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16 pages, 3263 KiB

Open AccessArticle

Simulation Analysis of a Three-Degree-of-Freedom Low-Frequency Resonant Mixer

by Jinsheng Liang, Zheng Liu and Bolun Chang

Appl. Sci. 2025, 15(9), 4861; https://doi.org/10.3390/app15094861 - 27 Apr 2025

Viewed by 112

This study aims to model and analyze the performance of a three-degree-of-freedom low-frequency resonant mixer to verify the feasibility of its design approach. Based on the completion of the device design in reference to related theories, the working performance and vibration isolation characteristics [...] Read more.

This study aims to model and analyze the performance of a three-degree-of-freedom low-frequency resonant mixer to verify the feasibility of its design approach. Based on the completion of the device design in reference to related theories, the working performance and vibration isolation characteristics of the device at different resonance frequencies were determined through modeling and simulation. The results indicate that at the third-order natural frequency, the phase difference between the payload assembly and the vibration-isolating assembly is 180°, which counteracts a portion of the force applied to the rack, thereby demonstrating effective vibration isolation. Moreover, it is found that the phase difference between the excitation force and the excitation assembly response has a great influence on the vibration isolation effect of the equipment. The acceleration and amplitude were amplified, which facilitated efficient mixing. It has been verified that at the third-order natural frequency, the device can achieve amplification of acceleration and amplitude as well as vibration isolation. This ensures efficient mixing while reducing the impact on the external environment. Full article

(This article belongs to the Special Issue Technical Advances in Vibration Analysis: Modeling, Simulation and Applications)

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15 pages, 4229 KiB

Open AccessArticle

Regular and Chaotic Vibrations of a Nonlinear Rotor-Stator System

by Urszula Ferdek

Appl. Sci. 2024, 14(22), 10214; https://doi.org/10.3390/app142210214 - 7 Nov 2024

Cited by 1 | Viewed by 872

Abstract

The paper is concerned with the analysis of a six-degree-of-freedom non-linear model which describes the vibrations of a rotor. The model takes into account the impacts between the rotating element and a limiter of motion. Using numerical integration and spectrum analysis, the influence [...] Read more.

The paper is concerned with the analysis of a six-degree-of-freedom non-linear model which describes the vibrations of a rotor. The model takes into account the impacts between the rotating element and a limiter of motion. Using numerical integration and spectrum analysis, the influence of the excitation frequency, static loads, and the position of the limiter of motion on the type of vibrations of the system was studied. A multiparametric analysis has been performed to determine the areas of influence of two system parameters on the type of excited vibrations. Different types of vibration are further illustrated by plots of time histories, frequency spectra, phase portraits, stroboscopic portraits and bifurcation diagrams. The quality index of the system has also been determined and defined as the average value of the rotor kinetic energy. Depending on the parameters of the system, periodic, quasi-periodic or chaotic oscillations take place. The article primarily focuses on the risk of chaotic vibrations occurring in the system. Full article

(This article belongs to the Special Issue Technical Advances in Vibration Analysis: Modeling, Simulation and Applications)

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19 pages, 5688 KiB

Open AccessArticle

Dynamic Instability Investigation of the Automotive Driveshaft’s Forced Torsional Vibration Using the Asymptotic Method

by Mihai Bugaru and Ovidiu Vasile

Appl. Sci. 2024, 14(17), 7681; https://doi.org/10.3390/app14177681 - 30 Aug 2024

Viewed by 850

Abstract

This paper aims to investigate using FOAM to analyze the dynamic instability in the APPR for ADFTV based on a dynamic model (DMADFTV). The DMADFTV considers the following aspects: AD kinematic nonuniformity (ADKN), AD geometric nonuniformity (ADGN) of inertial characteristics for the spinning [...] Read more.

