Jaw Functional Orthopedics and Cranoficial Growth
Not a member yet
968 research outputs found
Sort by
Random vibration analysis and mechanical performance research of large-span spatial structures using new building materials
No full textIn order to analyze the performance of large-span spatial structures made of new building materials, improve the seismic resistance of large-span spatial structures made of new building materials, analyze the random vibration of large-span spatial structures made of new building materials, and determine the mechanical properties of large-span spatial structures made of new building materials. The paper takes carbon fiber reinforced polymer (CFRP) as an example, and prepares CFRP large-span structural specimens through surface coating treatment of carbon fiber and composite material preparation process; Enhancement effect of interfacial bonding strength of CFRP large-span spatial structures through bidirectional shear experiments; Design large-span spatial structures of carbon fiber composite buildings and establish multi-scale finite element models of vibration reduction systems; Analyze the random vibration of large-span spatial structures, improve the Kanai Tajimi model through the random vibration power spectral density function, calculate the structural response power spectrum, analyze the response of CFRP large-span spatial structures through the H-V coherence function model, and verify the mechanical properties of CFRP material large-span spatial structure specimens through experiments. The test results show that after the tensile test, the CFRP specimen connecting plate did not fail, indicating that the CFRP specimen has a significant impact on its connection strength in this situation. However, the compression and shear failure of the CFRP large-span spatial structure specimen will occur in local areas due to the compressive action of the specimen
Modal analysis and optimization design of ultra-high acceleration platform rail frame
No full textThe ultra-high acceleration macro and micro motion platform has the advantages of high positioning accuracy and small error, and the key mechanism rail frame of the ultra-high acceleration macro and micro motion platform is optimized based on modal analysis to achieve the performance optimization of the platform. SolidWorks software was used to build the rail frame model, and ANSYS Workbench software was used to carry out modal analysis, topology optimization and response surface optimization, etc., so as to reduce the quality of the rail frame as much as possible under the premise of maintaining the stability of the first-order natural frequency. The results show that the optimization of the response surface meets the expected goal, the first-order natural frequency of the guide rail frame increases by 0.7 %, the mass decreases from 6.165 kg to 5.592 kg, and the change rate is 9.2 %, which achieves the purpose of lightweight
Modal analysis of key components of crusher based on digital simulation technology
No full textThe modal characteristics of the crusher rotor and shell constitute the crucial factors influencing vibration and noise. Based on the principle of simplification, the rotor component model was established. Through mesh optimization, the model accuracy and calculation efficiency can be ensured, and the calculation of natural frequency and modal shapes was completed based on ANSYS. To verify the accuracy of the finite element model, the modal test was carried out by the hammering method. Sensors were set in three different directions to obtain the frequency response function and the modal assurance criterion matrix mode confidence criterion. Using the same research method, the modal characteristics of the shell model were simulated and analyzed. The research results show that the modal parameters identified by the modal test are basically consistent with the simulation model. The natural frequencies of the rotor and the shell are quite different from the excitation frequency of the motor, and resonance problems will not occur when the crusher is proper functioning
Simulation analysis of force and fatigue life of circular wheel of crawler vehicle
No full textDuring loading and driving, the wheels bear the vertical load from the body mass and the excitation load generated by uneven road surface on the one hand, and bear the driving torque on the other hand. The load-bearing methods of wheels are generally divided into bottom load-bearing and top load-bearing. This paper describes the structural characteristics of the track system of the articulated track vehicle and the interaction relationship between the main components of the track system. Finite element calculation is carried out based on ANSYS software to obtain the stress distribution of each key component under various loading methods. It can be seen from the results that all key components of the track system can meet the strength and rigidity requirements; although there are also areas with large local stress, they are all within the safe range, which is mainly caused by stress concentration. Safe life is obtained through fatigue analysis
Ameliorating vibratory roller quality based on two methods of cab’s horizontal damper and cab’s active suspension
