最新刊期
卷 47 ， 期 5 ， 2025
- 摘要：Under the medium and high speed of spherical hybrid sliding bearings, the dynamic pressure effect causes the fluid in the wedge space to whirl, and the vibration characteristics of the rotor may be affected by the oil whirl, so the rotation accuracy of the main shaft is reduced. The spherical hybrid sliding bearings with the orifice throttle was divided into cylindrical and conical whirl. The lubrication mathematical model and rotor dynamic model were established and solved simultaneously, the journal center trajectory and vibration amplitude were obtained. The influence of the centroid offset distance and initial deflection angle on the vibration characteristics of the rotor system were studied.The results show that, compared with the pure cylindrical whirl, the stability of the journal center trajectory decreases and the vibration amplitude increases after considering the conical whirl.With the increase of the centroid offset distance, the stability and vibration amplitude of the journal center trajectory decrease greatly.With the increase of the initial deflection angle, the stability and vibration amplitude of the journal center trajectory decrease only slightly.It can be concluded that changing the distance of the centroid offset has more influence on the stability of the journal center trajectory and the vibration characteristics of the rotor system than changing the initial deflection angle.关键词：Spherical hybrid sliding bearing;Oil whirl;Journal center trajectory;Vibration characteristic2|0|0更新时间：2025-05-19
- 摘要：Aiming at the problem of nonlinear vertical vibration control during the dynamic rolling of strip mills, a nonlinear vibration absorber with the disc spring was designed. Firstly, considering the constraints of dynamic rolling force of the rolling mill in the vertical direction, the mathematical model of the rolling mill under the control of the nonlinear vibration absorber was established, the amplitude-frequency characteristic curve equation of the system was solved by the multi-scale method, and the influence of damping, excitation amplitude and nonlinear stiffness on the vibration suppression effect of nonlinear dynamic vibration absorber was discussed. Secondly, by analyzing the spectrum curve and time domain curve, the vibration absorber device could increase the distance between the resonance frequency and the main resonance frequency, and shorten the time of the rolling mill system from the unstable state to the stable cycle was concluded. The results show that the addition of nonlinear vibration absorber can effectively increase the anti-vibration ability of the system and suppress the vertical vibration of the system.关键词：Rolling mill;Vertical vibration;Nonlinear vibration absorber;Multi-scale method;Amplitude-frequency characteristic2|0|0更新时间：2025-05-19
- 摘要：Since the fault vibration data collected in the real engineering may be accompanied by noise, traditional diagnostic models are difficult to identify fault categories. To address this problem, a rolling bearing fault diagnosis research method based on channel and spatial reconstruction and progressive convolutional neural networks (CSRP-CNN) was proposed. The model utilized channel and spatial reconstruction convolution （CSConv） to reduce the redundant information of channels and space in fault features, and reduced the complexity and computation to improve the performance; using the convolutional block attention module (CBAM), attention enhancement operation was carried out in the channel and spatial dimensions to make the model pay attention to the important fault feature information; and the progressive convolutional network structure was used in the shallow layer of the network, which would fuse the previous fault feature information with the current input to obtain the richer feature information. The performance of CSRP-CNN was evaluated by two different datasets of Case Western Reserve University (CWRU) and machinery fault simulator magnum (MFS-MG). After the noise and ablation tests, it is verified that CSRP-CNN has strong robustness and the effects of CSConv, CBAM and progressive convolutional neural network (PCNN) on the model noise immunity performance.关键词：Fault diagnosis;Channel and spatial reconstruction convolution;Progressive convolutional neural network;Robustness443|24|0更新时间：2025-05-19
- 摘要：In order to study the dynamic behavior of stiffened cylindrical shells with composite material sandwiched by co-cured damping films under the clamped boundary condition, the specimens of stiffened cylindrical shell with composite material sandwiched by co-cured damping films were prepared, and the dynamic modal test platform was set up. The fundamental frequency, damping ratio and modal shapes of stiffened cylindrical shell specimens were solved, and the accuracy of finite element model was verified. The influence of geometric parameters on structural vibration characteristics was further discussed by the numerical simulation method. The results show that, the fundamental frequency, damping ratio and modal shape of the structure will change abruptly when the height of stiffeners changes, and there is a suitable height value before the abrupt change to make the whole structure consider both damping and stiffness requirements; when the thickness of composite materials is constant, the fundamental frequency of the whole structure decreases gradually and the damping ratio increases gradually with the increase of the damping thickness or damping layer number of single layer; for the stiffened cylindrical shell of single layer damping composite materials, the closer the damping layer is to the inner skin, the higher the stiffness is, and vice versa, the damping capacity is better.关键词：Co-cured damping film embedded composite;Reinforced cylindrical shell;Dynamic behavior;Modal test;Numerical simulation2|0|0更新时间：2025-05-19
