Experimental Vibration Research Articles

Design method for controlling gear surface cutting textures to reduce noise

To address the issue of cutting textures formed on gear tooth surfaces during the manufacturing process, a design method is proposed where the cutting textures are distributed according to a sine function. Initially, a simplified mathematical model of the actual gear tooth surface cutting texture was constructed based on a four-axis machining center and cylindrical milling cutter. Ten design cases were created with different sine function phases, aiming to minimize angular acceleration. These cases were compared with normally processed gear pairs to identify the optimal design. Subsequently, using the established actual tooth surface model, the optimal design gear pair was compared with normally processed gear pairs through noise simulation experiments. The correctness of the simulation results was verified through vibration and noise testing experiments. The results indicated that the maximum amplitude of the first-order frequency of vibration and noise sound pressure levels decreased by 14.93% and 11.16%, respectively, validating the effectiveness of the surface cutting texture optimization method. This method provides a novel solution for reducing vibration and noise in gears.

Theoretical and experimental nonlinear vibration analysis for a spacecraft solar array connected with flexible hinges

Theoretical and experimental nonlinear vibration analysis for a spacecraft solar array connected with flexible hinges

On Low-Frequency Vibration Suppression Characteristics of Corrugated Metamaterial Beams

A class of corrugated metamaterial beams is constructed by attaching local resonators into the available internal space of a corrugated sandwich beam, and the low-frequency vibration suppression characteristic is realized and researched using the spectral element method (SEM) and finite element method (FEM). The transmission coefficient and vibration distribution of the corrugated metamaterial beam are obtained, and the results demonstrate that the low-frequency locally resonant band gap can be opened and utilized in low-frequency vibration control of corrugated sandwich beams. Further research is conducted on the parameter design and band gap coupling of corrugated metamaterial beams, and vibration suppression performance is achieved over a broader low-frequency range. Vibration experiment on the corrugated metamaterial beam is also carried out, which validates the effectiveness of low-frequency vibration suppression characteristics of the corrugated metamaterial beam. The present research can provide a novel idea of metamaterial design for the low-frequency vibration suppression of corrugated sandwich structures.

Mechanical Properties and Vibrational Behavior of 3D-Printed Carbon Fiber-Reinforced Polyphenylene Sulfide and Polyamide-6 Composites with Different Infill Types

The aim of the present study is to investigate the performance of two carbon fiber-reinforced composite polymers used to manufacture end-use parts via the fused filament fabrication (FFF) method. The materials under investigation were carbon fiber-reinforced Polyamide-6 (PA6-CF15) and carbon fiber-reinforced polyphenylene sulfide (PPS-CF15). To evaluate their mechanical properties and vibrational behavior, specimens were fabricated with four distinct infill patterns: grid, gyroid, triangle and hexagon. In particular, the vibrational behavior of the 3D-printed composites was determined by conducting cyclic compression testing, as well as modal tests. Additionally, the mechanical behavior of the reinforced polymers was determined by conducting both uniaxial tensile and compression tests, as well as three-point bending tests. The results of the mechanical experiments revealed that the grid pattern exhibited the best overall performance, while the gyroid pattern exhibited the greatest strength-to-weight ratio, making it the most durable infill for use with composite filaments. In vibration experiments, PA6-CF15 structures exhibited higher damping ratios than PPS-CF15, indicating superior damping capacity. Among the infill patterns, the hexagon pattern provided the greatest vibration isolation performance.

Enhancing CFRP damping with graphene nanoplatelets: experiments versus finite element analysis

This study investigates the enhancement of damping properties in carbon fiber-reinforced polymer (CFRP) composites by incorporating graphene nanoplatelets (GNPs) into the epoxy matrix. Epoxy and CFRP specimens with varying GNP concentrations, were developed and tested through free vibration experiments to measure damping ratios. Additionally, a computational model based on the finite element method was developed to simulate the damping behavior of these hybrid nanocomposites. Using periodic representative volume elements under sinusoidal axial loads, the model accurately predicted damping performance by calculating the time lag between applied loads and resulting deformations. Comparison of numerical results with experimental data revealed a strong correlation, confirming the model's effectiveness in capturing the influence of GNP mass fraction on damping enhancement.

