Lattice structures have become a research highlight in the fields of aviation, aerospace and automobile because of its high specific strength and stiffness. The development of additive manufacturing technology makes it possible to manufacture mechanical metamaterials with complex geometric shapes and special mechanical properties. However,traditional additive manufacturing processes are difficult to coordinate the contradiction between the cost, geometric size and accuracy of such structures. In view of this, a mechanical metamaterial structure concept of reversible assembly and the connection method of its basic voxels were proposed, which can effectively overcome the size limitation of manufacturing equipment, and can construct a macro lattice structure with rich mechanical properties through different combination sequences. Aiming at the basic voxel type of reversible assembly, the influence of voxel geometric parameters, relative density and voxel numbers on its mechanical properties through parametric modeling method was analyzed, and the experimental results were compared. The results show that the three basic voxels have great rigidity difference, and Poisson’s ratio covers the range from negative to positive. Therefore, different combination sequences of these three basic voxels can produce macro structures with different mechanical property distributions, which proves the rationality of using these three basic voxels as the basic voxels of the reversible-assembly structure. In addition, the mathematical relationship between geometric parameters and mechanical properties can provide guidance for the engineering application of such mechanical metamaterials.

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.

An online measurement method of a dynamic unbalance force of the geotechnical centrifuge was carried out based on monitoring the change of the axial preload of anchor bolts. Firstly, the change model of the axial preload of the anchor bolt under different unbalanced force states was deduced theoretically, which proved the feasibility of indirectly measuring the unbalanced force of the centrifuge. Then, the typical testing case was carried out on the TLJ-500 centrifuge, and the law of the dynamic unbalance moment changing with the counterweight was obtained. By fitting the change of the axial force at the measuring point, the relation between the axial force at the measuring point and the unbalance mass and the running gravitational acceleration g value of the centrifuge was established. Finally, the relation between the change of the axial preload of anchor bolts, acceleration of the centrifuge and counterweight mass were obtained by measuring the preload change of one anchor bolt and fitting the response surface. The results show that it is feasible to obtain the unbalanced force of the centrifuge operation by monitoring the change of anchor bolts’ pre-tightening force，and the centroids of different counterweights should be kept consistent in the test. When calculating the counterweight mass to balance the rotating arm according to the fitting formula, a larger acceleration should be used as far as possible to reduce the error caused by the centrifuge not being leveled.

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.

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.

In order to clarify the influence of different working conditions on the wear of tapered roller bearings, the wear state of tapered roller bearings was carried out. A quasi-statics model of tapered roller bearings including roller balance equation and inner ring balance equation was established, and a wear depth calculation model suitable for wear analysis of tapered roller bearings was derived based on Archard wear theory. The wear distribution characteristics of bearing inner and outer raceways and roller elements under light load, medium load and heavy load conditions were comparative analyzed. The results show that the wear depths of the tapered roller and the inner/outer raceways on the contact line show bimodal distribution characteristics, and the wear distribution of the outer raceway is closely related to the positions of the rolling elements. For light load condition, the peak wear depth of bearing raceways and roller elements increases by 20% as bearing speed increases 25%, and for heavy load condition, the peak wear depth of bearing raceways and roller elements increases more than 17% as bearing load increases 16%. The comparison of bearing wear peaks under the three working conditions shows that the product of the equivalent load and the speed of the bearing is not the determining factor controlling bearing wear，and the load change has a significant impact on the bearing wear.