Background and Objectives: This study’s purpose was to examine the benefit of using a tibial extension in the primary operation of total knee arthroplasty (TKA). This is important because it is not a common practice to use the extension in a primary TKA, a standard configuration offering sufficient stability and good long-term survivorship. The following question arises: which situation requires the use of a standard configuration implant (without a stem) and which situation requires using the extension? Materials and Methods: The opportunity to use the tibial extension in the primary TKA was analyzed in correlation to the tibial bone structural properties. Using finite elements (FEs), the virtual model of the tibial bone was connected to that of the prosthetic implant, with and without a stem, and its behavior was analyzed during static and dynamic stresses, both in the situation in which the bone had normal physical properties, as well as in the case in which the bone had diminished physical properties. Results: The maximum stress and displacement values in the static compression regime show that adding a stem is only beneficial to structurally altered bone. Compression fatigue was reduced to almost half in the case of altered bone when adding a stem. Dynamic compression showed slightly better results with the tibial stem in both healthy and degraded bone. Conclusions: It was concluded that, if the bone is healthy and has good structural properties, it is not necessary to use the tibial extension in the primary operation; and if the bone has diminished physical properties, it is necessary to use the tibial extension at the primary operation, enhancing the stability, fixation, and implant lifespan.

The aim of the paper was to develop a device (“pin-on-disc” type) for the measurement of friction in plane friction couplings with sliding movement. On tribometric device (made in our laboratory) we can measure the friction force, friction coefficient and wear, for different loading conditions, speeds, time and material coupling. For the measurement of the frictional force as well as of the coefficients of friction, mainly the method with a resistive tensiometric transducer is used. With a DataQ DI 245 data acquisition board it is possible to record up to 2 kHz frequencies in the range of -10 ÷ +10 mV with a resolution of 13 bits. To test the functionality of the device, a preliminary test was carried out for a steel pin- on- cast iron disc, for different values of the normal pushing force. The device was calibrated and the measurement results were recorded and processed on the computer.

Long steel products type 16CD4 used in car industry must meet high quality conditions regarding chemical composition, surface quality, macro-structural, microstructural and mechanical characteristics. The paper presents the correlations between mechanical characteristics and the main alloying elements of 16CD4 steel; this will give varying characteristics Rm, A5 and KCU, in correlation with the various proportions of chrome, molybdenum and carbon contained by steel. This steel brand is part of the chosen alloy steels, presenting plastic deformation resistance in conditions of high temperature. See that it is not necessary maximum carbon content for the mechanical characteristics have maximum values. The material studied was 16CD4 steel (17MoCr11), developed in EBT and treated steel to LF. Mechanical properties dependent of the content of carbon, chromium and molybdenum have been analyzed in this paper, using a mathematical model. Model verification was conducted by test Fischer and the results indicate that there are strong correlations between the mechanical properties and the percentage of carbon, chromium and molybdenum.

This paper presents experimental results revealed on the samples type 2024 aluminum alloy used in aeronautics. Adequate characterization of 2024 aluminum alloys with special destination (aviation) was achieved by combined investigations:(i) wet chemical analysis, (ii) spectrochemical analysis, (iii) X-ray diffraction and (iv) electron microscopy. The main conclusion that emerges from the investigations carried out on aluminum samples revealed that: (a) alloys fits in terms of composition with the standard specification for 2024, in all cases; (b) microstructure vary in fineness of grain, but meets the requirements of aviation rules; the investigated microstructures have been appreciated as adequate of aluminum alloys type "2024".

In the first part of this paper, there are presented the computing relations for kinematic (getting the velocity and the accelerations) and kinetostatic (getting the reactions – force and moment from the links) of a plan mechanism which has five elements. In the second part of the paper, there is a three-dimensional model of the mechanism created of SolidWorks and the analysis of this mechanism motion using COSMOSMotion under SolidWorks, the goal is a comparison between the results that we obtained on analytical way and the ones from this program.