Search Results (187)

In the extraction of shale gas and oil, the vibration characteristics of the drill string significantly influence wellbore quality, potentially leading to wellbore instability, excessive tool wear, and diminished drilling efficiency. This study tackles the challenges associated with drill string vibrations by developing an integrated technical framework of multi-field coupled dynamic modeling, Sobol-based key parameter identification, and NSGA-II-driven multi-objective structural optimization, and proposes a synergistic vibration suppression strategy combining structural parameter adjustment and hydraulic damper configuration based on multibody dynamics and finite element analysis. Initially, a dynamic model that accounts for the coupling between the wellbore and the drill string is developed to scrutinize the impact of various vibration modes on wellbore quality. Subsequently, detrimental vibrations are mitigated through the optimization of structural parameters, including but not limited to stiffness distribution and the strategic placement of vibration absorbers. Finally, the efficacy of the optimized design is substantiated through numerical simulations and field experiments. The results demonstrate that the optimized drill string achieves a simulation average reduction of 30% in lateral vibration amplitude across the rotational speed range of 60–120 RPM and a simulation average improvement of 25% in the attenuation of axial vibration energy. These enhancements notably bolster drilling stability and elevate wellbore quality. This research furnishes both theoretical and technical underpinnings for the efficient development of shale gas and oil resources. Full article

Low-frequency broadband vibration isolation poses a critical limitation for marine power equipment, as conventional passive isolators fail below 50 Hz. Targeting the 10–315 Hz band (dominant for marine pumps), this study proposes a passive isolator integrated with a disk-like acoustic black hole. This article aims to address the core engineering issues in the operating frequency band of marine power equipment, specifically the failure of traditional passive vibration isolators in low-frequency vibration isolation and the insufficient reliability of active/hybrid vibration isolation schemes in the marine high-salt fog environment. Meanwhile, it breaks through the theoretical bottleneck of traditional acoustic black hole (ABH) structures, which have a high cut-off frequency and a weak low-frequency vibration suppression capability. A passive vibration isolator integrating a disk-shaped ABH and a damping layer is proposed to achieve efficient low-frequency broadband vibration isolation. The modal participation factor was calculated via finite element modal superposition to identify the dominant low-frequency modes, and a high-fidelity dynamic model was established to analyze the key ABH parameters and damping layer configurations. A prototype validation was conducted on an ISG vertical centrifugal pump acceleration response. The results show that the isolator (L_ABH = 95 mm, h_uni = 10 mm, disk-shaped damping layer) achieves 8.87 dB and a higher vibration level drop of 17.52 dB in 10–315 Hz and 315 Hz–10 kHz, respectively, than non-ABH designs, with simulation–experiment errors of less than 5%. The ABH–dynamic vibration absorber synergistic mechanism overcomes the low-frequency limitation of conventional passive isolators, providing a reliable solution for marine power equipment vibration suppression. Full article

To address the demand for a micro-power supply for vehicle suspension control, a novel harvester is proposed to recover vortex-induced vibration energy in the wake of a shock absorber. A suspension dynamic model was established to simulate the spring compression process and identify the wind-shielding condition. The spring-shock absorber assembly was then simplified as a stepped cylinder with two cross-sections. Flow-field analysis showed that the size, shape, and rising angle of the wake vortices were affected by the bluff-body geometry, Reynolds number, and boundary conditions. The downwash motion was found to directly influence vortex development, and two new vortex-connection modes were identified. These results provided guidance for harvester optimization. A two-way fluid–structure interaction model was developed to describe the electromechanical conversion behavior of the proposed harvester under flow excitation. Numerical results showed that the output voltage increased with vehicle speed. An average peak voltage of 1.82 V was obtained when the piezoelectric patches were installed two larger-cylinder diameters downstream. The optimal patch length was 120 mm, and further increasing the length did not significantly improve the harvesting performance. Finally, a full-scale prototype was tested, and the measured voltage agreed well with the simulation results. The proposed harvester can therefore serve as a potential micro-power source for low-power suspension electronics. Full article

