Search Results (90)

To address the impact of environmental and equipment factors on signal identification in highway tunnel drainage pipeline blockage monitoring, this study aims to elucidate the influence patterns of pipeline flow rate, optical fiber deployment scheme, and fiber performance on blockage-induced acoustic signals. A full-scale concrete pipeline experimental platform was established. Data were acquired using a HIFI-DAS V2 sensing system. The time–frequency domain characteristics of acoustic signals under different flow rates (50 m³/h and 100 m³/h), fiber deployment schemes (inside the pipe, outside the pipe, and outside a soundproofing layer), and fiber materials (six typical types) were analyzed and compared. The degree of influence of each factor on signal amplitude and dominant frequency components was quantified. The experimental results indicate that: Compared to a flow rate of 50 m³/h, the amplitude characteristic value at the blockage channel exhibited a marked increase at 100 m³/h, accompanied by an increase in the number and amplitude of dominant frequency components. While the dominant frequency components of the acoustic signals were less stable across the three deployment schemes, the overall amplitude at the blockage channel was consistently higher than that at non-blockage channels. When the fiber was deployed farther from the fluid core (outside the soundproofing layer), the dominant frequencies essentially disappeared, with energy distributed in a broadband form. The peak amplitude and array energy of the sensitive vibration sensing fiber were 2 times and 3.6 times those of the worst-performing type, respectively. Furthermore, its physical properties are better suited to the tunnel environment, effectively enhancing signal acquisition stability and the signal-to-noise ratio. Comprehensive analysis demonstrates that deploying sensitive fibers inside the pipe is more conducive to the accurate identification of blockage events. Moreover, uniform dominant frequency components and threshold criteria are not recommended along the entire length of the drainage pipe. This research provides theoretical and experimental support for parameter optimization of DAS systems to achieve high-precision pipeline blockage monitoring in complex tunnel environments. Full article

Due to low thermal conductivity and high specific strength, nickel-based superalloys are prone to service performance degradation caused by thermal damage during traditional high-efficiency grinding processes. Although the heat pipe grinding wheel with minimum quantity lubrication (HPGW-MQL) technology can reduce the probability of thermal damage to a certain extent, further breakthroughs are still needed. Therefore, this study proposes a new integrated process of ultrasonic vibration-assisted grinding by heat pipe grinding wheel with minimum quantity lubrication (UVAG-HPGW-MQL), aiming to balance the requirements of green grinding and the optimization of grinding performance for nickel-based superalloys. However, the mechanism of action of ultrasonic vibration on the cooling and lubrication performance of the proposed process remains unclear. Given that, comparative experiments between UVAG-HPGW-MQL and HPGW-MQL were conducted, focusing on exploring the influence of ultrasonic vibration on their cooling and lubrication performance. The experimental results, obtained when the grinding speed, workpiece feed rate, and grinding depth were set at 15–35 m/s, 40–120 mm/min, and 0.05–0.25 mm, respectively, indicate that, compared with HPGW-MQL, ultrasonic vibration causes periodic “contact-separation” between grains and workpiece. This dynamic process shortens the contact length between grains and workpiece, leading to maximum reductions of 43.85%, 22.15%, 34.16%, and 30.77% in grinding force, grinding force ratio, grinding temperature, and specific grinding energy, respectively. On the other hand, the ultrasonic cavitation effect causes atomization of the lubricating oil film adsorbed on the workpiece surface, leading to a decrease in lubrication performance and resulting in a maximum increase of 27.27% in the friction coefficient. This study provides new theoretical support and technical approaches for the green grinding of nickel-based superalloys. Full article

