical applications were analyzed. To do that, an experimental set-up with well-controlled mechanical and chemical conditions was used based on a unidirectional ball-on-disk tribometer coupled to a potentiostat. Tribocorrosion tests were carried out in artificial saliva at different applied potentials, this is, different chemical conditions of the surface. Wear damage of the titanium/zirconia pair was influenced by the properties and the behavior of wear debris in the contact. Under passive conditions metallic and oxidized titanium particles (formed by the cyclic removal of the passive film and subsequent repassivation) were smeared and mechanically mixed within the contact forming compacted wear debris through which the loading was carried out. Properties and amount of oxidized titanium lead to low wear at low passive conditions (OCP) and higher wear at high passive conditions. Zirconia did not suffer any damage under all the studied conditions and oxidized titanium was transferred to the ball at anodic applied potentials.Authors would like to acknowledge the Generalitat Valenciana for the financial support under the PROMETEO/2016/040 and GV/2017/042 projects. A. Dalmau acknowledges the Generalitat Valenciana for her contract (APOSTD/2017/051).Dalmau-Borrás, A.; Roda Buch, A.; Rovira, A.; Navarro-Laboulais, J.; Igual Muñoz, AN. (2019). Chemo-mechanical effects on the tribocorrosion behavior of titanium/ceramic dental implant pairs in artificial saliva. Wear. 426-427:162-170. https://doi.org/10.1016/j.wear.2018.12.052162170426-42

Máquinas y mecanismos

Este libro aborda fundamentalmente el estudio de la Cinemática y Dinámica de mecanismos planos, con contenidos teóricos apoyados en problemas resueltos.Comienza con la introducción de los conceptos básicos que se manejan en la Teoría de Máquinas y Mecanismos: grado de libertad, barra, par cinemático, etc. A continuación se aborda de un modo progresivo el problema cinemático (cinemática de la partícula, sólido rígido y mecanismos), siempre empleando procedimientos vectoriales y resolución analítica. Más adelante se introduce el problema general dinámico, distinguiendo claramente entre el problema dinámico inverso o análisis de fuerzas y el problema dinámico directo o análisis del movimiento. El primero se aplica fundamentalmente al control de maquinaria, mientras que el último a la simulación del movimiento. Dentro del equilibrado de mecanismos se consideran los rotores y los mecanismos de biela-manivela-deslizadera.Roda Buch, A.; Mata Amela, V.; Albelda Vitoria, J. (2016). Máquinas y mecanismos. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/70967EDITORIA

Diagnostic and monitoring of historical vehicle engines by acoustic emission testing

The ACUME project aims at developing a non-invasive diagnostic tool for the engines of historical vehicles conserved in museums and collections. This tool will help conservator-restorers to make a decision and implement the reactivation of engines stopped for long time. The Acoustic Emission (AE) technique allows to detect malfunctions before they are audible by human ear. It is used in the field of automotive industry for the diagnostic of new engines and in different fields of cultural heritage for the evaluation of historical objects and artworks

Running historical engines safely

The aim of the research project, entitled Acoustic Emission Moni-toring of Historical Vehicles (ACUME_HV), is to develop a diag-nostic tool to help people in charge of historical vehicles (conser-vators, technicians, mechanics...) during the condition report and the maintenance of the engines. Ancient vehicles can be conserved statically or working. In this second option, historical vehicles can be started or used more or less frequently, depending on the purpose of the museum or the private collection. However, heritage institu-tions have always the responsibility to maintain the vehicle in a safe condition, for the artefact itself as well as for the driver, passengers and for the public

Fault detection and diagnosis of historical vehicle engines using acoustic emission techniques

The reactivation of artefact mechanisms is always a challenge for conservators. Non-invasive diagnostic techniques, applicable directly on the artifacts, allows for performing early-stage diagnostics and avoiding damage. The Acoustic Emission Monitoring of Historical Vehicles (ACUME_HV) project represents the first use of acoustic emission (AE) as a non-invasive technique for the diagnostics of historical vehicles. The aim of this project is to develop an objective, human-independent method. This will help museum personnel to make decisions regarding the reactivation of historical vehicle engines using measurements and data analysis rather than merely personal experience. Herein, we present the results of the first phase of the ACUME_HV project, which was focused on the development of a protocol for the use of AE during cold tests

Data analysis techniques for the visualization and classification of historical vehicle engines’ health status using data-driven solutions

