Volume 4, No. 15 (2009)
Articles
REALISING OF THE COMPONENT ELEMENTS OF LOADED CARDAN TRANSMISSIONS WITH THE HELP OF RAPID PROTOTYPING
AVRIGEAN EUGEN(1), PASCU ADRIAN(1), OLEKSIK VALENTIN(1)
The paper presents the realizing of the component elements of cardan transmissions with the help of rapid prototyping. The finite elements study was carried out on the component elements of cardan transmissions with the help of the Cosmos - SolidWorks software, after which an optimization was realized, the optimal results achieved being physically realized by means of rapid prototyping.
CHARACTERIZATION OF THERMAL SPRAY COATINGS BY THEIR STRUCTURAL AND MICROSTRUCTURAL PROPERTIES
AXENTE MARIANA, GEĂMAN VIRGIL
Thermal spraying techniques are coating processes in which melted or heated materials are sprayed onto a surface [1]. Thermal spray coatings have a wide range of applications, for instance, in repairing machine parts damaged in service or in the production of parts with high wear resistance [2]. Coating quality is usually assessed by measuring its porosity, oxide content, macro and microhardness, bond strength and surface roughness. Generally, the coating quality increases with increasing particle velocities [1].The present paper analyze the thermal spray coatings by their structural and microstructural characteristics.
AN ANALYSIS REGARDING IMPELLER GEOMETRY OF CENTRIFUGAL PUMPS IN ORDER TO OBTAIN A MINIMAL AVAILABLE NPSH
BUDEA SANDA
In this paper I analysed the influence of the impeller geometry over the NPSH available of centrifugal pumps, in order to design and manufacture the best impeller. In centrifugal pumps design, a special attention must be given of the impeller feature of NPSH (net positive suction head, available to the pump), to forestall the cavitational working. The methods of the NPSH available computation take account by the admission diameter of impeller, by the number of blades and by the inlet angle of the blade, ?1 , by the speed variation, etc. I used in this analyse an own software that calculate the impeller geometry and estimate the available NPSH and I determinated the influence of the impeller geometry over the NPSH available feature for centrifugal pumps, by simulation different geometries of impellers. I proposed also a graphical analyse regarding these design influences over the NPSH available feature of the centrifugal pumps, for radial or diagonal impeller, with small and medium dimensions.
MANUFACTURING DOUBLE-ELLIPTICAL CAVITIES FOR LASER PUMPING MODULES USING CNC MANUFACTURING UNITS
DONTU OCTAVIAN(1), BESNEA DANIEL(1), STOICA MADALINA(1)ANDGHEORGHE I. GHEORGHE(2)
The present paper presents the steps of CAD/CAM design using CATIA as the work environment as well as the execution of how specific for optical pumping laser cavity using CNC manufacturing centers.
ANALYTICAL AND PHOTOELASTICITY DETERMINATION OF STATE OF STRESSES IN A PLANE PLATE WITH INNER HOLE SUBJECTED AT CONSTANT PRESURE
FRĂŢILĂ MARCU
The paper presents and compares the results obtained by using the analytical determination and photoelasticity methods in the study state of stresses in a finite plane plate with inner hole subjected at constant pressure
CONSIDERATIONS REGARDING THE ANALYTICAL SOLUTION OF THRUST BEARING LUBRICATION
IONESCU MIHAIL, MIHAI C. IOAN, AMARANDEI DUMITRU
The present paper proposes a quantitative calculation of thrust bearings, focusing on the numerical solution of equation energy in the thermal field and on the analytic solution [1], in hydrodynamic one. For that, the slider bearing pad has been replaced with the partial bush of a journal bearing. Subsequently, the differential equation of pressures is presented, and its verification in several concrete cases provided by the literature in the field. The validation consists in comparing the pad's hydrodynamic parameters, calculated by means of numerical methods, with those of the proposed journal bearing, calculated analytically
INNOVATION MANAGEMENT AND ORGANIZATION COMPETITIVENESS
JOKIĆ BOJANA
Global experience shows that in modern economy and social development only those companies that are fast and innovative in their development can sustain and successfully develop. If a company wants to exist and develop, it has to accept these characteristics of today's world. That is why comfort and complacence are necessary to be replaced by continual creative thinking on how the company can be most efficiently included into creative competition. In short, it means that it is necessary to think, plan, organize, control and perfect the work process constantly in order to fulfill market demands, as completely as possible, and thereat constantly develop new products-services. Today's companies are faced with serious challenges: the global economy expansion, deadly battle over markets, drastic contraction of life span of products, fast technological changes, structural transformations, etc. In order to respond to these challenges, companies constantly need to increase the productivity, improve the product's and service's quality, develop new products and meet the demands and desires of the consumers. Shortly, the companies need to be constantly innovative because the imperative of modern business of a company is perfecting all the components of the company's structure and business operations. Fitness of the company to place on the market quality, functional and cheaper products points out the development of the innovation processes in the company. The purpose of research in this paper is advancement of praxis of research development projects of multidisciplinary character having the task to direct innovations on the market of marketing profit, financial capital market, production researches that transform the innovation into a concrete product. The offered research can be beneficial to economists, managers, entrepreneurs, as well as to all the participants in the operational activities of development character, responsible for the innovation realization in technical and economic sense, to provide conditions for product creation, as well as the conditions in the environment so that the product could come into life.
