The paper presents the synthesis of mechanism on the basis of associate relative position with the imposed values of the velocity. For many path generating mechanisms used in today’s machines, the velocity of tracer point may be a criterion for adequate mechanism performance. In the first part of the paper, the synthesis of the basis of the tracer point positions and velocity for a planar mechanism is presented.
This paper presents a unitary method for the synthesis of the cam profile with translation motion. The tappet has various forms with translation or oscillation movement. The pressure angle, the transformation of coordinates and some equivalent dimensions, are the fundament of this method. These equations, of cam profile, are simply and easily programmed.
The authors critically analyze the concept of the mechanisms synthesis in the context of the latest innovations in this field, with the accent on the design integrated with the new fabrications. A logical diagram for the description of the synthesis algorithm of the mechanism according to the new conception of the authors is presented and commented. The logical diagram was proposed to be discussed and completed.
Because the evolution of construction and implementing industrial robots within flexible production systems is very fast, building a computer program to optimum choosing and transaction of these robots for the right application is very necessary. The paper presents such a computer program, from structural point of view. The program can make the right choice from a data base function of certain parameters which are defined in the beginning part of the program to realize an efficient utilization of each industrial robot function of their functional and technical parameters.
The automation of the design activity in the machine-tool field requires the establishment of a mathematical model to describe the designing problem. The paper presents such a model which use different functions for the description of the designing activity.
In the operating process of the technological systems the machine-tool must fulfill a great number of functions. This paper present the ensemble of machine-tool functions and defines the relations which can be established between these.
Beginning with the ACAD 12, programs written in C++ programming language and compiled with common compilers, Microsoft or Borland, are admitted. The paper presents the link between C++ programming language and ACAD 12 design software.
The paper presents the causes of appearance and also the effect of noise on human body. One of the causes is the noise and vibrations produced when shafts pass through critical speed. The paper presents a method to active control the shafts passing through critical speed by changing the rigidity of supports with the help of memory metals. Through this method the vibration of the shaft due to whirling is controlled by means of heating (on) and cooling (off) of memory metals for bearing supports.
The paper presents the mathematical model of a pneumatic system. The model is composed from a case with mass m1 a piston with mass m2, and channels for air evacuation.
The paper presents the unsteady supersonic flow around the intersected plane surfaces using the “Mach box” method. In order to achieve computational accuracy and effectiveness for handling solutions in the high frequency range, the harmonic spatial character of the source distribution is taken into account.
The “Mach box” method, based on the theory of sources distribution, has imposed as convenient in the study of nonstationary supersonic flows. The disadvantage of this method consist in the fact that for the numeric values of nonstationary potential and of pressure coefficient fluctuation of the results are registered caused by the shearing of the portent surfaces in rectangular network with finite area elements. In this paper is presented a method which lead to considerably elimination of these fluctuations and the classic method is optimized.
Various numerical methods based on the theory of distribution of sources, of distribution of doublets and on the theory of potential of acceleration, were advanced for the study of unstationary supersonic movements around thin airfoils. The paper presents an adaptation of “Harmonic Gradient Method” of sources distribution theory.
The study of unstationary supersonic flows represents an important chapter in the aerodynamics of high speed. The method of sources distribution has been imposed in the last period. The paper present a way to obtain the solution of movement equation using the Fourier transforms.
A special problem in unstationary supersonic aerodynamics is the study of movements around wing-fuselage joint. The paper present a simulation by distribution of sources placed on the surface of the fuselage and wing and in the diaphragm area. The limit conditions on the surface of the wing and fuselage are written differently.
Taking into account the main factors which alter the durability of a structure (the stress range, the characteristics of materials, the environment and technological factors, etc) – the present paper presents a way for assessing the durability. In this respect, there has been endorsed the linear cumulative degradation criterion Palmgren-Miner, used in the assessment of the average degradation level attained by the end of the operating period.
