The misalignment of the dual-rotor system for the aero-engine will lead to abnormal increase of the vibration which results in the rotor-stator rubbing and affects the safty and stability of the rotor operation. The dual-rotor system was taken as the research object. Considering the combination misalignment-rubbing fault, the dynamic model of the rotor system is established based on the lumped mass method. The differential equation of the system motion was established according to the Lagrange equation, and the Range-Kutta method was used to solve it. The influence mechanism of the key parameters such as the speed, the misalignment angle and the coupling misalignment on the nonlinear dynamic characteristics of the system was studied. The results show that the system presents complex dynamic characteristics such as periodic, multi-periodic, quasi-periodic and chaotic motion with the increase of the rotor’s speed. When the speed is in the range of 1 500-2 200 rad/s, the system switches between periodic 2 motion and chaotic state through multiple paroxysmal bifurcations and paroxysmal inverted bifurcations. There are nonlinear phenomena such as jump in the bifurcation diagram of the vibration response with the change of the parallel misalignment of the coupling. As the misalignment angle of the bearing increases, the chaotic interval of the high speed decreases, and the stable periodic motion interval increases.

In response to the challenging task of fault feature classification in the current working conditions of pumping units，which results in poor adaptability and low recognition rate of the established diagnosis model. The dynamometer card was pretreated by mathematical morphology through the analysis of the motion state of the pumping unit valve and the sucker rod. Then, two methods of obtaining valve opening and closing points and load variation characteristics were proposed, and 54 new features of global faults of pumping units were extracted, and the characteristic database of working conditions of the pumping unit was established. Finally, the algorithm of decision tree, logistic regression and support vector machine was used to verify that the feature database has good classification effect under different working conditions. The characteristic indexes of different fault conditions were evaluated, and the private rule database of each working condition was obtained. The research results demonstrate that the proposed features in this study are capable of effectively identifying comprehensive faults in pumping units, exhibiting a high level of recognition accuracy.

The torsional vibration of reciprocating compressor crankshaft system can cause major problems such as burnt bearings and shaft fracture. In order to understand the torsional vibration response of the compressor rotor system, a torsional vibration mechanics solution method for the flexible rotor system of the compressor considering the bushing-pin collision clearance and the oil film clearance of the crankshaft-bearing was proposed, which provided a new idea and method to avoid the natural frequency of the crankshaft system. Based on the multi-body dynamics and Hertz contact theory，the torsional dynamic response of the crankshaft system with collision clearance was solved. The results show that the torsional vibration amplitude of the 4th column crank pin is the largest, the torsional angular displacement amplitude is 0.051°, and the dynamic angular velocity peak value is 156.026 rad/s. Based on this, the crankshaft-bearing oil film clearance was considered, the oil film pressure of sliding bearings was calculated by the finite difference method and the over-relaxation iterative method, and the dynamic characteristic coefficients of bearings were solved according to pressure perturbation method. The effects of the bushing-pin collision clearance and the crankshaft-bearing oil film clearance on the dynamic response of the crankshaft system were comprehensively considered in the modal analysis of the crankshaft system under preload. The resonance of the crankshaft with and without oil film clearances was compared. The results show that the natural frequencies of the 3rd and 8th orders of the crankshaft system decreases by 44.64% and 21.23%, and when considering the reduction of the resonant speed point of the crankshaft with comprehensive clearance in the same speed range, the 2nd order critical speed is reduced by 38.55%, and the probability of resonance increases.

A two-degree-of-freedom collision system with gap and elastic constraint was used as the research object, and the regional distribution and transitions of the periodic motion of the system under low frequency conditions were studied by numerical simulation. It was obtained that with the decrease of excitation frequency, the p/1 periodic motion occurs with grazing bifurcation transitions to（p+1）/1 periodic motion. When the number of collisions was large enough, the Chatteringimpact characteristics were presented. Then a circuit model that was completely equivalent to the collision system was established and simulation experiments were carried out. The results show that the results generated by establishing the equivalent circuit are consistent with those generated by numerical simulations, and the equivalent circuit is more efficient in simulation experiments, which can realize fast modal transitions and parameter adjustments，making it more convenient and providing a research method for the study of nonlinear dynamics.

In order to avoid large vibration response and transcritical motion instability of ultra-high speed centrifugal impeller rotor system caused by unbalanced excitation, the unbalanced excitation response of ultra-high speed centrifugal impeller rotor system was analyzed by using Ansys rotor dynamics response analysis module and comprehensively considering the stiffness and damping of sliding bearing, the dynamic response of ultra-high speed centrifugal impeller rotor system under different unbalanced excitation was obtained. At the same time, DEWESoft vibration test system was used to track and record the rotating frequency vibration value of ultra-high speed centrifugal impeller rotor system, and compared with the unbalanced response analysis results, it was concluded that the dynamic balance accuracy level of the ultra-high speed centrifugal impeller rotor system should be better than G1 level. The unbalanced excitation response analysis and control method has been well verified by tests, which has important engineering application significance.