- 摘要：The noise of automotive electronic water pump (EWP) is an important indicator of the performance of EWP, and its active control is conducive to improve the sound quality of the car. In order to achieve the active control of the noise of EWP, a hybrid random carrier space vector pulse width modulation (HRCSVPWM) strategy was proposed. Firstly, the Xorshift algorithm was used to design a random sequence generator to generate random numbers with good randomness to disperse a large number of harmonics concentrated in the carrier frequency and its integer multiples. Secondly, the sawtooth wave period function was combined to increase the weakening effect on the pulse width modulation (PWM) harmonic amplitude. Then, the simulation model of the EWP was constructed to investigate the harmonic suppression effects of control strategies of space vector pulse width modulation (SVPWM), random carrier space vector pulse width modulation (RCSVPWM) and HRCSVPWM, to verify the ability of HRCSVPWM to suppress PWM harmonics. Finally, EWP noise test platform was constructed to analyses the noise of EWP under three types of control strategies.The results show that the noise suppression effect of HRCSVPWM is remarkable, which can make the noise’s sound pressure level of EWP decrease significantly, with an average decrease of about 3 dB.关键词：Electronic water pump;Noise active control;Harmonic suppression;Random carrier;Xorshift algorithm2|0|0更新时间：2025-05-19
- 摘要：In order to reveal the nonlinear dynamics behavior of the marine rotor-bearing system under complex transport motions (heaving, swaying, yawing and pitching), the dynamical model of the rotor-bearing system with the nonlinear oil film force and transport inertial forces was built based on, Lagrange’s equation.The effects of the rotating speed and transport motion parameters on the nonlinear dynamics behaviors of the system were mainly analyzed. The results show that the amplitude and oil film whirl interval of the system are larger when considering the coupling motion of heaving, swaying, yawing and pitching than those when not considering this motion. Affected by the coupled transport motion, the rotor will deflect obviously at a lower speed. At a certain rotational speed, with the increase of heaving amplitude, swaying frequency or swaying amplitude, the amplitude jump phenomenon caused by the oil whirl appears in the vibration response of the system， and the motion state of the system undergoes quasi-periodic and chaos. With the increase of swaying frequency, yawing amplitude, yawing frequency, pitching amplitude or pitching frequency, the system is always in a quasi-periodic vibration state, but the vibration amplitude of the rotor increases in varying degrees.关键词：Complex transport motion;Marine rotor-bearing system;Nonlinear dynamics;Nonlinear oil film force2|0|0更新时间：2025-05-19
- 摘要：Limited by the vibrator structure, there are some problems such as low down-going earth energy and shallow down-going depth of shear-wave signals when the shear-wave vibroseis is excited. Therefore, the influence of different combinations of shear-wave vibroseis vibrators on the excitation effect was innovatively studied through the three-dimensional finite element numerical simulation. Firstly, based on three-dimensional nine-component data and two types of combinations, eight modes of vibration excitation of combined shear-wave vibroseis were considered, a vibrator-earth finite element model was established, and an evaluation system of the vibration excitation effect of the combined shear-wave vibroseis was constructed. Secondly, based on this evaluation system, the influence of the various combined excitation modes of the shear-wave vibroseis on the downward energy of the earth, the downward depth of shear-wave signals and the mutual interference between combined excitation waves was analyzed in detail. The results show that, compared with a single shear-wave vibroseis, when two SHY shear-wave vibroseises are arranged side by side for the normal excitation, the incoming earth energy is increased by 86.36%, and the displacement amplitude of earth particles is increased by 73.40% on average. When two SHX shear-wave vibroseises are excited in the normal direction, the incoming earth energy increases by 97.48%, and the displacement amplitude of earth particles increases by 58.61% on average, which greatly improves the excitation effect. The research results can provide the guidance for improving the excitation effect of the shear-wave vibroseis and the reference for the design of combined excitation mode of the shear-wave vibroseis.关键词：Shear-wave vibroseis;Combined shear-wave vibrator;Combined excitation effect;Seismic prospecting;Finite element method2|0|0更新时间：2025-05-19