The paper synthetically presents a new constructive solution for sealing systems used in the aircraft industry, using combined solutions and materials (elastomers and polymers) with high qualities. There has been stressed the importance of accomplishing high quality contact surfaces of the sealing system. The research performed on some sealing systems mounted on the landing gear absorbers made in Romania, shows an obvious improvement of technical and reliability effectiveness of this equipment.
The paper presents some modalities to estimate the necessary power for mixing in case of mechanical mixing devices. Some particularities regarding the mixing of Newtonian and nonnewtonian fluids are presented. In the end of the paper an example is given for estimating the necessary power for mixing in case of a standard centrifugal impeller mixer.
The paper presents the mathematical model and the block diagram for computer program for an electromagnetic piston valve functioning. Different functioning phases were modeled by numeric methods. The program determine the influence of different parameters on electromagnetic piston valve functioning.
This paper proposes a computational method for analyzing the behavior of two elastic bodies coming into contact with friction, obeying volume forces of density, surface traction of density and thermal load. Thermal load results from the computation of the distribution of the thermal field in the two bodies, assuming the existence of the heat source. In this computation, attenuation is concentrated on contact problem in elasticity and on thermal transfer through the contact zone, using contact finite element and the thermal contact finite element.
This paper proposes a computational method for analyzing the behavior of two elastic bodies coming into contact with friction, obeying volume forces of density, surface traction of density and thermal load. Thermal load results from the computation of the distribution of the thermal field in the two bodies, assuming the existence of the heat source. In this computation, attenuation is concentrated on contact problem in elasticity and on thermal transfer through the contact zone, using contact finite element and the thermal contact finite element.
The elastic properties of isotropic solid body are described in elasticity theory using some elasticity characteristics. It is necessary to study the base and derivate characteristics of elasticity of a body because of different types of load of solids submissive to plastic deformation.
The paper presents general considerations regarding the elasticity characteristics of materials. The paper presents the differences between theory and practice.
The paper presents general considerations regarding the elasticity characteristics of materials. The paper presents the differences between theory and practice.
Threading the pipes with rolls by eddy process reduce the stress by 10-15 times than classic process of cutting. The paper presents a simplified theoretical calculus of deformation loads based on the properties of sliding lines.
The paper presents the analysis of the influence of elastic and plastic deformations, on the quality and behavior in exploitation of the interior threads, obtained by plastic deformation. The computer processing with finite element method and the experimental results of the authors, concerning threads deformations, led to a complex diagram which contains the stratification of the deformation in the turn of an interior thread.
Some results of a computer simulation of a wire-winding process regarding winding tensions, radial and circumferential stresses as a radial position in the high pressure vessel, under initial condition and under maximum pressure, are presented. It is discussed, also, a comparison between results of Tresca and von Mises yield criterion used for winding tension calculation.
The focus of this paper is the formulation and application of an optimization technique for the design of wire wind high pressure vessels. The capability to explicitly calculate the winding tension which would be necessary to produce required wind working stress is also presented. With a computer program based on the Tresca and von Mises yield criterion the whole process of wire winding can be simulated and the initial and working stresses in a cylinder can be quantitatively estimated and graphically represented.
This paper presents compared results obtained on studying the damaging phenomena in the superficial layers of samples in severe wear and in fatigue process, respectively. The experimental data partially confirm the hypothesis that the damaging of the superficial layers submitted to wear process has a fatigue character.
By now, the oxidative degradation of lubricating oils for thermal engines was exclusively charged to the tough working conditions (high pressures and temperatures, catalytic action of metal traces) from the engines. The paper proves that oxidative degradation of oil occurs even under normal pressure and temperature conditions, only under the influence of vibrations. Using UV-VIS spectroscopy, the worsening of oil quality, mainly the acid content, is evidenced and explained.
The paper presents different stages of paper tape passing on the wet presses and the influence of rolls on paper roughness.
The paper presents some experimental results regarding filling material distribution in different composition of supercalendered paper as well as of calandered paper and light plated on Speed-Former HS. It is also presented the influence of paper composition on exploitation properties.
