Ivanov

pp. 41-48

pp.1-14

pp. 9-29

The article proposes a direct method for designing the Stockbridge dampers. The method allows determination of damper element dimensions using the arbitrary natural frequencies randomly specified by a designer. Relation between the input and output design parameters is defined by a regression equation obtained as a result of regression analysis. The mathematical model makes it possible to solve various design problems, including extreme tasks with conflicting requirements for design parameters. This method allows a selection of the optimal solution from a set of results, and at the initial stage of the analysis an identification of problems with no solutions.

The article presents a method of determining optimum tolerances in size of elements of planar lever mechanisms according to assigned deviations of output component. In contrast to the matrix method developed earlier by the authors, the approach presented in this work gives the possibility of determining the global space of admittances, and then directly evaluate admittances for the elements of planar lever mechanisms. A special feature of the proposed method consists in the possibility of random setting of the function type of the mechanism error and determining nonexistent solutions of the problem at an early stage of designing the mechanism. The order of admittances determination is illustrated with an example of positioning four-link lever mechanisms - jointed four-link mechanism and slider-crank mechanism. The authors provide a comparison of the calculation results according to the proposed approach and the previously developed matrix method.

The paper deals with 3-D finite element analysis (FEA) of different metal forming processes in terms of Eulerian description of continuun motion. Three technological processes being characterized by high plastic strain ratio have been researched. The processes analyzed are: the piercing of solid cylindrical billet on a helical piercing mill; the high-reduction pendulum rolling of a flat bar; the lengthwise rolling of a rectangular bar billet in profiled roll pass of a heavy merchant mill. As a result of computer simulation the time-dependent stress and strain fields and deformed shape of the billets during the rolling process were obtained. Power consumption of the processes studied was estimated too. Eulerian problem formulation has allowed not only to solve a problem of high plastic deformations, but also to analyze the phenomena of intense mass transfer without finite elements grids distortion.

The paper deals with 3-D finite element analysis (FEA) of solid billet helical rolling process in terms of Eulerian description of continuun movement. The strained and stressed state of solid copper billet under 3-roll cold helical rolling process was investigated. The metal flow during the rolling process was estimated by using lengthwise and transversal rods specially implanted into the finite element model of the billet. As a result of computer simulation the time-dependent stress and strain fields and deformed shape of the billet and implanted rods were obtained. Power consumption of the process was estimated too. The analysis results were compared to the experimental ones and to the results of FEA in terms of Lagrangian finite element modelling problem definition.