Analysis of No‐Load Normal Vibration in Single‐Sided Permanent Magnet Synchronous Linear Motors With Different End Structures

ABSTRACTThis paper investigates the no‐load normal vibrations of single‐sided permanent magnet synchronous linear motors (S‐PMSLMs) with different end structures, addressing a significant gap in the current literature. By employing the Maxwell stress tensor method, analyzes the harmonic orders and frequencies of the no‐load normal force density are analyzed. Comparative research between the comb‐type auxiliary tooth (CTAT) and conventional auxiliary tooth (C‐AT) structures indicates that while the CTAT marginally increases the amplitude of the no‐load normal force density, it significantly reduces harmonic amplitudes and vibration levels. The theoretical and simulation analyses are validated through no‐load vibration experiments, providing valuable insights for the design optimization of S‐PMSLMs, particularly beneficial for high‐speed transportation systems that require high precision and reliability.

Long-Term Monitoring of Dynamic Properties and Device Characteristics of a Base-Isolated Building by Vibration Experiments and Observations

Long-Term Monitoring of Dynamic Properties and Device Characteristics of a Base-Isolated Building by Vibration Experiments and Observations

Calibration and Testing of Discrete Element Simulation Parameters for Ultrasonic Vibration-Cutter-Soil Interaction Model

This paper established an accurate discrete element for ultrasonic vibration-cutter-soil interaction model to study the interaction mechanism between the soil-engaging component and the soil. In order to reduce the interaction between calibration parameters and improve the calibration accuracy, it is proposed that the soil constitutive, contact parameters, and bonding parameters be calibrated by combining the soil repose angle experiment and the soil resistance experiment of ultrasonic vibration cutting. The study adopts the Hertz-Mindlin (no slip) contact model used in EDEM, to explore soil particle interactions. The central composite design is used to achieve systematic investigation. 3-factor 3-level orthogonal design experiment was employed using the coefficient of restitution, the coefficient of static friction, and the coefficient of rolling friction as key test factors and soil’s repose angle as the response index. Based on the Hertz-Mindlin with bonding contact model, Design-Expert 13.0 software was used to design the Plackett-Burman experiment, the steepest ascent, and the Box-Behnken experiment. With the maximum soil cutting resistance in ultrasonic vibration cutting experiment used as the response value, the adhesion parameters were optimized, and the optimal solution combination was obtained as: Normal Stiffness = 4.635 × 106 N/m, Shear Stiffness = 3.401 × 106 N/m, and Bonded Disk Radius = 2.57 mm. The optimal parameter combinations obtained from the calibration experiments were verified in two ways: ultrasonic vibration cutting and non-ultrasonic vibration cutting. The results showed that the errors between the simulation values and the actual values of the two comparative experiments were less than 5%, and the model calibrated for the three parameters can be used to study the drag reduction mechanism of ultrasonic vibration cutting in soil.

Multi-direction vibration isolation via transverse isotropy control of metal rubber

Abstract Metal rubber (MR) is widely used for vibration isolation due to its high damping and designable stiffness, but the isolation efficiency is relatively low in the non-molding direction due to its transverse isotropy. In this paper, the transverse isotropy of MR is controlled by design of manufacturing parameters (wire diameter, spiral diameter and compression ratio), material parameter (relative density) and geometric structure, to improve the isolation efficiency in the non-molding direction. Firstly, the helix unit was adopted to establish the relation between the transverse isotropy of MR material and manufacturing parameters, and manufacturing parameters were designed to control the transverse isotropy of MR material. Next, based on parametric modeling and genetic algorithm, material parameters and geometric structure were optimized to control the transverse isotropy of MR isolator. Finally, the transverse isotropy of the designed MR isolator was tested by quasi-static experiments, and multi-direction vibration isolation performance was verified by random vibration experiments. It is demonstrated that the transverse isotropy is controlled efficiently, and the vibration isolation efficiencies of the proposed MR isolator are all up to 85% under 15-2000Hz broadband random vibration in X, Y and Z directions.

A Simplified Estimation of Spindle Dynamic Compliance From Current Measurement for Contactless Electromagnetic Excitation

Abstract Dynamic stiffness during spindle rotation is important in the performance evaluation of machine tools. A method for measuring dynamic compliance, which is the reciprocal of dynamic stiffness, using a load generator in uniaxial and unidirectional was investigated. An electromagnetic force generation model was experimentally constructed using static coil current and load measurements. Using this model, the vibratory force was calculated. The excitation conditions without gap effect were set, and the dynamic compliance was estimated by conducting actual vibration experiments. The estimated dynamic compliance was in good agreement with the dynamic compliance obtained from the force measurement, indicating that the proposed method can perform the measurement efficiently.

A Modified Multiaxial Fatigue Model and Its Application for the Fatigue Life Prediction of Aircraft Hydraulic Pipes.

