Journal of Mechanical Engineering, Automation and Control Systems
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Structure design and sensitivity analysis of flexible ultrasonic transducer array
Get PDFTo investigate the influence of element parameters on the performance and acoustic field of flexible ultrasonic transducer arrays, this study employs finite element multiphysics simulation software to analyze various parameters of flexible ultrasonic transducers within a multiphysics coupled field. The analysis begins with simulating the width and thickness of piezoelectric materials in a single-element ultrasonic transducer structure. Simulation results indicate that the electromechanical coupling coefficient of the ultrasonic transducer exhibits a quasi-sinusoidal relationship with width. When the piezoelectric material width is 1.8 mm, the electromechanical coupling coefficient reaches its maximum at a thickness of 0.4 mm. Subsequently, simulations were conducted on various parameters of the flexible ultrasonic transducer array. Key investigations included the effects of piezoelectric unit count, inter-unit spacing, and frequency on the ultrasonic focusing performance of linear phased array transducers. Findings indicate that the focusing capability of flexible ultrasonic transducer arrays improves with reduced spacing and increased unit count. However, due to varying practical application requirements and manufacturing precision constraints, array parameters should be selected by comprehensively considering real-world factors. Overall, this study employs multiphysics coupling simulation to visually demonstrate how array element parameters influence the performance of flexible ultrasonic transducers. It provides valuable reference for advancing flexible ultrasonic technology from laboratory research toward commercial application
Investigation of transient processes in auxiliary asynchronous electric motors of locomotives using differential equations
Get PDFThe aim of this research is to scientifically substantiate the operating conditions of small and medium-power auxiliary asynchronous electric motors currently in use on mainline electric locomotives of the VL60, VL80, and Ermak 3ES5K types. The goal is to draw conclusions based on scientific research, such as evaluating the operational efficiency of auxiliary asynchronous electric motors and creating the possibility to predict their service life based on the assessment results. This, in turn, will enable timely maintenance of auxiliary engines in locomotives
Theoretical assessment of the mechanical properties of fiber concrete using the dispersion analysis method
Get PDFThis paper examines how the type of fiber and the amount of fiber in concrete impacts the mechanical characteristics of fiber-reinforced concrete (FRC) by both experimental testing and statistical modelling. Basalt, polypropylene, and steel fiber reinforced concrete specimen were cast at different percent ratios (0, 0.1, 0.2 and 0.3) and subjected to laboratory conditions to measure compressive strength. At every dose and fiber type, three specimens were tested, and average values of the strengths were computed. OriginPro was used to fit the data in polynomial regression models (second degree) to quantify the connections between the parameters of this fiber and compressive strength. The most important statistical indicators provided in the assessment of the model accuracy were coefficients of determination (R2), adjusted R2, F-statistics, p-values, and residual analysis. The results revealed that the models were all characterized by high predictive accuracies (R2= 0.72, 0.93) and found to be significant using ANOVA (p< 0.0001). Results validated that the type of fiber along with the dosage were critical in the effectiveness of strength with optimal amount enhancing performance and loads beyond or below those levels decreasing the matrix bonding. The produced models offer a predictive predicting model that would be helpful in FRC mixture optimization. The study presents significant information in the field of structural engineering where a newly established structure will be needed to have superior durability, dependability, and load capacity
Graphical analytical modeling of the kinematic scheme of a rock-piston pump
Get PDFTwo kinematic diagrams are presented, consisting of two combined toggle mechanisms and a piston pump. Kinematic calculations of the moving link parameters for both kinematic diagrams resulted in the determination of the displacement of the working and idle stroke lengths S of the piston as a function of the toggle mechanism swing angle φ and the change in the toggle length and crank radius of the piston pump. The numerical value of the coefficient K of the average toggle mechanism slider velocity, K= 2, and the displacement of the piston stroke S were obtained: for a toggle-piston pump, S= 1.25, and for a crank-toggle mechanism, SK= 0.7 m. Various asymmetric phase angles were calculated for the working φp and idle φx strokes of the slider during rotation of the toggle mechanism crank for both kinematic diagrams. The relationship between the center distance α and the position of the fixed support point O1 of the crank axis of rotation to the support point O2 of the rocker arm is obtained. The numerical values of the stroke displacement SD, linear velocity VD, and acceleration αD of the pump piston for both kinematic diagrams of the rocker-piston pump mechanism are presented in tabular form by numerical values and in kinematic diagrams
Dual-stator ultrasonic motor achieving 2-DOF linear and rotary motion with single-phase excitation
Get PDFThis study proposes a novel dual-stator linear-rotary ultrasonic motor. The piezoelectric ceramic excites both out-of-plane and in-plane vibration modes within the stator. These distinct vibration modes independently drive the slider (rotor), generating reciprocating linear and rotational motions, respectively. Finite element analysis and laser vibrometer-based vibration testing validated the motor's operational principle. The close agreement between simulated and measured resonant frequencies for both vibration modes, with mere discrepancies of 3 % and 4 %, respectively, underscores the accuracy of the stator’s vibrational characteristics. Subsequently, two stators are fabricated and assembled to the ultrasonic motor prototype. Experimental results demonstrate the motor’s impressive performance, achieving a maximum linear velocity of 265 mm/s and a peak rotational speed of 1600 rpm. Furthermore, the motor delivers a maximum thrust force of 0.18 N and a stalling torque of 1.8 mN·m
