最新刊期
期 4 ， 2019
- 摘要：Aiming at the problem that the fault information of rolling bearing was weak and susceptible to noise, which was difficult to judge the damage degree of bearing failure, a new method was proposed. Bearing fault location and damage diameter size could be obtained using the method based on third-order cumulant diagonal slice spectrum and gray correlation theory. Bearing fault location information could be determined using the characteristics of third-order cumulant diagonal slice spectrum to suppress the Gaussian noise and to identify the secondary phase coupling signal. And gray relational theory was used to analyze the kurtosis index, the pulse index and the margin index of the third-order cumulant diagonal section data to obtain the curve of the damage degree. Finally, actual signal is analyzed to obtain the bearing fault location and the damage diameter, which indicates the feasibility and practicability of the method.关键词：Rolling bearing;Damage degree assessment;Diagonal slice spectrum;Grey incidence grade
- 3
- |
- 204
- |
- 2
发布时间：2022-09-22 - 摘要：In order to overcome the difficulty of feature extraction of non-stationary faulty signals in rolling bearing fault diagnosis under strong noise background, a method based on local characteristic-scale decomposition and synchrosqueezing wavelet transform is proposed. Firstly, the measured vibration signals are processed with LCD and decomposes into a series of intrinsic scale component（ISC）. Then a number of ISCs containing valid information components are selected for SWT and processing them by SWT so that we can extract the effective frequency characteristics. The analysis results from rolling bearing signals with out ring, inner ring and rolling body faults which in a strong noise background shows that comparing with LCD and SWT, the approach of synchrosqueezing wavelet transform based on LCD can effectively suppress the noise and extract the effective signal frequency characteristics. It also has a high time-frequency resolution for accurately determining the operation of rolling bearings. While the method can also effectively reconstruct the signal.关键词：Fault diagnosis;Synchrosqueezing wavelet transform（SWT）;Faulty signal extraction;Local characteristic-scale decomposition（LCD）
- 4
- |
- 249
- |
- 4
发布时间：2022-09-22 - 摘要：Combined with multi-scale analysis ability of wavelet, the wavelet identification of 1/f process is proposed for the characterization of machined surface topography, based on the fractal surface profile obtained by MB function, the fractal dimensions of different wavelet functions and different decomposition scales are calculated,by comparison, the more appropriate wavelet basis function and decomposition scale are selected. The calculation results of the wavelet identification of 1/f process are compared with the box counting method, variance method, R/S analysis method, power spectral density method（PSD）, root mean square method（RMS）, structure function method and the method of equations, and the results show that the wavelet identification of 1/f process is more accurate and more convenient than other algorithms, further shows that the wavelet analysis method can be well applied to the multi-scale fractal analysis on the surface. Finally, the wavelet identification of 1/f process is applied to 3 actual machining surfaces, verified the practicality.关键词：Machined surface topography;Fractal dimension;Wavelet identification of 1/f process;Wavelet basis function;Fractal model
- 4
- |
- 187
- |
- 4
发布时间：2022-09-22 - 摘要：Turbulent winds and earthquakes are the two main factors that lead to the vibration of the wind turbine tower. In order to study the dynamic response characteristics and anti-seismic of wind turbine structure under wind-earthquake coupling condition, NREL 5 MW wind turbine is studied. A soil-structure interaction model was established by Wolf Method, and based on the multi body dynamics simulation and open source software FAST, the seismic load calculation module is developed. The structural control of the wind turbine tower under the seismic condition is carried out by configuring a tuned mass damper（Tuned Mass damper, TMD） at the top of the tower by self-compiling program. The results show that the seismic load greatly increases the lateral vibration of the tower, and the excitation frequency is the first-order lateral natural frequency of the tower. Under the control of TMD, the dynamic response of tower and nacelle are obviously reduced, where the amplitude of lateral displacement of the tower top is reduced by 18%, the standard deviation is reduced by 67%, and the response amplitude of the first order natural frequency of tower is greatly reduced, as high as 90%. Additionally, the variation of the lateral acceleration of the tower top is reduced by 4%, the standard deviation is reduced by 61%, and the peak vibration of the first-order natural frequency decreases by 88%. Therefore, the TMD can be used for anti-seismic of wind turbines in extreme environments such as earthquakes, and improve the stability of wind turbines.关键词：Wind turbine;Earthquake;Tuned mass damper（TMD）;Dynamic response;Stability
- 4
- |
- 248
- |
- 5