- 摘要：Abnormal vibration in the pipeline associated with large synchronous condensers not only reduces the lifespan of the pipeline but also affects the supply of the lubricating oil and coolant for the synchronous condenser, posing a serious risk of major safety accidents and jeopardizing the stability of the power system. The lubricating oil supply pipeline of a specific ultra-high voltage converter station synchronous condenser was taken as the research object. Multiple methods, including field measurements, fluid-structure coupling, and harmonic response analysis, were used to investigate the causes and mechanisms of the pipeline vibration. The results indicate that the periodic excitation force generated by the synchronous condenser itself is the main cause of pipeline vibration. Furthermore, a pipeline vibration reduction measure based on a tuned mass damper (TMD) was proposed. Experimental and simulation data shows that installing a TMD at the intermediate positions between suspension supports 4 and 5, as well as 6 and 7 in the lubricating oil supply pipeline system, yields the best vibration reduction effect. This approach can reduce the vibration acceleration of the pipeline system by over 90% and exhibits the excellent vibration reduction performance.关键词：Synchronous condenser;Pipeline vibration;Fluid-structure coupling;Harmonic response analysis;Tuned mass damper2|0|0更新时间：2025-05-19
- 摘要：Aiming at the noise problem of the automobile electric seat adjuster, a pair of modified worm and modified helical gear was adopted for its main transmission system to reduce the meshing impact. The mathematical model was established, and several worms and helical gears with different modifications were processed. The noise test bench was built, and the acceleration spectrum of the automobile seat adjuster under the original models and different modifications were tested. Then the whole device’s noise reduction test was conducted with the optimized combination of tooth profile modification. The analysis results show that the appropriate profile modification of the worm and helical gear can effectively reduce the acceleration spectrum peak. With 0.04 mm and 0.02 mm modification respectively for the helical gear and the worm, the acceleration peak value of seat adjuster is significantly lower than that of the original product. The difference between the 6 sets of test products maximum noise and the standard products is within 1.6 dB, and the acceleration spectrum and acceleration peak of the experimental products are significantly reduced compared to the original product, which can verify noise reduction by the tooth profile modification of worm and helical gear pair is feasible.关键词：Seat adjuster;Worm;Helical gear;Tooth profile modification;Noise reduction2|0|0更新时间：2025-05-19
- 摘要：An improved northern goshawk optimization (INGO) algorithm was proposed to address the local optimization problem that swarm intelligence algorithms often encounter when optimizing support vector machine (SVM) models, and it was applied to fault diagnosis of rolling bearings. By introducing an adaptive inertia weight factor based on the cosine variation and a Cauchy mutation strategy, the northern goshawk optimization (NGO) algorithm was improved, and an INGO-SVM fault diagnosis model was constructed using SVM. In order to evaluate the performance of the improved algorithm, firstly, benchmark testing functions were used for experiments, and the improved algorithm was compared with existing optimization algorithms such as NGO, particle swarm optimization (PSO), sparrow search algorithm (SSA), etc. The results show that the performance of the improved algorithm is improved to a certain extent. At the same time, the original diagnostic signals were feature extracted through wavelet packet decomposition and divided into 10 categories. The energy of each frequency band in the 3rd layer was used as the feature vector and input into the fault diagnosis model. Finally, the performance of the improved algorithm was compared with the other three algorithms in optimizing SVM parameters for fault classification. The results show that the improved algorithm can effectively and accurately achieve different fault classifications, with an accuracy rate of 99.39%, verifying the effectiveness and feasibility of this method.关键词：Fault diagnosis;Improved northern goshawk optimization algorithm;Cauchy mutation strategy;Wavelet packet decomposition;Support vector machine2|0|0更新时间：2025-05-19
