Vibration Speed Research Articles

Improving Dynamic Performance of a Small Rhizome Chinese Herbs Harvesting Machine via Analysis, Testing, and Experimentation

The small rhizome Chinese herbal medicine harvesting machine is used for excavating the underground rhizomes of Chinese medicinal plants. The reliability of an existing machine of this type was found to be suboptimal due to high vibration levels, as confirmed by direct measurements. To remedy this issue, the differential equation of motion was derived, solved, and visualized using MATLAB software (R2017a). The impact of various parameters on the equation of motion was analyzed through both time and frequency domain plots, as well as experimental analysis. The parameters studied included the rotational speed of the tractor’s power take-off (PTO) shaft, the machine’s overall mass and stiffness, the transmission ratio, and the excitation force generated by the machine’s reciprocating parts. To reduce vibration in the non-resonant state and avoid resonance as the natural frequency changes, several modifications were necessary: the PTO speed needed to be controlled, the stiffness of the machine had to be increased, and the mass of the reciprocating parts had to be decreased. Additionally, expanding the transmission-ratio range of the operational machinery was essential. Sandbags were added to the machine’s frame to increase its overall mass. The above measures have reduced the vibration speed of the harvester during operation. The vibration speeds Vmax and VRMS of the harvester under both working and non-working conditions have decreased by half compared to their original values, reducing the occurrence of resonance in the harvester and effectively mitigating vibration damage, thereby enhancing operational reliability.

Experimental Study of an Industrial Data Transmission Network in the Automatic Control System of a Wind Turbine

This article explores and optimizes network technologies for wind energy systems, focusing on the RS-485 interface to ensure reliable data transmission in extreme conditions. The study aims to address the impact of various distortions on data quality and wind turbine management. A system was proposed with two wind turbines, each equipped with a Raspberry Pi 4, connected to sensors measuring temperature, vibration, and wind speed. The research examined how data transmission rates affect signal shape, calculating the distortion coefficient. At 460,800 baud, the signal was almost completely distorted, with significant amplitude loss. The distortion coefficients were 1.84 for logic ‘1’ and 1.92 for logic ‘0’. The optimal speed to minimize distortions was found to be 19,200 baud, providing the most stable signal. Additionally, temperature significantly impacted transmission quality, highlighting the need to consider climatic conditions in system design. The findings and methods can help improve existing data transmission systems and enhance wind turbine performance.

Effect of Ultrasound on Microstructure and Properties of Aluminum–Copper Friction Stir Lap Welding

In this paper, the influence mechanism of ultrasound on plastic flow and microstructure features of the aluminum–copper friction stir lap welding (Al/Cu-FSLW) process is systematically investigated by adjusting the welding speed and improving the shear rheology in the plastic stirring zone. Through adjusting the ultrasonic vibration and welding speed, the directional control of mechanical properties is realized. It is found that increasing the welding speed properly is beneficial to enhance the mechanical shear between the tool and the workpiece, thus forming more staggered layered structures at the copper side and improving the tensile strength of the weld. The acoustic softening enhances the viscoplastic fluid mixing and strengthens the mechanical interlock of the Al/Cu lap interface. As the welding speeds increase or ultrasonic vibration is applied, the thickness of Al/Cu intermetallic compound (IMC) decreases, and the tensile strength and elongation of the Al/Cu joints are enhanced. Compared with adjusting the welding speed, the ultrasonic vibration can further refine the copper particles which are stirred into the plastic zone, and the thinning effect of ultrasound on IMC layers is better than that of increasing welding speed. At the welding speed of 60 mm/min, the IMC layer thickness is reduced by 42% under ultrasonic effect. In three welding speed conditions, the UV reduced the absolute value of the effective heat of formation (EHF) for Al2Cu and Al4Cu9 and suppressed the formation of AlCu phase. Meanwhile, only when the welding speed is increased from 60 mm/min to 100 mm/min can the formation of AlCu be suppressed. Under the ultrasonic optimization, the stable improvement of welding efficiency is ensured.

