Journal of Mechanical Engineering, Automation and Control Systems
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The properties of self-compacting fine-grained concrete mixtures for energy-efficient vibration-free construction technologies
Full text linkThe article presents the results of the development and research of self-compacting fine-grained concrete mixes for energy-efficient vibration-free construction technologies. The main focus is on selecting optimal compositions that ensure the required level of mobility and self-compaction through a rational ratio of components and the use of complex modifying additives. The results of research into the rheological characteristics of concrete mixtures, as well as the physical and mechanical parameters of the materials obtained, are presented. The patterns of the influence of the composition and structure of concrete on its density, strength, water absorption and deformability have been established. The results obtained confirm the possibility of creating effective self-compacting fine-grained concretes with high structural homogeneity and reduced energy consumption during production and laying
An analysis of the ultrasonic technology to stitch materials, and conceptualization and realization of a new sewing machine
Full text linkUltrasonic stitching is a thread-free and green technology for stitching fabrics, which uses the vibration energy of high frequency to transform it into heat at the joint to achieve local fusion. This paper provides the conceptual design and experimental validation of a roller-based ultrasonic sewing system for thermoplastic and composite textile. This work introduces a portable roller-type ultrasonic actuator coupled with a physics-based thermal model which allows the controlled and threadless joining of textiles, which is the main innovation of this paper. When operated at 27 kHz, 100 W and contact pressure of 5 MPa, the method gives maximum lap shear strengths of 86 N for polyester and 67 N for cotton + LDPE. The measured results define the process window and show the possibility of low-waste industrial utilization. Novelty: (I) a small size ultrasonic stitching unit based on the roller technology; (II) a closed-form thermal model for the relationship between energy input and joint strength; (III) validated process parameters towards a sustainable textile bonding application
Influence of angular speed of tedder on kinematic parameters of linter machine drive
Full text linkThis article investigates the influence of the tedder’s angular speed on the kinematic and power characteristics of the drive system of the 5LP linter machine. The linter machine is a complex technological unit used to remove residual fibres from the surface of cotton seeds. One of the key factors determining linting efficiency is the interaction between the tedder and the seed roller inside the machine’s working chamber. A detailed kinematic and force analysis is presented, taking into account the resistance forces generated by the seed roller during its movement and processing. Particular attention is given to the development of a calculation model that describes the interaction between the tedder blades and the seed roller. In this model, each blade is treated as a cantilever beam subjected to variable loads resulting from the non-uniform mass and density distribution of the seed material. The analysis demonstrates that variations in the mass and density of the seed roller significantly affect the load transmitted to the drive and the stability of the saw cylinder. The obtained results enable more accurate selection of drive parameters and optimisation of the operating modes of the linter machine. These findings are crucial for improving the productivity and reliability of the equipment, as well as for accounting for both transient and steady-state operating conditions in real industrial environments
Effect of parametric modulation on the stability of a periodic oscillator: a study with Airy functions
Full text linkThis work investigates the stability of a linear oscillator with a periodically varying stiffness composed of constant and linearly time-dependent segments. By combining Floquet theory with an analytical formulation in terms of Airy functions, the monodromy matrix is obtained in closed form and the characteristic multipliers that determine the stability regime are calculated. Unlike the classical literature on Hill or Mathieu systems, where the stiffness profile is assumed to switch instantaneously or vary sinusoidally, the present model explicitly incorporates finite transition times through linear ramps. This allows us to quantify how the duration of these transitions affects the onset of parametric resonance. The resulting stability map reveals alternating bands of stable and unstable regions reminiscent of Arnold tongues, and shows that the proportion of the cycle spent in the linear-ramp stage plays a decisive role in either promoting or suppressing instability. Overall, the study provides a compact analytical and numerical framework for assessing stability in periodically driven parametric systems of practical relevance in physics and engineering
Research on bearing equipment fault diagnoses via SAWOA-LSTM
Full text linkTo address the current low fault diagnosis accuracy problem for bearing equipment, and improve the detection methods, in this paper a sine-adapted whale optimization algorithm (SAWOA)-based optimization of a long short-term memory (LSTM) network is proposed as the equipment fault diagnosis method (SAWOA-LSTM). First, an optimization strategy based on sinusoidal population initialization and adaptive optimization is proposed for the whale optimization algorithm, which has the two drawbacks of slow convergence and easily falling into a local optimum. Second, to improve the accuracy and efficiency of fault diagnoses, the SAWOA is used to optimize the number of hidden units and the learning rate parameter of the LSTM. Compared with ACO-, PSO-, and WOA-based LSTM models, the proposed method improves diagnostic accuracy by 14.17 %, 15.03 %, and 4.32 %, respectively. In tests on 50 bearing samples, SAWOA-LSTM further improves accuracy for RBD, IRA, and ORD by 1.08 %, 1.62 %, and 1.10 %, respectively. Our algorithm provides an innovative solution for the health management of complex industrial bearing equipment
Identification and analysis of pavement structure features based on vibration behavior parameters