Cylinder–plate combined structures (CPCS) are widely used in aerospace, marine engineering, and offshore platform systems. During service, they are frequently subjected to stochastic excitations induced by turbulent boundary layers, acoustic loads, hydrodynamic disturbances, and broadband operational vibrations. Excessive random vibration responses may significantly reduce structural reliability, accelerate fatigue damage, and compromise operational safety. To address these engineering challenges, a unified stochastic dynamic analysis and vibration suppression framework is established for functionally graded graphene platelet-reinforced composites (FG-GPLRC) CPCS equipped with distributed dynamic vibration absorbers (DVAs). Adopting the First-order Shear Deformation Theory (FSDT), a comprehensive energy functional for the CPCS is established, in which the penalty method is implemented to impose boundary conditions and ensure interface continuity. Subsequently, the Pseudo-excitation Method (PEM) is utilized to convert the stochastic vibration analysis into an equivalent deterministic harmonic problem, and the governing equations are spatially discretized by combining the spectral geometric method (SGM) with the Ritz variational procedure, enabling efficient evaluation of power spectral density (PSD) and root-mean-square (RMS) responses. The reliability of the proposed model is verified through a series of numerical validation comparisons. On this basis, comprehensive parametric investigations are conducted to assess how material properties, structural geometries, and critical DVA parameters influence system behavior. The results demonstrate that the incorporation of distributed DVAs can achieve superior vibration suppression performance. This study provides an efficient and reliable theoretical framework for stochastic vibration analysis and damping design of advanced composite plate–shell coupled structures operating in complex random environments, offering important theoretical support for dynamic optimization design in aerospace and marine engineering applications. Full article

To address the limited capability of conventional hydro-pneumatic suspensions in coordinated damping–stiffness regulation, this paper proposes a new semi-active hydro-pneumatic suspension (SAHPS) system based on a dual-valve shock absorber. A damping valve architecture composed of a spring check valve–solenoid proportional valve–spring check valve is arranged between the rod and rodless chambers of the hydraulic cylinder, enabling coordinated adjustment of suspension damping and equivalent stiffness. Furthermore, a genetic algorithm optimization with model predictive control (GA-MPC) is designed to enhance the overall dynamic performance of the suspension while effectively reducing the operating frequency of the solenoid proportional valve. Finally, AMESim–Simulink co-simulations and hardware-in-the-loop (HIL) experiments are conducted under bumpy road excitation and Class C random road conditions. Under Class C random road conditions, compared with passive hydro-pneumatic suspension and semi-active suspension with conventional MPC, the proposed method achieves maximum reductions of 11%, 25%, and 12.9% in the root mean square values of body acceleration, suspension working space, and dynamic tire load, respectively. The discrepancies between experimental and simulation results remain below 7%, confirming the effectiveness of the proposed system and control strategy. This study provides a new technical guidance for low-frequency vibration suppression in vehicle suspension systems. Full article

This paper presents theoretical studies on the vibration control of an elastic beam using a lever-type dynamic vibration absorber (Lever-Type DVA). The simply supported beam is adopted as the primary system to investigate the suppression mechanism and parametric influence of a novel lever-type DVA applied to such elastic members. Under harmonic excitation, the H_∞ optimization criterion is employed to design the DVA parameters, thereby determining its maximum vibration reduction capacity. A detailed parametric analysis is carried out to examine the effects of key variables, such as the lever amplification factor and fulcrum position on the dynamic response of the beam. The results show that the well-designed DVA can significantly improve the control performance, offering theoretical support and design guidance for the application of lever-type DVAs in beam engineering. Full article

Whole-body vibration (WBV) remains a critical factor influencing ride comfort, driver performance and occupational health in vehicle applications. Despite the widespread use of standardized indicators, assessing WBV exposure and its perceptual implications remains challenging due to the complex interaction between road excitation, vehicle dynamics, seat transmissibility and human biodynamic response. This review provides a comprehensive synthesis of contemporary methods for WBV assessment, emphasizing their theoretical foundations, practical implementation and inherent limitations. The paper examines classical evaluation metrics, including frequency-weighted root mean square acceleration and vibration dose value, alongside complementary approaches such as overall vibration total value, absorbed power and motion sickness indicators. Biodynamic modeling strategies for the human–seat–vehicle system are critically reviewed, highlighting trade-offs between model simplicity and physiological realism. Particular attention is given to road surface representation and excitation modeling, discussing the implications of ISO 8608-based stochastic profiles versus measured, time-domain inputs on WBV assessment outcomes. Simulation frameworks, experimental platforms and driving simulators are reviewed as complementary tools for evaluating vibration exposure and validating predictive models. Emerging methods, including time–frequency analysis and data-driven approaches, are discussed with a focus on interpretability, validation and integration with established standards such as ISO 2631. The review consolidates recent advances in integrated evaluation approaches, including the role of driving simulators and simulation-, hardware- and driver-in-the-loop (SiL/HiL/DiL) frameworks as enabling tools for repeatable testing, objective–subjective comfort correlation and early-stage vibration-control development. By critically examining both established and emerging methodologies, this review aims to support informed selection and interpretation of WBV assessment tools in vehicle design and evaluation. The findings underscore the need for integrated, transparent and application-oriented approaches to advance vibration comfort assessment and guide future research and standardization efforts. Full article

