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Welding of living tissues replaces stitching of tissues with threads during surgical operations. It simplifies and shortens the time of operation performance, lowers their cost and probability of postoperative complications. Water makes up more than half of the biological tissues mass. During welding the melting stage is not clearly expressed. In the post-operative period the weld should be gradually replaced by a healthy tissue without loss of strength. Computer modeling greatly accelerates, simplifies and lowers the cost of studying the mechanical, electromagnetic and thermal processes, running in live tissue welding. Different mathematical packages allow modeling these processes simultaneously. The paper gives an example of mathematical modeling using the finite element method. Its application enables overcoming the difficulties, when studying the processes running in live tissue welding and allows using a 3D computer model, which models the processes of tissues compression and alternating current passage. [ABSTRACT FROM AUTHOR]

The object of research is the process of dynamic interaction of a complex system of cyclically symmetric parts of the support joint, taking into account the presence of stationary cracks. A significant number of structural elements and parts operated under dynamic loads are characterized by the occurrence and propagation of cracks in areas of significant plastic deformation. In particular, for the supporting device, it is a cyclically symmetric body with a limiting case of heterogeneity, under the action of pulsed loads, plastic flow zones arise at the boundaries of the joints of the cylindrical part with projections. If there are cracks in these areas, it becomes necessary to reliably determine the fracture parameters and predict the crack growth over time. To build models of this class of objects, one of the most universal and reliable numerical methods is the semi-analytical finite element method. In this paper, the results of calculating of the parameters of fracture mechanics on the basis of the semi-analytical method of finite elements are presented for an object with inhomogeneous physical and mechanical properties in the presence of stationary cracks under conditions of pulsed loading and plastic deformations. The numerical study is performed in two stages. At the first stage, the laws of the elasticplastic dynamic deformation of the system are established. The most probable zones of damage accumulation and cracking are determined, which is the reason for the failure of structural elements. At the second stage, a model with a crack located in the zone of plastic deformations is considered, the calculated values of the dynamic stress intensity factors are studied, and their evolution over time is investigated. The obtained research results can be used in numerous calculations of inhomogeneous bodies with damage such as cracks in the conditions of elastic-plastic dynamic deformations. [ABSTRACT FROM AUTHOR]

Based on the analysis of the literature it was found that with cutting and turning speed increase during processing (spindle frequency) resonant phenomena that significantly affect the performance of cutting tools and quality (roughness) of finished surface can occur. The aim of the work is to determine the dynamic characteristics of metalworking system on the design phase that is without a full-scale experiment. This paper describes a stand based on constructed 3D model of modernized machine tool mod. 1700VF30 (spindle frequency 10000 rev/min) and the method and algorithm of development of finite-element model of dynamic state of designed 3D models of machine tool is proposed. With the help of developed model the modal analysis of the machine tool mod. 1700VF30 using the method of finite elements that can let to detect the resonant frequencies of oscillations within any range of the setting of the cutting was made. The finite element method using ANSYS executed a complex research of amplitude-frequency characteristics of constructed 3D model depending on the speed of the spindle rotation and frequency at which resonance phenomena occurs. Adequacy of the developed analytical model of dynamic state of the elements of a manufacturing system based on the upgraded machine tool 1700VF3 was proved experimentally. Results, received with its help differ from the experimental ones less than for 5 %. [ABSTRACT FROM AUTHOR]