Noise & Vibration Worldwide

In steam turbines, the operation of turbine blades can lead to vibrations, which may result in turbine accidents. Traditional calculation methods are difficult to use due to the complex structure of the torsional blade, and simulation analysis can be time-consuming. Therefore, it is necessary to use the equivalent model instead. Most of the previous studies have simplified the straight blade to a cantilever beam model without considering the shear effect, and used harmonic response analysis to study the vibration of the blade for simulation. The blade body of the torsional blade can be regarded as a torsional variable section beam, and the Timoshenko beam model is the same as the variable section beam. Therefore, the Timoshenko beam model can be regarded as the equivalent of the sheathed torsional blade. Considering the complexity of the calculation of the self-shrouded torsional blade model. According to the theory of Timoshenko beam, the model of the shrouded blade of Timoshenko beam with different torsion angles was established. The first sixth-order modes of the blade model and the vibration response of the adjacent blades under forced vibration are compared, respectively. The results show that the results obtained from the Timoshenko beam blade model considering the torsion angle are closer to the torsional blade model. In addition, the blade vibration response of the same model under different excitation force amplitudes was further compared, and the results showed that the vibration amplitude, acceleration and velocity of the shrouded blade increased with the increase of the excitation force amplitude. However, the magnitude of the inter-shroud collision force and the number of collisions between adjacent blade shrouds are non-linearly related to the amplitude of the excitation force.

The purpose of this paper is to study the impact of road structure on traffic noise from an urban network planning perspective, to provide solutions to control and prevent traffic noise at source. The process is divided into three parts. Firstly, the stochastic user equilibrium model for traffic flow allocation is improved to be more accurate. Secondly, a global traffic noise simulation method is proposed for the network based on the noise prediction model, and the noise data is visualized. Finally, a noise evaluation system is established to study the traffic noise evolution patterns under different road structures. The results show that with the increase of network density, the traffic noise value of the network decreases. The layout of one-way roads will reduce the regional traffic noise value. The impact of road grade adjustments on traffic noise is positively correlated with the rate of change in road capacity. The study can provide an effective basis for control traffic noise from the network planning stage.

In this paper, the free vibration behavior of isotropic and orthotropic cylindrical shell panels with variable curvature subjected to certain ends boundary conditions is analyzed by the transfer matrix technique and solved by the Romberg integration approach. Flügge’s shell theory is employed to model the governing three-dimensional equations of vibration and Fourier’s approach is used to deform the displacement fields as trigonometric functions in the longitudinal direction. As a result of a semi-analytical procedure is conducted, the coupled governing equations of panel problem can be written in a matrix partial differential equation of first order with variable coefficients and reduced from the two-dimensional problem to one-dimensional one which is solved numerically as an initial-value problem. The proposed model is applied to get the natural frequencies and mode shapes for the vibration behavior of two-side simply-supported cylindrical panels with simply-supported, free-free, clamped-free and clamped-clamped ends boundary conditions lying at their curved edges. The sensitivity of the vibration behavior to the variety of curvature, panel parameters and material orthotropy of shell is studied.

The hydraulic motor will generate noise in operation and it has fluid-structure coupling and compact internal structure. The sound intensity measurement is difficult to distinguish the noise sources of motor. In this paper, a high-precision localization method for noise sources of bent-axis motor is studied to improve the resolution of the sound intensity images to locate noise sources accurately. Firstly, the structural characteristics of the motor are analyzed, and the sound intensity images are obtained through the experiment. Then the high-resolution optimization method based on compressed sensing is designed according to the characteristics of the sound intensity field. Finally, the sound intensity images with high resolution are constructed. The high-resolution images can distinguish the position of the prominent points, and the error is less than 0.4 dB. The identification distance of noise sources can reach 30 mm, and it breaks through the highest resolution of the traditional sound intensity test.

