Applied Mechanics and Materials Vols. 809-810

Abstract: Experimental investigation methods and techniques are used to obtain accurate information on the tension and deformation of materials. Results underlying the limit stress state that aply to materials at this moment come from experiments on plain specimens and specimens showing stress concentrations. The study of stress concentrations is necessary to determine how it influences the limit stress state, distribution of stresses and yielding section. The article presents a series of specimens with stress concentrations and finite element analysis for thorough research.

Abstract: Testing cruciform specimens under static biaxial loading conditions is the method with the best results used to determine the mechanical behavior of materials. A static stress with nonlinear material analysis was applied for only one-eighth of the specimen geometry, due to symmetry conditions, to evaluate stress state from different cruciform specimens subjected to equi-biaxial tension. For the majority of isotropic materials with ductile behavior, such as metals, the most suitable yield criterion used to predict failure is von Mises.

Abstract: The ankle joint injuries are very common and their recuperation to fully operational capabilities involves rehabilitation. The existent ankle rehabilitation equipment is simple (like elastic bands, foam rollers) and they allow only simple rehabilitation exercises, which cannot be use safe without the aid of a therapist [1]. Actuated devices are advantageous because they allow many types of exercises on same device, and also they accurate measure forces and angular motions. Thus, the field of rehabilitation robotics is constantly evolving, with novel mechanisms that improve the recovery of the ankle joint. The aim of this paper is to propose a new platform, which can realize a large range of ankle related foot movements. This device can perform plantar flexion/dorsiflexion movements as well as the inversion/eversion movements. A 3D design is presented, as well as input angle variation function of output angle.

Abstract: In fluid power systems, flow control may be done either with variable displacement pump or using variable orifice. In this paper is considered the second method for flow control. In a hydraulic system, working pressure is frequently variable and therefore the use of the method does not provide constant flow rates in all operating conditions. In order to keep a constant flow, if this is important in a certain case, the flow control must be accomplished using a pressure compensated flow control valve. In this paper are analyzed possible structural diagrams, mathematical model, block diagram and functional diagram for this kind of equipment. The influence of the spring compression is analyzed also. The diagrams proposed in the paper will be used for the study of a hydraulic system designated for applications with strict flow control. It will represent an important research instrument for such cases.

Abstract: This paper approach the issue of side mill profiling, for generation of helical surfaces – the sealing worms from the construction of the helical pumps with cycloid worms. The issue of side mill profiling is based on the complementary theorem of the “substitutive circles family”. This method will be applied as so as for profiling the crossing section of the worm, in order to generate the helical flute and for profiling the revolution surface that constitutes the primary peripheral surface of the side mill. They are discussed some aspects related to singular points onto profiles and problems related to discontinuities onto the tool’s profile. For a certain case, are presented profiles determined in numerical form, which may serve for design of templates for side mill check and, obviously, for design of relieving tools.

Abstract: The paper presents the process of building and testing a geometric and kinematic model of a five-axis machining center, which can be used for accurate cutting processes simulation of complex parts. After building the model, it was be tested by simulating the machining process of a hip joint prosthetic device. The prosthetic device was chosen because of its complex shape and because it was obtained by a 3D scanning process, which means that the part was reconstructed using meshes, instead of surfaces, which makes the toolpath control more difficult.

Abstract: By the developed applicative research we look for setting up a procedure for dynamically diagnosing the technological equipment proposed for remanufacturing. Actually, this paper presents some of the results of the research carried out for the establishment an analysis method of the non-functioning technological equipment structure, using the Finite Element Analysis, for stating the own vibration modes, thus based on the structure own frequencies to be stated the maximum critical rotation up to the new equipment would function in the imposed quality and safety conditions. With the proposed procedure we could exactly state the structure own frequencies that yet appear within the working frequencies band of the analyzed technological equipment, and thus we could find the revolutions at which the mechanic system could enter into resonance.

Abstract: The complex variable nature of the milling process complicates the scientific effort to understand it. Most scientific papers in this domain have focused on giving a particular solution for a specific subject of study, like: tool life, cutting forces, obtained surfaces after machining and so on. However a systematical analytical method for developing end milling cutter tools has not been found in the current literature. The main goal of this paper is to introduce and to give a general overview in the field of developing end milling cutters. The step-by-step approach focuses on the main element of a cutting tool: material, coating and geometry. Through an analytical study of the development of end milling cutters all elements in the design, manufacturing and testing have been taken into consideration. Such a method can be implemented when trying to analyze and summarize the research in the field of end milling cutters. The current paper is a preliminary evaluation in the development of end milling cutters. Further research will be accomplished in partnership between the Technical University of Cluj-Napoca and tool company Gühring KG.

Abstract: The cooling systems on machine tools are particularly important; these have a positive influence on the cutting operation and the quality of machined surface. A particular importance represent finding an optimal correlation between the lubricant and coolant used, the material to be processed, processing method and the cutting regime. A high temperature in the working area over a certain value allowable can be harmful in terms of both the resulted surface quality and repercussions on the life of the cutting tool. The parameters of the cooling-lubricating fluid flow can be influenced by the nature of the fluid or fluids, or the nozzle geometry used, which generally has a convergent-divergent geometry in order to achieve a better dispersion of the coolant/lubricant on the area to be machined.

Abstract: The paper focuses on evaluating the stability of the railway vehicle during running on a track horizontal irregularities and investigating the possibilities to improve the dynamic behavior on a lateral direction. The evaluation method for the stability relies on the homologation specifications of the railway vehicles from the perspective of the dynamic behavior included in the UIC 518 Leaflet, where the lateral accelerations of the bogies represent evaluation units for the stability. The lateral accelerations are derived from numerical simulations, developed on a non-linear complex model of the vehicle/track system, where the vehicle is described by a mechanical system with 21 degrees of freedom. The results thus presented outline the possibilities of improving the vehicle stability by adopting the best values of the lateral damping of the secondary suspension or of the lateral stiffness of the primary suspension that will lead to the minimizing of the lateral acceleration in a bogie.