In order to determine the sensitive vibration characteristic parameters of coal and gangue in the process of top coal caving and improve the intelligent identification accuracy of coal and gangue, the dynamic characteristics of the tail beam of the hydraulic support were studied. Firstly, the rigid-flexible coupling dynamic model of top coal caving hydraulic support and coal gangue was established, and the vibration acceleration of the tail beam of the hydraulic support in the process of coal caving was calculated. Secondly, the acceleration response was decomposed by variational mode decomposition (VMD) to obtain the intrinsic mode function (IMF), and the time domain and frequency domain characteristics of each IMF component were analyzed. Thirdly, the t-distributed stochastic neighborhood embedding (t-SNE) method was used to reduce the dimension of these features, and the average silhouette coefficient (ASC) of different features was calculated. The vibration characteristics of the tail beam under the impact of coal gangue were compared and studied. Finally, the bench of the top coal caving hydraulic support was built to verify the calculation results of the model. The results show that the energy, singular value, mean frequency, peak frequency, spectral centroid and frequency variance in the IMF component of the vibration acceleration of the tail beam are sensitive to the characteristics of coal and gangue, which can be used as the characteristic parameters of the coal and gangue identification.

Considering the actual excitation load, the nonlinear dynamics characteristics of the bolted structure have a certain impact on the whole mechanical system. The dynamics model of actual bolted structure is more complex with considering joint surface morphology parameters and plasticity index. Therefore, with considering the influence of the surface mopography parameters, plastic index on the normal contact stiffness, contact damping and under the various conditions such as external harmonic excitation, the existing normal contact model of bolted structure was modified, and the obtained nonlinear normal contact stiffness and nonlinear contact damping were applied to the dynamics response characteristics analysis of forced vibration of bolted joints structure. The influences of surface morphology parameters and plasticity index on the dynamics characteristics of bolted structure were studied.

Aiming at the research on intelligent identification of caving coal and gangue, in order to provide a complete and effective vibration signal acquisition scheme of coal and gangue, an optimal layout strategy of tail beam sensors of caving coal hydraulic supports based on vibration characteristics of coal and gangue was proposed. Firstly, the modal analysis of the tail beam model was carried out, extracting the vibration mode matrix，and the effective independent method was used to select the measuring points. Secondly, the vibration signals of coal falling and gangue falling at the corresponding primary measuring points from the tail beam test bench were obtained, and the feature extraction was carried out. Thirdly, the extracted features were visualized by t-distributed stochastic neighbor embedding（t-SNE） dimensionality reduction, and five features which were sensitive to the distinction between coal and gangue signals were selected as target features. Finally, the probability density functions of target features were estimated by the kernel density estimation method. The K-L（Kullback-Leibler） divergence was used to evaluate the approximation between combined signal of each measuring point and the complete signal and the difference between characteristics of coal and gangue. The evaluation indexes of coal and gangue vibration signals were constructed. Combined with Fisher information matrix criterion, a comprehensive evaluation index was formed to determine the optimal scheme of tail beam sensor arrangement. The results show that the sensor arrangement scheme determined by this method not only reduces the number of sensors on the basis of satisfying modal observability, but also makes the measured vibration signals have better coal gangue difference and information integrity.

The planetary gear system is widely used in aircraft transmission equipment because of its small size, light weight and large load capacity，but the problem of bias load caused by various errors cannot be avoided, and a serious bias load condition will lead to under utilization of the advantages of the planetary system cannot be fully exploited. The influence mechanism of the flexible change of the inner gear ring on the bias load behavior of the system was investigated by taking a certain type of aeronautical planetary gear system as the research object. The deflection，stress and strain of the inner gear ring were measured by experiments with different number of planets and different rim thicknesses, and the mechanism of bias load was analyzed and the degree of influence of the number of planets and rim thickness on the bias load behavior of the system was evaluated. The advanced simulation calculation and analysis of a large aeronautical planetary system was completed by using a hierarchical finite element model to quantify the influence mechanism of the variation of inner gear ring flexibility on the load distribution and gear ring deflection of the system. The accuracy of the simulation results was evaluated by fitting the experimental and simulation results to the same parameter range for comparison. The research results provide targeted structural optimization guidance for the development and design of internal gear rings of large aeronautical planetary gear systems, which can greatly reduce the cost of this type of large aeronautical equipment in the design and iteration process.

Based on the low temperature tensile test data of the rubber, Ansys software was used to fit the Mooney-Rivlin hyperelastic constitutive model of rubber material parameters, and the thermo-solid coupling simulation was carried out on the U-shaped rubber outer windshield according to three real working conditions, and the influence of different working conditions on the U-shaped rubber deformation was studied. The low temperature test was carried out on U-shaped rubber outer windshield and three rubber samples with different batten thicknesses，the influence of temperature and batten thickness on its deformation was studied. The results show that the U-shaped rubber deformation is mainly caused by the temperature change,the U-shaped rubber height decreases obviously, and the shape variable of the side wall thickness and the rubber length is small. In addition, the batten thickness has a greater influence on the rubber shape variable at the bolt hole. Compared with the batten of 5 mm and 6 mm thickness, the 4 mm batten produces a larger deformation under the bolt preload action, resulting in a larger deformation at the bolt hole, and then increasing the batten thickness can effectively reduce the hole removal risk. Comparing the finite element simulation data with the low temperature test results, it is found that the two results are basically consistent，which indicates the finite element analysis feasibility and the low temperature test reliability. The research results provide some guidance basis for the U-shaped rubber outer windshield under low temperature application reliability.