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The battery pack in electric vehicles is subjected to road-induced vibration and this vibration is one of the potential causes of battery pack failure, especially once the road-induced frequency is close to the natural frequency of the battery when resonance occurs in the cells. If resonance occurs, it may cause notable structural damage and deformation of cells in the battery pack. In this study, the natural frequencies and mode shapes of a commercial pouch lithium-ion battery (LIB) are investigated experimentally using a laser scanning vibrometer, and the effects of the battery supporting methods in the battery pack are presented. For this purpose, a test setup to hold the LIB on the shaker is designed. A numerical analysis using COMSOL Multiphysics software is performed to confirm that the natural frequency of the designed test setup is much higher than that of the battery cell. The experimental results show that the first natural frequency in the two-side supported and three-side supported battery is about 310 Hz and 470 Hz, respectively. Although these frequencies are more than the road-induced vibration frequencies, it is recommended that the pouch LIBs are supported from three sides in battery packs. The voltage of the LIB is also monitored during all experiments. It is observed that the battery voltage is not affected by applying mechanical vibration to the battery.

Vortex-induced vibration (VIV) of bluff bodies is one type of flow-induced vibration phenomenon, and the possibility of using it to harvest hydrokinetic energy from marine currents has recently been revealed. To develop an optimal harvester, various parameters such as mass ratio, structural stiffness, and inflow velocity need to be explored, resulting in a large number of test cases. This study primarily aims to examine the validity of a parameter optimization approach to maximize the energy capture efficiency using VIV. The Box–Behnken design response-surface method (RSM-BBD) applied in the present study, for an optimization purpose, allows for us to efficiently explore these parameters, consequently reducing the number of experiments. The proper combinations of these operating variables were then identified in this regard. Within this algorithm, the spring stiffness, the reduced velocity, and the vibrator diameter are set as level factors. Correspondingly, the energy conversion efficiency was taken as the observed value of the target. The predicted results were validated by comparing the optimized parameters to values collected from the literature, as well as to our simulations using a computational-fluid dynamics (CFD) model. Generally, the optimal operating conditions predicted using the response-surface method agreed well with those simulated using our CFD model. The number of experiments was successfully reduced somewhat, and the operating conditions that lead to the highest efficiency of energy harvesting using VIV were determined.

The automotive and aerospace industries increasingly use lightweight materials to improve performance while reducing fuel consumption. Lightweight materials are frequently used in electric vehicles (EVs). However, using these materials can increase airborne and structure-borne noise. Furthermore, EV noise occurs at high frequencies, and conventional materials have small damping. Thus, there is an increasing need for procedures that help design new materials and coatings to reduce the transferred and radiated noise at desired frequencies. This study pioneered new techniques for microstructure modeling of coated and uncoated materials with improved noise, vibration, and harshness (NVH) performance. This work uses the microstructure of materials to study their vibration-damping capacity. Images from an environmental scanning electron microscope (ESEM) show the microstructure of a sample polymer and its coating. Tensile tests and experimental modal analysis were used to obtain the material properties of the polymer for microstructure modeling. The current work investigates how different microstructure parameters, such as fiberglass volume fraction and orientation, can change the vibration performance of materials. The damping ratio in the study was found to be affected by changes in both the direction and volume ratio of fiberglass. Furthermore, the effects of the coating are investigated in this work. Through modal analysis, it was observed that increasing the thickness of aluminum and aluminum bronze coatings caused a rightward shift in resonance frequency. Coatings with a thickness of 2 mm were found to perform better than those with lower thicknesses. Furthermore, the aluminum coating resulted in a greater shift in frequency than the aluminum bronze coating. Additionally, the coating with a higher damping ratio (i.e., aluminum bronze) significantly reduced the amplitude of surface velocity due to excitation, particularly at higher frequencies. This study provides engineers with an understanding of the effects of layer coating on the NVH performance of components and a modeling approach that can be used to design vehicles with enhanced noise and vibration performance.

The dynamic development of electromobility has resulted in new directions of research, one of which is the analysis of the noise of traction motors. The designs of the motors used in electric vehicles are relatively new and often modified. In addition, strong competition also forces an increase in the power generated per unit mass of the motor, often at the expense of weakening the mechanical structure. This may result in an increase in the noise level generated by the electric drive, so this issue should be analyzed at the motor design stage. Different construction and operating conditions in relation to industrial or railway traction motors make it necessary to constantly develop methods for the noise analysis of the motors for electric vehicles. The aim of this article is to review the methods used so far in an analysis of the noise generated by the motors for electric vehicles. Three main methods are used by the authors of this paper: the analytical method, the hybrid method using two-dimensional models, and the hybrid method using three-dimensional models. In addition to the review of these methods, the paper also focuses on a synthetic summary of the most important factors determining the level and nature of the noise generated by electric vehicle motors.