The fatigue failure of a structure may occur under a multiaxial vibration environment; it is necessary to establish a better multiaxial fatigue life prediction model to predict the fatigue life of the structure. This study proposes a new model (MWYT) by introducing the maximum absolute shear stress into the WYT model. The feasibility of the MWYT model is verified by using the multiaxial fatigue experimental data of 304 stainless steel, Q235B steel, 7075-T651 aluminum alloy and S355J0 steel. Further, finite element vibration simulations are performed on a typical parallel hydraulic pipe structure, and the vibration simulation results of the pipe structure are verified through the vibration experiment. Finally, the MWYT model is used to predict the fatigue lives of the pipe structure under random excitation and pulsation excitation, respectively, and the fatigue life of the pipe structure under the combined loading from random excitation and pulsation excitation is predicted based on Miner's rule. By comparing with the design life of the aircraft, the predicted life of the pipe structure meets the service requirements for it.

The Role of Vibrations in Unmanned Aerial Vehicles Efficiency Measurement Techniques and Performance Effects

Vibrations in unmanned aerial vehicles (UAVs) significantly impact flight stability, sensor accuracy, and structural integrity, with common sources including propeller rotation, motor dynamics, and aerodynamic forces. Addressing these vibrations is essential to enhancing UAVs performance and operational durability. This paper examines both theoretical and experimental vibration analysis techniques such as frequency analysis, modal analysis, and finite element analysis as key tools for understanding and controlling vibration dynamics. Various strategies for vibration mitigation are explored, including structural optimization, flight control systems, and active/passive isolation systems, all aimed at improving stability and durability. By accurately identifying vibration sources and effects, along with applying effective engineering solutions, UAVs can achieve enhanced performance, extended operational longevity, and broadened applications in sectors requiring high precision and stability. Consequently, vibration mitigation emerges as a critical factor not only for performance improvement but also for the reliable deployment of UAVs technology in demanding environments.

Topological mechanical states in geometry-driven hyperuniform materials.

Disordered hyperuniform materials are increasingly drawing attention due to their unique physical properties, associated with global isotropy and locally broken orientational symmetry, that set them apart from traditional crystalline materials. Using a dynamic space-partitioning process, we generate disordered hyperuniform cellular structures where distinct patterns of pentagonal and heptagonal topological defects emerge within hexagonal domains. The microscopic defect dynamics are guided by local topological transitions, commonly observed in viscoelastic systems. This leads to a reduction in the system's structural entropy as hyperuniformity is attained, marked by the rise and fall of certain locally favored motifs. Further, we introduce an elastic hyperuniform material that exhibits evolving topological mechanical states in the continuum. Through vibration experiments and numerical analysis, we show energy localization around these defects, which is tied to the topological band gaps inherent to our geometry-driven material. We suggest that this robust dynamic mechanism influences a broad spectrum of disordered systems, from synthetic materials to biological structures guided by stigmergic interactions.

Full-field measurements of high-frequency micro-vibration under operational conditions using sub-Nyquist-rate 3D-DIC and compressed sensing with order analysis

High-speed imaging is essential for high-frequency vibration measurement techniques that utilize images, such as digital image correlation (DIC). However, it poses challenges, including reduced displacement resolution due to decreased image resolution, increased measurement and calculation costs, and greater data volume. A previous method used compressed sensing to reconstruct time information from images captured with a high-resolution, low-speed camera, allowing high-frequency vibration measurements. However, this method was limited to steady vibrations since waveforms were reconstructed using the Fourier basis. In this study, order analysis is introduced into compressed sensing to measure operational vibrations, including rotation speed fluctuations, such as those in automobile engines. An out-of-plane vibration experiment on an aluminum plate confirmed the method’s accuracy in identifying mode shapes and displacement spectra of operational vibrations. The proposed method reconstructed vibrations (amplitude: several μm to several hundred μm, frequency: 33.3–133.2 Hz) using images captured at 10 fps. The modal assurance criterion (MAC) indicated 0.98 accuracy compared with finite element analysis. The mean squared error below 1 % compared to the frequency spectrum obtained with a laser Doppler vibrometer. Applied to automobile engine vibrations (amplitudes of a few μm), the method achieved errors under 2 % over a 1225 mm × 960 mm field of view. However, error increased for vibrations below the DIC displacement resolution. This method shows promise for analyzing vibrations in rotational machinery, such as engines and motors, through the full-field measurement of high-speed operational vibrations. In addition, the developed compressed sensing with order basis is expected to contribute to the advancement of the recovering missing signals and data compression.