This study presents the design, modeling, and experimental validation of a frequency-tuned mechanical sensor (MS) integrating a fiber bragg grating (FBG) for the detection of leak-induced vibrations in pressurized steel pipelines. Unlike conventional bonded FBGs—which directly follow the local wall deformation—the proposed MS consists of a base-fiber-mass transducer geometrically tuned so that its natural frequencies coincide with the dominant vibration modes of the pipe in the 5–7 kHz range. A combined framework of finite element analysis (FEA), computational fluid dynamics (CFD), and laboratory measurements was developed to assess the coupling between the pipe and the sensor. Results show that the MS behaves as a selective mechanical amplifier, enhancing strain sensitivity and signal-to-noise ratio (SNR) by up to 15 dB compared to a directly bonded FBG. The workflow integrates modal tuning, an equivalent harmonic excitation derived from CFD-based pressure fields, and frequency–response validation, leading to a mechanically optimized FBG transducer capable of discriminating high-frequency leak signatures. The excellent agreement between the simulation and experiment confirms that geometric resonance coupling provides an effective route to amplify leak-induced strain, offering a compact, scalable, and high-sensitivity solution for vibration-based leak detection in industrial pipelines. Full article

This study presents an analysis of transverse vibration behavior of a fluid-conveying pipe mounted on an elastic foundation, incorporating both classical analytical techniques and modern physics-informed neural network (PINN) methodologies. A partial differential equation (PDE) architecture is developed to approximate the solution by embedding the physics PDE, initial, and boundary conditions directly into the loss function of a deep neural network. A one-dimensional fourth-order PDE is employed to model governing transverse displacement derived from Euler–Bernoulli beam theory, with additional terms representing fluid inertia, flow-induced excitation, and stochastic force modelled as Gaussian white noise. The governing PDE is decomposed via separation of variables into spatial and temporal components, and modal analysis is employed to determine the natural frequencies and mode shapes under free–free boundary conditions. The influence of varying flow velocities and excitation frequencies on critical buckling behavior and mode shape deformation is analyzed. The network is trained using the Resilient Backpropagation (RProp) optimizer. A preliminary validation study is presented in which a baseline PINN is benchmarked against analytical modal solutions for a fluid-conveying pipe on an elastic foundation under deterministic excitation. The results demonstrate the capability of PINNs to accurately capture complex vibrational phenomena, offering a robust framework for data-driven modelling of fluid–structure interactions in engineering applications. Full article

Small-scale wind turbines are becoming increasingly important in renewable energy systems due to their ability to operate in low-wind-speed environments and adapt to various installation locations, especially in areas with energy shortages. This paper presents the design, analysis and development of a Helical Vertical Axis type Wind Turbine (H-VAWT) using uPVC pipe as the blade material, offering a lightweight, low-cost, and corrosion resistant solution. The blade structure is optimized for use in residential and off-grid areas with unstable wind conditions. Structural analysis is conducted in ANSYS, including static load analysis (deformation, equivalent stress, shear stress, maximum stress), torsional and bending stress, and modal analysis to assess mechanical performance and vibrational stability. Three blade designs are initially considered, and the helical model (0–45° twist) is selected based on simulation results. The prototype is successfully fabricated and tested under different wind speeds, showing effective power generation, with favorable results in power output, power coefficient, tip-speed ratio (TSR), and relative velocity. Full article

Underground high-voltage transmission cables, especially high-pressure fluid-filled (HPFF) pipe-type cable systems, are critical components of urban power networks. These systems consist of insulated conductor cables housed within steel pipes filled with pressurized fluids that provide essential insulation and cooling. Despite their reliability, HPFF cables experience faults caused by insulation degradation, thermal expansion, and environmental stressors, which, due to their subtle and gradual nature, complicate incipient fault detection and subsequent fault localization. This study presents a novel, proactive, and retrofit-friendly predictive condition monitoring method. It leverages distributed accelerometer sensors non-intrusively mounted on the HPFF steel pipe within existing manholes to continuously monitor vibration signals in real time. A physics-enhanced convolutional neural network–long short-term memory (CNN–LSTM) deep learning architecture analyzes these signals to detect incipient faults before they evolve into critical failures. The CNN–LSTM model captures temporal dependencies in acoustic data streams, applying time-series analysis techniques tailored for the predictive condition monitoring of HPFF cables. Experimental validation uses vibration data from a scaled-down HPFF laboratory test setup, comparing normal operation to incipient fault events. The model reliably identifies subtle changes in sequential acoustic patterns indicative of incipient faults. Laboratory experimental results demonstrate a high accuracy of the physics-enhanced CNN–LSTM architecture for incipient fault detection with effective data feature extraction. This approach aims to support enhanced operational resilience and faster response times without intrusive infrastructure modifications, facilitating early intervention to mitigate service disruptions. Full article