Rotary ultrasonic surface machining of silicon: Effects of ultrasonic power and tool rotational speed

The surging demand for monocrystalline silicon materials in the production of microelectronic components highlights its crucial role in the semiconductor and optic industries. Hence it is inevitable to produce a silicon workpiece with high quality finish to meet the demand in semiconductor industries. Due to high brittleness, controlling the quality of silicon in surface machining is quite difficult. Traditional manufacturing processes induce issues like rough surfaces and edge chipping. It was reported that rotary ultrasonic surface machining (RUSM) can effectively reduce cutting force, roughness, and edge chipping in machining of brittle materials. There have been several studies on drilling and sliding silicon materials using rotary ultrasonic machining investigating the effects of machining parameters on the output variables such as cutting force, torque, edge chipping, surface roughness etc. However, to the best of the authors’ knowledge, there are no reported investigations on effects of machining variables (ultrasonic power and tool rotation speed) in surface machining of silicon materials using the rotary ultrasonic machining. This study aimed to investigate the impacts of ultrasonic power and tool rotation speed on the cutting force, edge chipping, and surface roughness. Experimental results show that the ultrasonic vibration and tool rotation speed had a notable impact on edge chipping and cutting forces. Lastly, the current research has paved the way for widening the research on investigating grinding of the silicon wafer in semiconductor manufacturing with ultrasonic vibration and high rotation speed. In semiconductor wafer manufacturing, grinding process is used to reduce the flatness but generate surface and subsurface damage. With further investigations, RUSM can contribute to reducing these damages.

A continuous concrete vibration method for robots based on machine vision with integrated spatial features

The traditional manual concrete vibration work faces numerous limitations, necessitating efficient automated method to assist in this task. This study proposes a vision-based continuous concrete vibration method for vibrating robots. By enhancing the YOLOv8n model with attention mechanisms, our proposed method demonstrates a high AP of 93.31 % in identifying reinforcing grids, and an FPS of 25.6 on embedded systems. For the first time in concrete vibration tasks, this study utilizes spatial positional information to cluster coordinate data, transforming confidence-sorted data into spatially ordered sequences. Vibrating robot case test shows that the proposed method enhances the vibration speed by 22.18 % and improves the vibration success rate by 11.67 % compared to traditional strategies. Additionally, the on-site experiment conducted at four construction sites demonstrated the robustness of the proposed method. These findings advance automation in concrete vibration work, offering significant implications for the fields of robotics and construction engineering.

Fault diagnosis of new type screw compressor of helium liquefier by vibration signal

A diagnostic method for screw compressor faults using vibration signals was introduced and applied to a new type of helium oil-injected screw compressor in the 80L/h helium liquefier. The study revealed that the destruction of the oil film due to impurity particles could lead to rotor rubbing and poor meshing, compromising the reliability of these compressors. Based on frequency-domain analysis, the major vibration occurred at the meshing frequency of screw rotors and a series of its harmonics. The vibration of the characteristic frequency of bearing parts also indicated that the bearing had slight wear in the early stage. The vibration waveform’s time domain diagram exhibited clear clipping, and the axis trajectory shew disorder, which were common characteristic of rotor rubbing. When compressing helium with low molecular weight, the meshing clearance, tooth tip clearance, and end clearance of the rotor were significantly lower than those of traditional refrigerants or air media. Additionally, the thermal gap caused by thermoelastic deformation was smaller due to the large adiabatic index of helium. Therefore, rubbing faults between rotors and between rotors and casing were more likely to occur. The article recommended establishing a vibration signal monitoring system, optimizing the design of helium screw rotor profiles, and setting up reliability standards for screw compressor operation, such as limiting the vibration speed to ≤ 8 mm/s. Additionally, attention should be given to cleaning gas pipelines in cryogenic engineering and monitoring compressor vibration and noise signals during operation to prevent rotor damage due to particle impurities.

