Advanced Materials Research Vol. 1036

Abstract: In this paper are presented the results of experimental studies determining the dependence of the impact of an innovative welding micro-jet method on the intensity of abrasive wear of chrome-manganese 20MnCr5. The presented method is generally used for the constructions work items matrix for the production of silicate. The results confirm that the micro-jet welding method reduces the abrasive wear intensity of about 20% compared to the steel after thermo-chemical treatment. Other parameters such as the friction coefficient and power friction show comparable value, and therefore do not have a significant impact on working conditions.

Abstract: The unique properties of laser radiation determine his special technological applications. Surface treatment is a subject of considerable interest at present because it is able to save strategic materials or allow improved components with perfect surfaces. Optical energy is an ideal form of energy for surface treatment. The advantages offered by the laser, the highly localized clean nature of the process, low distortion and high quality of finish demonstrate that. In this paper we will present the main aspects about experimental arrangements for appropriate ideal power distribution to gives a uniform temperature over the area to be treated and metallurgical results and properties of hardened steels.

Abstract: Manufacture of steel pipes micro-alloyed with Ti, V, Nb by high frequency electric resistance welding (HF-ERW) is a modern and efficient method, but requires a good knowledge and adjustment of various parameters influencing the welding process. This study aims to determine the influence of the main process parameters (electrical and mechanical) and establish correlations between them, in order to optimize the welding process. This was possible only by controlling and monitoring the welding parameters used and conducting experiments and tests on welded pipes in different conditions.

Abstract: The paper presents the results of experimental research on the wear mechanism of the tool-electrode as a result of machining metal materials by applying electric discharges in pulse. It examines several phenomena noticed on the tool - electrode surface, exactly, the oxide layer formation and the modification of the micro geometry of the tungsten tool electrode surface. The paper presents the experimental results on the behavior of the tool electrode made of stainless steel after the metal parts have been machined. It also presents the phases of mass transfer in the gap between electrodes.

Abstract: This paper shows some possibilities to adjust the exposure time and output power of a given microwave device according to the process to be executed, taking into account the special operating conditions of the magnetrons and the efficiency of the microwave device. Since the exposure time is rather easy to set by means of timers, the microwave power level is difficult to modify because of the magnetron requirements voltage, current, magnetic field which must be carefully observed in order to ensure reliable operation. The research has been carried out at the University of Oradea and INCDTIM Cluj-Napoca, during the activities of the Microwave Collective of the University of Oradea and during the preparation of the doctoral thesis of Mr.Ursu.

Abstract: This paper presents the results of laser remelting influence on structure and properties of the surface of the AlSi9Cu2 aluminium cast alloy as well as X40CrMoV5-1 and 32CrMoV12-28 hot work tool steels, carried out using the high power diode laser (HPDL). Structure changes were determined in the work, especially structure of the surface after wear resistance test. Also hardness investigation of the different remelting areas was performed. The reason of this work was also to determine the laser treatment parameters, particularly the laser power, to achieve a good layer hardness for protection of this constructional and tool materials from losing their work stability and to make the material surface more resistant for work extreme conditions. Tungsten carbide and boron nitride powder was used for alloying. The goal of this work was also to determine technical and technological conditions for remelting the surface layer with HPDL. The remelted layers which were formed on the surface of the investigated aluminium and steels were examined metallographic and analysed using a hardness and wear resistance testers. Key words: Wear resistance, HPDL treatment, aluminium alloys, tool steel, remelting, alloying, surface treatment, boron nitride, tungsten carbide.