It is known that the paper quality is depending on standard characteristic of the mass. The paper presents determinations and results of some tests performed to obtain a higher quality paper.
The paper presents the influence of supercalandred paper with light plating composition on its properties. The conditions in which the experimental studies were made are also presented.
More than 95% of water from paper paste is eliminated in the forming part of the wet tape and the good functioning of the forming part depends mostly on the final paper quality. This is the reason why paper machine constructors pay attention to this part.
The paper presents a method for progressive obtaining of necessary vacuum for a moderate extraction of water, so the fiber loses from fat waters to be minim.
The dimensional stability of paper is determined both on the individual behavior of the cellulosic fibers and on the structure of the sheet of paper which is made final after the forming, pressing and drying of the paper. The analysis of some factors which lend a certain space layout to the structure of the sheet of paper an development of a characteristic system of physico-chemical bonds leads to the development of some ways of improving the dimensional stability of paper. Their application must be correlated with the technological and economical requirements of paper manufacturing.
The paper presents an analysis of functioning capacity of hydrofoils with respect to their dimensions and the influence of hydrofoils on the paper tape properties.
The author analyses, based on experimental investigation, the thermal and dynamic performances of extended aluminum surfaces with sinusoidal ribs. Those performances are compared with performances of similar exchangers but with straight ribs. The conclusion is that the sinusoidal ribs are superior to straight ribs. The sinusoidal ribs could be used for recuperators.
The paper presents a new method to optimize the geometrical parameters of eddy microtubes used as coolers. The method is based on the physico-mathematical model of energetic separation which takes place in these equipments. The proposed computer program determines the main geometrical dimensions of eddy tubes with a minimum deviation from experimental results.
Functional parameters of a microtube depend mostly on the fraction of cool gas which results after the energetic separation process. The authors determine the correlation between functional characteristics of microtube, the flow capacity of cool current and the scope of energetic separation (minimum cooling current temperature or maximum frigorific efficiency).
In this paper, the author has determined, based on experimental investigations, the optimum flowing speeds of the fluid through an aluminum heat recuperator. These speeds give the maximum energetic efficiency.
The results from this paper are based on experimental results. The original computer program has been implemented at S.C. REMAR S.A Pascani
This paper presents the influence of the geometry of the burning chamber and also the influence of injection process in diesel engines with direct injection on the performances of such engines: power, torque, consumption and noise.
This paper present a few solutions for future, in idea that conventional fuels will be finished in the following 50 years, solution which can be applied on existing internal burning engines. We also present a few solutions for unconventional engines, using unconventional fuels.
The paper presents the positioning system in open circuit with step by step linear motor. The electronic command and alimentation device assure the successive switching of input tension.
The paper presents the synthesis of crone regulator used in command systems for industrial robots. The constant phase Crone regulator is used within an action system with an AC motor.
Shaft positioning sensing is essentials in switched reluctance motors (SRM). A low cost positioning sensing scheme using stator impedance measurement is presented in this paper. An analog electronic technique can be applied to measure the inductance of phase by using a linear frequency modulated converter.
This paper presents a new adaptive control strategy of the switched reluctance motor (SRM). After reviewing the motor operation, the control variables and the related ranges are identified. The basic scheme for the speed control of the SRM drives is also formulated.
The study presents the investigations which were made for diminution of rattling of piston compressors and also of lob-type air blowers. These investigations permitted the determination of the pressure pulsations and the tracing of graphics in time for the variation of pressure. The theoretical investigations were made for determining of the pressure spread speed, proceeding from continuing equation of mass.
This study presents the flow through radial damper, attached on the equipment for air supply considering the operation being adiabatic and the fluid with viscosity. Using numerical method for solving the set of equations which characterize the flow through the damper, we obtain the relation for speed and pressure at different radius of damper.
The paper presents a method for choosing the quality of pieces used in mechanical construction field.