- 摘要：Single tube towers are widely used as the foundation for carrying 5G communication equipments. Due to construction needs, the mounted equipments often changes with the changes in 5G construction. Due to the small damping of the single tube tower, the increase of mounted equipments may cause an excessive vibration, reducing its load capacity. Therefore, the control of tower top vibration is particularly crucial. A particle damping tuned mass damper (PDTMD) method was proposed to control the problem of excessive vibration at the top of 5G communication towers. Based on a collision theory, a mathematical model using PDTMD to control the vibration of the communication tower was established. The vibration response of the tower under effects of PDTM was verified by the detailed calculation, and the damping mechanism of PDTMD was analyzed. The damping effectiveness of PDTMD was compared with the traditional tuned mass damper (TMD). The results show that the particle damping has good energy dissipation ability. Compared with traditional tuned mass dampers, PDTMD has better damping effect and higher robustness. Finally, based on the actual signal tower, the usage parameters of PDTMD in complex environments were optimized. Effects of gaps between damping particles and honeycomb structures, particle materials, and particle mass ratios on the damping effect of dampers were analyzed.关键词：Vibration control;Particle damping;Tuned mass damper;Communication single pipe tower2|0|0更新时间：2025-05-19
·Vibration·Noise·Monitoring·Diagnosis·
- 摘要：To achieve quantitative detection of bolt loosening angles through single frame images, a method based on color segmentation and connected domain feature processing was designed. Firstly, a method for performing nonlinear stretching, normalization and optimal threshold segmentation on a component successively in the Lab color space was designed to segment and represent the red anti-loosening line image of the bolt loosening angle. Secondly, the morphological operations were performed on the image by using the open operation. Then, the orientation vector of the connected domain in the anti-loose line image was determined by computing the geometric moments. Finally, the bolt loosening angle was determined through the four-quadrant arctangent function. The results demonstrate that the precise measurement of the bolt loosening angle through a single frame image can be achieved by this detection algorithm, with a maximal relative error of 1.80%, its accuracy meets the needs of engineering practice and has strong engineering application value.关键词：Bolt loosening;Angle detection;Color segmentation;Connected domain feature;Geometric moment;Vector calculation3|0|0更新时间：2025-05-19
- 摘要：In order to gain insight into the stability of the tracking frame structure of shipborne large-aperture telescopes, the stability of typical ground-level telescope tracking frames was studied. According to the external load borne by the equipment in the case of ship, the external load was parameterized and entered into the finite element software. The pre-treatment software and finite element software were used to analyze the structural deformation under static wind load. Then, the natural frequency of the structure was solved, and a simple response spectrum analysis calculation was proposed instead of the tedious random response analysis to analyze the stability of the equipment under dynamic wind load and wave excitation. According to the stress and deformation values obtained from the results, it was ensured that the shipborne telescope tracking frame theoretically meets the strength requirements and design accuracy requirements under shipborne conditions. Under the static wind load, the maximum stress value of the tracking frame structure is about 14.07 MPa, which was less than the yield strength of steel 355 MPa, the maximum deformation variable was about 0.02 mm, which was less than the design accuracy error coaxiality
- 摘要：In order to clarify the dynamic response, damage situation, and failure mode of titanium/steel corrugated composite plates and interfaces under impact loads, small energy (53 J） impact experiments were conducted on titanium/steel corrugated composite plates using a light air cannon. On the basis of verifying the effectiveness of the numerical calculation model, numerical simulations were conducted on composite plates under various velocities to study the impact mechanical response of composite plates and their interfaces under various energies. The results show that, under low energy impact conditions, the front of the corrugated composite plate shows plastic expansion damage, and the back plate has protrusions with cracks at the raised areas. The corrugated interface layer is tightly bonded and overall concave; cut the target plate along the impact center and observe that there are no cracks, delamination, or other damages on the cross-section. This is different from fiber reinforced composite laminates. There will generally be obvious delamination inside when there is barely visible damage on the impact surface. In numerical simulation, the cohesive force interface damage area of the corrugated composite plate under impact is less than that of the planar interface composite plate. When subjected to low energy impact, the absorption of bullet kinetic energy by the corrugated plate is mainly dominated by overall deformation energy absorption, and the damage to the titanium/steel composite plate at the corrugated interface is relatively small. Under various energy impacts, corrugated interface composite plates have tighter interface bonding, better structural integrity, and are less prone to damage compared to planar interface composite plates.关键词：Low energy impact;Corrugated interface titanium/steel composite plate;Damage analysis;Numerical simulation;Cohesive element2|0|0更新时间：2025-05-19