Design and Implementation of Real-Time Sensors for Three-Phase Induction Motor Performance Monitoring using Internet of Thing (IoT)

This article delves into the design and implementation of cost-effective sensors tailored for real-time monitoring of three-phase induction motor performance. The research primarily centers on the assessment of the operational effectiveness of a suite of sensors, including the PZEM-004t power sensor, MLX90614 temperature sensors, NJK-5002C rotation sensors, and ADXL345 vibration sensors, within the context of three-phase induction motor performance analysis. The monitoring system for three-phase induction motor performance is built around the ESP-32 platform, incorporating the ADXL345 vibration sensor. This article successfully presents the individual sensor performance, which was systematically evaluated through testing on a three-phase induction motor that had been meticulously designed and closely observed. The unit tests reveal that all sensors employed in the experiments exhibit an average error rate of less than 5%. When assessed as an integrated system, the three-phase induction motor performance monitoring system demonstrates robust functionality, effectively measuring critical variables such as voltage, current, power factor, temperature, vibration, and rotational speed.

Pengaruh Ketinggian Beban Jatuh dan Kekentalan Oli Suspensi Depan Terhadap Getaran Shock Absorber Sepeda Listrik

One important aspect in choosing a vehicle is comfort, where the suspension plays a significant role. The main suspension component, namely the Shock Absorber, has a crucial role in minimizing vibrations and optimizing driving comfort. The function of the Shock Absorber depends on the viscosity value of the damper, which must support the effectiveness of the suspension. A quantitative experimental type approach was used by taking data using a Vibrator meter. The test is carried out by dropping a load on a load test tool with predetermined variables with the aim of obtaining vibration values ​​on the Shock Absorber. This type of synthetic oil with a viscosity of 77.22 mm²/s, which is used as a filler for the front shock absorber on e-bomber electric bicycles, has the lowest viscosity among other types of oil, resulting in the highest vibration speed. The type of mineral oil with a viscosity of 79.35 mm²/s, which is used as a filler for the front shock absorber on e-bomber electric bicycles, has the highest viscosity among other types of oil, resulting in the lowest vibration speed. This type of semi-synthetic oil with a viscosity of 78.31 mm²/s, has a viscosity that is between synthetic and mineral oil types, resulting in a higher vibration speed compared to synthetic oil types but lower than mineral oil types.

Simulation research on blasting of an open pit mine slope considering elevation conditions and slope shape factors

This study established a numerical model that considers elevation conditions and slope shape factors by the modified Sadovsky formula to analyze the vibration attenuation law of open-pit slopes under blasting vibration conditions. The blasting excavation of a slope in a certain open-pit mine in Yunfu, Guangdong, is selected as an example. Using a numerical model that considers elevation conditions and slope shape factors by the modified Sadovsky formula, a triangular pulse load was utilized to approximate the time-history characteristics of explosion vibration with FLAC3D software. The simulation results showed the radiation range of the blasting vibration seismic wave. By comparison with field monitoring data, the numerical model that considers the slope shape factor had a relative error of ∼10%, while the numerical model that disregards the slope shape factor had a relative error of ∼15%. The relative accuracy of the calculation results of the new numerical model is higher and closer to the actual attenuation law of blasting particle vibration speed, providing more reliable results for slope stability assessment. The peak particle velocities obtained from the numerical simulation results were generally higher than the field monitoring data. These discrepancies might be attributed to the use of simplified models that disregard the discontinuous structural planes within the rock mass. This study provides an important reference for the stability assessment of open-pit slopes under blasting vibration conditions, offering guidance for improving slope stability assessment and related engineering practices.

Simulation Analysis and Experimental Research on Vibration Characteristics of Series Reactors in Multiple Operating Status

Abstract This article examines the vibration properties of reactors across various operational scenarios, including normal operation, interturn arc short circuit faults, and interturn metal fusion short circuit faults. It begins by analyzing the vibration mechanism of reactors, drawing upon principles of electromagnetic induction and Ampere’s law. Then, a multi condition mechanical-electromagnetic interaction model was established for the series reactor, and the axial electrodynamic force distribution of the reactor was analyzed. Finally, a vibration characteristics test platform for series reactors under multiple operating conditions was built, and the vibration velocity distribution of the reactors was analyzed. The research results indicate that under normal operating condition, the maximum vibration velocity of the reactor appears at its lower end; When the Interturn arc short circuit fault occurs, the vibration speed at different positions of the reactor increases, and the vibration velocity at the short-circuit point will significantly increase with the development of the short-circuit fault; When the interturn metal fusion short circuit fault occurs, the amplitude of the vibration signal at the short-circuit point is greater than that of the arc short-circuit vibration signal.

