Control of vibrational field in an elastic vibration unit with DC motors and time-varying observer

In the paper the problem of feedback control of vibrational fields in a vibration unit is analyzed taking into account the influence of the elasticity of cardan shafts, the drive dynamics, saturation for control torques. In addition, the synthesized rotor synchronization control algorithm uses the estimates of a non-stationary observer, which makes it possible to implement it practically on a two-rotor vibration unit SV-2. The performance of the closed loop mechatronic systems is examined by simulation for the model of the two-rotor vibration unit SV-2.

The use of the vulnerability factor in the study of vibration signals on the soil surface from the movement of subway electric trains

Microseismic vibrations of the upper part of the soil strata occur continuously under the influence of endogenous and exogenous processes of both natural and artificial origin. Micro-oscillations of technogenic nature are especially characteristic of densely built-up urban areas. The practice of monitoring seismological monitoring observations shows that under such conditions it is possible to observe various types of microseismic vibrations, including elastic vibration signals in the frequency range of 1—100 Hz, generated by passing subway trains. In the calculations of the seismic stability of the designed structures, special attention is paid to the resonance characteristics of the upper part of the soil strata, which at certain frequencies can significantly enhance seismic vibrations, for example, from external vibrations sources. By traditional methods, the characteristics of resonant oscillations and their accounting are carried out, as a rule, with an insufficient degree of reliability and completeness, as a result of whichand so they are usually used as auxiliary ones. In this paper, a methodological complex is considered using modern methods for measuring and processing microseismic signals in order to identify areas with maximum amplitudes of response to external elastic influences in the study area for construction and take them into account in the future in design and construction. The study of vibroseismic noises formed on the surface of the soil layer, for example, by passing subway trains, allows one to estimate the amplitude-frequency properties of these soils, and the spectral ratio of horizontal displacements of soils to vertical H/V and the derivative of these ratios — the coefficient of vulnerability of the Ky — provide a confident selection of weakened zones that are subject to the greatest impact of external elastic vibrations.

PARTIAL WAVE BASIS ADAPTED TO EXTERIOR BOUNDARY CONDITIONS OF AN ELASTIC PLATE

An approach to describing normal elastic vibration modes in confined systems is presented. In a standard treatment of the problem, the displacement field is represented by a superposition of partial waves of a general form, e.g., plane waves. The unknown coefficients of superposition are then obtained from the equation of motion and the full set of boundary conditions. In the proposed approach, the functional form of partial waves is chosen in such a way as to satisfy the boundary conditions on exterior surfaces identically, i.e., even if the unknown quantities determined by the remaining constraints are found in an approximation, numerically or analytically. Some examples of solutions for composite elastic plates are discussed to illustrate the efficiency of the approach and its relevance for applications.

Piezo-based flexural vibration suppression for an annular rotor via rotating-frame H2 control optimization

Elastic vibration can arise in annular and thin-walled rotor structures, impacting on operating performance and the risk of failure. Feedback control to reduce flexural vibration can be realized using lightweight actuators and sensors embedded in the rotor structure. To design optimal controllers, rotating-frame models of both the structural dynamics and sources of excitation are required. This paper describes a solution to this problem for the case of an annular rotor equipped with piezo patch actuators and sensors. To account for space-fixed external excitation sources, a forcing function is considered involving specified spatial and frequency domain distributions. A model-based [Formula: see text] synthesis is used to compute optimal control solutions. These are tested experimentally on a thin-walled cylindrical steel rotor for cases with narrowband and broadband excitation sources, applied from the fixed frame. The results show that frequency-splitting within the rotating-frame dynamics plays a key role in predicting and controlling resonance. The effectiveness of the optimal control methodology in reducing circumferential vibration of the annular rotor is also confirmed.

Rockburst Prediction on the Superimposed Effect of Excavation Accumulation Energy and Blasting Vibration Energy in Deep Roadway

In deep mining, much elastic energy is stored in rock mass due to the high geostress. Rockburst will be induced by accumulated energy during excavation. Meanwhile, because of blasting vibration energy in the host rock, there will be an obvious superimposed effect on the probability and intensity of rockburst. To explore the most reasonable and effective method for understanding rockburst problem under blasting, a deep roadway of Sanshandao gold mine was studied. On the basis of in situ geostress data, the accumulated energy of three-centered arch roadway after quasi-static excavation was derived. Then, a series of in situ blasting vibration were monitored, and the blasting vibration energy was calculated by employing the equivalent theory of elastic vibration boundary. Finally, the tendentiousness of rockburst was evaluated qualitatively with the superimposed energy. The results indicated that the disaster-driven energy was increased by 45.1% and 28.2% on different places of roadway. Also, the probability and intensity of rockburst would be raised.

Elastic vibration of rotationally ring-shaped periodic structure subjected to three-axis angular velocity components

The elastic vibration of rotationally ring-shaped periodic structure (RRPS) subjected to angular velocities applied about three orthogonal directions are examined. An analytical model having in-plane radial and tangential displacements is developed by using Hamilton's principle. The modeling leads to a partial differential equation with revolution effect, based on which the eigenvalue splitting, mode contamination and vibration instability are examined by focusing on their evolutions with the support count, support strength and revolution speed. The eigensolutions are formulated by perturbation-superposition method. The results imply that the splitting, contamination and instability follow similar rules with those of stationary RRPS, which are heavily affected by the revolution speed. The dependence of parameters on eigensolutions and especially the relationships between eigenvalue splitting and principal instability, and those between mode contamination and combination instability are demonstrated based on a sample RRPS. The principal instability can occur at splitting eigenvalues, and the combination instability can arise in the presence of mode contamination. Main results are compared with the existing ones in the open literature.

Research on the Influence of Wheel Polygonization on Axle Stress

To study the influence of wheel polygonization on the dynamic stress of the wheel axle, a vehicle-track rigid-flexible coupling dynamic model was established. In the model, the wheelset, axle box, and track system were modelled as flexible bodies to consider the influence of elastic vibration. At the same time, the dynamic stress on key positions of the axle under the wheel polygonization excitation was measured on the high-frequency vibration test rig. The accuracy of the model was verified by comparison with the test results. The wheel axle stress under the excitation of the wheel polygonization with different orders, wave depths, and running speed was calculated. The results show that the wheel polygonization can increase the amplitude of the axle dynamic stress, and the larger the wave depth of the wheel polygonization, the larger the stress amplitude. When the wheel polygonization frequency is close to the frequency of the wheelset elastic vibration mode, the wheelset first-order bending and second-order bending modes have a great influence on the axle stress. The resonance vibration of the wheelset elastic modal can cause the dynamic stress on key positions of the axle increase sharply.