Papers by Keyword: Elastic Deformation

Abstract: During the experimental study, a pronounced beating and sealing of the side surface of the tubular, cylindrical blanks was recorded. It is established that cracks appear and develop in the central part of the lateral surface, i.e., it are destroyed. This fact confirms the claim that the destruction of tubular, cylindrical blanks of some materials begins on the side surface. It is established that the bases of analytical dependencies between the components of deformations describe the obtained results of the experimental study of SR tubular, cylindrical blanks within the error of the experimental data, which made it possible to construct a number of mathematical models for the purpose of further study of the SDS and the method of their determination.

Abstract: This article deals with the heat transfer in a Walter’s liquid B fluid through a stretching sheet subject to elastic deformation. We have incorporated the combined effects of aligned magnetic field and viscous dissipation. The effect of viscous dissipation regulating the heat transfer is considered. In addition, prescribed power law surface temperature and prescribed power law surface heat flux boundary conditions are introduced. The transformed non-linear coupled governing equations are solved analytically using hyper geometric function. The effects of various embedded pertinent parameters on velocity and temperature profiles are well discussed with the aid of appropriate graphs and tables. Our results are verified with previously published results of some noteworthy researchers. It is found that the augmenting aligned magnetic field strength reduces the flow velocity and the related momentum boundary layer thickness.

Abstract: Quenching is an important step during age hardening of aluminium alloys. It significantly influences on microstructures, properties, residual stresses and component distortion. Due to high heat transfer, thermal stresses occur in quenched components. I.e., all premature precipitates during undercritical quenching form on condition of mechanical stresses. Opposite, quench sensitivity investigations, e.g. recording of continuous cooling precipitation diagrams, are usually performed in stress-free conditions and may therefore be incomplete. We have developed a new method of thermomechanical analysis and calorimetric reheating to investigate stress induced precipitation during quenching of aluminium alloys. For aluminium alloy 2024, it has been shown for the very first time that mechanical stresses during quenching also influence on quench-induced precipitation reactions.

Abstract: The proper selection of fixtures and its locations is necessary to avoid the dimensional and form inaccuracies that are developed due to elastic deformation of the workpiece during machining. It is necessary to predict the elastic deformation with higher precision in order to eliminate the above inaccuracies during the design of fixtures. In the present work, a Finite Element Method (FEM) based 3D contact analysis has been proposed to evaluate the elastic deformation of the workpiece under the influence of fixtures and machining forces. In the proposed model, workpiece has been considered as flexible body and fixture elements (locators and clamps) as rigid bodies. A new concept of pre-stressed harmonic analysis has been introduced in order to simulate the machining forces. The contact area of the locators has been considered using contact elements and the clamping forces as point forces. The model for the analysis is developed in ANSYS environment with suitable elements. The effect of material removal has also been considered in the analysis in view of obtaining more accurate and realistic results. The deformation of the workpiece has been predicted for a particular location of clamps, locators and machining forces and presented. It is possible to optimize the location of clamps and locators under the influence of machining forces, the above analysis is suggested.

Abstract: Journal bearings are widely used in heavy industry and in internal combustion engine applications. There is a need to increase the power density of various machine parts which leads to increased bearing loads and reduced lubrication film thicknesses. This type of development may increase deformations on the bearing surfaces which need to be considered in the bearing design process.The main purpose of this work was to develop a parameterized calculation model for hydrodynamic radial journal bearings which takes into account elastic and thermal deformations of the bearing surfaces. Hydrodynamic calculations were based on the numerical solving of the Reynolds equation by assuming rigid surfaces. Elastic and thermal deformations of the bearing and shaft surfaces were calculated by using the finite element method. It is concluded that elastic and thermal deformations are partly canceling each other out at the loaded side of the bearing and depending on the sliding speed and the external normal force either one of them could be more significant.

Abstract: In order to study the differences in load-carrying capacity of surface-textured soft materials and stiff materials, a theoretical hydrodynamic model considering elastic deformation is developed for numerical simulation analysis. Minimum oil film thickness at a certain load is computed as an index to evaluate the load-carrying capacity of textured sliding surfaces made of soft materials and stiff materials. The results show that the elastic modulus affects greatly on the load-carrying capacity. In the case of the surface texture with a dimple aspect of 0.05, textured soft materials has a higher load-carrying capacity than that of the stiff materials. In the case of the surface texture with a dimple aspect of 0.01 and only under high loads, textured stiff materials provides a better load-carrying capacity than that of the soft materials.

Abstract: In the stamping operation, springback causes geometrical inaccuracies and defects in final shape of metal stampings. This defect is actual problem in stamping production. Nowadays the detailed description of the springback is not clarified well regarding production of more complicated shape. To eliminate springback problem in stamping production there are methods, discovered and approved by advanced procedures. However applying these methods, particularly in drawing operations is much more complicated. The research describes theoretical analysis of springback phenomenon and possible experiments for the springback compensation. The research also describes analysis of springback using software for numerical simulation AutoFormplus R5 which is currently used to design the process of stamping production in company ŠKODA AUTO.

Abstract: On the basis of nonlinear features analysis of restoring torque, damping torque and especially hull deformation, a nonlinear roll equation of rotary molding boats has been established. The equation includes elastic deformation term which differs from existing ones usually borrowing ideas of steel boats. By numerical simulation, it’s found roll frequency and velocity increase when elastic deformation occurs, i.e. the roll stability margin shrinks which can underlie how to amend the stability evaluation criteria on rotary molding boats.

Abstract: In cylindrical traverse grinding of a long workpiece with high aspect ratio, the shape accuracy of a workpiece worsens due to its low stiffness. In this study, the grinding force was measured during grinding process to calculate the elastic deformation of a workpiece caused by the normal grinding force. By comparing calculated elastic deformation with the measured shape error of ground workpiece, the cause for the shape error in case of grinding a long workpiece was investigated experimentally. From experimental results, it is confirmed that the main factor of the shape error of the long workpiece is its elastic deformation during grinding process.

Abstract: Through discussing the characteristics of metal matrix composites, the mechanical properties of metal matrix composites is analyzed, the mechanical parameters of metal matrix composites is tested by experiment, the specific application is instructed in the field of aviation, the development direction of metal matrix composites is pointed out combining with the characteristics of material itself.