This paper aims to investigate using FOAM to analyze the dynamic instability in the APPR for ADFTV based on a dynamic model (DMADFTV). The DMADFTV considers the following aspects: AD kinematic nonuniformity (ADKN), AD geometric nonuniformity (ADGN) of inertial characteristics for the spinning movements (ICSM) of the AD elements (ADE), and the excitations induced by the gearbox–internal combustion engine modulations. The DMADFTV is considered the already-designed dynamic model developed by the first author of the ADFTV in a previous publication. This DMADFTV was used to compute the stationary frontiers of instability and the nonstationary spectral velocity amplitude (NSVA) versus nonstationary spectral amplitude (NSA) in the configuration space in transition through APPR, using the FOAM. The use of FOAM is much more versatile, from the analytical point of view, than the method of multiple scales and allows the computation of the NSA and the NSVA in the APPR. In contrast, these computations cannot be performed using the harmonic balance method. MATLAB Software R 2017 was developed based on DMADFTV and used the FOAM to compute the stationary frontiers of instability and the NSVA versus the NSA in transition through APPR for the ADFTV. The numerical results were compared with the experimental and numerical data published in the literature, finding agreements. The computation of the NSVA versus NSA in the configuration space using FOAM represents a method of detection of the chaotic manifestation of ADFTV. Full article

(This article belongs to the Special Issue Technical Advances in Vibration Analysis: Modeling, Simulation and Applications)

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15 pages, 676 KiB

Open AccessArticle

Flutter of a Plate at High Supersonic Speeds

by Aziz Sezgin, Birkan Durak, Alaattin Sayın, Huseyin Yildiz, Hasan Omur Ozer, Lutfi Emir Sakman, Sule Kapkin and Erol Uzal

Appl. Sci. 2024, 14(11), 4892; https://doi.org/10.3390/app14114892 - 5 Jun 2024

Viewed by 1169

Abstract

The vibrations of plate structures placed in a supersonic flow was considered. The undisturbed fluid flow was parallel to the plate. This type of problem is especially important in the aerospace industry, where it is named panel flutter. It has been noticed for [...] Read more.

The vibrations of plate structures placed in a supersonic flow was considered. The undisturbed fluid flow was parallel to the plate. This type of problem is especially important in the aerospace industry, where it is named panel flutter. It has been noticed for a long time that panel flutter may be problematic at high speeds. In this article, two specific problems were treated: in the first one, the plate was in the form of an infinite strip and the flow was in the direction of its finite length. Rigid walls indefinitely extended from the sides of the plate. In the second problem, the plate was a finite rectangle and the flow was parallel to one of its sides. The rest of the plane of the rectangle was again rigid. The first problem was a limiting case of the second problem. The flow was modeled by piston theory, which assumes that the fluid pressure on the plate is proportional to its local slope. This approximation is widely used at high speeds (supersonic speeds in the range of M > 1), and reduces the interaction between the fluid flow and the vibrations of the plate to an additional term in the vibration equation. The resulting problem can be solved by assumed mode methods. In this study, the solution was also found by using the collocation method. The contribution of this study is the correlation between the flutter velocity and the other parameters of the plate. The main result is the flutter velocity of the free fluid flow under which the plate vibrations become unstable. Finally, simple expressions are proposed between the various non-dimensional parameters that allows for the quick estimation of the flutter velocity. These simple expressions were deduced by least squares fits to the computed flutter velocities. Full article

(This article belongs to the Special Issue Technical Advances in Vibration Analysis: Modeling, Simulation and Applications)

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17 pages, 9032 KiB

Open AccessArticle

Design and Experiment of a Passive Vibration Isolator for Small Unmanned Aerial Vehicles

by Chan-Hwi Kang, Hun-Suh Park, Seong-Weon Seo and Dong-Gi Kwag

Appl. Sci. 2024, 14(10), 4113; https://doi.org/10.3390/app14104113 - 12 May 2024

Cited by 4 | Viewed by 2580

Abstract

The advancement of sensor, actuator, and flight control technologies has increasingly expanded the possibilities for drone utilization. Among the technologies related to drone applications, the vibration isolator technology for payload has a significant impact on the precision of optical equipment in missions such [...] Read more.

