Polytech Lille is a well-known graduate school of engineering which belongs to the University of Lille, a comprehensive university located in the north of France in the triangle between London, Paris and Brussels.
Over the past years, the University of Lille has increasingly places its international outlook at the heart of its administration, academic programmes and research.
With 67,000 students and 8,000 foreign students welcomed each year, the University of Lille atracts many students thanks to a dynamic academic environment enriched by the proximity of international universities. It offers a truly European experience to all international students.
The quality of its research has been widely recognized. With its 66 laboratories, 3 300 researchers and research professors, as well as 1,800 doctorates, the university’s many research groups, networks and facilities contribute to effective multidisciplinary research.
A large offer of engineering degree courses
With 350 engineering graduates each year and more than 10,000 alumni (graduate engineers), Polytech Lille offers nine engineering degree courses, 5 degree courses in apprenticeship, three specialized masters and one English-taught international master.
At the heart of a high-level research environment in a large scientific and technical pole
With 172 research and academic staff, Polytech Lille offers state of the art courses that are at the cutting edge of new technologies. The research activities are carried out in 13 research laboratories (9 of which are associated to the CNRS). The school hosts 148 doctoral students.
Close relationships with companies
Various companies are present in different levels of management of the school.
Polytech Lille has developed more than 3,600 industrial contacts and 354 lecturers come from the socio-economic world (industrialists, managers, engineers…).
The engineering students undertake at least 26 weeks of internship as part of the study programme.
A « Grande Ecole » and founder member of the Polytech group
Polytech Lille belongs to the largest network of graduate engineering schools in France « the Polytech group ». This group of 15 graduate schools of engineering in France share a common student recruitment and admission process.
The education offer of the Polytech group consists of 80 curricula classified in 12 engineering fields.
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Video + Slides
Dr. Hoang Long Le Tran, École Centrale de Lille, FRANCE
Dr. Anne-Lise Cristol, École Centrale de Lille, FRANCE
Dr. Vincent Magnier, Ecole Polytech Lille, FRANCE
Dr. Jérôme Hosdez, University Lille, FRANCE
Sintered metallic composite is widely used as brake pad material for high energy railway thanks for its good resistance to severe solicitations caused by braking loads. Despite its efficiency, the degradation of the material properties under the effect of brake loads has been noticed in literature which is undoubtedly induced by the microstructure evolution. However, the microstructure evolution and its relation with mechanical behavior have so far not been intensively investigated due to the complexity of braking solicitations.
To solve the problem without tackling it in all its complexity, two experimental tests were proposed where physics are decoupled; but still inspired by the braking sequence in terms of applied temperature and compressive load. The first one is the thermal solicitation test where a temperature gradient from 400°C to 540°C was applied to the material. The second one is the thermomechanical test where a compressive load at 20 MPa was applied under the same thermal gradient. The experiment time is fixed for two minutes, equivalent to the time of one braking stroke. Besides, the local microstructure evolution of the sintered metallic brake pad was characterized by Electron Microscopy (SEM) coupling with Energy-dispersive X-ray Spectroscopy (EDS) and X-ray microtomography. The evolution of mechanical properties was characterized by a series of compressive tests equipped with a Digital Image Correlation (DIC) for analyzing deformation behavior.
Based on the deformation behavior characteristics, the considered thermal and mechanical solicitations have no separate effect on the mechanical properties of the material. The sole evolution of mechanical behavior is due to the coupled thermomechanical solicitation, which increases the hardness of friction material. From the strain field analysis, the evolution takes place on the strain lines determined by the compressive test, which strongly depends on the distribution of graphite inclusions in the microstructure. The change in mechanical behavior is induced by the local microstructure evolution. Indeed, thermomechanical stresses cause the densification of the graphite in the normal direction, this structural change induce some shear cracks in the basal plane. In terms of the metallic matrix, the segregation of carbon in steel is investigated as a reason for the increased stiffness.
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