Application of intelligently controlled technologies in designing of technological processes for explosive forming of shell parts

The object of research is the processes of pulse metalworking (hydroexplosive, magnetic pulse, electrohydraulic, gas detonation forming, etc.). Among these methods of forming for the production of aircrafts engines parts from cylindrical and conical blanks, the most efficient in terms of its energy capabilities and overall dimensions is explosive. The modern level of theory and practice of metal forming processes allows, on the basis of a systematic approach and control theory, to determine the optimal parameters of plastic forming processes, select the best technical solutions, and create a precondition for the transition to complex automation. The most difficult task of metals forming methods optimizing is to find the best solution among many potentially possible ones, considering the introduced restrictions and efficiency criteria, environmental, economic, technical, ergonomic, and other requirements. The most problematic is that it is impossible to optimize the process of forming post-factum (finishing works, elimination of defects in shape and size, welding of cracks, etc. are required), therefore, when solving optimization problems, the implementation of the feedback principle is required - comparison of the value of the controlled variable, determined by the control program, with the desired value. In general, the processes of metal forming by pressure are characterized by a variety of problems of the theory of optimal control, the solution of which is carried out by methods of mathematical programming. And, although the equipment for pulse processing can have a different design, it necessarily includes structural elements that make it possible to convert the energy of the source and with its help (through the action of a solid body, transmitting medium, or field) to deform the metal of the workpiece. Due to this, in this work, it is proposed to control the quality of the obtained parts by varying the degree of deformation of the workpiece in the process of forming. The result of the work is the development of an integrated intelligent system, with the help of which it is possible to carry out the computer-aided design of almost all pulse-action processes based on the intelligent selection of suitable forming parameters.

Investigation of propagation dynamics of material deformations caused by laser pulse action

The mechanoluminescent materials attract increasing attention of scientists due to their capability of visualizing the mechanical stresses and deformations experienced by them. The deformations of materials arising under the action of powerful laser pulses were studied. The composite mechanoluminescent materials based on the polymer and phosphor powder were used for visualization and registration of deformation evolution dynamics. The mechanoluminescent materials were deposited on the surface of the materials under study. It has been shown that the spatial distribution of glow intensity of the mechanoluminescent layer and the rate of its change make possible judging the value and rate of material deformation under laser pulses.

Operating Parameters of Electric Pulse Activation for Internal Tapping-Screw Operations and its Justification

The processes of intensification of thread-cutting opera-tions by electric current have been known since the 70s of the last century. Internal threading operations are associated with the mechanism of plastic deformation, and, accordingly, with high values of forces and torques. This reduces the reliability of the process and requires additional measures to reduce power ten-sion. The use of the energy of short stimulating current pulses makes it possible to solve such problems due to the so-called electro-plastic effect (EPE). It is manifested due to additional stresses that cause an increase in the plasticity of metals in the presence of an electric potential and a temperature field in the de-formation center. At present, there is still no clear understanding of the phys-ical processes that determine the change in the VAT of a metal when an electric current is passed. The article presents an analysis of information in this area, which allows us to establish a number of physical phenomena, which are formed into three theories that explain the essence of EPE in metals: electron-dislocation interaction, joule heating, and magnetoplasticity. A description of experiments and equipment for electro-pulse stimulation of the threading operation is presented. The author offers a number of indicators that evaluate the possibilities of electric pulse action on the formation of internal threads when rolling threads, screwing thread-pressing parts, etc. A system of calculated coefficients evaluating the efficiency of the pulse current, its parameters and modes is established.

Establishing conditions for the existence of bounded solutions to the weakly nonlinear pulse systems