发布时间：2022-09-22 - 摘要：The main approach to cut the brittle-hard material is the use of the fixed abrasive wire saw at present. The vibration of the wire saw is inevitable during the cutting process for the reason of its flexibility. The main vibration patterns include the incentive of abrasive grains to the wire saw and vibrations transmitted by the machine itself. For the sake of investigating the effect of abrasive grains on the vibration of wire saws during cutting process, based on the oscillation theory of the string, the vibration equations of the wire saw in the case of a damped axially uniform motion were constructed and together with an analysis of the force in the wire saw during the process of cutting. The normal random force model, which has an important influence on the lateral vibration of the wire saw,was further established and an analysis of linear vibration of the wire saw in the small offset state was conducted. Based on the cutting experiment of WXD170 reciprocating diamond wire sawing machine, the validity of the normal random force model is verified. The results show that the simulation of the vibration model can accurately predict the vibration during the sawing process.关键词：Wire saw cutting;Wire saw vibration;Random force modeling;Slicing experiment
- 4
- |
- 200
- |
- 0
发布时间：2022-09-22 - 摘要：During the rolling process, the rolling mill’s working stability is determined by the system’s dynamic characteristics. Among which, the roll system’s rigid motion and the work roll and backup roll‘s flexural deformation movement are the main factors that affect both the steel strip’s thickness precision and surface quality. Especially for the heavy plate four-high mill system, the work roll’s flexural deformation movement significantly affects the shape control of steel strip due to its direct contact with the stock. The influence of the dynamic properties of rolling mill system’s rigid vibration on work roll and backup roll’s flexural deformation movement was investigated in this paper. Furthermore, a rigid flexible coupling dynamic model of the strip rolling mill is established. Consequently, the difference between the natural mode shape function of the roll derived by the traditional structural dynamics and the mode shape function deduced with the influence of rolling mill’s rigid vibration has been analyzed in different moments.关键词：Strip rolling mill;Flexible multi-body mechanical system;Roll system;Coupling vibration;Mode shape function
- 3
- |
- 218
- |
- 3
发布时间：2022-09-22 - 摘要：To monitor the health of rolling bearing, the vibration signals are always used for fault diagnosis. However, the non-linear and non-stationary characteristics of vibration signals have not been solved in current methods. In this work, an intelligent fault diagnosis method is proposed, which is a sequential combinations of variational mode decomposition（VMD）, Kurtogram, and artificial fish algorithm（AFSA）. To begin, original vibration signals are decomposed into intrinsic mode functions（IMFs） using VMD, among which the most effective fault information is selected based on the Kurtogram algorithm and the rules of maximum correlation coefficients. Then the feature vectors are identified using the morphological entropy and energy entropy of the above IMFs. Next, two crucial tunable parameters, penalty coefficient C and Gaussian kernel width coefficient σ are optimized through AFSA algorithm. At last, the fault diagnosis model is developed based on AFSA-SVM algorithm, in which the extracted fault features are employed as inputs. The experimental results show that the proposed method accurately identifies fault features of the original signal. It has also improved model learning efficiency and classification accuracy.关键词：Variational mode decomposition;Kurtogram;Artificial fish swarm algorithm;Optimal combination of kernel function parameters
- 4
- |
- 195
- |
- 1
发布时间：2022-09-22 - 摘要：Aiming at the fact that the fault diagnosis performance of relevance vector machine（RVM） in motor bearing highly depends on the parameters selection, a motor bearing fault diagnosis method based on RVM optimized by fruit fly optimization algorithm with reverse cognition（RCFOA） was proposed. In order to improve search ability of FOA, reverse cognition strategy was introduced and improved the original FOA algorithm. Use the RCFOA to optimize RVM parameters can effectively improve the classification performance of RVM. Different fault type and different fault degree of motor bearing fault diagnosis experiment results show that the RCFOA can obtain better parameter when compared with some other methods, improved the fault diagnosis accuracy of RVM and can applied to fault diagnosis efficiently.关键词：Fruit fly optimization algorithm;Reverse cognition;Relevance vector machine;Fault diagnosis;Bearing
- 5
- |
- 300
- |
- 6
发布时间：2022-09-22 - 摘要：Bearing is one of the most critical and the most vulnerable parts of mechanical transmission system,Accurate identification of its faults is the key to achieve stable operation of equipment. The five degree of freedom dynamic model of rolling bearing system with local fault is established by considering the nonlinear factors such as oil film and the sliding of rolling element. An improved model of pitting failure is proposed, and the corresponding models of different fault parameters are analyzed. The system vibration signal of the inner ring and the outer ring with pitting fault is simulated, and the corresponding fault characteristics are analyzed. Through the comparative analysis of the simulation signal and experimental signal, the correctness of the model is verified, which can help to realize the early diagnosis of bearing fault.关键词：Rolling bearing;Pitting;Dynamics;Fault diagnosis
- 4
- |
- 800
- |
- 3