ORGANISATIONAL CHANGES MANAGEMENT UNDER THE INFLUENCE OF INNOVATIONS
JOKIĆ BOJANA
Innovation management as a series of activity for choosing and implementation of ideas is conducted within the specific internal and external context. Regarding this, macroeconomic movement of status in international market represents external environment which is difficult to control. Innovations can be precipitated by creating the appropriate internal environment presented through organizational structure, organizational culture and leadership style. The aim of this research is to offer analysis of arranged changes where leaders' tasks are particularly emphasized. Changes strategy approaches are given through changes made under the influence of compulsion, power, and rational negotiating. The subjects of the analysis are the reactions of organization to change resistance. Technological changes that require special harmony of business relationships, practice and people, are presented as a special challenge.
AN EXPERIMENTAL RESIDUAL STRESSES ANALYSIS FOR A STEAM LINE STEEL
LEIŢOIU BOGDAN, MAREŞ MARIAN, GOANŢĂ VIOREL, BÂRSĂNESCU PAUL-DORU, GHERASIM SERGIU
The paper is focused on the experimental determination of residual stresses, using the hole-drilling strain gage method, described by a well known ASTM standard. Some practical difficulties of the experimental technique are emphasized, together with the contingency of obtaining a non-uniform stress distribution, for the studied specimen. As a consequence, a special calculus program is recommended to be used, as presented in the paper. Three possible calculus methods are exemplified, for the selected program. Some differences were observed, when comparing the corresponding residual stress values, and caution is recommended for choosing the suitable method, in any practical situation.
ON THE RESIDUAL STRESSES DETERMINATION FOR A LOW-CARBON POWER PLANT STEEL
LEIŢOIU BOGDAN, MAREŞ MARIAN, GOANŢĂ VIOREL, BÂRSĂNESCU PAUL-DORU, GHERASIM SERGIU
An experimental procedure is proposed and presented, for determining some corrected values for two coefficients that appear into the relationship for the residual stresses determination. The method is based on some tensile tests on specimens (from the studied material) that are instrumented with a special strain gage rosette (for the hole drilling strain gage method). Every specimen is twice loaded - before and after the hole drilling process. The resulted stress-strain dependences (for the three transducers of the rosette) are used for the calculus of some material parameters, included into the determination of corrected values, for the two above-cited coefficients.
SIMULINK APPLIANCES FOR AN ADAPTABLE HYDRAULIC SYSTEM WITH SECONDARY CONTROL
MIHAI C. IOAN, IONESCU MIHAIL, CIORNEI FLORINA-CARMEN
The authors present the results of using a simulation in MATLAB of an adaptable hydraulic system with secondary regulation. The hydraulic actuator system has two consumers and uses a Variable-Displacement Motor, actuated by a variable pump. The load is simulated by a winch and the scheme also includes a mass, a damper and the gravity force. The regulation requires a Secondary Control Unit. The latter uses a proportional 4 way servo-cylinder that controls the Variable-Displacement Motor according to the signal received from the electronic regulator. The model is designed as a closed loop control system, with angular velocity feedback loop.
OPTIMUM TUNING OF AN ADAPTABLE HYDRAULIC SYSTEM WITH SECONDARY CONTROL
MIHAI C. IOAN, CIORNEI FLORINA - CARMEN, IONESCU MIHAIL, AMARANDEI DUMITRU
The application presents a MATLAB Simulink model regarding optimum tuning of an adaptable hydraulic system with secondary control aiming to obtain the optimum in conformity with the adopted criterion. It is known that the perturbations occurring in the system are relevant. Therefore, from the possible solutions giving responses of the system according to the input signals (ensuring the imposed performances), the solution conducting to the best behaviour must be chosen. To this end, a series of parameters of the simulation scheme will be modified, according to the theoretical requirements of tuning an adaptable system.
DETERMINATION OF THE MINIMUM SIZE MECHANISMS WITH DISK CAM AND TRANSLATING FLAT-FACE FOLLOWER
MOISE V., TABĂRĂ I. A., DUGĂEŞESCU I., IONIŢĂ C. L.
To design the cam-follower mechanism it must be taken into consideration the different conditions imposed by the task design. In order to the mechanism function according to the imposed conditions and in the same time to occupy a minimum space, it must proceed to optimize the size of the mechanism. The minimum dimensions of the disk cam and translating flat-face follower mechanism is determined so that the radius of curvature of directory curve of cam surface doesn't change the sign, in terms of design requirements
INTRODUCTION OF LESSONS LEARNED INTO AN PRODUCTION SYSTEM WHICH IS PRODUCING MOLDS TO INCREASE COMPETITIVENESS
RĂŞINĂ MARIANA CRISTINA
Production systems worldwide are using techniques and technologies to manage their knowledge and experience better. Their objectives are to improve the quality of knowledge and experience sharing by exploiting and explicit knowledge of successes and failures. Knowledge's gained from positive or negative experiences had to be well managed and are one of the important sources of knowledge today. In these article I make an introduction in lesson learned, I explain why lessons learned need to use in an production system producing molds, I present the necessary steps in introducing lessons learned and I explain how it's made the continuous improvement using lessons learned in an production system producing molds and why it's necessary that.