Practical testing of a novel underwater circulating towing experimental system has revealed that vibrations induce unstable vehicle operation, necessitating the implementation of vibration mitigation strategies. This paper first establishes a dynamic model of the system using mechanical system dynamics theory and analyzes its vibrational characteristics. The analysis shows that the third-order natural frequency closely aligns with the rotational frequency of the traction motor, thereby risking resonance and performance instability. To address this, shock absorbers are incorporated, and the spring stiffness of the tensioning device is adjusted. Using the vehicle’s vibration acceleration root mean square as the objective function, an annealed particle swarm optimization algorithm is employed to optimize parameters including the equivalent stiffness and damping coefficients of the shock absorbers, as well as those of the spring tensioning device, thus refining the vibration mitigation strategy. The results demonstrate a 6% increase in the initial third-order natural frequency, effectively avoiding resonance. Additionally, the average vibration displacement and acceleration are reduced by 45.8% and 20%, respectively, significantly enhancing operational stability. This research provides substantial theoretical support for improving system stability. Full article

The present study systematically investigates, for the first time, the combined influences of detonator position (top-edge and bottom-edge initiations) and anvil material (steel and sand) on the interfacial microstructure and mechanical performance of explosively welded A1050/AZ31 dissimilar joints. When welding was conducted using a steel anvil with the detonator positioned at the top edge, significant cracking occurred both at the surface and along the weld interface. In contrast, placing the detonator at the bottom edge noticeably reduced these defects. Moreover, the use of a sand anvil nullified these defects by damping the reflecting shockwaves and minimizing vibrations. Hardness measurements revealed substantial increase at the interface under all the conditions, with the highest value observed with the steel anvil. Welds subjected to top-edge detonation showed higher hardness values compared to those of welds subjected to bottom-edge detonation. Overall, the results suggest that sand anvils with bottom-edge detonation provide the optimal weld quality. The rigid steel anvil reflects the shockwave, generating high pressure and velocity at the interface, whereas the sand anvil absorbs a part of the shock energy, suppressing high-magnitude reflections. The position of the detonator influences the propagation dynamics of the detonation wave and the resulting collision velocity, which in turn, affect the interfacial morphology and overall quality of the weld. Full article

During takeoff and landing, aircraft operate in a variety of situations, posing significant challenges to landing gear systems. Passive hydraulic–pneumatic dampers are commonly used in conventional landing gear to absorb impact energy and reduce vibration. However, due to their fixed damping characteristics and inability to adjust to changing operating conditions, these passive systems have several limitations. Recent research has focused on creating intelligent landing gear systems with magnetic dampers (MR) to overcome these limitations. By changing the magnetic field acting on the MR fluid, MR dampers provide semi-active control of the landing gear dynamics and adjust the damping force in real time. This flexibility reduces structural load during landing, increases riding comfort, and improves energy absorption efficiency. This study examines the current state of MR damper application for aircraft landing gear. The review categorizes current control techniques and highlights the structural integration of MR dampers in landing gear assemblies. Purpose: The magnetorheological (MR) damper has become a promising semiactive system to replace the conventional passive damper in aircraft landing gear. However, the mechanical structure and control strategy of the MR damper must be designed to be suitable for aircraft landing gear applications. Methods: Researchers have explored the potential structure designed, the mathematical model of the MR landing gear system, and the control algorithm that was developed for aircraft landing gear applications. Results: According to the mathematical model of the MR damper, three types of models, which are pseudo-static models, parametric models, and unparameterized models, are detailed with their application. Based on these mathematical models, many control algorithms were studied, from classical control, such as PID and skyhook control, to modern control, such as intelligent control and SMC control. Full article