The advancement of sensor, actuator, and flight control technologies has increasingly expanded the possibilities for drone utilization. Among the technologies related to drone applications, the vibration isolator technology for payload has a significant impact on the precision of optical equipment in missions such as detection, reconnaissance, and tracking. However, despite ongoing efforts to develop vibration isolators to mitigate the impact of vibrations transmitted to optical equipment, research on drone-specific natural frequencies and payloads has been lacking. Consequently, there is a need for research on vibration isolators tailored to specific drone types and optical equipment payloads. This study focuses on exploring the correlation between the natural frequencies of drones and the weight of the payload, and proposes methods for developing and testing vibration isolators that consider both factors. To achieve this, the study measured the stiffness of vibration isolator rubbers and conducted cross-validation between random vibration tests and finite element method (FEM) analyses to verify the vibration reduction effects resulting from changes in the dynamic characteristics of vibration isolator rubbers. The rubber with a shore hardness of 70 exhibited relatively high damping and damping performance during random vibration tests. Additionally, it showed relatively high stability with only one resonance point measured within the operational frequency band. Through the findings of this study, a methodology for selecting vibration isolators for drones is proposed, aiming to enhance the stability of optical equipment. Full article

(This article belongs to the Special Issue Technical Advances in Vibration Analysis: Modeling, Simulation and Applications)

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20 pages, 1013 KiB

Open AccessArticle

Bandgap Dynamics in Locally Resonant Metastructures: A General Theory of Internal Resonator Coupling

by Hossein Alimohammadi, Kristina Vassiljeva, S. Hassan HosseinNia and Eduard Petlenkov

Appl. Sci. 2024, 14(6), 2447; https://doi.org/10.3390/app14062447 - 14 Mar 2024

Cited by 2 | Viewed by 1093

Abstract

The dynamics of metastructures, incorporating both conventional and internally coupled resonators, are investigated to enhance vibration suppression capabilities through a novel mathematical framework. A close-form formulation and a transfer function methodology are introduced, integrating control system theory with metastructure analysis, offering new insights [...] Read more.

The dynamics of metastructures, incorporating both conventional and internally coupled resonators, are investigated to enhance vibration suppression capabilities through a novel mathematical framework. A close-form formulation and a transfer function methodology are introduced, integrating control system theory with metastructure analysis, offering new insights into the role of internal coupling. The findings reveal that precise internal coupling, when matched exactly to the stiffness of the resonator, enables the clear formation of secondary bandgaps, significantly influencing the vibration isolation efficacy of the metastructure. Although the study primarily focuses on theoretical and numerical analyses, the implications of adjusting mass distribution on resonators are also explored. This formulation methodology enables the adjustment of bandgap characteristics, underscoring the potential for adaptive control over bandgaps in metastructures. Such capabilities are crucial for tailoring the vibration isolation and energy harvesting functionalities in mechanically resonant systems, especially when applied to demanding heavy-duty applications. Full article

(This article belongs to the Special Issue Technical Advances in Vibration Analysis: Modeling, Simulation and Applications)

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17 pages, 5208 KiB

Open AccessArticle

Optimization Design of Double Wishbone Front Suspension Parameters for Large Mining Dump Truck and Analysis of Ride Comfort

by Jianqiao Zhao, Xueping Ren, Zhiming Dong and Tongtong Liu

Appl. Sci. 2024, 14(5), 1812; https://doi.org/10.3390/app14051812 - 22 Feb 2024

Cited by 1 | Viewed by 2323

Abstract

With the advancement of technology, mining trucks are gradually becoming larger, imposing higher performance requirements on the front suspension. There is a need to transform the original integral non-independent front axle of mining dump trucks with a payload exceeding 300 tons into an [...] Read more.

