Papers by Keyword: Bar

Abstract: In this study, a disk caster to cast thin bars was proposed and assembled, and the test casting of thin bars was carried out. The disk caster consists of a casting disk, a dam disk, and a tundish. A groove was machined on the side of the casting disk and, enclosed by the dam disk, acted as a mold in which to cast the bar. The diameters of the casting and the dam disks were 600 and 400 mm, respectively, and the cross-sectional area of the groove was 59.5 mm2. The casting speed was varied from 4 to 10 m/min. Molten Al–5%Mg was poured into the groove from the tundish. The groove was filled by the molten metal, and the bar could be cast continuously. The effect of the rotation speed of the dam disk on the casting of the bar was investigated.

Abstract: At present, casting and wrought high-strength and light aluminum alloys are widely used in the creation of a number of products and units in mechanical engineering, aviation and space technology. The process of developing alloys includes the formation of initial design data covering the operating conditions, the necessary physical, mechanical and other characteristics of products, and also considers the requirements of manufacturability in their manufacture and ensuring a given structure. To achieve these goals, when smelting aluminum alloys, Al-Mg, Al-Cu, Al-Mn, Al-B, Al-Ti ligatures are used. Despite the widespread use of ligatures, there is no single set of requirements for their quality. However, recent studies in the field of structural heredity in the "charge - melt - cast product" system have shown that the structure of the ligature has a significant hereditary effect on the crystallization process, structure and properties of the modified alloy. In this work, a study of the Al-5Ti-1B master alloy was carried out using synchronous thermal analysis, which made it possible to establish such properties as: the magnitude of the thermal effect, the temperature of its onset, enthalpy, and the crystallization interval. The results obtained make it possible to expand the bank of initial data to improve existing programs for modeling casting processes and to develop new ones.

Abstract: The Boundary Element Method (BEM) is one among the most popular simulation techniques employed to simulate mechanical behaviour of materials, including smart engineering materials. Although BEM is a quite well-established numerical technique, literature tells that the method may not be well suited to simulate structures where one or two of the dimensions is much smaller than the remaining dimension/s (for a 3D problem). Hence in this work, deflection of a cantilever beam is simulated using constant boundary elements to get a feel of the accuracy of the BEM when used to simulate such type of structures. Although the concept is not new, the study assumes significance because studies which list the results in detail are not readily found in the literature. In this study, the results are obtained for different mesh resolutions also. The results indicate that - as expected - constant boundary elements are not a good choice for simulating the mechanical behaviour of smart materials when the structural member to be simulated is thin. Although it is a known fact that constant boundary elements converge very slowly, the present study helps to get a clearer picture on the accuracy and the convergence rate that one can expect from constant boundary elements. This paper heavily borrows content from this author’s PhD thesis [1]. The geometry considered in this paper is a bar. One may also note that the author is publishing another paper [2] (“Simulation of Mechanical Behaviour of Materials using Constant Boundary Elements - A Discussion on the Accuracy of Results for Beams”) that is very similar to this paper except that the geometry considered in that paper is a beam.

Abstract: A simple twin-wheel caster is proposed for casting thin bars. The lower wheel of this caster has a trapezoidal groove with an area of 25 mm2. A 1070 pure aluminum bar with a convex, not concave and trapezoidal, cross section could be cast at speeds ranging from 3 to 4 m/min. The area of the bar was 38 mm2 when the wheel speed was 3 m/min. The area decreased with increasing wheel speed.

Abstract: The nonlinear second-order differential eigenvalue problem describing eigenvibrations of a bar with elastically attached load is investigated. This problem has an increasing sequence of positive simple eigenvalues with limit point at infinity. The sequence of eigenvalues corresponds to a system of normalized eigenfunctions. The initial nonlinear eigenvalue problem is approximated by the quadrature finite element method on a uniform grid. The existence and accuracy of approximate solutions are studied. Investigations of the present paper can be generalized for the cases of more complicated and important problems on eigenvibrations of beams, plates and shells with elastically attached loads.

Abstract: Studying the diagrams of characteristics of complex subsystem of mechatronic one it has been determined that in case of approximate method the resonance frequencies cover with those which have been determined with exact method. However the values of the characteristic in other areas are different. Therefore there is the mistake of approximate method, which in case of studying the single systems does not have any influence because in resonance areas the characteristic values of the system approach to the infinity. However the difference in values of flexibility within two methods has the great influence on the result of complex systems. The main subject of deliberation was to determine the flexibility of the complex system with constant cross section using the exact and approximate that means Galerkin's method. The mechanical and/or mechatronic system composed from many mechanical subsystems having the same length and variable cross section, loaded by the focused moment was analysed. One case of attachment the complex system that means free torsional vibrating bar were examined. That why it was necessary to correct the results of approximate method. The problems presented in this paper, that means the analysis of subsystem of mechatronic and mechanical complex systems is however the introduction to the synthesis of torsional vibrating mechatronic systems with assumed frequency spectrum.

Abstract: In bar rolling of S31803 duplex stainless steel, the surface crack is easy to appear. Through the observation on the microstructure, ferrite and austenite morphology and phase ratio were analyzed. The surface cracks of S31803 duplex stainless steel bar is mainly because of the dual phase microstructure softening mechanism of different in thermal processing, and the double phase stainless steel heat plasticity decrease. When the ferrite and austenite proportion close, and the heating temperature is too high, to reduce the binding force between the grains of billet surface, easy to cause the crack surface of a bar.

Abstract: The research of subsystems establishes the foundation to complex systems analysis with cascade structure. Analysing the diagrams of characteristics of confirmed system it has been determined that in case of approximate method the resonance frequencies cover with those which have been determined with exact method. However the values of the characteristic in other areas are different. The main aim of the paper is to study the dynamic characteristic of the discrete continuous mechatronic system determined by exact approximate, that means Galerkin's method for torsionally vibrating complex mechanical subsystems. The system composed from many subsystems having the same length and variable cross section, loaded by the focused moment was analysed. The main subject of deliberation was to determine the flexibility of the mechanic system with constant cross section using the exact and approximate Galerkin's method. Next the method comparison and the correction of approximate method where made. As far as the mechatronic system flexibility determinations concerned the Galerkin's method has been chosen. The analysis of subsystems of mechatronic and mechanic complex systems is however the introduction to the synthesis of torsionally vibrating mechatronic systems with assumed frequency spectrum.

Abstract: The three-dimensional models of rolling are established with Pro/E. Based on the finite element analysis software ANSYS/LS-DYNA, the procedure of bar tandem rolling is simulated. The nephograms of stress and strain of bar deformed area and the curve of roll force during rolling are obtained. Compared the result with the other result which comes from optimization, the precision of calculation will be verified.

Abstract: People remained optimistic about the safety of the space grid structures, because the seismic damages of space grid structures were quite rare and rather light. However, two space grid structures got damaged in 2013 Lushan Ms 7.0 earthquake. The two structures are the double-layer reticulated shell structure and flatbed grid structure, namely Lushan Gymnasium and Lushan Middle School Gymnasium respectively. This paper briefly reviews the seismic damage phenomena of grid structures in historical earthquakes, and then focuses on the two damaged space grid structures in Lushan earthquake. The reason why the two space grid structures got damaged are derived from the force state analysis of the rods, ball joints and bearings. Finally, we come up with the effective advice for the seismic design and construction of the space grid structure.