Modeling damped spring vibration using python to train students' critical thinking and scientific reasoning

Programming has been carried out to model the vibration of a mass spring system with no damping and with damping variations using Python programming language coding. This research aims to simulate the simple harmonic vibration of a mass spring (without damping) and the vibration of a damped mass spring. The programming is designed after formulating the equations of motion of damped mass spring vibrations that behave as second-order differential equations and analyzing the numerical formulation of the Feynman-Newton algorithm arrangement. The method used is experimentation using python to simulate the vibration of the spring. Simulation by varying the damping constant (c = 0, c < √4mk, c = √4mk, and c > √4mk). The simulation results show various vibration graphs, namely simple harmonic vibration, under damped vibration, critically damped vibration, and over damped vibration. The shape of the vibration graph is influenced by the mass, spring constant, and damping constant. The greater the damping constant, the less the maximum speed of vibration. This research has succeeded in visualizing the simple harmonic vibration of a massless spring (without damping) and the vibration of a damped massless spring. This modeling can help the physics learning process in high school in understanding the concept of spring vibration to obtain critical reasoning in accordance with physical phenomena. Modeling of damped spring vibrations using Python can be used as a physics learning media on vibration material to train scientific and critical reasoning skills, and as a learning innovation because it is a new thing where the curriculum and high school learning in Indonesia are not used to being delivered.

Simultaneously enhanced electrical properties and high-power characteristics of (K,Na)NbO3 lead-free piezoceramics by hot-pressing

Piezoelectric materials enabling direct conversion between electrical and mechanical energies are ubiquitously implemented in high-power apparatuses, where both superior piezoelectricity and high-power performance are demanded. However, it remains a challenge to simultaneously achieve the two goals, which are hindered by their antagonistic relationship. Herein, hot-pressing is employed to address this dilemma, as exemplified in lead-free (K,Na)NbO3 (KNN) piezoceramics. In contrast to the samples prepared using normal sintering (NS–KNN), hot-pressed KNN (HP–KNN) polycrystals show higher density, lager piezoelectricity (d33∼129 pC/N), and more active domain wall movement. In particular, the normalized strain d33* of HP-KNN piezoceramics exhibits high thermal stability (variation of d33*<10 %) in a broad temperature range from ambient temperature up to 150 °C. Moreover, the HP-KNN samples show superior high-power characteristics with a maximum vibration speed of 1.1 m/s, which is almost 78 % larger than that of NS-KNN. This study not only demonstrates that the HP-KNN lead-free piezoceramics hold great potential for high-power implements, but also opens a new avenue for integrating antagonistic properties for the enhancement of the collective performance in functional materials.

Fourier-Based Vibration Model of Electrical Machines Considering Nonideal Orthogonality Between Electromagnetic Forces and Structural Modes

This paper proposes a Fourier-based model of vibration synthesis, improving both precision and speed. For the first time, the nonideal orthogonality between electromagnetic (EM) forces and structural modes is theoretically proposed and modelled by spatial harmonics. Different from the discrete vectors used in previous literature, the proposed method achieves a one-dimension (1-D) continuous model of EM forces and modes. On the basis, the vectors of modes and forces on tooth surfaces are decomposed by fast Fourier transform (FFT), so that the vibration response is synthesized based on Fourier coefficients. Further, the proposed model is applied to a 12-slot/10-pole (12s/10p) interior permanent-magnet (IPM) machine. The spatial harmonics of mode vectors are elaborated to identify the key orders of EM forces before the vibration response is completed. Then, the proposed model is compared with the coupled-field finite element analysis (FEA). The advantages are verified in terms of computational accuracy, speed, and sensitivity to mesh quality. Finally, the feasibility of the proposed model is verified by both coupled-field finite element analysis (FEA) and experiment.