Effect of boron oxide and basicity on viscosity and crystallization onset temperature of СаО–SiO<sub>2</sub>–B<sub>2</sub>O<sub>3</sub>–12%Cr<sub>2</sub>O<sub>3</sub>–3%Аl<sub>2</sub>O<sub>3</sub>–8%МgO slag system

The rapid growth of demand for stainless steel and, accordingly, its production, which occurred in the second half of the 20th century and continues till today, makes it necessary to conduct studies of the properties of oxide systems that will contribute to the improvement of metallurgical production technologies for such steel. Therefore, in this paper, using the method of simplex grids for experimental planning and vibration viscometry, a study was conducted of the effect of basicity and boron oxide content on the viscosity and crystallization onset temperature of slags of the СаО–SiO2–B2O3–12%Cr2O3–3%Аl2O3–8%МgO oxide system formed during the reduction period of the production of low-carbon stainless steel by the argon-oxygen decarbonization (AOD) process, which is currently the main method for producing corrosion-resistant steel. The introduction of boron oxide into AOD-slags is a possible solution to the problem of instability of the physical properties of slags during smelting, caused by the volatility of fluorspar fluorides, traditionally used as a flux, and compliance with increasingly stringent environmental requirements by eliminating the formation of toxic fluorine compounds. Based on the results of experimental studies of the viscosity of slags of the studied oxide system depending on the chemical composition and temperature, approximating mathematical models in the form of a reduced third-degree polynomial are constructed. Graphically, the results of mathematical modeling are presented in the form of “composition – property” diagrams, which allow quantitatively determining the effect of temperature and chemical composition of the slags under study on viscosity and their composition on the crystallization onset temperature. It is noted that at 1600 and 1650°C, an increase in the boron oxide content in the slag from 3.0 to 6.0% has a favorable effect on the fluidity of the formed slags in the basicity range of 1.0-2.5. For example, an increase in the boron oxide concentration from 3.0 to 6.0% ensures a decrease in the viscosity of the slags from 2.0 to 0.5 Pa s at a temperature of 1600°C and from 0.4 to 0.3 Pa s at a temperature of 1650°C in the region of increased basicity up to 2.0-2.5.

A quantitative characterization model for nonlinear dynamic parameters of O-rings

When the rubber O-ring follows the primary seal in the axial direction as a secondary seal, there is hysteresis behavior between the restoring force and displacement. However, the dynamic parameters of O-rings are mostly expressed as constants in dynamic analysis at present, which cannot accurately describe the dynamic behavior of sealing systems. In response to the problem of poor track performance of mechanical seals, based on the actual working conditions in nuclear reactor coolant pumps, vibration experiments with high pressure and water lubrication are carried out on ethylene-propylene-diene monomer (EPDM) rubber O-rings, which can reveal the laws in the actual situation. The experimental results confirm that there are nonlinear variations of O-ring dynamic parameters in vibration, which cannot be expressed by constants. In order to quantitatively characterize the nonlinear behavior, this study establishes a novel mathematical model and analyze the influence of working conditions. A method combining the nonlinear properties of both interfacial sliding and body viscoelasticity of O-rings is proposed. The nonlinear stiffness, damping and friction (NSDF) model is established based on the adjusted Iwan model and the trace method. The finite element analysis and vibration experiments are carried out to study the hysteretic behavior and determine the parameters of the model. Furthermore, the influence of medium pressure and vibration amplitude on interfacial stiffness and O-ring stiffness and damping are discussed. It is pointed out that O-ring stiffness and damping decrease with increasing amplitude and increase with increasing pressure. The comparative analysis of experiments and model shows that the proposed model can provide an accurate determination of the nonlinear behavior of O-rings in vibration. The results and the proposed model can provide a basis for the evaluation of the dynamic performance of mechanical seal systems.