Compared to onshore turbines, floating offshore wind turbines (FOWTs) take advantage of the increased availability of offshore wind while causing less environmental impact. However, the strong winds, waves, and currents to which they are subjected trigger oscillations that can cause significant damage to the entire structural system and reduce its useful life. To reduce these loads, active tower damping techniques such as filter banks can be used. These filters must be carefully tuned to block specific vibration frequencies. Therefore, it is essential to analyze the nature of the oscillations in the FOWT and to understand how the frequencies vary in time. This topic is usually approached from a point of view very focused on a specific turbine. What is proposed here is a general method, which can be applied to any type of wind turbine, to automatically study the relationship between vibration frequencies and the degrees of freedom (DOF) of the turbine, which facilitates the design of structural control. Each frequency is associated with the DOF of the FOWT that produces it. This methodology has been successfully validated in simulation experiments with the NREL 5 MW ITI Barge FOWT. Under the wind conditions of the experiments, the main frequency found is 0.605 Hz. This frequency coincides with the 3P theoretical frequency of the FOWT. This proposal may help to design structural control systems able to damp these vibration frequencies with accuracy and efficiency.

The hydrodynamic forces on an oscillating circular cylinder are predicted using neural networks under flow conditions where Vortex-Induced Vibrations (VIV) are known to occur. The derived neural network approximators are then incorporated in a dynamical model that allows prediction of the cylinder motion given flow conditions and initial conditions. Using experimental data, a minimum-least-squares compensator is tuned that includes linear stiffness and damping su-perimposed with a constant force offset. The compensator is decoupled, i.e., with equations in-dependent for each degree of freedom. By applying the neural network approximators and the derived compensator simulated experiments can be performed. These simulated experiments show that the compensator which cancels the linear components and any bias in the hydrody-namic forces effectively stabilizes the VIV motion. To support this time-domain analysis is per-formed along with phase-plane investigations. Maximum Lyapunov exponent analysis is also shown.

With the rapid development of high-speed railroads and subways, there has been an increasing number of bridge–tunnel overlapping structures. To study the dynamic response characteristics of bridge–tunnel structures under the synergistic effects of the vibration generated by high-speed railway and subway trains, the dynamic response characteristics of a bridge–tunnel structure under single-point vibration loading was analyzed by conducting numerical simulations and model tests, with the frequency response function and peak acceleration as the evaluation indices. The dynamic response characteristics of the overlapping structure under moving vibration loads of the high-speed railway and subway trains were further analyzed. The results showed that the dynamic response of the bridge–tunnel overlapping structure increased with the increase in the frequency under the full frequency domain single-point sweep vibration load. The dynamic response of the tunnel hance near the pile foundation side was significantly greater than the vault and invert. Compared with the effect of high-speed train loads alone, the dynamic response of the bridge–tunnel overlapping structure under the synergistic effects of high-speed railways and subways increased significantly and varied at different locations. This investigation provides theoretical support for the design and construction of bridge–tunnel overlapping structures under the synergistic effects of high-speed railways and subways, contributing to improving engineering quality and safety.

At present, a variety of standardized 18650 commercial cylindrical lithium-ion batteries are widely used in new energy automotive industries. In this paper, the Panasonic NCR18650PF cylindrical lithium-ion batteries were studied. The NEWWARE BTS4000 battery test platform is used to test the electrical performances under temperature, vibration and temperature-vibration coupling conditions. Under the temperature conditions, the discharge capacity of the same battery at the low temperature was only 85.9% of that at the high temperature. Under the vibration condition, mathematical statistics methods (the Wilcoxon Rank-Sum test and the Kruskal-Wallis test) were used to analyze changes of the battery capacity and the internal resistance. Changes at a confidence level of 95% in the capacity and the internal resistance were considered to be significantly different between the vibration conditions at 5 Hz, 10 Hz, 20 Hz and 30 Hz versus the non-vibration condition. The internal resistance of the battery under the Y-direction vibration was the largest, and the difference was significant. Under the temperature-vibration coupling conditions, the orthogonal table L9 (34) was designed. It was found out that three factors were arranged in order of temperature, vibration frequency and vibration direction. Among them, the temperature factor is the main influencing factor affecting the performance of lithium-ion batteries.