Design and verification of a new type of hydraulic vibration isolator for high-speed train floors
Get PDFWith the development of high-speed trains, the requirements for noise, vibration, and comfort are becoming increasingly stringent. The train body floor, as one of the main pathways for vibration transmission, is crucial to be treated for vibration reduction and noise attenuation. This paper, in response to this demand, has developed a new type of floor vibration isolator specifically for high-speed trains. Through finite element simulation analysis and experimental verification, it has been proven that this vibration isolator can effectively reduce the vibration of the train body floor and significantly enhance the NVH (Noise, Vibration, and Harshness) performance of the train
Experimental analysis of the process of purifying transformer oil from various impurities under the influence of a constant electric field and assessment of mathematically modeled results
Get PDFThis paper has examined the cleaning of transformer oil by using electricity field on a theoretical and practical basis. Scientific analysis was done on the physicochemical characteristics of the oil and the effects of impurities on the electrical insulation characteristics of oil. A mathematical model explaining the movement of impurities under the action of an electric field was constructed on the basis of which, the extent of oil purification was established. According to the carried out theoretical and practical studies, the efficiency of transformer oil purification by constant electric field was tested. Based on the findings of theoretical modeling, the level of oil extraction against mechanical impurities is 40, and the electrical strength of the oil is enhanced by 16 and based on the findings of experiments that are carried out under laboratory conditions, the electrical strength is enhanced by 21. Due to the comparison between theoretical and practical outcomes, the deviation of the electrical strength indicator of the oil does not exceed 5 % and this fact supports the validity of the theoretical model developed. It was also determined that the purification process is affected by environmental factors like temperature, humidity, strength of electric field and composition of the oil. Enhancing oil purified in constant electric field is one of the effective solutions to the enhancement of the reliability of transformers and their service life
The effect of Cranial Postural Balance (CPB) appliance on re-establishing mandible and body posture in an adult patient. Case report
Get PDFThis case report intends to present a functional appliance designed by the first author, that follow the principles expected for all functional appliances. It is not anchored on teeth. It does not produce mechanical forces and uses tongue and mandible posture change as natural forces. The appliance was used for 24 months, only to sleep. The patient came complaining discomfort with improper occlusion of the teeth and temporomandibular pain. Body balance was evaluated by DIERS and was also altered. It was possible to find out the presence of a unilateral crossbite and alteration on condyle position inside the cavity evaluated by CBCT. After the treatment with CPB (Cranial Posture Balance) appliance associated with osteopathic procedures, the occlusion and the temporomandibular complains were improved
Design of a composite repetitive controller for grid-connected inverters with a notch filter
Get PDFTo address the resonance peak issue of LCL (Inductor capacitor inductor) grid-connected inverters at the resonant frequency and reduce system losses caused by passive damping, this paper proposes a novel plug-in composite repetitive controller based on an active damping strategy utilizing a notch filter, along with detailed parameter design for the controller. Simulation results demonstrate that the notch filter-based repetitive controller maintains high gain at the fundamental frequency while exhibiting rapid gain attenuation at higher frequencies. Since the harmonic content of the inverter system is predominantly concentrated in the low-frequency range, the controller achieves excellent harmonic suppression performance within the low-frequency region. The low gain at high frequencies enhances system stability. Compared with conventional repetitive controllers, the proposed controller adopts a low-loss notch filter damping method, preserves the superior harmonic suppression capability (the grid current harmonic is reduced by 1.37 %), and improves system stability
Comparison of different experimental methods for measuring droplet size in inkjet printing
Get PDFIn the inkjet printing process, controlling the droplet size is essential to ensure uniform thin film, a critical factor for achieving high performance of electronic devices. In this study, we evaluate the accuracy and applicability of three droplet measurement methods using inks with different properties. The first method is the laser diffraction method, which measures individual droplets based on the Fraunhofer diffraction in real time. The second is the mass measurement method, which calculates the droplet mass using a microbalance and employs evaporation compensation to minimize evaporation effects, and the third method is the shadow imaging method, a widely adopted commercial technique based on the international standard. To evaluate the accuracy of these measurement methods with three inks having various boiling points (BP), laser diffraction serves as a benchmark here to compare the results of the shadow image and mass measurement methods. Laser diffraction was selected because it shows better coefficient of variation about 1.7 % than the coefficient of variation of mass measurement and shadow imaging methods about 8.7 % and 6.4 %, respectively. The BP of the ink and measurement precision based on laser diffraction results were proportional to each other. These insights guide the selection of optimal measurement method for inkjet printing applications with printed electronic inks. When printed electronic inks with various boiling points were used, the laser diffraction method consistently demonstrated better measurement errors in droplet size than the mass measurement and the shadow imaging method