发布时间：2022-09-22 - 摘要：Aiming at the fact that the gear vibration signal would exactly display non-stationary characteristics and fault features is hard to extracted, a fault extraction method of gear based on multiscale base-scale entropy of LCD was proposed. The vibration signal was decomposed adaptively with local characteristic-scale decomposition（LCD） to obtain the components in different scales of the original signal. Considering the ability of the base-scale entropy in distinguishing the complexity of different signals effectively, the base-scale entropy of intrinsic scale components（ISCs） by LCD was calculated. Thus the complexity metric in different scales of the original signal was gained, which was consequently taken as the feature parameter to describe different gear states. The feature parameters were then put into relevance vector machine（RVM） for diagnosing the gear faults. Experiment results of gear show that the proposed method can classify typical fault of gear exactly and has certain superiority when compared with some other methods.关键词：Local characteristic-scale Decomposition;Base-scale entropy;Feature extraction;Gear
- 4
- |
- 85
- |
- 2
发布时间：2022-09-22 - 摘要：Cellular metal materials structure is a new type of porous metal material, it is made up by lots of metal hollow spheres（MHS）, and mechanical behavior research of the single metallic hollow sphere is the foundation of the whole material mechanical performance. The individual MHS with 2 mm to 3 mm outside diameter,10 μm to 40 μm thick walls with porosity were studied, and nano-indentation test, quasi-static uniaxial compression experiment and elastic compression test were performed on the metallic hollow spheres to get the Young’s modulus and hardness of the MHS and the material which was made up of the sphere, also single MHS compression deformation process and characteristics could be observed, finally simulated elastic stage of metallic hollow sphere by finite element software ABAQUS, analyzed the influence of the Young’s modulus of the whole MHS by porosity on thin wall, and result shows that with the porosity increasing, the elastic modulus of MHS will decrease, and present nonlinear distribution, it can be described the same format of a power law function as the relation of porosity with the porous thin wall.关键词：Metallic hollow sphere;Thin-walled structure;Nano-indentation;Mechanical properties;Numerical simulation
- 6
- |
- 206
- |
- 0
发布时间：2022-09-22 - 摘要：The empirical ridgelet transform has the ability of direction selectivity and adaptive decomposition. 2 DPCA can directly use the original image toconstruct the covariance matrix. Combined with the advantages of Empirical ridgelet transform and 2 DPCA, anidentification method ofmetal fracture based onempirical ridgelet-2 DPCA. At the same time, the proposed method is compared with the Ridgelet-2 DPCA, Ridgelet-PCA recognition method. The experimental results show that the bidimensional intrinsic mode Function（BIMF） component has more abundant feature information than ridgelet coefficient. 2 DPCA has more complete image structure informationthan PCA. Therefore, the proposed empirical Ridgelet-2 DPCA has achieved better recognition effect than experience Ridgelet-PCA and Ridgelet-2 DPCA recognition method.关键词：Empirical ridgelet transform;Two-dimensional principalcomponent analysis（2DPCA）;Metal fracture;Pattern recognition
- 5
- |
- 112
- |
- 0
发布时间：2022-09-22 - 摘要：In order to accomplish accurate measurement for Capto shank’s key dimensions, based on analyzing Standard ISO detailedly measurement parameters were determined and measurement system for Capto shank was designed. Positioning scheme was decided according to the idea about restraining the degrees of freedom in space, axial positioning was achieved by shank’s own weight, radial positioning was achieved by the rational configuration of three supporting nails, and circumferential positioning was achieved by controlling ring gauge’s cavity dimension strictly. Measurement for Capto shank with equal precision was done by using the developed measurement system, measurement results accorded with the accuracy requirement stipulated by ISO. Research shows that positioning method of the measurement system is feasible and can meet the demand of measurement for Capto shank’s key dimensions.关键词：Capto shank;Key dimensions;Measurement;Positioning;Triquetrum circle
- 2
- |
- 82
- |
- 0
发布时间：2022-09-22 - 摘要：In order to study the cutting energy consumption characteristics of coal miner under complicated conditions, the MG500/1180-WD shearer was cut out under different working conditions by collecting the cutting energy consumption model of coal mining machine. Pin and idler axle load data, and finally through the different conditions of coal miners cutting energy consumption calculation, the following conclusions: to keep the other conditions remain unchanged, the linear cutting energy consumption with With the increase of the traction speed increase; the oblique cut cutting energy consumption value is far more than the straight cutting energy consumption value; shearer cutting energy consumption in addition to the speed of traction, cutting mode, but also by the impact of coal hardness, With the increase in the hardness of coal and cutting cutting energy consumption also increased. The results of this study provide the theoretical basis for the development and use of shearer, and provide the theoretical basis for the scientific and efficient production of coal mining industry.关键词：Coal cutter;Cutting energy consumption;Energy Consumption Model;Idler shaft;Rack pin
- 4
- |
- 100
- |
- 0