In the field of cultural heritage, the use of non-destructive techniques to determine the state of conservation of an artifact is of the utmost importance, to avoid damage to the object itself. In this paper, we present a data pipeline and several machine learning techniques for the visualization, analysis and characterization of engines in historical vehicles. The paper investigates the use of vibro-acoustic signals acquired from the engines in different states of conservation and working conditions to train machine learning solutions. Data are classified according to their state of health and the presence of anomalies. The t-SNE algorithm is used for dimensionality reduction for data visualization. The machine learning algorithms tested showed encouraging performance in associating acoustic emission data with the engine signature, the type of anomaly and the working conditions. Nevertheless, a larger dataset would allow us to improve and strengthen the results.Em património cultural a utilização de técnicas não destrutivas para determinar o estado de conservação de um artefacto é de extrema importância para evitar danos no próprio objeto. Neste artigo, apresentamos um canal de dados e técnicas de aprendizagem automática para a visualização, análise e caraterização de motores de veículos históricos. O artigo investiga a utilização de sinais vibro-acústicos adquiridos nos motores em diferentes estados de conservação e condições de funcionamento para treinar soluções de aprendizagem automática. Os dados são classificados de acordo com o seu estado de conservação e a presença de anomalias. O algoritmo t-SNE utilizou-se para a redução da dimensionalidade para a visualização dos dados. Os algoritmos de aprendizagem automática testados revelaram um desempenho promissor na associação dos dados de emissões acústicas com a assinatura do motor, o tipo de anomalia e as suas condições de funcionamento. Porém, um maior conjunto de dados permitir-nos-ia melhorar e reforçar os resultados

Diagnostic of historical vehicle’s engines by acoustic emission techniques

The reactivation of artefacts’ mechanisms is always a challenge for conservators and proper noninvasive diagnostic techniques, applicable directly on the artifacts, allows to perform a precocious diagnostic and to avoid damages. The ACUME_HV project (Acoustic Emission Monitoring of Historical Vehicles) represents the first use of acoustic emission (AE) as non-invasive technique for the diagnostic of historical vehicles. The aim of this project is to propose an objective, human-independent method that will help the personnel of the museums to take decisions concerning the reactivation of the historical vehicles’ engines using measurements and data and not only personal experience. In this paper the results of the first phase of the ACUME_HV project are presented. This first phase focused on the development of a protocol for the use of AE during cold tests

Acoustic Emission Monitoring as a Non-invasive Tool to Assist the Conservator in the Reactivation and Maintenance of Historical Vehicle Engines

Historical cars are an important part of the cultural heritage of the last 150 years. Their preservation in technical museums raises the question of how to preserve their primary functionality, namely their mobility. This implies being able to reactivate and to maintain their thermal engines, which are the source of their motion. However, the diversity and complexity of these engines generally require the presence of highly qualified personnel as well as detailed condition reports to assist the conservators. This study proposes to use acoustic emission techniques to facilitate these conservation procedures by objectifying the evaluation of the state of the engines and by providing systematic quantitative indicators for their health monitoring. To illustrate the implementation and the potentialities of this approach, different tests have been carried out at the National Automobile Museum of Mulhouse, on a Renault Type AG1. A dedicated experimental setup and the associated measurement protocol are presented in this paper. The derived results show the ability of this method to detect specific types of engine malfunctions, both during bench test and in situ measurement conditions. A critical discussion is finally proposed to highlight the feasibility and the possibilities of such laboratory techniques in the context of conservation assistance

Acoustic emission techniques for the detection of simulated failures in historical vehicles engines

Technical and industrial heritage artefacts are characterized by the presence of mechanisms. The possibility to activate, or reactivate, these mechanisms is an integral part of the cultural values of this kind of patrimony. The artefacts’ functionality, however, requires an effective diagnostic in order to detect the onset of malfunctioning at a very early stage to avoid wear and breakdowns. The assessment of moving mechanisms of heritage objects may be performed using non-destructive methods, such as acoustic emission (AE). The ACUME_HV project aimed at developing diagnostic and monitoring protocols for historical vehicles’ engines using AE techniques. The case studies were performed on 2-cylinders Renault AG1 vehicles (collection of the “Musée National de l’Automobile – Collection Schlumpf” of Mulhouse, France). These cars are maintained in working conditions, and their engines are started periodically. After a first phase consisting in recording the reference signals of the selected engines, the project focused on detecting faults simulated on purpose, the latter reproducing common failures occurring in historical vehicles’ engines