In modern conditions, when designing and optimizing complex technical systems in the field of mechanical engineering, developers analyze a variety of alternative technical and technological solutions synthesized within the framework of the technical specifications. The number of potential technological solutions may include thousands or more potential options that require clustering (grouping) for subsequent analysis and selection; accordingly, clustering, as a way of reducing the number of options under consideration, is a key component for solving this problem. However, the efficiency of clustering directly depends on the chosen metric between objects and the method for assessing the quality of the resulting clusters. In the context of technical systems, where decisions are often encoded as binary or discrete vectors (presence or absence of a component, choice of node type, etc.), such classical metrics as Euclidean distance may not be informative enough. The article discusses the application of the inverse Hamming distance to assess the quality of clustering of alternative technological solutions, which allows moving from formal clustering to a structural-content model.
This article focuses on the development of an engineering calculation methodology for a multisector crimping tool used for calibrating the ends of thin-walled cylindrical pipes and fittings. The objective of the study is to establish analytical relationships between the geometric parameters of the crimping die and the force characteristics necessary for designing equipment for calibrating thin-walled pipes by crimping, ensuring the required accuracy and quality when preparing circumferential joints of pipes and fittings for automatic welding. Calculation formulas are proposed for determining the specific force required to compress a multisector die by a given amount of radial displacement of its sectors and for estimating the resulting bending stress. The resulting relationships enable optimization of tool design for calibrating pipes of various diameters.
A hybrid surface treatment, combining shot and laser shock peening, can produce high compressive residual stresses in the near-surface region. This article develops a finite element model to study the hybrid surface hardening technology for Ti–6Al–4V biomedical titanium alloy and its effect on residual stresses. A comparison of the finite element modeling results with known experimental data is provided, demonstrating good agreement. It is shown that, compared to using either technology alone, the hybrid technology can increase the maximum depth and magnitude of compressive residual stresses by 1060 µm and 50–80 MPa, respectively.
Litol-24 lubricating grease is one of the most widely used greases in the Commonwealth of Independent States. It has good tribological properties that are insufficient for the operation of road construction machine joints under severe conditions. Therefore, Litol-24 grease is being modernized by the incorporation of nanoparticles into its composition. This work examines the effect of modifiers of Litol-24 grease, such as nickel particles (at concentrations of 0.1, 0.5, and 1.0
An engineering approach to determining the temperature of a steel strip under conditions of dry external friction during longitudinal cold rolling on a laboratory single-stand mill is proposed, taking into account the effect of the thermal effect of a pulse current.
The article pays special attention to the issues of strength of materials, resistance to destruction, and reliability of their functioning under special operating conditions. The mechanical properties during the production of blanks, fatigue, and dynamic loading, as well as wear resistance as a relationship between the properties of materials and strengthening technologies, are studied. The problems of fracture mechanics and issues of resource assessment of industrial materials are considered.
A computational and experimental model for soundproofing and dynamics of a cylindrical shell is proposed. This model makes it possible to estimate the acoustic pressure inside a composite compartment according to known external acoustic pressure and radial vibration acceleration values. The model has been tested on a currently operating composite head fairing, where measurements of these parameters have been conducted. This has made it possible to estimate the acoustic pressure on the inner side of its shell and to achieve values comparable with the acoustic pressure measurements obtained in the payload region.
The article presents a comprehensive study of heat transfer in the flow path of oil-free screw vacuum pumps with variable rotor pitch. A calculation method is proposed that combines mathematical modeling of the work process using the chamber method with finite element analysis. A distinctive feature of the approach is the use of an iterative algorithm that takes into account the mutual influence of the temperatures of the rotor and the gas in the working cavity. An assessment of the adequacy of the model using the SVP-650 pump as an example showed a discrepancy with experimental data of no more than 4
A design for a face-type bearing support with self-unloading by rare-earth permanent magnets is developed. A range of magnetic antifriction materials is proposed to ensure high tribological performance of the developed units. An analysis of the magnetic unloading force and friction processes during operation of the face-type self-unloading bearing supports under high-temperature conditions is conducted. Tribological tests have revealed low effective friction coefficients for the developed tribological units.
A comparison was made of the influence of electric pulse treatment of different intensities and annealing in a furnace at the same temperatures and duration on the process of static recrystallization of commercially pure aluminum. Structural changes were monitored by measuring microhardness as well as by observation in optical and scanning electron microscopes. For some samples, the results of using electric pulse treatment were compared with the results of using annealing to evaluate the nonthermal effect of current on the recrystallization process. It has been shown that the use of electric current, compared to heat treatment in a furnace, accelerates the process of nucleation of recrystallization centers, which leads to refinement of the microstructure. The practical significance of using current is to reduce the processing temperature, increase the energy efficiency of the process, and obtain a material with improved mechanical properties.