发布时间：2022-09-22 - 摘要：With the "MG2×100/455-BWD" new type of thin coal seam shearer cutting project as the object, its key parts which include the output shaft, shell, carrier load situation have been depth analyzed. Considering the number of loads, the dynamic reliability model of each key part failure mode which Based on the reliability interference theory of stress-intensity distribution is established to calculate and analyze its reliability. By Compiling miner load samples with MATLAB, building Solid modeling with Pro/E, generating key parts Flexible body with ANSYS, the rigid and flexible coupling model of the shearing part of the shearer was established and the simulation was carried out by using the special interface MECHANISM/Pro to import ADAMS to get the stress information of the key parts under different working conditions. Taking condition parameters as neural network training samples, the neural network and the virtual prototyping technology are combined to predict the stress under other working conditions, which reduces the simulation time and the workload of the virtual prototype. The research in the paper provides the basis for the design of the shearer, improves its dynamic reliability, shortens the product design cycle, has important theoretical significance and high application value.关键词：Output shaft reliability analysis;Collaborative simulation;Dynamic reliability;Neural Networks
- 3
- |
- 178
- |
- 0
发布时间：2022-09-22 - 摘要：MEMS device structure plays an important role on the performance of the sensor. To improve its stability, oval variable beam is selected to decrease stress concentration and widen the gap between the non-detection directional stiffness and detection directional stiffness, thereby reducing cross sensitivity and improving stability; To achieve the best dynamic performance, damping ratio ξ should be appropriate and theoretical stiffness of beam is calculated. By establishing the pure bending model of the beam, the stiffness formula and the strength condition of the beam is derived. Under the same rigidity of trapezoidal beam with equal section and trapezoidal variable section beam, the quality of the beam with variable cross section increases slightly, but the stress at the dangerous section decreases greatly.关键词：Oval variable beam;Stiffness;Dynamic characteristics;Stability;Strength
- 4
- |
- 169
- |
- 3
发布时间：2022-09-22 - 摘要：The snap-through and pull-in instability of the electrostatically actuated micro shallow arches incorporating Casimir force was investigated based on the modified couple stress theory. The nonlinear governing equation and boundary conditions were derived by using the principle of minimum total potential energy. The snap-through voltages, the pull-in voltages, the non-dimensional snap-through displacements and the non-dimensional pull-in displacements of the electrostatically actuated micro shallow arches were calculated by applying the generalized differential quadrature method（GDQM） and the generalized integral quadrature method（GIQM）. The results show that the snap-through and the pull-in instability of the electrostatically actuated micro shallow arches are size-dependent. The snap-through and pull-in voltages of the electrostatically actuated micro shallow arches based on the modified couple stress theory are smaller than the classical results. The Casimir force can reduce the snap-through voltages, the pull-in voltages, the non-dimensional snap-through and the pull-in displacements of the micro shallow arches. The initial rise of the micro shallow arches affects the snap-through and pull-in instability.关键词：The modified couple stress theory;Snap-through;Pull-in;Size effect;Casimir force
- 3
- |
- 56
- |
- 0
发布时间：2022-09-22 - 摘要：To more accurately and effectively solve the problem of comprehensive reliability of multi-failure mode with the thermal creep, dual response surface method（DRSM） was adopted to implement the reliability of aero-engine turbine blisk. The numerical characteristics of the material parameters were obtained through the creep test data. The gas temperature, material density, elastic modulus and working rotation speed of the blisk structure were select as input variables. By constructing the finite element model of the blisk and the thermal-structural coupling analysis method, the stress and strain of turbine blisk were obtained. The mathematical model of dual response surface for stress and strain of turbine blisk was established by using the Latin hypercube small sampling technique. The comprehensive reliability analysis of the blisk was completed by using Monte Carlo method with linkage sampling of dual response surface model. The results indicate that the comprehensive reliability of blisk with thermal creep is 0.985 6. The comparison of method shows that dual response surface method can significantly improve computational efficiency without the loss of accuracy.关键词：Reliability analysis;Turbine blisk;Creep;Dual response surface method;Linkage sampling
- 2
- |
- 249
- |
- 3
发布时间：2022-09-22 - 摘要：With the problem of lightweight for body-in-white, a parametric optimization method based on mixed sensitivity analysis was proposed. The bending stiffness and modal properties of body-in-white were calibrated through the finite element simulation. Then the model was used to do mixed sensitivity analysis about stiffness and modal by experiment design, and related parts that have little influence on stiffness and modal properties were screened out. Takes thickness of related parts as design variables, the body-in-white quality and bending and torsion stiffness as the optimization targets, modal properties as constraint. The body-in-white lightweight of multi-objective optimization design was carried out by NSGA-II. Then simulate calculation was carried out by Isight to optimize the thickness of those parts, so as to realize the lightweight optimization design of the body-in-white structure. The simulation results show that its stiffness and modal performance were guaranteed after the parametric optimization, and the weight of the body-in-white was reduced by 5.7% of the original structure.关键词：Body-in-white;Lightweight design;Mixed sensitivity;Multi-objective optimization
- 3
- |
- 404
- |
- 4