Vibration, Buckling and Stability Analyses of Spinning Bi-Directional Functionally Graded Conical Shells

This paper investigates the free vibration, buckling and dynamic stability of spinning bi-directional functional gradient materials (BDFGMs) conical shells. The material properties vary along the thickness and axial direction. The dynamics model is established based on the first-order shear deformation theory and the governing equations and boundary conditions of the conical shell are derived employing Hamilton’s principle. Subsequently, the differential quadrature (DQ) method is employed to discretize the governing equations into an algebraic system of equations for solving and analyzing the free vibration characteristics of the conical shell. The theoretical model’s accuracy and the solution method’s reliability are rigorously verified. The effects of temperature, functional gradient index, and rotation on the vibration characteristics, traveling wave vibration and critical speed of the conical shell in a thermal environment are systematically explored through numerical analysis. The results indicate that both the material gradient index and temperature increase lead to a decrease in the shell’s natural frequency. For the spinning BDFGMs shell, elevated temperature causes the occurrence of trailing wave vibration to advance to the critical speed. Centrifugal force emerges as the primary factor influencing the critical buckling load and unstable region variation of the spinning shell.

Investigation of the effect of ultrasonic vibration on the performance of the friction drilling by FEM simulation

The friction drilling process is very important in various industries such as automotive, aerospace, and oil and gas industries. Therefore, they have always sought to find methods to improve this process. One of these methods is to optimize the application of ultrasonic vibrations in the process, and limited research has been done in this regard. The current research aims to investigate the effect of ultrasonic vibrations simultaneously with the parameters of drilling on the friction drilling process to optimize this process with the help of finite element simulation. Due to the nature of the complex transformations of the process, a Coupled Eulerian–Lagrangian model of the process was first created in the Abaqus software. Then, the process simulation was carried out in the presence and absence of ultrasonic vibrations. Rotational speed, feed rate, and amplitude of vibrations are the influencing parameters, and sheet temperature and axial force, and torque applied to the tool are the parameters investigated in this research. The results show that higher rotation speed and lower feed rate lead to a reduction of axial force and torque. Also, the application of ultrasonic vibration reduces up to 50.48% the axial force and up to 46.67% torque, and this reduction is improved by increasing the range of vibrations. The optimal mode was selected After analyzing 12 different modes based on the lowest amount of axial force and torque on the pin. It was found that the ideal mode occurs at a feed rate of 4.23 m/s and a rotation speed of 3000 rpm, with a 20-µm range. These findings and optimizing drilling parameters bring new horizons in material bonding techniques in various industries.

Editorial

Dear Readers, It gives me great pleasure to announce the third regular issue of 2024. In this issue, 6 papers by 20 authors from 6 countries - China, Ecuador, Spain, The Netherlands, Turkey, United Kingdom - cover various topical aspects of computer science. In a continuous effort to further strengthen our journal, I would like to expand the editorial board: If you are a tenured associate professor or above with a strong publication record, you are welcome to apply to join our editorial board. We are also interested in high-quality proposals for special issues on new topics and trends.&amp;nbsp; As always, I would like to thank all the authors for their sound research and the editorial board for their extremely valuable review effort and suggestions for improvement. I also want to thank the readers for their interest on our articles indicated by an increasing access number and PDF downloads. These contributions, together with the generous support of the consortium members, sustain the quality of our journal.&amp;nbsp; In the third regular issue, I am very pleased to introduce the following 6 accepted articles: In a collaboration between researchers from The Netherlands and the United Kingdom, Jan Bergstra and John V. Tucker discuss their research on synthetic fracterm calculus, more specifically they introduce a new intermediate and informal axiomatisation of elementary arithmetic. Yasir Yakup Demircan and Serhat Ozekes from Turkey highlight their research on least significant bit steganography technique based on image segmentation. In a collaborative research effort between Spain and Ecuador, Alberto Jimenez-Macias, Pedro Mu&amp;ntilde;oz-Merino, Margarita Ortiz-Rojas, Mario Mu&amp;ntilde;oz-Organero, and Carlos Delgado-Kloos present their study on a systematic literature review on content modeling using machine learning algorithms in smart learning environments considering content indicators based on student interaction. Melih Kuncan, Kaplan Kaplan, Y&amp;#305;lmaz Kaya, Mehmet Recep Minaz, and H. Metin Ertun&amp;ccedil; from Turkey focus on computer numerical control (CNC) systems, more specifically on classification of CNC vibration speeds by Heralick features. Lifang Ren, Jing Li, and Wenjian Wang from China address in their research support vector regression (SVR) and the location-aware method for mobile QoS prediction to overcome the difficulty caused by the sparsity of data and to predict the unknown QoS more accurately. Last but not least, Emre Sad&amp;#305;ko&amp;#287;lu, &amp;#304;rfan K&amp;ouml;sesoy, and Murat G&amp;ouml;k from Turkey look into the vulnerability of artificial systems to cyber-attacks by applying a gradient descent-based method to generate fake data. Enjoy Reading! Cordially,&amp;nbsp; Christian G&amp;uuml;tl, Managing Editor-in-Chief Graz University of Technology, Graz, Austria