This paper introduces a novel 3D simulation framework that integrates the Pipe-in-Pipe (PiP) model with Finite Element Analysis (FEA) using Ansys Parametric Design Language (APDL). This framework is designed to incorporate a 3D building model directly, assessing ground-borne vibrations from metro tunnels and their impact on surrounding structures. The PiP model efficiently calculates displacement fields around tunnels in full-space, applying the resulting fictitious forces to the FEA model, which includes a directly coupled 3D building model. This integration allows for precise simulation of vibration propagation through soil into buildings. A comprehensive verification test confirmed the model’s accuracy and reliability, demonstrating that the hybrid PiP-FEA model achieves significant computational savings-approximately 40% in time and 65% in memory usage-compared to the traditional full 3D FEA model. The results exhibit strong agreement between the PiP-FEA and full FEA models across a frequency range of 1–250 Hz, with less than 1% deviation, highlighting the effectiveness of the PiP-FEA approach in capturing the dynamic behavior of ground-borne vibrations. Additionally, the methodology developed in this paper extends beyond the specific case study presented and shows potential for application to various urban vibration scenarios. While the current validation is limited to numerical comparisons, future work will incorporate field data to further support the framework’s applicability under real metro-induced vibration conditions. Full article

To address the difficulty in eliminating low-frequency vibrations in the hydraulic pipelines of large marine vessels, this study first investigates the vibration characteristics of hydraulic pipelines. The research is conducted based on the stress states of pipelines under external excitations—specifically axial (X-direction), radial (Y-direction), and combined radial–axial (X + Y) excitations and integrates theoretical derivation, simulation, and experimental validation. Firstly, a multidimensional directional vibration equation for the pipeline was derived based on its stress distribution, yielding a more accurate vibration model for marine pipelines. Subsequently, simulations were performed to analyze the effects of fluid velocity, pipeline layout, and support distribution on the pipeline’s vibration characteristics. Finally, experiments were designed to verify the simulation results and examine the impact of external interference on pipeline vibration. The experimental results indicate the following: the influence of flow velocity variations on pipeline modes is generally negligible; increasing the number of pipeline circuits effectively reduces its natural frequencies; increasing the number of supports not only lowers the overall vibration intensity of the pipeline but also achieves peak shaving, thereby effectively reducing the maximum vibration amplitude; and the impact of external environmental interference on the pipeline’s vibration characteristics is complex, as it not only enhances vibration intensity but also weakens vibrations in specific directions. This study lays a theoretical foundation for subsequent vibration reduction efforts for marine hydraulic pipelines. Full article

To study the vibration characteristics of viscoelastic slurry pipe structures under fluid–structure interaction (FSI), we constructed a three-dimensional FSI pipe model based on the finite element method to systematically investigate the effects of fluid effects, pipe length, and wall thickness on the vibrational characteristics of viscoelastic slurry pipes. A modal analysis demonstrated that fluid effects not only significantly reduced the natural frequency of the pipe but also disrupted the symmetry of the vibration modes and eliminated the phenomenon of frequency degeneracy. The frequency reduction caused by FSI reached 54%, which was dominant compared with the water-attached effects, and its impact intensified with the increasing vibration order. The water-attached effect exhibited differences between odd and even orders, attributed to the influence of vibration modes on the distribution of fluid inertial forces, with a contribution of 45.07% to 55.24% in the odd orders and of only 37.69% to 38.93% in the even orders. When the FSI and water-attached effects acted together, the frequency reduction was further aggravated, but the reduction ratio did not follow a simple linear superposition. The parametric analysis of the pipe showed that when the pipe length increased from 1 m to 3 m, the growth rate of its natural frequency was only 26.52% that of the shorter pipe, indicating that the longer the pipes, the slower the growth rate of frequency. When the wall thickness increased from 5 mm to 11 mm, the growth rate of the first-order natural frequency decreased from 15.43% to 7.44%, suggesting that the frequency improvement effect caused by the stiffness augmentation diminished with the increase in wall thickness. The research results hold significant guiding significance for the structural design of slurry pipe systems in practical engineering and the safe operation of pipe systems. Full article