发布时间：2022-09-22 - 摘要：Reliability sensitivity determines the relationship between reliability and the distribution parameters of uncertain variables, and guides reliability analysis and reliability design. A novel non-probabilistic reliability sensitivity analysis method based on ellipsoidal convex model was presented, in which non-probabilistic reliability sensitivity was defined as a partial derivative of non-probabilistic reliability index with respect to the distribution parameters of uncertain variables. The analytical equations of non-probabilistic reliability sensitivity for linear limit state functions were first derived. Through-two different choices of the linearization point, the approximate functions of non-linear limit state functions can be then obtained by using the first-order Taylor expansion, then the approximate analytical equations of non-probabilistic reliability sensitivity were given. Several numerical examples will be used to demonstrate the effectiveness and feasibility of the proposed methods.关键词：Non-probabilistic reliability;Convex model;Sensitivity analysis
- 3
- |
- 235
- |
- 2
发布时间：2022-09-22 - 摘要：Due to the complicated structure of the loop-type compound epicyclic gear system, the torque and power relationship between the basic components in the system is complex and variable, forming a variety of power flow types. In order to quickly judge the power flow type of the system during the design process, a composite lever analysis method is proposed. Based on the lever model of a single epicyclic gear train, combined with the structural characteristics of the coupled system, used the superposition principle, a composite lever model reflecting the characteristics of the loop system is established. Then the application method of this model during analyze the characteristics of single loop system is introduced. This composite lever model is found to intuitively reflect the speed, torque and power relationship among the basic components, and then derive the power flow type of the single loop system. The values of the above characteristics can also be calculated by the force arms of the model that reflect the characteristic parameters of the epicyclic gear systems. On this basis, the application of this method in the power flow analysis of dual-loop system is introduced, which provides a new idea for the analysis of multi-loop system.关键词：Loop-type compound epicyclic gear system;Composite lever model;Power flow;Circulation power
- 3
- |
- 89
- |
- 1
发布时间：2022-09-22 - 摘要：In order to study the crushing process and its influencing factors of the coal rock ploughing and planing by the plough cutters,the planing process is analyzed by numerical simulation, in view of the fact that coal and rock are heterogeneous media, coal rock images are identified, the three-dimensional model of coal rock is established by image reconstruction method, the accuracy of simulation is increased, it provides a new theory and method for three-dimensional finite element modeling of heterogeneous materials, and obtains more accurate simulation data. Through the simulation of coal crushing process under different conditions of plow bit,get contact force plow bit and simulation of coal wall. The results show that:with the increase of planing depth, plow bit stress force increase, the stress gradually stabilized,but because of the change of the coal quality, the forces fluctuate up and down near a steady value;planing speed has little effect on the plane load;coal rock firmness coefficient is larger,the greater the load simulation tool.关键词：Plough;Numerical simulation;Planing depth;Planing speed;Coal rock firmness coefficient
- 5
- |
- 82
- |
- 0
发布时间：2022-09-22 - 摘要：With tidal fluctuations, deep ship and deep draft changes, will inevitably lead to ship and offshore wind turbine collision location changes. In order to study the effect of collision location on the impact resistance of offshore wind turbine structure, a model of 3 MW wind turbine based on a monopile is established. The explicit dynamic theory and non-linear finite element method are used to simulate the 5 000 t impact of the wind turbine at different locations of the dynamic response process, through the support structure of the stress and crash depth, tower top response analysis of wind turbine structure crash performance. The results show that the higher the contact time is, the higher the contact force is. The higher the contact force is, the higher the contact force is, the higher the contact force is, the higher the contact force is. The lower the collision location of the support structure deformation energy and impact depth is greater than the collision location of the higher position. When the ship speed is 1 m/s, the higher the collision position, the greater the displacement and acceleration response of the tower wind turbine, When the ship speed is 4 m/s, the response amplitude of the tower wind turbine decreases as the collision position increases.关键词：Monopile;Offshore wind turbine;Collision location;Dynamic response
- 3
- |
- 111
- |
- 1
发布时间：2022-09-22 - 摘要：In order to solve the problem of large deformation of the rocker arm, the virtual prototyping technology is used to soften the front and rear rocker arm, and the dynamic and mechanical model of the shearer is established. The strain gauge data of the picking sensor are obtained, and the load data is obtained by quadratic fitting the actual calibration of the sensor and the data, and the life prediction of the key components is carried out. The results show that the stress value and the load fluctuation value of the rocker joint pin are larger when the flexible deformation of the rocker arm is considered, which indicates that the flexible deformation of the rocker arm increases the vibration impact of the whole machine and reduces the strength of the shearer And the life expectancy of the shearer’s rocker pin, the fatigue life is 1.738×10~6 times, which proves the feasibility of the experimental method and provides the theory for the selection of the rocker pin in the actual working condition.关键词：Shearer;Rigid-flexible coupling;Dynamics;Fatigue life
