Journal of Mechatronics and Artificial Intelligence in Engineering
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Prediction of operation vibration state of coal mine mechatronics equipment based on data mining
Get PDFIn order to explore the prediction of the operation vibration state of coal mine mechatronics equipment, the author proposes a method based on data mining in response to the problems of large amount of data in the operating state of coal mine electromechanical equipment, low data utilization, and slow speed of single-machine massive data mining, using Map Reduce technology, a dual Map Reduce mining prediction framework is proposed, establish a data mining prediction model for the running state of dual Map Reduce, using MapReduce1 to extract features of monitoring data, use MapReduce2 to predict and analyze feature data. Finally, by building the Hadoop platform, reveal the relationship between Hadoop cluster nodes and parallel processing speed, the efficiency of the data mining prediction framework is verified: Perform an experimental comparative analysis of the single prediction model and the proposed AGB combined prediction model, the prediction accuracy of the AGB combined prediction model is verified
Study on bearing mechanical and thermal characteristic evolvement rules affected by higher ambient temperature
Get PDFIn this paper, the bearing mechanical characteristics and thermal characteristics as it is running under constant speed (2400 r/min) and constant temperature (100 ℃) adopting bearing mechanical-thermal coupling model built on the basis of quasi-statics and elastohydrodynamic lubrication theory are discussed. Among which, the contact deformation between ball and inner/outer ring has same evolution law, besides, the same as the amplitude. Whose curve shape changes in the form of “circular-oblique D”, its amplitude rearches minimum value at 10thd3h between the location of 120° and 270°. The curve shapes belonging to contact angular between ball and inner/outer ring are similar to “circular”. There is opposite trend of them within the range of 90-300°. The amplitude of contact angular between ball and outer ring is the minimum at 10thd3h and 11thd1h. At the same time, the amplitude of that between ball and inner ring is the maximum. The evolution rules of contact stiffness between ball and inner/outer ring are generally consistent, which are similar to “crab”. But the amplitude of that between ball and outer ring is dominant. The maximum value of them occurs at 10thd3 and 11thd1h. The evolvement tendency of node temperatures maintains stable. Thereinto, the temperature of inner ring equals to that of contact location between ball and inner ring, which is the maximum value. It is obvious that ME, MD, MS, MCB, MCR and MOil devote themselves to heat production, the contribution rates of ME, MS, MCB and MCR are 100 %, the contribution rate of MD ranges from 52.6 % to 65.2 %. However, the amplitudes of friction moments have the opposite trend compared to “heat contribution factor”. The expansion amount owing to heat production is dominant in displacement variation and the effect of clearance on displacement can be ignored, whose evolution rules are contrary. The evolution rules of oil film thickness and oil film stiffness between ball and inner/outer ring are alike. Among which, the oil film thickness between ball and outer ring is dominant, its maximum value emerges at 10thd3h. The curve shapes of oil film stiffness between ball and outer/inner ring are oblique “D”, their amplitudes reach the maximum at 11thd1h-11thd3h
Damage localization in beams based on the analysis of modal parameters
Get PDFThis paper presents a two-step method for damage localization in beams by combining natural frequencies and mode shapes. The general locations of the damage are first identified from an indicator developed using relative natural frequency change (RNFC) curves and the values of RNFCs. A curvature-mode-shape-based method is then utilized to determine the specific location of the damage in the second step. The proposed two-step method is verified by detecting damage in a simulated simply-supported beam. The identified damage location agrees well with the actual damage location. A strategy for fast and accurate damage localization based on general localization using natural frequencies and specific localization using mode shapes is the main novelty of the paper
Experimental hysteretic behavior of high strength concrete columns confined by butt-welded closed composite stirrups
Get PDFSix specimens of high strength concrete columns with butt-welded closed composite stirrups were tested under cyclic lateral loads, to study the structural performance (deformation) and hysteretic characteristics of the columns. The influences of the axial compression ratio and the volume-stirrup ratio were considered. According to the regression analysis of the test results, it was determined that the unloading stiffness and strength degradation rate under repeated loading conditions are mainly dependent on the two parameters of the “displacement ductility factor” and “axial compression ratio”. According to the test results, the skeleton curves were determined by the section layer and the statistical regression analysis methods. By considering the influence of axial compression ratio and the volume-stirrup ratio to the hysteretic characteristics of high strength concrete columns confined by butt-welded closed composite stirrups, the shear force-lateral displacement restoring force model was established. The results show that the axial compression ratio has a great influence on the strength degradation of the columns. As the axial compression ratio increases, the strength degradation of the columns occurs faster. On the other hand, the volume-stirrup ratio has a reverse effect on the strength degradation of the columns, with the increase of the volume-stirrup, the strength degradation of the column is observed gradually and slowly. The stiffness degradation of the columns increases as the axial compression ratio increases while the volume-stirrup ratio decreases
Analysis of flow-induced vibration of cylinder with splitter plate based on overset grid method