Classification of CNC Vibration Speeds by Heralick Features

In the contemporary landscape of industrial manufacturing, the concept of computer numerical control (CNC) has emerged due to the optimization of conventional machinery, distinguished by its remarkable precision and expeditious processing capabilities. These inherent advantages have seamlessly paved the way for the pervasive integration of CNC machines across a myriad of industrial manufacturing sectors. The present study embarks upon a comprehensive inquiry, delving into the intricate analysis of a specialized prototype CNC molding machine, encompassing a meticulous assessment of its structural rigidity, robustness, and propensity for vibrational occurrences. Moreover, an insightful exploration is undertaken to discern the intricate interplay between vibrational signals and intricate machining processes, particularly under diverse conditions such as the presence or absence of the cutting tool, and at varying rotational speeds denoted in revolutions per minute (RPM). The trajectory of this research voyage encompasses an extensive array of empirical experiments meticulously conducted on the prototype CNC machine, with synchronous real-time acquisition of vibrational data. This empirical journey starts by generating two distinct datasets, each meticulously designed to encompass an assemblage of seven distinct rotational speeds, spanning the spectrum from 18000 to 30000 RPM, thereby facilitating enhanced diversity within the dataset. In parallel, a secondary dataset is meticulously derived from the CNC machine operating in the absence of the cutting tool, thereby encapsulating an exhaustive range of 20 discrete RPM values. The extraction of pivotal features aimed at discerning between the vibrational signals arising from distinct conditions (i.e., those emanating from situations involving the presence or absence of the cutting tool) and the associated variance in CNC machine speeds is facilitated through an innovative framework grounded in co-occurrence matrices. The culmination of this methodological framework is the identification of discernible co-occurrence matrices, thereby facilitating the subsequent computation of Heralick features. The classification effort was performed systematically using 10-fold cross-validation analysis, covering a number of different machine&amp;nbsp;learning models. The outcomes emanating from this intricate sequence of systematic methodologies underscore remarkable achievements. Specifically, the classification of vibrational signals corresponding to varying CNC machine speeds, contingent upon the presence or absence of the cutting tool, yields commendable accuracy rates of 94.27% and 94.16%, respectively. Notably, an exemplary accuracy rate of 100% is attained when classifying differing conditions (i.e., situations involving the presence or absence of the cutting tool) across specific RPM settings, prominently at 22000 &amp;nbsp;24000 &amp;nbsp;26000 &amp;nbsp;28000 &amp;nbsp;and 30000 RPM.&amp;nbsp;

Requirements for vibroacoustic methods of the quality assessment of vehicles traction electric motors