The mechanical vibration response in engineering is the superimposition of multi-frequency characteristic information. Therefore, it is of great necessity to utilize signal decomposition methods to extract fault characteristics for ultimate diagnosis. In the traditional variational mode decomposition (VMD) methods, the decomposition parameters (i.e. the mode number and quadratic penalty factor) are determined according to the principle of convenience and experience. This behavior reduces the performance of VMD methods to a great extent, and limits their decomposition accuracy and feature extraction capability. To resolve this problem, a novel VMD method for rotating machinery fault diagnosis is developed in this article. Firstly, a measurement index called weighted correlated kurtosis (WCK) is constructed by combining correlated kurtosis and Pearson correlation coefficient. Secondly, taking the maximum WCK as the goal function, salp swarm algorithm is utilized to find the optimum parameters. Lastly, the feature extraction is performed according to the selected sensitive mode possessing the maximum WCK. Two experimental examples demonstrate the effectiveness of the developed VMD method on mechanical vibration signal processing and fault diagnosis. Furthermore, by comparing with other two typical VMD methods, the superiority of the developed method is verified.

To decrease the operator’s seat vibration and control the cab’s shaking of the soil compactor, the seat’s control isolation (SCI) added by the QZS structure (SCI-QZS) and the cab’s control isolations (CCI) combined are proposed and investigated. A three-dimensional dynamic model of the soil compactor under the interaction of the tire and drum on the deformable terrain is established to calculate the vibration equation of the soil compactor. The vehicle’s experimental study with the seat’s isolation added by the QZS structure is also given to verify the mathematical model and study result. The isolation efficiency and stability of the SCI-QZS and CCI combined are evaluated based on the root mean square accelerations of the operator’s seat (aws) and cab’s pitching angle (a _wφc ) under the various conditions of the soil compactor. The research shows that with the isolation systems of the soil compactor seat and cab without the QZS structure and control, the operator’s ride comfort and the cab’s shaking are strongly affected under various operating conditions. With the soil compactor using the SCI-QZS and CCI combined, both the operator’s ride comfort and the cab’s shaking are greatly reduced under all the various operating conditions. Especially, the aws and a _wφc are remarkably reduced by 67.8% and 59.8% in comparison with the isolation systems of the soil compactor seat and cab without the QZS structure and control. Therefore, the SCI-QZS and CCI combined should be applied on the soil compactor to improve the operator’s ride comfort and control the cab’s shaking of the soil compactors or other off-road vehicles.

This article presents the parametric optimization of the free vibration characteristics of a functionally graded material (FGM) plate exposed to nonlinear thermal loading using the finite element method and nature-based algorithms. The one-dimensional (1D) Fourier heat conduction equation is used to calculate temperature distributions over the thickness of the plate. Using Lagrange’s equation, we get the dynamic equation of motion for the plate. An eight-noded iso-parametric plate element with five degrees of freedom per node is used in the finite element formulation based on first-order shear deformation theory. Rectangular plates have temperature-dependent material characteristics; the thickness of the plates is scaled using a straightforward power law distribution. Here, the investigation of the FGM plate is conducted with two different boundary conditions, such as simple support and fully clamped. Additionally, new hybrid optimization approaches, namely RSM-Composite Desirability Optimization (RSM-CDO), Whale Optimization Algorithm (WOA), Corrected Moth Search Optimization (CMSO), Lichtenberg Algorithm Optimization (LAO), Sunflower Optimization Algorithm (SFO), and Forensic-Based Investigation Algorithm (FBI), are utilised to determine the best optimal solution, and the obtained findings are validated using confirmatory tests.

Independent sound zone technology aims to construct multiple independent sound zones with different sound fields, which are independent of each other and do not interfere with each other, and has wide research value and application prospects in today’s increasingly complex received information. To help scholars preparing to investigate independent sound zone techniques get started quickly, this paper presents research advances in three independent sound zone construction methods based on loudspeaker arrays, sound field reconstruction and parametric array loudspeakers, including the implementation principles and optimization schemes of these methods.