Applied Mechanics and Materials Vols. 809-810

Abstract: The bond graph modeling method was discovered by Henry Painter in 1959 and has quickly become a wide spread method all over the modeling engineering world. The method is based on the analysis of power circulation in systems and has some indisputable advantages over other modeling methods, based in principle on mathematical aspects. The paper proposes a comparison between the bond graph method and Lagrange's equations method, by applying both methods to model a mechanical system. The bond graph model is a graphical model. There are three possibilities to exploit the bond-graph diagram. The first one consists in deducing a system of differential or algebraic-differential equations from the diagram. The second one consists in obtaining the block diagram model from the bond graph diagram, without additionally writing any equations, followed by the block diagram implementation in the appropriate software, which permits to perform simulations at once. The third one consists in implementing the bond graph diagram directly in the appropriate software, where simulations can immediately run. The advantages and the disadvantages of the methods are emphasized, but the decision about the most appropriate method is up to the modeler.

Abstract: Paper approaches some characteristics and bioengineering applications of a handheld depth sensor for low-cost 3D scanning and reconstruction. The Kinect depth sensor used in this work was launched on June 2009 and was based around a gaming webcam peripheral. The Kinect sensor uses a structured light technique in order to develop real-time 3D surfaces. The 3D model of anatomic surface may have a lot of bioengineering applications. Some observations and comparisons are presented in connection with the scanning and 3D reconstruction of different anatomic surfaces.

Abstract: In the present paper is analyzed the stress level and the maximum displacements that occur in the elements of a mast of 500 kN maximum hook load under the action of wind with a 70 km/h velocity. The mast is a prototype which is equipping a workover rig used for interventions and overhauling works for oil and gas wells. The forces resulting from wind pressure on the exposed mast`s elements areas are calculated in accordance with the oilfield industry standards and distributed to all structure`s nodes, after it was modeled using the FEA software ANSYS. Being a new structure containing structural steel rectangular pipes and profiles as L, I, U-shaped cross section, this analysis is necessary in order to achieve the practical construction of mast and its safety during exploitation.

Abstract: The 500 kN mast, which is part of a workover rig used for interventions and overhauling works for oil and gas wells, is a spatial multiple indeterminate structure made of many bars, with rigid nodes. The aim of this paper is to determine, through computer simulation of overload test, the state of stress and displacements for the existing construction and to find an improved solution. The overload test is experimentally realized on specialized stands and involves the mast’s loading with the maximum hook load multiplied by a safety factor of 1.4 and, in addition, with the dead weight, the hoisting system weight, and with the corresponding forces due to the draw works drum socket and the blind end. Since this is a prototype construction made of structural steel rectangular pipes and profiles as L, I, U-shaped cross section, such an analysis is necessary to ensure the mast’s and rig’s safety during functioning.

Abstract: This paper presents a method of finite element modelling used to study the effect of laminates orientation and thickness on impact properties of a composite sandwich panel made of glass and kevlar fibers in an epoxy resin matrix. In this research, the composite sandwich panel consists of a fuselage skin panel from an aircraft having two configurations: (0/90/0/90/core/90/0/90/0) and (0/90/45/-45/core/-45/45/90/0). This panel is loaded with one uniform distributed abuse loading case and the stress variation within the composite panel for each configuration is determined.

Abstract: This article presents the method of solving the problem considered with the too fast wearing of a steel sheet paneling of a freight wagon body. The method, described in the work, bases on the use of additional components, which are made of composite materials. The proposed solution is based on the appropriate lining of the inside of a wagon body with composite panels. In order to verify the placing and fixing of composite panels to wagon walls, as well as to verify the behavior of joined composite panels in the given conditions of a wagon work it was used a computer analysis basing on the finite element method. Because of the scale of the analyzed problem it was also created a virtual model of the research stand, which allows experimentally verifying phenomena occurring between the joined composite panels mounted on walls of a freight wagon that is made in a natural size. Carried out researches allowed determining the method of arrangement the composite panels in the inside space of a freight wagon body. It was also determined the method of panels joining and the method of their fixing to the steel paneling of a wagon body. It was also determined the procedure of transferring the results of the experimental analysis of the wagon walls, made in a natural size, on a real object using the matching of a virtual model.