The vortex-induced vibration (VIV) dynamics of commercial-scale deep-sea mining risers with complex component arrangements (pumps, buffer stations, buoyancy modules) remain insufficiently explored, especially for 6000 m systems with nonlinear tension. This study investigates VIV control strategy by adjusting tension for a nonlinear riser system using the Iwan-Blevins wake oscillator model integrated with Morison equation-based analysis. An analytical model incorporating four typical current profiles was established to quantify the dynamic response under different flow velocities, internal flow density, and structural parameters. Increased buffer station mass effectively suppressed drift distance (over 35% reduction under specific conditions) by regulating axial tension. Dynamic comparisons demonstrated distinct VIV energy distribution patterns under different current conditions. Spectral analysis revealed that the vibration follows Strouhal vortex shedding lock-in principles. Spatial modal differentiation was observed due to nonlinear variations in velocity profiles, pipe diameters, and axial tension, accompanied by multi-frequency resonance, coexistence of standing and traveling waves, and broadband resonance with amplitude surges under critical velocities (1.75 m/s in Current-B). This study proposes to control the VIV amplitude by adjusting internal flow density and buffer mass, which is proved effective for reducing vibrations in upper (0–2000 m) risers. It validates vibration amplitude and frequency control through current velocity, buffer mass and slurry density regulation in a nonlinear riser system. Full article

Piping systems can be analogized to the “vascular systems” of vessels, but their transmission characteristics often result in loud noises and large vibrations. The integration of flexible inserts within these piping systems has been shown to isolate and/or mitigate such vibrations and noise. In this work, a novel sandwich flexible insert (NSFI) was presented specifically to reduce the vibrations and noise associated with piping systems on vessels. In contrast to conventional flexible inserts, the NSFI features a distinctive three-layer configuration, comprising elastic inner and outer layers, along with a honeycomb core exhibiting a zero Poisson’s ratio. The dynamic characteristics, specifically axial impedance, of the fluid-filled NSFI are examined utilizing a fluid–structure interaction (FSI) four-equation model. The validity of the theoretical predictions is corroborated through finite element analysis, experimental results, and comparisons with existing literature. Furthermore, the study provides a comprehensive evaluation of the effects of geometric and structural parameters on the dynamic characteristics of the NSFI. It is worth noting that axial impedance is significantly affected by these parameters, which suggests that the dynamic characteristics of the NSFI can be customized by parameter adjustments. Full article