Get PDFIn actual engineering, asymmetric flow often occurs, but rigid partitions are often installed in the direction of the flow field and are symmetric in the flow direction. This will result in a deflection angle between the dividing plate and the direction of the incoming flow. The research results show that when the declination angle is low, the partition plate has a limited impact on the system; when the deflection angle is about 10 degrees, the system vibration characteristics will have abrupt changes, the amplitude will decrease, and the vortex frequency will increase; at the deflection angle 10 degrees to 45 degrees As the declination angle increases, the amplitude increases, and the vortex frequency decreases; it can be seen from the motion trajectory that the declination angle changes suddenly after 10 degrees, and the system has a small amplitude between 10 degrees and 25 degrees. That is, in this declination interval, the partition plate has a better control effect on the vibration of the cylindrical system
Composite plate damage localization based on modal parameters
Get PDFA damage localization method based on natural frequency was proposed in order to complete the nondestructive diagnosis of a composite plate. The relationship between the damage position and the natural frequency of the composite plate was studied both qualitatively and quantitatively. Furthermore, the damage localization method proposed in this paper was proved by simulation and experimentation, with the results showing that this method can locate the position where the stiffness of the composite plate decreased in both simulation and experiment. Finally, the damage localization method based on natural frequency can be applied for non-destructive diagnosis of a delamination composite plate
Helicopter rotor blade vibration reduction with optimizing the structural distribution of composite layers
Get PDFIn helicopter rotorcraft design, two main approaches as passive and active control methods widely used to decline vibration. In this study passive control methods are used to reduce vibration in the helicopter rotor blade. The most common passive control devices are dynamic vibration dampers, isolators and structural distribution of the composite blades. A surrogate optimization formula is used as the objective function of vibration reduction which includes vibratory hub loads and bending moments. In optimization model, composite ply angles are design variables and spar frequency-placement, autorotation and stress conditions are constraints. As the optimization method, a hybrid solution is chosen. The gradient-based algorithms generate accurate results in trust region and heuristic methods scan very large area of solution space. Due to the aforementioned advantages, these algorithms are hybridized. As a result of the comparison of the optimization outcomes with the baseline UH-60 rotor blades, approximately 38 % vibration reduction is observed in the new design
Numerical model for the settlement of loess subgrade in operation period reinforced by rotary jet grouting pile
Get PDFThe problems of subgrade settlement failure and uneven settlement are quite prominent due to hydraulic migration. The loess in the natural state has the characteristics of high strength and low compressibility. Composite foundation method is to set a certain proportion of reinforcement (pile) in the natural foundation, so that the pile and soil jointly bear the load, and has the effect of compaction method and displacement method. Based on the actual case of a highway disease in Shanxi Province, this paper studies the influence of treatment measures of rotary jet grouting pile penetrating or not penetrating the loess soil on the uneven settlement of highway subgrade in loess region by means of field investigation, analysis and numerical calculation. The results found that the lateral friction resistance of rotary-jet grouting pile penetrates through the loess is small. When the rotarjet pile is long and the underlying soft layer is relatively thick (4.5 m), the settlement of the foundation also quickly enters the stable state. When the underlying loess is deep, the settlement of the foundation increases with time
Vibration characteristics analysis of face gear transmission system considering gyroscopic effect
Get PDFTo improve the dynamics of the face gear transmission system, a nonlinear dynamics model considering gyroscopic effects and including parameters such as time-varying meshing stiffness, meshing damping, tooth side clearance, support stiffness and damping is developed. The Runge-Kutta method was used to solve the nonlinear kinetic equations and analyze the accuracy and reasonableness of the model calculation results. The vibration displacement, vibration velocity and vibration acceleration along each direction of the face gear and straight cylindrical gear were analyzed, and the torsional vibration characteristics of the center of mass of the two gears were studied
Dynamic modeling and analysis of elastic isolation damping gears
Get PDFTransmission error is the main excitation source of gear vibration and noise, how to reduce the transmission error has always been the focus of the research on gear dynamics. In this study, a new type of cylindrical spur gear with elastic isolation is developed for the reduction of transmission error. The elastic isolation damping gear includes three parts: the gear body, the elastic isolation layer, and the involute profile body. Dynamic models are established with the elastic isolation damping gear using lumped parameter method. Dynamic characteristics are simulated via spur gear pair examples by the Runge-Kutta algorithm. By comparing the simulation results of three gear models, the dynamic response of the elastic isolation damping gear with sliding friction is illustrated. The influence of different parameters of the elastic isolation layer on the dynamic response for the elastic isolation damping gear model is carried out. The results indicate that the proposed elastic isolation damping gear model is effective in reducing dynamic transmission error, especially for torque fluctuation, high-speed and heavy-duty conditions. Parameter influence analysis guides the design of elastic isolation damping gears with low transmission error