- 摘要：Low-cycle fatigue is a typical failure mode of engine pistons. In order to study the influence of multi-source uncertainty factors on the reliability of low-circumference fatigue of pistons and improve the efficiency of the reliability analysis, a new reliability calculation method is constructed based on the polynomial-chaos-based Kriging (PC-Kriging) model and the Monte Carlo simulation (MCS), and the accuracy and efficiency of this method are proved by numerical examples. Taking the piston group structure of a certain diesel engine as the research object, a finite element model of the piston is established based on the thermal-mechanical coupling analysis, and the reliability analysis of the piston for low-cycle fatigue is carried out by using this method, taking into account the critical dimensions, the material properties, and the uncertainty of the load. The results of the reliability analysis show that, compared with the same type of method, this method is more efficient in calculation, requiring only 20+93 finite element calculations, and the probability of fatigue failure is 1.053% when the expected design life of the piston is 1.4×104. The sensitivity analysis shows that， the height of the piston, the piston diameter, the elasticity modulus of the material, and the parameters of the fatigue calculation model have a greater influence on the reliability. The analysis results can provide a guidance for the reliability design of the piston.关键词：Fatigue reliability;Piston;PC-Kriging model;Learning function;Sensitivity analysis2|0|0更新时间：2025-05-19
- 摘要：The slat of aircraft is subjected to the combined action of thermal load and aerodynamic force during its service, which has an impact on the safety of the structure. The typical aluminum alloy structure widely used in slat structure is taken as the main research object, and the stress distribution and structural strength under the combined action of heat and force were studied by experiment and finite element method. Firstly, in order to explore the influence of temperature on material properties, the linear tensile test of 2024-T62 rectangular thin plate and the high temperature tensile failure test of perforated thin plate were carried out under four different temperature conditions. The test shows that the high temperature environment has a reduction effect on the elastic modulus of the material, and at 190 °C, the bearing strength of the test piece decreased by 15%. Therefore, considering the reduction effect of temperature on material parameters can establish a more accurate model for predicting structural strength. Secondly, aiming at the thermal stress problem of aluminum alloy parts and structures, the test and simulation of aluminum alloy sheet and simplified slat structure under the combined action of heat and force were carried out respectively. A set of modeling method and thermal stress measurement test technology under the combined action of heat and force were established. The maximum error between the simulation and test results of aluminum alloy sheet is 10%. The thermal stress simulation of the simplified slat structure has a good trend compared with the experimental results, and the maximum error is 20%. In addition, through the experiment, it is also found that the thermal stress is particularly sensitive to the setting of boundary conditions. For the model with complex constraints, it is necessary to expand the modeling range to the stable boundary conditions to simulate the actual thermal stress.关键词：Aluminum alloy;Temperature dependence;Combined action of thermal and force;Thermal stress;Structural strength;Finite element analysis2|0|0更新时间：2025-05-19
- 摘要：The creep behavior of 7050-T7451 aluminum alloy under different temperatures and stresses was studied by the uniaxial tensile creep test. Based on continuum damage mechanics, a constitutive model describing the creep behavior of aluminum alloy at high temperature was established. The model took into account the precipitation coarsening, dislocation multiplication/annihilation and microvoid formation during the creep process, and introduced the corresponding damage factor evolution formula to reflect these three damage processes. In addition, the model took into account the additional damage caused by stress increase to reveal the effect of stress on the creep damage. Based on the comparative analysis of the test results and the predicted results, it was verified that the established physical constitutive model can accurately describe the creep behavior of 7050 aluminum alloy under different temperatures and stresses.关键词：Metal creep;Continuum damage model;Precipitation coarsening;Microvoid damage;Dislocation evolution2|0|0更新时间：2025-05-19
·Experimental Research·Testing Technology·
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