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Garcia-Gonzalez D.,Charles III University of Madrid | Rusinek A.,Metz National School of Engineering | Jankowiak T.,Poznan University of Technology | Arias A.,Charles III University of Madrid
Composite Structures | Year: 2015

This paper deals with the mechanical behavior of polyether-ether-ketone (PEEK) under impact loading. PEEK polymers are the great interested in the field of medical implants due to their biocompatibility, weight reduction, radiology advantage and 3D printing properties. Implant applications can involve impact loading during useful life and medical installation, such as hip systems, bone anchors and cranial prostheses. In this work, the mechanical impact behavior of PEEK is compared with Ti6Al4V titanium alloy commonly used for medical applications. In order to calculate the kinetic energy absorption in the impact process, perforation tests have been conducted on plates of both materials using steel spheres of 1.3. g mass as rigid penetrators. The perforation test covered impact kinetic energies from 21. J to 131. J, the equivalent range observed in a fall, an accidental impact or a bike accident. At all impact energies, the ductile process of PEEK plates was noted and no evidence of brittle failure was observed. Numerical modeling that includes rate dependent material is presented and validated with experimental data. © 2015 Elsevier Ltd.


Khatab A.,Metz National School of Engineering
Journal of Intelligent Manufacturing | Year: 2015

This paper deals with imperfect preventive maintenance optimization problem. The system to be maintained is assumed to be subject to random deterioration. To reduce the risk of failures, the proposed maintenance model takes into account two type of maintenance actions, namely corrective maintenance (CM) and preventive maintenance (PM). The system undergoes PM whenever its reliability reaches an appropriate value, while CM is performed at system failure. After a given number of maintenance actions, the system is preventively replaced by a new one. Both CM as well as PM are considered imperfect, i.e. they bring the system to an operating state which lies between two extreme states, namely the as bad as old state and as good as new state. The imperfect effect of CM and PM is modeled on the basis of the hybrid hazard rate model. The objective of the proposed imperfect PM optimization model consists on finding the optimal reliability threshold together with the optimal number of PM actions to minimize the expected total maintenance and replacement cost per unit of time. A mathematical model is then proposed. To solve this problem an algorithm is provided. A numerical example is also given to illustrate the proposed maintenance model. © 2013, Springer Science+Business Media New York.


Patent
University of Lorraine, Metz National School of Engineering, Arts, INSA Rennes and French National Center for Scientific Research | Date: 2012-11-07

According to a thermomechanical treatment process for a titanium alloy including between 23 and 27% niobium in atomic proportion, between 0 and 10% zirconium, and between 0 and 1% oxygen, nitrogen and/or silicon, the following steps are performed: a) an increase of a sample of the alloy to a temperature higher than 900 C., b) a fast quench, c) a severe cold strain, d) an ageing treatment at a temperature included between 200 and 600 C., the time of the ageing treatment being included between 10 seconds and 10 minutes. Alloy obtained by this process and prostheses made from such an alloy.


Leonard F.,University of Aleppo | Martini A.,Metz National School of Engineering | Abba G.,Metz National School of Engineering
IEEE Transactions on Control Systems Technology | Year: 2012

A helicopter maneuvers naturally in an environment where the execution of the task can easily be affected by atmospheric turbulence, which leads to variations of its model parameters. This paper discusses the nature of the disturbances acting on the helicopter and proposes an approach to counter the effects. The disturbance consists of vertical and lateral wind gusts. A 7-degrees-of-freedom (DOF) nonlinear Lagrangian model with unknown disturbances is used. The model presents quite interesting control challenges due to nonlinearities, aerodynamic forces, underactuation, and its non-minimum phase dynamics. Two approaches of robust control are compared via simulations with a Tiny CP3 helicopter model: an approximate feedback linearization and an active disturbance rejection control using the approximate feedback linearization procedure. Several simulations show that adding an observer can compensate the effect of disturbances. The proposed controller has been tested in a real-time application to control the yaw angular displacement of a Tiny CP3 mini-helicopter mounted on an experiment platform. © 2006 IEEE.


Vernadat F.B.,Metz National School of Engineering
Annual Reviews in Control | Year: 2010

Enterprise networking refers to any kind of organization structures in which two ormore geographically dispersed business entities need to work in interaction. This can happen within a single distributed enterprise (networked enterprise) or among several enterprises (network of enterprises), including the extended enterprise or virtual organizations. This concerns any kind of organizations, e.g. industrial firms, public organizations or large government agencies. Enterprise interoperability is a sine qua noncondition for enterprise integration and networking. It largely relies on information and communication technologies (ICT), especially Internet computing. The paper uses the European Interoperability Framework (EIF) as a foundational baseline to first discuss technical, semantic and organizational aspects of enterprise interoperability and networking and finally to address some open research issues. © 2010 Elsevier Ltd.

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