Journal of Machinery Manufacture and Reliability最新文献

Methods to produce a metal pipe with different diameters at the ends including joining pipes with different diameters and reducing the pipe using different methods and tools are described. Reduction by a press, including a hydraulic one, allows for the required reduction in the diameter at the ends of a thick-walled pipe on an industrial scale, within the permissible ovality parameters of the internal diameters, and for preserving the metal structure at the reduction site by means of dosing the press power. The important parameters include not only the press power and the ratio of the diameter to the wall thickness of the pipe but also the following: whether the pipe is pre-heat-treated, the material of punches used to set the required diameter, and others. An important issue is to achieve stability in obtaining the required diameters and the required level of ovality since in practice a thick-walled pipe behaves less stably than a thin-walled pipe under any plastic deformations.

The elements of systems for ensuring autonomous driving of electric vehicles are discussed; primary emphasis is placed on the processing of lidar data using various neural network architectures, such as PointNet, Dynamic Graph CNN, recurrent neural networks, and convolutional neural networks. The benefits of implementing machine learning methods when using lidar are discussed, which allows improving the safety and efficiency of autonomous electric vehicles. The problems of object recognition with noise filtering are considered. The need for further research and development of noise reduction systems to improve the reliability and sustainability of autonomous lidar systems in real-world conditions is substantiated.

The article presents a complex mathematical model of the surface hardening process of rotating parts in a plasma torch with a liquid electrode. The model takes into account key physical aspects, including electrical breakdown, plasma dynamics, heat transfer, phase transformations in the material and the effect of part rotation on the hardening uniformity. The proposed equations describe the conditions for the formation of an arc discharge, heat balance, plasma ionization, as well as the kinetics of heating and cooling. The results of modeling implemented in the Matlab environment confirm the possibility of achieving high surface hardness due to martensitic transformation at a cooling rate above 200°C/s. The model allows optimizing hardening parameters such as plasma torch power, rotation speed and exposure time, which helps to reduce the number of experiments and increase the efficiency of the technology.

The problems associated with belt elongation in belt drives and proposals for a new method for monitoring their conditions based on ferroprobe magnetic sensors are discussed. The main reasons for reduced efficiency of a belt drive, such as slippage, vibration, and plastic deformation, are described. The existing control methods and their advantages and disadvantages are considered. An innovative approach is proposed that permits noncontact and continuous monitoring of belt conditions with high accuracy. This method is based on the use of a magnetic mark and two ferroprobe magnetically sensitive sensors recording the time of passage of the mark and permits calculation of the speed and length of the belt. A mathematical model for calculating the belt length is presented, and the features of implementation of the system are described.

Studies of a material with the shape memory effect under various types of loading, compression, tension, and torsion, are considered. Methods for determining the temperature of shape recovery of titanium nickelide alloyed with iron and cobalt and the characteristics of recovery from the degree of external resistance are presented.

The efficiency of rail transport is significantly affected by its traction capacity, which depends on various factors and, of course, on the coefficient of adhesion of the locomotive wheel–rail system, which is significantly affected by climatic operating conditions. The relevance of finding and implementing a technical solution to eliminate icing of rails of railway transport operated in the Arctic and continental shelf of the Russian Federation is substantiated.

The application of artificial intelligence for structural analysis and synthesis of technical systems in mechanical engineering based on the morphological approach is discussed. A combined method is proposed that integrates advanced morphological analysis with artificial intelligence, which allows systematizing the process of generating a morphological set of solutions. As an example, the construction of morphological sets for additive technologies using artificial intelligence is considered and two platforms are compared. A conclusion is reached about the possible application of artificial intelligence.

The current problem of choosing a method for filtering a random loading process, which in some cases may be nonstationary, is considered. This issue is closely related to the task of assessing durability, since its solution determines how fully the components of the oscillations (including high-frequency ones) will be represented in the output load vector. The problem is considered using the example of loading processes obtained during operational measurements of a real object at several speeds of movement used most frequently. Various filtering methods are considered: using low-pass median filters, using the level method, and using mode decomposition. Since the processing involves subsequent assessment of the durability, conditional durability assessments were carried out in order to show the similarities and differences of the filtering methods when calculating the filtered processes. Recommendations are given for preprocessing of processes.

A mathematical model is developed that allows establishing an analytical relationship between the probability of detecting an element that affects the safety of a complex technical system in a state that creates prerequisites for an incident. Graphs of possible operating states are considered in cases where the analyzed system element is constantly involved in a potentially hazardous operation or is waiting to participate in a potentially hazardous operation or safety operation. The use of numerical methods gives the developed mathematical model flexibility, since there are no restrictions on the type of distribution functions under consideration. The obtained results can be used to assess the integrated index of the complex technical system safety and to determine rational parameters for their safe maintenance.

Connecting an external pulse voltage source to a conductor creates a rapidly changing electric field in it, which leads to a redistribution of current across its cross section. From the study of fast mechanical processes, it was established that, at the fronts of an electrical pulse, a short-term jump in the magnitude of magnetic induction occurs. These jumps are caused by the appearance of radial polarization currents. The interaction of radial currents with the annular component of the magnetic field of the main current leads to the emergence of the Ampere force. This force in the axial direction causes a shock wave response in the metallic material. The amplitude of mechanical vibrations was measured by determining the acceleration of the surface layers of the material. It has been established that the amplitude of the resulting vibrational response of the material depends linearly on the amplitude of the electrical pulse. The direction of the vibrational response depends on the direction (sign) of the external electrical impulse. The obtained results will help to form a consistent theory of the electroplastic effect and will contribute to the effective application of the electroplastic effect in technologies.