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Alexandru-Horia M.,National Institute for Research and Development in Mechatronics and Measurement Technique
Romanian Review Precision Mechanics, Optics and Mechatronics | Year: 2015

Today, all modern industrial processes are automated, being controlled by complex systems with the following advantages: Eliminate the possibility of human error;- Ensure a high level of security;- Allow a good tracking and a good analysis of technological flow up to workstation level;- Allow tracking and marking, up to each part level, for finished product in hand.One of the characteristics of units designated to industrial production of heavy equipment (as is the car manufacturing) consists in developing the technological process of production over large areas, with several stations for processing, testing and installation to be inter-related, and the existence of posts with multiple concomitant technological operations.To control this process distributed automatized systems are used, in which control and execution components are distanced from central units of tracking and decision.Such schemes involve the transport of data (information and commands) in both directions (central unitexecutive) over long distances and ensure a high degree of data security and immunity to interference characteristic industrial processes.To achieve these requirements, families of industrial equipment have been developed that are aligned to various standards such as Ethernet (option for distributed industrial systems as PROFINET), RS485 (version for distributed industrial systems as PROFIBUS), CAN. © 2015, Editura Cefin. All rights reserved.

Capitanu L.,Inslitute of Solid Mechanics of Romanian Academy | Badita L.L.,National Institute for Research and Development in Mechatronics and Measurement Technique | Bursuc D.C.,Military Technical Academy
Journal of the Balkan Tribological Association | Year: 2012

There have been inspected 8 modular total hip prostheses recovered, about surface state of their components joints bearing femoral head/acetabular cup. The inspection was done visually, microscopically and by surface profilometry of femoral heads. All acetabular cups were of very high density molecular polyethylene (UHMWPE). Femoral heads were Co-Cr alloy and Ti-6A1-4V coated with mono- or multi-layer thin films. This paper presents some research findings, concerning the wear behaviour of coatings, with emphasis on coverage of TiN and Co-Cr-Mo. It highlights the loss of coating adhesion, crushing them, embedding the resulting particles in acetabular cup and the failure of total hip replacements. It shows that the lack of a suitable adhesion layer - sub-layer is the main cause of failure of coatings femoral heads.

Rontescu C.,Polytechnic University of Bucharest | Pacioga A.,National Institute for Research and Development in Mechatronics and Measurement Technique | Iacobescu G.,Polytechnic University of Bucharest | Amza C.-G.,Polytechnic University of Bucharest
UPB Scientific Bulletin, Series B: Chemistry and Materials Science | Year: 2016

This paper presents a study on the microstructural and mechanical characteristics of a biocompatible Ti-6Al-4V alloy used for orthopedic implants. The Ti-6Al-4V test pieces were obtained by the Direct Melting Laser Sintering (DMLS) process. The test pieces obtained by sintering were properly processed and subjected to the tensile test. Following the analysis of the obtained results it was concluded that the values of the mechanical properties of the sintered test samples are within the limits as prescribed by the producer of the titanium biocompatible alloy powder. The products obtained by DMLS offer excellent combination of tensile strength, ductility and coefficient of elasticity, which proves the high mechanical biocompatibility of the Ti-6Al-4V alloy and its suitability for biomedical applications involving static or dynamic loading conditions, as for example orthopedic implants.

Badita L.-L.,National Institute for Research and Development in Mechatronics and Measurement Technique
Romanian Review Precision Mechanics, Optics and Mechatronics | Year: 2014

Hip prosthesis is a complex mechanical biotribosystem with multiple functions. Under the action of cyclic dynamic loadings, developed in a biological adversely environment, it can lose the optimal functionality during the time. As an alternative, to improve mechanical characteristics of hip prostheses, TiN thin films were deposited on cylindrical samples, made of 316L stainless steel, with hardness of 150 HV30 using pulsed laser deposition (PLD) technique. The number of applied laser pulses varied between 5000 and 20000 pulses. Adhesion strength of the layer on the substrate was evaluated by scratch tests accompanied by microscopy methods. The Atomic Force Microscopy (AFM) study offered information referring to the surface of deposited layers, before and after de scratch tests, by determining topographic parameters from ultraprecise measurements. Following these studies, and those made using Scanning Electron Microscopy (SEM) was concluded that the essential factor for increasing the hardness of femoral heads with thin layers is to provide a strong adherent coating to the substrate using PLD. This work points out that TiN protective coatings deposited by PLD technique with 20000 laser pulses can represent an alternative technology to ensure adhesion and scratch resistance of TiN coatings on femoral heads. The success condition for such coating is to provide an optimal surface roughness of femoral head that serves as substrate for TiN coating. © 2014, Editura Cefin. All right reserved.

Capitanu L.,Institute of Solid Mechanics of Romanian Academy | Florescu V.,Technical University of Civil Engineering Bucharest | Badita L.-L.,National Institute for Research and Development in Mechatronics and Measurement Technique
Acta of Bioengineering and Biomechanics | Year: 2014

Starting from the well-known fact that the rolling movement always has a lower friction compared to sliding friction, the authors have conceived and realized a pivoting movement joint on a "layer of balls" with "compensation space", placed between the acetabular cup and the femoral head. This technical solution allows free self-directed migration of the balls, depending on the resistance opposed, with successive occupation of the "compensation space". As a concept, the proposed technical solution excludes the existence of a cage for maintaining the relative positions of the spheres. It can be observed that the smallest values of the force and of the friction coefficient are obtained for the prostheses with balls and self-directed movement (approximately 5 times smaller than the values obtained for a classical prosthesis). For all the couples tested, the friction force grows with the growth of the normal load and of the oscillation speed. Changing the contact mechanism for the artificial hip joint from one sliding contact between two large surfaces, to a multitude of rolling contacts, could lead to some problems regarding functionality and durability of the active prosthesis elements. The key to an accurate evaluation of damaging mechanisms acting on thp with self directed rolling balls is a clear and complete picture of the load transfer mechanism.

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