The torsional, lateral, and axial vibrations that occur during drilling operations have negative effects on the drilling equipment. These negative effects can cause huge economic impacts, as the failure of drilling tools results in wasted materials, non-productive time, and substantial expenses for equipment repairs. Many researchers have tried to reduce these vibrations and have tested several models in their studies. In most of these models, the drill string used in oil wells behaves like a rotating torsion pendulum (mass spring), represented by different discs. The top drive (with the rotary table) and the BHA (with the drill pipes) have been considered together as a linear spring with constant torsional stiffness and torsional damping coefficients. In this article, three models with different degrees of freedom are considered, with the aim of analyzing the effect of variations in the stiffness and damping coefficients on the severity of torsional vibrations. A comparative study has been conducted between the three models for dynamic responses to parametric variation effects. To ensure the relevance of the considered models, the field data of torsional vibrations while drilling were used to support the modeling assumption and the designed simulation scenarios. The main novelty of this work is its rigorous comparative analysis of how the stiffness and damping coefficients influence the severity of torsional vibrations based on field measurements, which has a direct application in operational energy efficiency and equipment reliability. The results demonstrated that the variation of the damping coefficient does not significantly affect the severity of the torsional vibrations. However, it is highly recommended to consider all existing frictions in the tool string to obtain a reliable torsional vibration model that can reproduce the physical phenomenon of stick–slip. Furthermore, this study contributes to the improvement of operational energy efficiency and equipment reliability in fossil energy extraction processes. Full article

This study presents the design, optimization, and experimental validation of a large-air-gap voice coil motor (LAG-VCM) for high-precision magnetic levitation vibration isolation in vacuum environments. Key challenges arising from a large air gap, including pronounced leakage flux and a reduced flux density, were addressed by employing the equivalent magnetic charge method and the image method for the modeling of permanent magnets. Finite element analysis was applied to refine the motor geometry and obtain high thrust, low ripple, and strong linearity. To mitigate the severe thermal conditions of a vacuum, a heat pipe-based cooling strategy was introduced to efficiently dissipate heat from the coil windings. The experimental results demonstrate that the optimized LAG-VCM delivers a thrust of 277 N with low ripple while effectively maintaining coil temperatures below critical limits for prolonged operation. These findings confirm the suitability of the proposed LAG-VCM for vacuum applications with stringent requirements for both a large travel range and stable, high-force output. Full article

The use of suction pile wellheads with pre-tilted conductors is expected to help overcome the challenge of high tilting difficulty in offshore gas hydrate extraction. However, structural design and safety control technologies still lack theoretical guidance. In this study, based on Novak’s plane-strain assumption, the potential effects of the pre-tilted conductor on the pipe–soil interaction were considered, along with the influence of working loads and conductor structural parameters. A dynamic vibration model was established to describe the interaction between the suction pile wellhead’s pre-tilted conductor and the surrounding soil, and an analytical expression for the impedance at the conductor’s bottom was derived. Subsequently, parameter analysis was performed using a Python-based computational program (version 3.12.5) to investigate the mechanical response characteristics of the conductor under varying conductor sizes, total lengths, pre-tilted angles, external load magnitudes, and frequency. The results showed that increasing the conductor outer diameter from 32’ to 40’ significantly reduced end displacement by up to 91.24% and bending moments by 30.22%, while shear load decreased by 31.45%, providing important insights for the design of pre-tilted conductors in gas hydrate pilot production. The findings provide theoretical support for the optimal design and safety control technologies of suction pile wellhead pre-tilted conductors. Full article

This study investigates the mechanism behind the cavitation-induced noise in an automotive heater core and proposes a structural solution to eliminate it. Abnormal noise during cold-start conditions in a compact passenger vehicle was traced to cavitation in the heater core of the heating, ventilation, and air conditioning (HVAC) system. Controlled bench tests, in-vehicle measurements, and computational fluid dynamics (CFD) simulations were conducted to analyze flow behavior and identify the precise location and conditions for cavitation onset. Results showed that high flow rates and low coolant pressure generated vapor bubbles near the junction of the upper tank and outlet pipe, producing distinctive impulsive noise and vibration signals. Flow visualization using a transparent pipe and accelerometer data confirmed cavitation collapse at this location. CFD analysis indicated that the original geometry created a high-velocity, low-pressure region conducive to cavitation. A redesigned outlet with a tapered transition and larger diameter significantly improved flow conditions, raising the cavitation index and eliminating cavitation events. Experimental validation confirmed the effectiveness of the modified design. These findings contribute to improving the acoustic performance and reliability of automotive HVAC systems and offer broader insights into cavitation mitigation in fluid systems. Full article