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Number of results: 12
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Abstract

This paper presents the study of the impact of vibration induced by the movement of the railway rolling stock on the Forum Gdańsk structure. This object is currently under construction and is located over the railway tracks in the vicinity of the Gdańsk Główny and Gdańsk Śródmieście railway stations. The analysis covers the influence of vibrations on the structure itself and on the people within. The in situ measurements on existing parts of the structure allow us to determine environmental excitations used for validation and verification of the derived FEM model. The numerical calculations made the estimates of the vibration amplitudes propagating throughout the whole structure possible.
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Abstract

This article deals with the problem of determining the resistance of end-plate connections. A nonlinear FEM model of the joint was constructed in order to predict its carrying capacity. A standard code procedure was done as well. The analyses have been done to assess atypical end-plate joints designed and constructed as a part of roof structures.
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Abstract

Numerical analysis of the tensioning cables anchorage zone of a bridge superstructure is presented in this paper. It aims to identify why severe concrete cracking occurs during the tensioning process in the vicinity of anchor heads. In order to simulate the tensioning, among others, a so-called local numerical model of a section of the bridge superstructure was created in the Abaqus Finite Element Method (FEM) environment. The model contains all the important elements of the analyzed section of the concrete bridge superstructure, namely concrete, reinforcement and the anchoring system. FEM analyses are performed with the inclusion of both material and geometric nonlinearities. Concrete Damage Plasticity (CDP) constitutive relation from Abaqus is used to describe nonlinear concrete behaviour, which enables analysis of concrete damage and crack propagation. These numerical FEM results are then compared with actual crack patterns, which have been spotted and inventoried at the bridge construction site.
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Abstract

The article reports the results of a comparative analysis made for three novel unconventional gear wheel forging processes based on the authors’ patented [5,6,21] plastic forming methods developed chiefly for the purposes of extruding hollow products as well as valves and pins. These processes are distinguished by the fact that part of the tooling elements which are normally fixed during conventional forging are purposefully set in motion. This is intended to change the conditions of friction at the metal-tool contact surface and to induce additional thermal effects due to the transformation of the plastic deformation energy into thermal energy and, as a consequence, to improve the plastic flow of metal and to reduce the force parameters of the process.
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Abstract

The article proposes the implementation of a novel method of plastic forming of internal toothing in flange spline sleeves. A method being the subject of Polish patent application P.416772 has been used for this purpose, which involves a combination of the scheme of the direct extrusion of a cone hollow with the die press forming of the wall to obtain a flange. The entire process takes place in a single technological sequence. The operations come one after another, so that there is no need for reheating the stock or carrying out intermediate soft annealing. The proposed method is assumed to be an alternative to the operation of press forming of internal spline sleeve toothing in a conical die [1] and to the operation of swaging on rotary swaging machines [2]. It is assumed that this method, too, is alternative to other technologies known from the literature and industrial practice, whose specifications and literature references will be indicated later on in this paper. Computer simulations of the flanged sleeve plastic forming process were performed using the commercial numerical program Forge®3D. During the numerical computations, the distributions of temperature fields were determined on the cross-section of the plastically formed product. The computations enabled also the visualization of the plastic flow of metal, especially in the toothing forming regions, and the determination of the energy and force parameters of the process.
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Abstract

This paper is concerned with the 1st stage of HP rotor blade assembly steam turbine TK 120. The methodology was focused on the selection of mechanical properties and the way of the rotor disc modeling and estimating the degree of damage caused by creep. Then the dynamic interference between the frequencies of excitation and the natural frequencies was assessed. Static calculations were performed for the cyclic sectors consisting of the disc, disc blades, spacers and shrouding, including loads as temperature, mass forces from the angular velocity and the pressure on the blades. Then, the creep analysis using a Norton’s model and the modal analysis were performed. Static analysis gave information concerning the distributions of displacements, stress and strain components. In the creep analysis, the creep displacements and stress relaxation versus time were determined and the estimated degree of damage caused by creep was evaluated at each part of the rotor disc. In the modal analysis, the natural frequencies and modes of vibrations corresponding to the nodal diameters were found. The results of modal analysis were shown in the SAFE graph. Numerical calculations have shown that the rotor disc was a well-designed structure and did not reveal any dynamic interference.
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Abstract