No full textTo reduce both the seat's vertical acceleration and cab pitching vibration in vibratory rollers, an active horizontal seat suspension (AHSS) is proposed and researched based on the dynamic model of the vibratory rollers moving and working and off-road grounds. The fuzzy control is applied to calculate the control force of the AHSS. The indexes in the Root Mean Square acceleration in the seat (RMSas) and cab pitch angle (RMSaφ) have been selected as the objective functions. The isolation performance of the HASS is then compared with the cab isolations controlled (CC) and without control (WC) under two conditions of the vibratory roller moving and working on the off-road surface. The study results show that the vibratory roller’s quality using the AHSS has been strongly ameliorated in comparison with both the CC and WC under both moving/working conditions. Especially, comparison with the WC, both the values of RMSas and RMSaφ with the AHSS are greatly reduced by 54.2 % and 52.6 % under the moving case and by 44.5 % and 50.0 % under working conditions of the vibratory roller. Therefore, the AHSS should be applied to improve both the seat's vertical comfort and shaking in vibratory rollers
Reliability analysis of cable crimping terminals with different applicator tools
No full textThis study provides a comprehensive evaluation of the stability of crimping of the same terminal on FLRY A cables using three different applicators. The research involved conducting pull tests on 50 samples for each applicator type, analyzing the results using Minitab software to assess the consistency and strength of the crimp connections. The findings indicate that while the Demirel applicator produces the highest average pull test values, the Tyco applicator demonstrates superior consistency, making it more suitable for applications where process stability is critical
A broadband variable fluid damper with frequency selective valves for spacecraft micro-vibration isolation
No full textIn order to improve the vibration isolation performance of current three-parameter damper using bellow and fluid damping, a concept of fluid damper with variable damping and secondary variable stiffness was proposed, a prototype has been designed with several frequency selective valves to adjust the damping characteristics at specific frequency bands, especially that in the low-frequency range. Followed mathematical modelling and simulation of the damper have been carried out, the results show that the designed damper has obtained excellent damping characteristics both in the high- and low-frequency ranges, the micro-vibration isolation efficiency of the damper under realistic excitation of a Control Moment Gyroscope used in a manned spacecraft reaches a significant 71.03 %.The proposed damper concept and designed prototype have laid the foundation for further testing and optimization of high-end isolators for modern spacecrafts
Application of modal analysis to multi-objective optimization of gear box
No full textThe high stiffness and low mass gearbox structure design requirements were met through multi-objective optimization based on finite element modal analysis. The correlation between structural parameters and optimization objectives was identified, providing guidance for optimal design. A parametric finite element model of the box cover was established to calculate the first-order modal shape and equivalent stiffness. By using mass and equivalent stiffness as optimization objectives, a discrete data set was constructed with key dimensions of the box cover as design variables, from which a surrogate model was obtained. Standard response surface and full second-order polynomial fitted response surface function were applied after error verification. Different optimization algorithms were employed to search for the optimal value, resulting in obtaining design variables meeting the optimization objectives. The results indicated a reduction in optimized mass by approximately 6.8 %, with an error of less than 1 %
Assessment of the impact of TE33A diesel locomotive wheelsets on the railway track in a straight section of the track
No full textThe purpose of the article is an experimental study of the impact of the wheelsets of a mainline diesel locomotive on the railway track on straight sections of the track. The measurements were performed on a vibration measuring device consisting of MV25 DV type sensors and an oscillation converter for a digital signal. It is proved that the indicators of dynamic characteristics comply with regulatory requirements. As a result of the conducted research, digital data was collected from the ADC and general monitoring was carried out. Measurement and signal processing are carried out using special software of a personal computer such as a “Notebook”. Vertical static load of a wheelset of a railway rolling stock unit on rails: the load of a railway rolling stock unit on rails attributed to one wheelset, taking into account the actual location of the center of gravity of the superstructure
Motor fault diagnosis based on composite multi-scale weighted reverse slope entropy and neighborhood preserving embedding
No full textThe motors are critical components of the electromechanical transmission in vehicles, and its operating status directly affects the maneuverability of vehicles. To quickly and accurately identify the operating status of motors, this paper proposes a new entropy - Composite Multi-scale Weighted Reverse Slope Entropy (CMWRSlE) for motor fault diagnosis, which is a more interpretable entropy due to its deep exploration of signals. Firstly, the composite multi-scale weighted reverse slope entropy values are extracted from the vibration signals of the motor in different states; Secondly, the extracted features are dimensionally reduced by the manifold learning algorithm – Neighbourhood Preserving Embedding (NPE) and classified by the hierarchical prototype-based approach (HPA) to achieve the fault diagnosis of the motor. Finally, the method proposed in this paper is validated through two sets of experimental data: motor rotor faults and motor bearing faults. The results show that the accuracy of the proposed method in motor fault diagnosis reaches 100 %, which indicates the effectiveness of the proposed method