A novel optical apparatus for the study of rolling contact wear/fatigue based on a high-speed camera and multiple-source laser illumination

Rolling contact wear/fatigue tests on wheel/rail specimens are important to produce wheels and rails of new materials for improved lifetime and performance, which are able to operate in harsh environments and at high rolling speeds. This paper presents a novel non-invasive, all-optical system, based on a high-speed video camera and multiple laser illumination sources, which is able to continuously monitor the dynamics of the specimens used to test wheel and rail materials, in a laboratory test bench. 3D macro-topography and angular position of the specimen are simultaneously performed, together with the acquisition of surface micro-topography, at speeds up to 500 rpm, making use of a fast camera and image processing algorithms. Synthetic indexes for surface micro-topography classification are defined, the 3D macro-topography is measured with a standard uncertainty down to 0.019 mm, and the angular position is measured on a purposely developed analog encoder with a standard uncertainty of 2.9°. The very small camera exposure time enables to obtain blur-free images with excellent definition. The system will be described with the aid of end-cycle specimens, as well as of in-test specimens

Theatre teaches

[EN] Theatre teaches is a new experiment carried out at the University of Brescia. The growing importance of transversal competences i.e. those skills that essentially concern attitudes in the workplace and interpersonal relationships such as team work, language and communication skills, gave us the idea to develop an educational innovation to help students bring out these skills. We asked students to wrote a play using topics seen in class. So, they tried to wrap their mind around it and worked in team to write a script and get him to scene. Not to be confused to business theatre, this method is applicable in any framework. The assessment results reveal that students appreciate this method because this work helps them to express theirself better and, in general terms, they could improve their non techniocal skills. In conclusion, we can say that this experiment has been a success and gave the students the opportunity to show transversal competences. The ability to communicate, to teamworking, to manage conflicts, to speak in public, to problem solving, creativity, imagination, the ability to manage unforeseen situations and tolerate pressure and stress, leadership skills, negotiation skills and the ability to motivate are just few of the emergent competences.http://ocs.editorial.upv.es/index.php/HEAD/HEAD18Banno, M.; Albertini, A.; Bendar, A.; Bodini, I.; Trento, S.; Villa, V. (2018). Theatre teaches. Editorial Universitat Politècnica de València. 1-9. https://doi.org/10.4995/HEAD18.2018.8098OCS1855986

a study of wear and rolling contact fatigue on a wheel steel in alternated dry wet contact aided by innovative measurement systems

Abstract Wear and rolling contact fatigue are competing phenomena in railway wheels, as wear tends to shorten or remove surface cracks nucleated by ratcheting. The presence of water at the contact interface can enhance crack propagation leading to fatigue failure. This topic was studied taking advantage of innovative measurement systems developed for assessing the damage in bi-disc rolling contact tests, including a vision system for the acquisition and elaboration of surface images and a machine-learning technique for vibration measurement and analysis. Tests of different total duration with alternated dry and wet contact phases were carried out. The analysis of the collected measurements allowed identifying when crack propagation begins to prevail on wear: this occurred well earlier than the visible emergence of fatigue damage. If short dry and wet contact sessions are alternated, the onset of fluid driven crack propagation is delayed, because initially the dry sessions are not long enough to allow surface cracks to form by ratcheting, and in the subsequent wet session ratcheting is suspended due to low friction. If the alternated dry-wet contact sessions are longer, the onset of fluid driven crack propagation is accelerated, as in the dry sessions ratcheting proceeds more forming longer surface cracks, which are able to propagate in the subsequent wet phase

On-line 2D monitoring of rolling contact fatigue/wear phenomena in dry tests

We present the in-field use of a recently developed on-line, real time, optical monitoring system for bi-disk rolling contact tests on railway-wheel- and rail- steel disks, based on laser illumination and a high-speed camera. Qualitative, as well as quantitative information can be obtained by the use of specific indexes derived from the images using blob analysis. Monitoring the tests provides information about the initial transients of turning-crest removal, on the steady state reached, and on the dynamics of the surface in between. Blob anisotropy is a key element to draw information of the mechanisms governing this intermediate state