Abstract: The generation of new knowledge and its subsequent efficient implementation is an imperative requirement in modern society and often regarded as part of the struggle for survival. For universities this is a natural and assumed mission, ensuring the integrated development of education and scientific research.For over two decades, at Transilvania University of Brasov a very specific research topic has emerged and developed, concerning hypocycloid automaton (HA). The concept of equatorial spherical hypocycloid automaton (eS-HA), as a particular case of spherical hypocycloid automaton (S-HA), was addressed in a recently successfully completed doctoral thesis. In consideration of the fact that “novelty cannot be achieved by waiting for it to occur accidentally,... but by searching for it systematically, persistently, and scientifically”, are explored extensively the typological range of machines of this type, and has disseminated some of the results.The novelty of the concept called for its validation. The virtual modelling largely confirmed the predictions concerning the construction and operation of the considered type of automaton. Definitive validation beyond any doubt, however, is ensured by developing a real model, whether experimental or merely functional, depending on the objectives and resources of research.Certain restrictions allowed only for the development of a functional model. Several technical projects were devised, the selected constructive solution emerging consequently to their critical analysis. The functional model was achieved by means of rapid prototyping techniques and drew from the beginning on the facilities available at the ProDD Research Institute of Transilvania University of Braşov. The functional model fully confirmed the predictions, is useful and indeed used, including in lectures and laboratory works as an example of how a hypocycloid automaton works.

Abstract: In this article the issues related to Computional Fluid Dynamics of the occurrence of innovative aerodynamic effect were presented. Analysis were performed to determine the occurrence of Kammback aerodynamic effect and its application in a shape of a body of the real racing car in order to minimize drag forces of the vehicle. For the analysis, ideal aerodynamic shapes were modeled, subsequently they were subjected to modifications which were used to determine the occurrence of effect. The basic modeled shape was the raindrop shape solid, which is generally regarded as the ideal shape in terms of aerodynamics. The result of analysis was compared with the drag values known from the literature. Afterwards changes in the shape of the base solid were made to verify and determine the optimum Kammback shape, selected from a set of possible solutions, in which the geometrical changes has the lowest difference of values of drag force and drag coefficient Cx(Cd) in comparison to the basic raindrop shape. Results of the study were subjected to graphic analysis, especially the distribution of air pressure on the surface of a solid and in a virtual wind tunnel, distribution of the air velocity and the course of air streams around the shape. The results were used to design the body of electric race car. The main objective was to minimize the aerodynamic drag of the vehicle.

Abstract: Multispeed gears are noncircular gears whose kinematics varies during a rotational period, alternating uniform and variable motions. Due to the limited information on multispeed gears design and performance, the paper presents i) the generation of multispeed gears, using the design hypothesis of the transmission ratio variation and ii) investigations on meshing conditions, as a qualitative information on gears contact. To generate multispeed gears, the gears transmission ratio are defined by hybrid multiple parameters functions with parabolic and trigonometric variations. Virtual models of the multispeed gears, produced by the Matlab-PHP-MySQL-AutoCAD interference, are further used for the gear meshing analysis, the theoretical static contact evolution and distribution along the teeth being investigated and compared for both kinematics. It was found that the trigonometric variation of the gears transmission ratio improves the gears meshing in gear concave zones, while the parabolic variation has benefits on tooth contact pattern in zones where the gears centrodes geometry is changed from circular to noncircular shapes.

Abstract: The paper proposes to realize a simulative analysis following the theoretical notions regarding the hydraulic jump, at flow of fluids through open channels, when open a plane penstock, which is located in a trapezoidal channel. A penstock is formed from a plan panel with upright movement in supports, with the possibility of adjustment a fluid flow by means of a handling device.