- 3
- |
- 260
- |
- 1
发布时间：2022-09-22 - 摘要：When the load to be lifted after cold roll-beating forming the residual stress will appear, in order to effectively control its impact on the forming precision, now the relationship between roll-beating depth and the residual stresses were studied. According to basic principle of cold roll-beating, a finite element dynamic simulation model is established by ABAQUS software, the distribution of Mises force on the workpiece surface was obtained by dynamic simulation at different roll-beating depth. Because inner force of workpiece in result of dynamic simulation is at unbalance state, it cannot directly solve the residual stress, so the static simulation model is established on result of dynamic simulation, and the roll-beating depth of different roll-beating of forming gullet section residual stress in tangential direction, axial direction and radial direction is determined by static analysis. Experiment on self-developed cold roll-beating equipment, build experimental platform for residual stress measurement, and study on residual stress of cold roll-beating. The distribution of the tangential residual stress along the depth direction is obtained by the measurement of the workpiece under different roll-beating depth, the comparison between the experimental results and the finite element simulation results shows that the residual stress variation has a good consistency, which verified effectiveness correctly of the simulation model.关键词：Cold roll-beating;Roll-beating depth;Residual stress;ABAQUS
- 4
- |
- 83
- |
- 2
发布时间：2022-09-22 - 摘要：To predict the press-mounting quality, Aiming at the armature component’s press-fit process, the simulation was implemented on the press-fit process by using ANSYS Workbench. Thus the interference value’s rational scope and press-fit cure’s rational scope were obtained. On this base, the simulation was implemented on armature’s tilt press-mounting work. The results show that press-fit surface and bore of part’s tilt angle are main influence factors for press-mounting parallelism. When the press-mounting surface or the bore of part’s tilt angle was more than 0.03°, parts will be damaged, so the tilt angle should be less than 0.03°. On the basis of the simulation research mentioned above, the precise press-mounting experiment device was developed and fabricated for the press-mounting work of armature component, in which it included force sensor, the grating ruler and machine vision. The press-mounting experiments were carried out on the device. The results show that the difference between press-fit curves obtained from FEA and these obtained from experiment is relatively small. The deviation between maximum press-mounting force obtained from FEA and maximum push-out force obtained from experiment is 2.3%. In addition, the maximum push-out force obtained from experiment is 15% lower than maximum press-mounting force obtained from experiment. According to the comparison results, the press-mounting experiment results are correct, and then the FEA results can be applied for predicting the precise press-mounting quality.关键词：Armature component;Press-fit curve;Maximum press-mounting force;Maximum push-out force
- 4
- |
- 114
- |
- 1
发布时间：2022-09-22 - 摘要：Based on the coal rock material nonlinear theory and rigid flexible coupling multi-body system dynamics theory,the optimal matching of the parameters of shearer was studied.Using Ansys/LS-DYNA software, the coupling simulation model was established for shearer drum with gangue coal, the coal extraction process run down by three to the spiral drum three to force and torque, the volume of coal and rock was cut out.The relationship between the motion parameters and load fluctuation coefficient, cut down the coal volume, cutter safety coefficient, cutting energy consumption, coal loading rate and productivity were analyzed using these results; Using the MATLAB optimization toolbox, the load fluctuation coefficient, cut down the coal volume, cutter safety coefficient, cutting ratio energy consumption, coal loading rate and productivity as the goal function, the multi-objective optimization equation is established for motion parameters of shearer spiral drum. The results show that: when the roller speed is 86.3 r/min, traction speed is 3.87 m/min, the motion parameters of Shearer to achieve optimal matching.In the optimal state,the load fluctuation coefficient is 0.272; the cutting energy consumption ratio is 0.784 kw·h/m~3; cutter safety coefficient is 2.035; the loading rate is 57.132%; the maximum productivity is 3.025 t/min.关键词：Coal gangue rock;Shearer;LS-DYNA;Movement parameters;Multi-objective optimization
- 4
- |
- 208
- |
- 5
发布时间：2022-09-22 - 摘要：The pipeline leakage in T23 water wall of ultra-supercritical tower boiler was found after the units had been put into operation for a period of time, which seriously affected the safety of the boiler units. Fracture analysis found that the circumferential crack that caused by the axial tensile stress is the main factor for the weldment leakage.Welding process of T23 water wall tube was simulated by finite element analysis software ABAQUS, and the welding residual stress distribution field was obtained. On this basis, the influence of the assembly stress on the stress field of the welded joints of the T23 water wall tube was studied. The results show stress on the welded joints is seriously affected by the assembly stress, which could cause the leakage of the T23 water wall welded joints. The maximum bending moment can be given according to the allowable stress, which provides a reference for the construction of T23 water wall welding. The thermal fatigue caused by the temperature fluctuation of the water wall is the key factor of the annular crack propagation.关键词：ABAQUS;T23 water wall;Welded joints;Forced assembly;Thermal fatigue