Full text linkTo clarify the correlation between the service performance of asphalt pavement structures and their vibration behavior parameters, this study focuses on asphalt pavement structures as the primary research subject. A quarter-vehicle two-degree-of-freedom model of a standard vehicle was selected as the simplified vehicle dynamics model, while a semi-rigid asphalt pavement was adopted as the simplified pavement model. Based on the elastic layered system theory, a three-dimensional finite element model of the asphalt pavement was constructed by using the software of Abaqus. The effects of modulus variations in asphalt pavement structural layers on modal frequencies were analyzed. The impacts of coupled working conditions, such as structural layer cracking positions and interlayer failure, on the modal frequencies of asphalt pavement were investigated. Additionally, the attenuation process of dynamic responses in asphalt pavement structures under transient impact loads was examined. Building on this, the dynamic response behaviors of asphalt pavement structures under working conditions including structural layer cracking and interlayer failure were studied. The results demonstrate that as the vertical depth of the asphalt pavement structure increases, the modulus attenuation of structural layers significantly affects the overall modal frequencies and vibrational effects. When internal cracking and interlayer failure coexist in the asphalt pavement structure, the vibration acceleration characteristics under load align more closely with those of interlayer failure, while the vibration displacement exhibits greater magnitudes
Experimental diagnostics of the condition and behavior of an excavation machine: a review of the most important methods
Full text linkThe paper presents an integral procedure for conducting experimental measurements on excavation machines. Excavators have a complex structure with pronounced dynamic behavior. The identification of exploitation behavior is observed through experimental measurement of stress and acceleration, drive load, and vibrations. Electro-resistive measuring tapes were used to observe the steel structure, devices for measuring current, i.e. engaged power on the drives, as well as devices for measuring vibrations at characteristic points of the drive. The results obtained realistically reflect the condition and behavior of the structure and drive equipment. The goal is to introduce systematic research to monitor the condition and behavior of the equipment on the excavator. This approach forms the backbone of predictive observation, influencing the proper management of the excavator. Experimental measurements are performed to prove the correctness of the numerical model and to diagnose the condition and behavior of the structure and power units. By monitoring the condition and behavior of the equipment, we can optimally influence the process of maintenance of the equipment as well as the lifespan of the mining machine. This work includes the most important experimental measurements to carry out reconstructions, revitalizations, and modernizations on mining machines
Development of methodology for monitoring of metalworking fluids quality
Full text linkEfficient monitoring of metal-working fluids (MWFs) is crucial to maintaining optimal machining performance and ensuring the safety and health of workers in the metalworking industries. Knowledge of the performance of cutting fluids in the machining of various workpiece materials is very important to improve the efficiency of any machining process. Metal machining companies using MWS have the opportunity to choose the best product from the wide range offered, which can differ in physical parameters as it is designed to be best for the selected process. The unique adaptation to the manufacturing process poses certain challenges in monitoring MWS quality during machining. The importance of MWS quality is crucial, which can lead to costly defects and loss of workpieces. The monitoring only by the quality lab sometimes is insufficient. This article presents the development of a sensor for the indirect monitoring of MWFs, aiming to provide a cost-effective and nonintrusive solution to assess the quality and condition of these fluids. The measurement results are compared with those of other emulsion quality control protocols. Its implementation can significantly enhance the efficiency of MWF management, leading to improved machining performance, reduced downtime, and enhanced worker safety. The sensor's nonintrusive nature eliminates the need for frequent manual sampling, reducing costs and minimizing the environmental impact associated with traditional monitoring practices. Overall, the sensor described in this article offers a viable solution for indirect monitoring of MWFs, contributing to the advancement of smart manufacturing and the optimization of metalworking processes
Study on monitoring the loose bolts of transmission tower by vibration signal
Full text linkThe loose failure of transmission tower bolts may lead to structural instability and safety risks, so effective monitoring methods are crucial to the stable operation of transmission lines. The purpose of this study is to explore the effectiveness of vibration signal technology in monitoring the loose bolts of transmission tower. Based on vibration theory, the principle of bolt loosening of transmission tower is analyzed, vibration signal data is collected by means of vibration exciter and optical fiber vibration sensor, and then the monitoring test of transmission tower loosening fault is carried out. The obtained test results show that the time domain waveform is significantly different before and after excitation, and the wavelength after excitation has a significant mutation, increasing from 1550 nm to 1553 nm, and slowly decreasing to the original wavelength, which also means that the transmission tower bolt loosening fault monitoring system has a good monitoring ability and can be used for vibration measurement. According to these monitoring results, the conclusions can be obtained as follows: first, the frequency domain data amplitude changes before and after loosening can be used to judge whether the bolt is loose, so as to achieve the monitoring purpose; Second, the strength of the vibration signal is large, the vibration signal change caused by the loosening of the bolt is submerged, and the installation of excitation at the sensor should be avoided to ensure that the monitoring is not disturbed by external factors. The research provides a new technical way for real-time monitoring of loose bolt fault of transmission tower, which has practical value and popularization prospect