The progression and refinement of traction electric motors play a pivotal role in the enhancement of vehicles. With constant advancements in power efficiency, diagnostic tools, and reliability, electric traction motors are becoming more economical in terms of operational costs. This article underscores the significance of methods used in assessing the technical proficiency of traction electric motors, coupled with their testing techniques. The vibration characteristics of these motors serve as a prime criterion in assessing their quality throughout their lifecycle – from design and manufacturing to operation. A groundbreaking proposition made in this article is the evaluation of electric traction motors’ health based on their vibration acceleration within an expansive frequency range of 5 Hz to 10 kHz. This contrasts the conventional approach which focuses on vibration speed in a restricted frequency spectrum up to 1000 Hz, as outlined by current standards. Such permissible vibration classes are essential in ensuring the high-quality design, technical finesse, and dependability of traction electric motors. Exceeding these vibration thresholds can result in rapid wear and tear, diminishing the motor’s reliability and lifespan. Hence, motors that surpass these permissible vibrations are not advised for vehicular use. Additionally, the article sheds light on requisite equipment controls for accurately gauging vibrations and noise levels in electric motors. Delving deeper into the nuances, the methods for mounting vibration transducers and electric motors on testing platforms are elucidated. These methods are pivotal in obliterating any hindrances that could impede the precise measurement of vibrations induced by an electric motor.

Research on ultrasonic bone cutting mechanism based on extended finite element method.

The research on the crack propagation mechanism of bone has important research significance and clinical medical value for the selection of cutting parameters and the development of new surgical tools. In this paper, an extended finite element method (X-FEM) model of ultrasonic bone cutting considering microstructure was developed to further study the ultrasonic bone cutting mechanism and to quantitatively analyze the effects of cutting direction, ultrasonic parameters, and cutting parameters on the mechanism of ultrasonic bone cutting crack propagation. The results show that ultrasonic bone cutting is essentially a controlled crack propagation process, in which brittle crack and fatigue crack are the main crack propagation mechanisms. In order to improve the efficiency of ultrasonic bone cutting, large amplitude and high-frequency ultrasonic vibration are preferred. Compared with the other two cutting directions, the crack propagation deflection angle in the transverse cutting direction is the largest, resulting in the worst cutting surface. Therefore, in the path planning of orthopedic surgical robots, the transverse cutting direction should be avoided as much as possible. Frequency only has a significant effect on the crack propagation rate and has a positive correlation. There is a positive correlation between the deflection angle, propagation length, propagation rate, and amplitude, which provides the possibility to control the direction and length of crack propagation by controlling the amplitude of ultrasonic. The feed speed is much lower than the ultrasonic vibration speed, which makes the influence of ultrasonic vibration speed on the crack propagation characteristics dominant. The X-FEM model of ultrasonic bone cutting provides an effective method for selecting reasonable machining parameters of orthopedic robot and optimize the design of ultrasonic osteotome.

Seismic performance of soft rock tunnel under composite support conditions

In order to effectively improve the seismic and impact resistance performance of soft rock tunnels, a composite support method was proposed and validated in the paper. The UDEC (Universal Distinct Element Code) model of soft rock layers was established, and the movement and subsidence characteristics of the roof and floor of the rock layers under impact loads was simulated and calculated. As a result, a composite support scheme with good cushioning performance was proposed. The top and sides of the tunnel were supported by a combination of anchor rods of different lengths and metal mesh, reinforced by steel beams and vibration absorbing filler around. The anchor rod was designed as a segmented loading structure, and can be set to different preloading forces based on the internal deformation of the rock layer. The dynamic response testing scheme was designed, and the results indicate that the segmented loading anchor rod has a significant buffering effect on the response to impact load, and can provide reasonable tension feedback at different stages. Research has found that when the water cement ratio is 0.5-1.5, the curing efficiency and strength are both higher. In order to compare the seismic performance of composite support and traditional constant resistance anchor rod support, local blasting experiments were conducted. Based on a blasting vibration tester, a data detection and transmission system were designed to obtain the vibration speed of the tunnel roof during the vibration process. The research results show that composite support can reduce the maximum vibration by more than 40 %, stabilize the fragmentation coefficient at 1.38, and have a very significant vibration reduction effect.