- 2
- |
- 175
- |
- 5
发布时间：2022-09-22 - 摘要：In order to study the influence of thermal deformation of the cycloid ball meshing pair on dynamic performance of the precision ball transmission, the thermal deformation of contact point of the cycloid ball meshing pair was analyzed by the Green function method, and the influence of system parameters on thermal deformation was analyzed. According to the angle deformation of the planetary disk caused by thermal deformation of meshing pair, the expression of the meshing stiffness coefficient was derived, the factors affecting variation of the meshing stiffness coefficient were analyzed. The finite element single tooth model of meshing pair was established, the finite element simulation of thermal deformation of meshing pair was analyzed by thermal structure coupling. The results show that the thermal deformation of the epicycloid groove is higher than that of the hypocycloid groove, the maximum thermal deformation occurs in the vicinity of 1/3 tooth height of the epicycloid groove, the thermal meshing stiffness coefficient is approximately sinusoidal in a small range, the parameters of system have great influence on the thermal deformation and the thermal meshing stiffness coefficient. This study provides a theoretical basis for the thermal dynamic analysis of precision ball transmission.关键词：Thermal deformation;Cycloid steel ball meshing pair;Meshing stiffness;Finite element simulation;Green′s function
- 4
- |
- 68
- |
- 3
发布时间：2022-09-22 - 摘要：In order to prevent the failure of chain flat ring fatigue failure of scraper conveyor chain, the paper based on the field test data to predict the fatigue life of the chain. Taking the 38 × 137 mmC grade chain as the research object, firstly, the tension of the flat ring is monitored on-line during the operation of the scraper conveyor, and the two straight edges of the same flat ring are obviously unequal. The tension load spectrum as the simulation load data;Then, the finite element software is used to analyze the unequal load on the two right angles of the chain flat ring. The stress and strain results are obtained, and the weak key points are found.Finally, based on the results of static strength analysis, the fatigue load of flat ring was simulated by ANSYS nCode DesignLife.The simulation results show that the fatigue life of the flat ring of the scraper conveyor is 30750 cycles, and the chain link is 61500 times.The life conclusion can provide important reference for the later maintenance, replacement and structural optimization of the scraper chain.关键词：Scraper conveyor;Fatigue failure;Broken chain;Fatigue life
- 4
- |
- 194
- |
- 1
发布时间：2022-09-22 - 摘要：Stress intensity factor is an important parameter that characterizes the stress field near the tip in fracture analysis. The simple and effective methods to estimate intensity factor become significant. Based on the J2 conservation integral, a simple exact method is proposed to determine the stress intensity factor for periodic cracked pipe under the bending effect. The principle of this method is clear and the calculation process is simple.关键词：Pipe;Periodic cracks;J2 conservation integral;Stress intensity factor;Cracks;Fracture
- 4
- |
- 151
- |
- 2
发布时间：2022-09-22 - 摘要：The singular value truncation method is studied in this work for structural damage identification. The main advantage of the proposed method is that it can obtain the robust and accurate results by the ill-posed linear equations due to measurement noise. The influences of the truncation threshold value and the error level on the calculation result are discussed in detail. In addition, the second calculation using the singular value truncation method by another loading state is proposed in order to further improve the accuracy of the calculation. The numerical experiments show that the proposed method is reasonable and feasible, and has better anti-noise performance than the least squares method. When the noise level is less than 10%, the accurate enough results can be obtained. It was found that the proposed method is promising for structural damage identification.关键词：Damage identification;Singular value truncation;Measurement noise;Displacement parameter
- 4
- |
- 150
- |
- 1
发布时间：2022-09-22 - 摘要：In order to calculate the stress intensity factors of two-dimensional cracks emanating from elliptical hole, a solution method for stress intensity factor based on Muskhelishvili complex function theory and truncated conformal mapping approach is proposed in this paper. Firstly, the conformal mapping function formed by the transcendental function is expanded into a series with finite terms, and then the stress function is derived by using the complex function theory, so as to solve the mixed-mode stress intensity factors for two cracks of arbitrary length from an elliptical hole. Compared with other methods, the presented method is more applicable and efficient, the results are reliable. The results of examples show that the non-dimensional stress intensity factors for double cracks from an elliptical hole are under comprehensive impact of the elliptical hole semi-axes ratio, crack length and angle.关键词：Complex variable function method;Elliptical hole-edge cracks;Stress intensity factor;Conformal mapping
- 3
- |
- 218
- |
- 1