Processes that involve jump-like changes are observed in mechanics (the movement of a spring under an impact; clockwork), in radio engineering (pulse generation), in biology (heart function, cell division). Therefore, high-quality research of pulse systems is a relevant task in the modern theory of mathematical modeling. This paper considers the issue related to the existence of bounded solutions along the entire real axis (semi-axis) of the weakly nonlinear systems of differential equations with pulse perturbation at fixed time moments. A concept of the regular and weakly regular system of equations for the class of the weakly nonlinear pulse systems of differential equations has been introduced. Sufficient conditions for the existence of a bounded solution to the heterogeneous system of differential equations have been established for the case of poorly regularity of the corresponding homogeneous system of equations. The conditions for the existence of singleness of the bounded solution along the entire axis have been defined for the weakly nonlinear pulse systems. The results were applied to study bounded solutions to the systems with pulse action of a more general form. The established conditions make it possible to use the classical methods of differential equations to obtain statements about solvability and the continuous dependence of solutions on the parameters of a pulse system. It has been shown that classical qualitative methods for studying differential equations are mainly naturally transferred to dynamic systems with discontinuous trajectories. However, the presence of a pulse action gives rise to a series of new specific problems. The theory of systems with pulse influence has a wide range of applications. Such systems arise when studying pulsed automatic control systems, in the mathematical modeling of various mechanical, physical, biological, and other processes.

Study on Time Characteristics of Coupling Discharge in Pulsed Laser Induced Double-TIG Welding

Based on the dynamic behavior of laser keyhole, the time characteristics of coupling discharge of heat source in pulsed laser induced double-TIG welding (LIDTW) are studied. The behaviors of arc plasma and laser keyhole were directly observed by high-speed camera and auxiliary illumination source. The physical characteristics of arc plasma were analyzed by spectrometer and arc quality analyzer. A physical model is established to reveal the regulation mechanism of time characteristics of coupling discharge. It is found that after laser pulse action the coupling discharge between keyhole plasma and double-arc plasma does not end immediately, and its time depends on the existence time of keyhole. During hybrid welding, when the combined force of arc pressure and Marangoni force can overcome the gravity, the liquid metal is forced out of the keyhole and the keyhole remains open. Improving the electron density of arc plasma and arc voltage and reducing the diameter of arc conductive channel by selecting appropriate parameters to is the key to prolong the existence time of keyhole, which is beneficial to improve the welding penetration. The coupling enhancement of double-arc electromagnetic field in LIDTW can effectively suppress keyhole backfill and increase the duty ratio of coupling discharge. When the total current intensity is 200 A, compared with laser induced single-TIG welding (LISTW), the existence time of keyhole in LIDTW increases by 77 %, the duty ratio of coupling discharge increases by 12 %, and the weld penetration increases by 29.2 %.

Analysis of the Effect of Nd:YAG Laser Irradiation on Soft Tissues of the Oral Cavity in Different Modes in an In Vivo Experiment

The development of laser medicine has led to its use in dentistry further to improve existing treatment methods, including surgical techniques. The variety of lasers allows them to be used for procedures on the soft and bone tissues of the oral cavity as well as on the tissues of the teeth. The short duration of laser pulse action on tissues, selective action on pathological tissues in a sterile surgical field, and activation of local and humoral immunity of the oral cavity provides an increase in the regeneration potential of tissues of the postoperative area, which contributes to the shortening of wound process phases, favorable course of the postoperative period, and shortening of the healing time. Our article presents the experience of using the Nd:YAG laser in different modes in replicating the effect of curettage of periodontal pockets in an experiment on laboratory animals. According to the study results, there was a difference in the healing time of soft tissues after their exposure to several modes of the Nd:YAG laser, which makes it possible to recommend each of them for individual clinical cases.

Phase composition of galvanic iron-nickel alloys obtained using pulsed current

The paper presents the results of studying the phase composition of iron-nickel alloys obtained by unsteady electrolysis. It was found that the use of a unipolar pulse current leads to a significant increase in the crystallization overvoltage at the crystallization front at the moment of the pulse action, which affects the component composition of the coatings. The phase composition of the alloys formed at the cathode differs from that shown in the iron-nickel equilibrium diagram.

Modeling the Conditions for Microdroplets Formation and their Detachment from the Molten Metal on the Electrode

Formation of nanostructure states on the surface of materials exposed to concentrated flows of energy is one of the relevant problems of modern materials processing. In the paper the authors describe the mechanism of the micro-scale droplets formation based on the study and modeling of the physical processes and technological aspects of the interaction between the heterogenic plasma flows and the molten substance at the electrode tip. The authors show new physical mechanisms and criteria for micro-and nanoparticles origination, develop a physical-mathematical model of the interaction between the molten metal and the plasma discharge with imposed high-frequency pulse action.