With the advancement of technology, mining trucks are gradually becoming larger, imposing higher performance requirements on the front suspension. There is a need to transform the original integral non-independent front axle of mining dump trucks with a payload exceeding 300 tons into an independent front suspension with a double-wishbone suspension. The changing of the front suspension is bound to have an impact on the overall vehicle’s handling stability and ride comfort. Therefore, the following research is conducted to investigate and analyze these effects. Firstly, the paper proposes a method for optimizing the parameters of the double-wishbone front suspension. The double-wishbone front suspension is modeled, and a comparison with a kinematic model is conducted to validate the accuracy of the model. Secondly, unreasonable hardpoint parameters are optimized. Thirdly, a dynamic model of the entire vehicle is established based on the optimized parameters, and an analysis of handling stability and ride comfort for the entire vehicle is performed. Finally, simulation results are compared and analyzed against experimental data. The results indicate that the optimized positioning parameters not only effectively enhance the suspension performance of the mining dump truck but also meet the requirements for handling stability and smoothness. The overall smoothness of the vehicle is significantly improved after the modification. This study not only holds significant engineering value in reducing vibrations in dump trucks and enhancing driver comfort, but also provides theoretical support for subsequent research and development in the industry. Full article

(This article belongs to the Special Issue Technical Advances in Vibration Analysis: Modeling, Simulation and Applications)

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19 pages, 6535 KiB

Open AccessArticle

Microgravity Decoupling in Torsion Pendulum for Enhanced Micro-Newton Thrust Measurement

by Linxiao Cong, Jiabin Wang, Jianfei Long, Jianchao Mu, Haoye Deng and Congfeng Qiao

Appl. Sci. 2024, 14(1), 91; https://doi.org/10.3390/app14010091 - 21 Dec 2023

Viewed by 1662

Abstract

To enhance the accuracy of micro-Newton thrust measurements via a torsion pendulum, addressing microgravity coupling effects caused by platform tilt and pendulum mass eccentricity is crucial. This study focuses on analyzing and minimizing these effects by alleviating reference surface tilt and calibrating the [...] Read more.

To enhance the accuracy of micro-Newton thrust measurements via a torsion pendulum, addressing microgravity coupling effects caused by platform tilt and pendulum mass eccentricity is crucial. This study focuses on analyzing and minimizing these effects by alleviating reference surface tilt and calibrating the center of mass during thrust measurements. The study introduced analysis techniques and compensation measures. It first examined the impact of reference tilt and center of mass eccentricity on the stiffness and compliance of the torsion pendulum by reconstructing its dynamic model. Simscape Multibody was initially employed for numerical analysis to assess the dynamic coupling effects of the tilted pendulum. The results showed the influence of reference tilt on the stiffness and compliance of the torsion pendulum through simulation. An inverted pendulum was developed to amplify the platform’s tilt angle for microgravity drag-free control. Center of mass calibration can identify the gravity coupling caused by the center of mass position. Based on the displacement signal from the capacitive sensor located at the end of the inverted pendulum, which represents the platform’s tilt angle, the pendulum’s vibration at 0.1 mHz was reduced from 5.7

μ

m/Hz^1/2 to 0.28

μ

m/Hz^1/2 by adjusting the voltage of piezoelectric actuator. Finally, a new two-stage torsion pendulum structure was proposed to decouple the tilt coupling buried in both pitch and roll angle. The study utilized theoretical models, numerical analysis, and experimental testing to validate the analysis methods and compensation measures for microgravity coupling effects in torsion pendulums. This led to a reduction in low-frequency noise caused by ground vibrations and thermal strains, ultimately improving the micro-Newton thrust measurement accuracy of the torsion pendulum through the platform’s drag-free control. Full article

(This article belongs to the Special Issue Technical Advances in Vibration Analysis: Modeling, Simulation and Applications)

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