发布时间：2022-09-22 - 摘要：The fracture problem of the functionally graded material with collinear cracks under the condition of different elasticity moduli. The stress fields and displacement fields of cracks in the functionally graded strip can be obtained by means of the method of integral transform. And solving the problem of cracks is equivalent to solving the problem of singular integral equations combined with boundary conditions and continuity conditions after solving the stress fields and displacement fields of each crack. The stress intensity factors can be obtained after solving the singular integral equations. The effects of elasticity moduli of materials and geometric parameters of cracks on SIFs are discussed. The results show that the distribution of elasticity moduli may affect SIFs significantly. And this study can provide scientific basis for forming FGMs and designing the property distribution in FGMs.关键词：Functionally graded materials;Cracks;Stress intensity factors
- 4
- |
- 149
- |
- 1
发布时间：2022-09-22 - 摘要：Road simulation test has become an important means to develop the vehicle with high quality and high efficiency, but there is no uniform criterion for compiling the load spectrum of road simulation test. In this paper, the time-domain damage editing method was applied to compile the measured load spectra from a vehicle proving ground. By studying the change tendencies of time shortening rate, damage attenuation rate and load characteristics（time,amplitude and frequency domain） of the developed accelerated spectra, An optimal accelerated spectrum compilation limiting principle was proposed based on load characteristic changes and relative change rate（relative change rate=damage attenuation rate/time shortening rate）. The flow chart of compiling test load spectrum according to the optimal accelerated spectrum compilation limit criterion was put forward, and the flow chart of compiling test load spectrum under each typical working condition was applied in the test field. Finally, a vehicle road simulation test was established by using the accelerated spectrum, which achieves a good simulation effect of load spectrum and verifies the rationality of the method.关键词：Road Simulation Test;Time Correlated Fatigue Analysis with Damage Editing Method;Best acceleration limit
- 8
- |
- 313
- |
- 3
发布时间：2022-09-22 - 摘要：The simply supported double composite beam with moving mass is investigated. During the analysis,the acceleration of the moving mass can be arbitrary. With some assumptions, the strain energy and the kinetic energy of the system are gotten. Then the axial-bending coupled equations of motion are derived by the Hamilton’s principle, and solved by the finite element method combined with Newmark method. The numerical examples show that, the larger the speed of moving mass the larger the maximum vertical displacement of the beam; the horizental displacement of centre point of the beam is zero when the moving mass on the centre point; under the same conditions, the double composite beams have higher stiffness-to-weight ratio than the single layer ones. The conclusions obtained here provide theoretical references for designing the structures with high strength and light weight.关键词：Double composite beam;Moving mass problem;Coupled equations of motion;Finite element method analysis
- 3
- |
- 71
- |
- 2
发布时间：2022-09-22 - 摘要：In this paper, the expansion tube type energy absorbing element was taken as the research object, and 9 samples were tested by automatic electro-hydraulic servo press and large drop hammer impact tester. Based on the experimental data and numerical simulation results, the effects of wall thickness, cone outer diameter and impact velocity on the energy absorption characteristics of energy absorbing components were studied. The test results show that the expansion tube type energy absorbing element is not sensitive to the impact speed. The ratio of the smooth crash force of the energy absorbing element under the drop hammer impact to the smooth crash force of the quasi-static compression is about 0.96～0.98; when the outer diameter of the cone is constant, the force of the energy absorbing element is substantially linear with the wall thickness of the expansion tube; when the wall thickness of the expansion tube is constant, the force of the energy absorbing element is approximately linear with the outer diameter of the cone, and with the outer diameter of the the cone increases, the amount of increase in the force tends to decrease. This paper provides a basis for the design of the expansion tube type energy absorbing element.关键词：Expansion tube energy absorbing element;Quasi-static compression;Dynamic impact;Energy absorption characteristics
- 4
- |
- 109
- |
- 3
发布时间：2022-09-22 - 摘要：For evaluating and optimizing the trailing am fatigue performance, taking the trailing arm of a certain vehicle model as the research object, the finite element analysis and the strain signal road data acquisition were carried out. The accuracy of the finite element analysis was verified by comparing finite element analysis results with the test data. The structural optimization of the trailing arm was carried out based on its failure mode. The rapid test multi-level load spectrum was generated based on the road load data, and the rig durability test was carried out for original trailing arm and optimized trailing arm respectively. The rig durability test results were consistent with the finite element simulation and the proving ground durability test.关键词：Vehicle engineering;Structural optimization;Rig test;Trailing arm;Multi-level load spectrum
- 4
- |
- 112
- |
- 0
发布时间：2022-09-22
- Technical support is provided by Beijing Founder electronics co., LTD 豫ICP备05013835号-4
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0