The rigid finite element method (RFEM) has been used mainly for modelling systems with beam-like links. This paper deals with modelling of a single set of electrodes consisting of an upper beam with electrodes, which are shells with complicated shapes, and an anvil beam. Discretisation of the whole system, both the beams and the electrodes, is carried out by means of the rigid finite element method. The results of calculations concerned with free vibrations of the plates are compared with those obtained from a commercial package of the finite element method (FEM), while forced vibrations of the set of electrodes are compared with those obtained by means of the hybrid finite element method (HFEM) and experimental measurements obtained on a special test stand.
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Abstract

Residual stress has a great influence on the metal, but it is difficult to measure at small area using a general method. Residual stress calculations using the Vickers indentation can solve this problem. In this paper, a numerical simulation has been made for the residual stress measurement method of metal material deformed by high-speed impact. Then, the stress-strain curve at the high-speed deformation was confirmed through actual experiments, and the residual stresses generated thereafter were calculated by the Vickers indenter method. A Vickers indentation analysis under the same conditions was performed at the position where a residual stress of about 169.39 MPa was generated. Experiments were carried out and high speed impact was applied to the specimen to generate residual stress. The obtained results indicate that it is possible to identify residual stresses in various metals with various shapes through Vickers indentation measurements, and to use them for process and quality control.
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Abstract

The publication presents a novel concept of the process of plastic forming of variable longitudinal-section cylindrical products, being the subject of Patent Application P.427426 [1]. Additionally, these products are provided with a connection stub pipe. The plastic forming method proposed in the article combines many advantages and utilitarian benefits associated with the manufacturing technology itself, as well as with its further implementation. Using stock in the form of normalized bar commonly available in the metal product market as a finished product obviously reduces the process costs involved with stock preparation, i.e. casting, rolling, machining, etc. It also results in obtaining a much smaller surface area of stock contact with the tool and, as a consequence, a smaller surface of stock friction against the tool, which contributes to a reduction of force needed for the plastic forming of the product. The smaller contact surface area and the shorter time of stock contact with the cooler tool cause, above all, less intensive heat exchange and stock chilling. This has a significant effect on the plasticity of the cast material and, as a consequence, the plastic forming force. The proposed method enables also manufacturing cylinders with either a closed or open stub pipe with a regulated length and a varying section. In addition, unlike the method known from Polish Patent Specification PL 212062 [2], the proposed method does not require using a multi-tool press. The upper punch is furnished with a flange, whose job is to start the stock extruding sleeve at the next process stage.
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Abstract

In the paper, a solution to the problem of elastic deformation of thin-walled shell structures with complex shapes within the theory of geometrically non-linear shells has been presented. It is a modification of the Newton-Raphson method. In a variational formulation, the problem is based on a Lagrange’s functional for increments of displacements. The method has been applied to investigations of a harmonic drive, in particular to analysis of the stress state in the flexspline with a variable curvature as well as bearings of the generator. For verification of the obtained results, a more adequate FEM model calculated by ANSYS has been used.
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Abstract

The paper presents selected simulation and experimental results of a hybrid ECPMS-machine (Electric Controlled Permanent Magnet Synchronous Machine). This permanent magnets (PMs) excited machine offers an extended magnetic field control capability which makes it suitable for battery electric vehicle (BEV) drives. Rotor, stator and the additional direct current control coil of the machine are analyzed in detail. The control system and strategy, the diagram of power supply system and an equivalent circuit model of the ECPMS-machine are presented. Influence of the additional excitation on the performance parameters of the machine, such as: torque, efficiency, speed limits and back-EMF have also been discussed.
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