Proof of Concept Experience in the SPES Experiment: First Solutions for Potentiometers Replacement in System Maintenance

AbstractSPES (Selective Production of Exotic Species) is a large facility, currently under advanced construction at the INFN-LNL (Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro) for the production of Radioactive Ion Beams (RIBs). Coordinated efforts are being dedicated to the development and upgrading of both the accelerator complex and the up-to-date experimental set-ups. This paper describes a work of upgrading as far as the inspection and maintenance of the system is concerned, and it deals with human-centered design methods to reduce the time spent in the radioactive environment of the facility during ordinary maintenance operations and to simplify them, also considering stress conditions of the operator and the mandatory wearable radiation protection devices (such as tracksuit, gloves, oxygen tank mask) which make simple operations difficult

Cosmic ray detection based measurement systems: a preliminary study

Cosmic rays, mostly composed of high energy muons, continuously hit the Earth's surface (at sea level the rate is about 10 000 m−2 min−1). Various technologies are adopted for their detection and are widespread in the field of particle and nuclear physics. In this paper, cosmic ray muon detection techniques are assessed for measurement applications in engineering, where these methods could be suitable for several applications, with specific reference to situations where environmental conditions are weakly controlled and/or where the parts to be measured are hardly accessible. Since cosmic ray showering phenomena show statistical nature, the Monte Carlo technique has been adopted to numerically simulate a particular application, where a set of muon detectors are employed for alignment measurements on an industrial press. An analysis has been performed to estimate the expected measurement uncertainty and system resolution, which result to be strongly dependent on the dimensions and geometry of the set-up, on the presence of materials interposed between detectors and, ultimately, on the elapsed time available for the data taking

Metodologie non distruttive per la diagnostica di continui mediante misure accelerometriche e/o acustiche

This study considers the possibility to assess quality and structural health of the block by vibration measurements. The aim is to make the method and the acquisition system suitable to be used in a weakly controlled environment, such as a quarry. The adopted methodology is based on operational modal analysis techniques, in particular on the frequency response function of an impulse excitation, which is achieved by hitting the blocks with a mallet or with an impact hammer and then measuring the vibrations in specific points on the block faces. The frequency response function is needed to define a physical model, then also a virtual FEM model has been performed and compared to the physical one, in order to choose which one was better for the proposed methodology. The physical model has been chose and its frequency response function has been compared to the one of a damaged block in order to find the differences between the two examined blocks and to identify the fracture. Then a new comparison between physical model and damaged block has been performed in order to identify the position of the fracture.Lo scopo di questo lavoro consiste nel verificare la possibilità di utilizzare le vibrazioni meccaniche come strumento utile per effettuare test non distruttivi su solidi continui, al fine di individuare cricche e discontinuità, adottando una strumentazione adatta ad ambienti debolmente controllati come cave e cantieri, partendo dal principio intuitivamente semplice che un qualsiasi oggetto ha delle frequenze proprie alle quali vibra se sollecitato e che tali frequenze cambiano se, nello stesso oggetto, intervengono delle discontinuità. La finalità è quella di indagare la possibilità di rendere oggettivo e standardizzato questo metodo intuitivo. Per far ciò si è deciso di operare per confronto, passando attraverso la definizione, validazione e scelta di un modello, reale o virtuale (FEM - Finite Element Method), per ottenere una funzione di risposta in frequenza campione, da utilizzare come riferimento e termine di paragone. Il passo successivo consiste nel confronto fra modello fisico, preferito al FEM, e dei blocchi con fratture evidenti, per identificare le differenze fra i diversi tipi di provini e riconoscere la presenza della frattura. Infine, si sono confrontati modello fisico e blocchi con discontinuità evidenti, per localizzare la posizione della frattura