Abstract: The paper deals with a new approach in data analysis of a measured mechanical parameter. The classic approach is mainly based on the deterministic statistics that cant cover the whole field of a complete analysis. The stochastic approach, to be used in this paper, offers far more information about the mechanical parameter and can take into account the non-linearity of the signal, eventually, the mechanical parameter itself. Starting from the point of view that, in real life, there is no steady evolution of any parameter, we decide to take into account the importance of the non-linear components of any signal. After e thorough investigation, we hope we could make the difference between the noise, as non-linear components of the measured parameter, and the useful non-linear components (e.g. important shocks, typically met within a vehicles transmission). Using the stochastic modeling procedures, we aimed at issuing comprehensive, accurate and valuable dynamic models of the phenomenon. These models cam be used in a large variety of situations, from describing the process, to evaluating the health of a mechanical system and to controlling a real-time process based on the pre-set models (previously drawing a map of the systems normal behavior and permanently assessing the deviation from it and acting accordingly). The data were measured within the transmission system of a military vehicle. Specifically, we have gathered information about torque and angular speed of different shafts of the driveline. As everybody knows, the power flows within any vehicles transmission in transient modes mainly and it is accompanied by plenty of noise. It is rather challenging to separate (filter) the useful signal form the noise but, on the other hand, it is the only way to achieve useful data. Therefore, a spectral analysis is a must, but not the conventional one, which has its drawbacks, but a multi-spectral one, which is able to insulate the noise. Moreover, starting from the analysis developed with this method, mathematical models, both in discrete and continuos time can be achieved. It is easy to notice that the models that we have achieved are featured by a very good accuracy. We could push the data processing even further, getting generalized models that provide the needs we have mentioned before, with respect to the mapping of a normal (averaged) behavior of a system, to be used in controlling procedures.

Abstract: The simulation procedure has always been considered as a giant leap forward, especially in the field of basic designing of a product. There is nothing new underneath the basic concept, but the scientific and technical progress always brings up new techniques that improve simulation in its whole. When we talk about a vehicle, especially about a military one, we consider that it is much cheaper to simulate a process involving the weapon system than performing countless tests that are rather expensive. In this respect, we tried to develop a simulation mathematical model, check its accuracy with a set of extensive tests, prove it reliability and further extrapolate the behavior of the simulated model to a larger number of military vehicles of the same kind. It could help in various fields, such as diagnose (by comparing the simulated results with the real ones got from a faulty vehicle) or automatically regulating some functions (an intelligent vehicle, having an implemented, simulated model, that is able to feel the status of a subsystem in real time and regulate its behavior, accordingly). Hence, the paper presents a model that simulates the longitudinal dynamics of a tracked vehicle. It has been issued using Simulink module of Matlab programming environment. It aims at pointing out the performances of the vehicle. The models interface is friendly and its structure is modular. The main modules of the model are the engine, the torque converter, the transmission and the track. The engine and the torque converter are modeled using the experimental maps obtained by the tests that have been previously developed by the manufacturer. The main principle of the equations that describe the system is to set a balance among the forces (both active and resistive) that load the vehicle. The inputs of the model are the technical and dimensional features, provided by the manufacturer or experimentally determined. The output of the model is a dynamic behavior. Comparing the results with the experimental data eventually validates or invalidates the model. But the results were excellent, so the model was validated. Also, the results proved that the developed model is able to predict the performances of the take-off stage of the tracked vehicle.

Abstract: An operation of a single-machine manufacturing system is modeled by an unreliable finite-buffer-type queuing system with Poisson arrivals, in which service times, failure-free times and times of repairs are totally independent and exponentially distributed random variables. Applying the idea of embedded Markov chain and the formula of total probability a system of integral equations for the transient conditional queue-size distributions of jobs present in the system at fixed time t is built. The solution of the corresponding system written for Laplace transforms is obtained in a compact form using the potential technique.

Abstract: Paper presents a proposal of mathematical algorithm used for analysis of influence of type of selected passive electric circuit on dynamic flexibility of system with piezoelectric transducer used for shunting vibration damping. Mathematical model of one-dimensional, vibrating system with shunted piezoelectric transducer is proposed and using approximate method the systems dynamic flexibility is calculated. Influence of type of used passive electric circuit on the systems dynamic flexibility are analysed. The purpose of this work is to obtain a functional mathematical tool that can be used to design such kind of systems obtaining the best efficiency of their work. In order to make it possible it is necessary to know the influence of type and parameters of elements of chosen passive electric circuit on the systems characteristic. In order to realize the assumed aims, the discrete-continuous mathematical model of the considered system is created. It is not possible to use an exact methods to analyse such kind of one-dimensional, vibrating systems with piezoelectric transducers, this is why the approximate method is used.