Vol 38, No 3 (2018)

A local approach is developed for calculating the fatigue strength of welded metal structures, selecting the basic weld structure, and identifying the group of welded structures corresponding to that basic structure. To that end, the stress state of typical welded structures is analyzed on the basis of two-level stress concentrators. The results may be used to develop standards for calculating the fatigue strength of welded metal structures.

Existing equations for the temperature distribution along a plate produced by a point heat source are analyzed. Experimental values are compared with theoretical results from a formula employed in the development of a thermoelectric element for borehole use. On that basis, the influence of the heat-transfer coefficient on the calculated temperature distribution is established. In order to ensure agreement between the distribution calculated by the proposed formula and the experimental distribution, the value of the heat-transfer must be corrected.

The reinforcement of wood–polymer composite beams and other long structural components by means of strong continuous prestressed elements is considered, in theoretical and practical terms. The use of plunger extrusion to introduce such reinforcement during the shaping process is proposed.

Optimal batch composition is developed for porous permeable SHS cermets that may be used in processing smokestack gases at factories and also auto exhaust emissions. The physicomechanical properties of the cermets are determined when different batch compositions are employed. The permissible range of vibrational frequencies when such cermets are used as filters is determined.

Formulas are derived for calculation of the grinding force in the presence of ultrasound whose amplitude changes the microcutting kinematics of the abrasive grains. The formulas are verified experimentally.

Software for analysis of the efficiency of high-tech production is proposed. The software is based on a multidimensional model of product-information transformation during the manufacturing process, with a complex relation between the product parameters. Technological inheritance is taken into account.

A model is developed for the synchronous brush drive of an airfield sweeper. This machine is equipped with a throttle flow divider that is not of gate-valve type, and employs a plunger-type control system. Methods are proposed for improving the static and dynamic properties of the synchronized system.

Traditional approaches to improving the technological system of CNC metal-cutting machines include increasing the rigidity, periodic maintenance and repair of its components, and operating at lower speeds. In practice, the most economical approach is stabilization of the inputs to the system. The development of adaptive control systems with stabilization of the cutting forces improves the precision and quality of machining in CNC metal-cutting machines, the productivity, and tool life. However, classical PID controllers are only effective in stabilizing the cutting forces in such systems if continuous real-time parameter adjustment is possible. That sharply increases the complexity of the controller. A new mathematical apparatus based on artificial intelligence (including fuzzy logic) permits the solution of adaptive control problems that previously could hardly even be formulated. The present work addresses the use of fuzzy logic in automatic stabilization of the cutting force for CNC lathes. Simulation of a fuzzy controller shows that this approach to automatic stabilization of the cutting force increases the machining efficiency on existing equipment with indeterminacy in the characteristics of the cutting system and the working environment.

The removal of metal during reverse motion of the grinding wheel at extreme cross sections of holes in the workpiece during internal grinding is considered. In a single double pass of the wheel, the vibration of the contact area and the cutting forces are found to be significantly different in reverse motion within input and output holes. That disrupts the stability of metal removal and the machining precision over the length of the hole being machined. Approaches to the modeling of internal grinding with reverse motion of the grinding wheel are considered.

A threaded joint for pipelines and high-pressure hoses is described. The benefits of the new design are outlined. A test prototype is presented.