(Invited) Unraveling the Impact of Different Thermal Quenching Routes on Luminescence Efficiency of Y3Al5O12:Ce3+ Phosphor: Insights from Mode-Selective Vibrational Excitation Experiments

Cerium doped yttrium aluminium garnet, Y3Al5O12:Ce3+, is the prototype material for solid-state white lighting and it still is an important white LED phosphor. However, fundamental understanding of the thermal quenching of luminescence, which leads to a pronounced reduction of the emission intensity under high-power light-emitting diode operation, remains to be obtained. Here we show, through a multi-technique approach based on photoluminescence, thermoluminescence and mode-selective vibrational excitation experiments that thermal quenching of luminescence in Y3Al5O12:Ce3+ is caused by a combined effect of thermal ionization, thermally activated concentration quenching, and thermally activated 5d - 4f crossover relaxation via electron-phonon coupling, and establish the general trends upon variation of the Ce3+ concentration and temperature. Thermal quenching below 600 K is primarily the result of concentration quenching and crossover relaxation, which can be suppressed by keeping the Ce3+ dopant concentration far below 0.7 mol%, whereas for temperatures above 600 K thermal ionization is the predominating quenching process. This new insight into the interplay between different thermal quenching processes provides design principles for optimizing the light emittance and colour stability of new phosphor materials used in white lighting devices characterized by certain operating temperatures.

Vibration properties of full ceramic bearing under elastohydrodynamic fluid lubrication based on the energy approach

As an important part of rotating machinery, heat generation due to friction is inevitable during the rotating process of bearings. A large amount of heat causes the temperature of lubricating oil to increase, viscosity of lubricating oil to decrease, and lubricating performance decreases. Addressing the issue of inadequate lubrication between the rolling element and raceway due to increased lubricating oil temperature, this study focuses on full-ceramic ball bearings. It examines the impact of temperature fluctuations on the bearing's lubrication condition and investigates the vibration characteristics of the full-ceramic bearing. The variation in the viscosity of lubricating oil with respect to temperature is measured via a rotary viscometer. A dynamic model of the silicon nitride full-ceramic ball bearing, which considers the effects of elastohydrodynamic lubrication, is established. The impacts of changes in lubricating oil viscosity due to different temperatures on oil film pressure, oil film thickness, and bearing vibration are analyzed and then compared with experimental data. It is observed that under conditions of constant load and speed, the film thickness of the lubricating oil decreases as the viscosity decreases. Additionally, the second peak value of oil film pressure is reduced with the declining viscosity of the lubricating oil. As the viscosity decreases, the vibration of the bearing increases. The amplitude discrepancy between the simulated vibration signal and experimental vibration signal of the full-ceramic bearing is found to be less than 10 %, verifying the validity of the dynamic model.

A novel method for failure probability prediction of plain weave composites considering loading randomness and dispersion of strength

A new method based on combined residual stiffness-strength degradation is developed to predict the failure probability of plain weave composites subjected to random fatigue loadings. All the parameters presented in the proposed analytical model are characterized using the outcomes from quasi-static and constant amplitude fatigue testing. The evolution of residual strength is obtained based on combined residual stiffness-strength degradation model, which can greatly reduce the cost of the experiments. The Weibull distribution with two parameters is used to account for the dispersion of residual strength. Combing with randomness statistics of the fatigue loadings and the interference criterion of stress-strength, the fatigue failure behavior and failure probability are obtained. The narrow-band random vibration experiments were conducted to generate the random loadings and validate the predicted results. The approach proposed in this paper takes full advantage of residual stiffness or residual strength method and has better accuracy.

Experimental investigation of the relation between operating conditions and offshore wind turbine drivetrain dynamics

Abstract This study investigates the impact of operating and environmental conditions on the vibration induced on an offshore wind turbine drivetrain. Furthermore, it explores the role of the dynamic response of the global wind turbine structure to vibration on the drivetrain. A prolonged experimental campaign dedicated to condition monitoring the drivetrain provides experimental vibration signals. These vibration signals are acquired under varying operating conditions across multiple locations of an offshore wind turbine drivetrain of a Belgian Offshore Wind farm and serve as the basis for analysis. The signals’ statistics facilitate establishing connections between dynamic behaviour and operational variables, such as active power, rotor speed, blade pitch angle, and turbulence intensity, sampled at every second and provided by Fast-SCADA. The initial phase of the analysis involves a comprehensive examination of various statistical properties of the vibration signals to link the drivetrain’s dynamic response to operational conditions. This exploration includes both active and standstill periods of the wind turbine. A comprehensive summary that relates the global vibration characteristics with the operating conditions is formed by scrutinizing the overall vibration signals. In the study’s second phase, a detailed investigation is conducted on the vibration signals recorded during standstill conditions. Investigation of standstill data ensures that the structural modes’ spectral content does not interfere with the machines’ kinematic content. The analysis of standstill data proceeds from determining the most energetic resonance frequencies through the average power spectral density of the vibration signals. These identified frequency bands enable a thorough exploration, revealing the interlink between the offshore wind turbine drivetrain’s dynamic response and the operating/environmental conditions.