To address the impact-induced damage to concrete pile foundations of transmission structures caused by nearby blasting vibrations, this study investigates the dynamic splitting tensile behavior of an environmentally friendly lightweight rubberized concrete—Rubber-Toughened Ceramsite Concrete (RTCC)—under impact loading. Quasi-static tests show that the static splitting tensile strength increases first and then decreases with increasing rubber content, reaching a maximum value of 2.01 MPa at a 20% replacement ratio. Drop-weight impact tests indicate that RTCC20 exhibits the highest peak impact force (42.48 kN) and maximum absorbed energy (43.23 J) within the medium strain-rate range. Split Hopkinson Pressure Bar (SHPB) tests further demonstrate that RTCC20 shows the highest strain-rate sensitivity. Overall, RTCC with 20% rubber content provides the best comprehensive performance, achieving a favorable balance between strength and toughness across the entire strain-rate range. These findings offer experimental support for applying RTCC to blast-vibration-resistant transmission structure foundations. Full article

Viscoelastic dampers (VEDs) in seismic structures comprehensively enhance the dynamic performance of the structure by dissipating energy, providing additional stiffness and damping. The optimization analysis of dampers is the core link to ensure the safety, economy, and effectiveness of seismic design schemes. This work aims to develop low-frequency high-performance viscoelastic damping materials (VEMs) and verify the seismic control effect through three-dimensional solid engineering structure analysis. Four different damping systems of Acrylate Rubber (ACM) based viscoelastic materials were fabricated and performance characterization tests were conducted. The results indicate that all four damping modification systems can significantly improve the energy dissipation capacity of viscoelastic damping materials at low-frequency room temperature. The viscoelastic damping material with the best comprehensive performance has been selected and applied to the viscoelastic dampers of the three-dimensional shock-absorbing structure. Through the analysis of the structural vibration control effect, the universality of the vibration control effect of ACM-based viscoelastic materials under different seismic loads was further verified. It provides a feasible approach for the trans-scale research of “Material–Device–Structure” in viscoelastic damping technology. Full article

Vibrational spectroscopy is one of the most powerful techniques available for the characterization of materials for Li-ion batteries (LIBs) and one of the most useful tools when X-ray diffraction is ineffective for amorphous substances. Raman spectroscopy is essentially a probe to examine the surface of compounds that strongly absorb visible light, which is the case for all electrode materials, while infrared spectroscopy is a tool that examines the entire volume of particles. The purpose of this review is to study the lattice dynamics of cathode, anode, and electrolyte materials of advanced LIBs, especially nanomaterials for high-power-density application. Ex situ and in situ analyses are presented, which satisfy several key issues, such as structural stability over long-term cycling. Full article

To address issues such as chassis attitude deviation, reduced operational efficiency, and diminished precision when agricultural machinery operates in complex terrains—including steep slopes and fragmented plots in hilly and mountainous regions—a servo electric cylinder-based active suspension levelling system has been designed. Real-time dynamic control is achieved through a fuzzy PID algorithm. Firstly, the suspension’s mechanical structure and key parameters were determined, employing a ‘servo electric cylinder-spring-shock absorber series’ configuration to achieve load support and passive vibration damping. Secondly, a kinematic and dynamic model of the quarter-link suspension was established. Finally, Simulink simulations were conducted to model the agricultural machinery traversing mountainous, uneven terrain at segmented stable operating speeds, thereby validating the suspension’s control performance. Simulation results demonstrate that the system maintains chassis height error within ±0.05 m, chassis height change rate within ±0.2 m/s, and response time ≤ 0.8 s. It rapidly and effectively counteracts terrain disturbances, achieving precise chassis height control. This provides theoretical support for designing whole-vehicle levelling systems for small agricultural machinery in hilly and mountainous terrains. Full article

Metamaterials show perfect physics characteristics for controlling elastic wave propagation. Their potential offers a lot of useful applications in low-frequency sound absorption and vibration reduction systems. However, traditional materials have inherent deficiencies in terms of functionality. There are a few designs in both acoustic and solid-mechanics domains that simultaneously exhibit sound attenuation bands and vibration bandgaps. The question poses new challenges for metamaterial development. To address this, we propose a gradient-symmetric multilayered metamaterial. The structure is capable of concurrent sound and vibration absorption. First, we established an acoustic model based on Helmholtz resonators and a vibration model by spring-mass systems. This model can predict the sound attenuation frequencies and natural frequency positions accurately. Second, through a combined simulation and experimental approach, we investigated how variations in the number of structural layers affect sound attenuation bandwidth. In addition, we analyzed the mechanisms of sound pressure distribution inside and outside the bandgaps. Finally, we elucidated the influence of lattice constants on vibration bandgap positions, demonstrating possibilities for passive control of metamaterials. This research provides robust support for the dynamic design of acoustic and mechanical metamaterials, structural modeling methodologies, bandwidth regulation strategies, and the development of sound-absorbing and vibration-damping devices. Full article