The paper is devoted to investigation of complex elastoplastic deformation processes in thin‑walled cylindrical shells and the resulting “dives” of the stress‑vector modulus on experimental deformation diagrams. Two‑segment piecewise‑linear paths were chosen as deformation trajectories. After preliminary proportional tension with torsion to the level E1 = E3 = 1
Vibration isolating compensators of various designs are used to reduce vibrations in power‑plant piping. Their efficiency can be significantly reduced by pressure pulsations of the working fluid arising from various sources. Pressure pulsations can be mitigated by different types of pulsation dampers. Results are presented for pulsation reduction obtained by the combined use of a broadband damper based on spherical air cavities located outside the main pipe cross‑section and a Helmholtz resonator. Tuning the Helmholtz resonator to the frequency at which the spherical damper exhibits negative efficiency reduces the amplitude of the low‑frequency resonance by two orders of magnitude and widens the frequency range over which pulsations are efficiently attenuated. The design of a test rig is described for investigating the influence of the placement of high‑efficiency broadband pulsation dampers on vibration levels, pressure pulsations, and dynamic forces in a three‑dimensional pipeline system with a pump and working‑fluid flow, including placement of the dampers inside compensators.
This article examines the existing types of mobile robotics used to carry out work to eliminate man-made accidents and extinguish fires at oil and petroleum product storage facilities associated with the risk of death, injury, and poisoning of firefighters and to conduct fire reconnaissance and deliver fire-extinguishing agents to the source of the fire in areas of elevated temperatures and other damaging hazardous and harmful factors. The main shortcomings of existing fire-fighting robotic systems have been identified. A new design of a mobile robotic complex equipped with a reel with fire hoses for laying main hose lines at a distance ensuring the safe location of firefighters is proposed and described. A three-dimensional model of the designed robotic complex is presented; its main tactical and technical characteristics and the results of the calculations are given.
The article considers the problem of increasing the efficiency of diagnostics of metal structures in the oil and gas complex using mobile robotic systems. A design of a three-wheeled mobile robot on magnetic wheels is proposed, intended for movement along metal surfaces of tank equipment and for carrying out nondestructive testing. A model of robot motion has been developed that allows one to determine the trajectory radius, speed, and traction force of the drive wheels. A simulation of the traction characteristics when moving on an inclined surface was conducted, demonstrating the possibility of stable movement of the robot on surfaces with a large angle of inclination.
This paper examines the design features and functionality of mobile modular parallel robots based on the Platonic solids. These enable unlimited expansion of identical modules along any of their faces, creating a variety of active surfaces and structures. When autonomous mobile modular robots communicate with each other, they are capable of self-organizing into swarm robotic systems with collective intelligence, capable of solving a range of tasks that are beyond the capabilities of autonomous modules. The effectiveness of the Octahedral Dodecapod mobile modular robot with 12 degrees of freedom (DOF) and a parallel octahedron structure is shown. Its functionality in autonomous and collaborative applications is analyzed.
This article examines the results of computational and experimental studies of models for the generation of dynamic forces from pressure pulsations in the compensator working fluid in a frequency range of up to hundreds of hertz. It is shown that pressure pulsations and dynamic forces generated in the compensator are related to the frequency of its vibrational deformation by a quadratic relationship and, with increasing frequency, can increase the compensator stiffness by three to four orders of magnitude over a wide frequency range compared to low frequencies. An increase in the vibrational stiffness of the compensator proportional to the square of the disturbance frequency can be a diagnostic indicator of the predominance of this stiffness model component in the compensator. Proposals are developed for reducing pressure pulsations, dynamic forces, and vibration transmission through liquid-filled compensators over a wide frequency range.
The study aims to develop an empirical model for the dependence of longitudinal ż and angular θ̇ rotational speeds along the pipe axis on a control action in the form of pulse-width modulation of the signal on the omni-wheel drives of a robotic device. The model is based on second-order rotatable planning. Data was obtained from tests in a DN150 pipe. The model enables planning of motion along a helical trajectory of a robotic device within a pipe.
A two-frequency method for monitoring the surface hardening of ferromagnetic parts is proposed. The physical processes occurring in the surface layer of metal under the influence of low- and high-frequency magnetic fields are considered. It is shown that the spectral composition of the output signal of the measuring coil contains informative harmonics that allow one to evaluate the properties of the hardened layer. Particular attention is paid to the second harmonic, which is most sensitive to changes in layer thickness and microhardness. The results confirm the possibility of using the method for fast and reliable quality control of hardened parts.
An approach based on reliability indices is presented for assessing the competitiveness of a cutting tool with working part is nanostructured by a low-temperature plasma gas discharge.
In matters of design quality assurance, special attention is paid to the reliable operation of products under various operating conditions, ensuring the operability of the material property relationships. The article examines approaches to studying the patterns of processes and phenomena and formalized procedures for making changes to their mathematical description. The necessity of testing physical concepts and representations that are geometric, statistical, and then thermodynamic analogies (integral or averaged) is shown. The problems of generalization are considered using the example of critical phenomena of different nature.
