Open Access

Article

Article ID: 4379

Structural modal study of vertical system vibration based on large axial Cross-Wedge rolling mill

by Chuanchuan Ma, Xinglong Zhao, Wenchang Zhong, Junjie Wang, Junsheng Xu, Yang Zhang, Zhibing Chu

Sound & Vibration, Vol.60, No.6, 2026;

With the surge in demand for large shaft components in the railway transportation industry, traditional rolling mills are insufficient to meet actual production needs, leading to the development of wedge cross-rolling mill equipment suitable for producing large shaft components. This paper focuses on the study of the vibration characteristics of the vertical system of large axial Cross-Wedge rolling mill. By constructing a four-degree-of-freedom (4-DoF) vertical vibration dynamic model of the mill frame structure, the vibration characteristics of the vertical system were investigated, and the natural frequencies and main vibration modes of each order were obtained. To facilitate subsequent research and optimization of the overall mill structure, the 4DoF vertical system model was simplified into a symmetric single-degree-of-freedom (SDoF) model, and the sensitivity of the second-order mode to stiffness was explored. At the same time, finite element analysis (FEM) was used to conduct modal analysis on the mill vertical system, and vertical system velocity signals were obtained through on-site data collection. The results indicate that the simplified vertical system structural model matches the vibration characteristics of the mill's vertical system, and the natural frequencies of the vertical system calculated are basically consistent with the results from modal analysis and on-site data collection. This study provides a theoretical basis for the prediction, diagnosis, and structural parameter optimization of vertical vibration in large axial Cross-Wedge rolling mill.

Open Access

Article

Article ID: 4699

Interval type-2 fuzzy α-plane minimax co-design of multi-tuned mass dampers for broadband vibration control under bounded uncertainty

by Suleiman  Ibrahim Mohammad, Yogeesh  Nijalingappa, Seif Al  Bustanji, Poornachandran  William, Asokan  Vasudevan

Sound & Vibration, Vol.60, No.6, 2026;

Passive tuned mass dampers are effective near their design frequencies but can lose performance or exceed travel limits when structural properties are imprecise. This paper develops an interval type-2 fuzzy α-plane minimax method for the simultaneous allocation, tuning, and damping design of a three-absorber bank on a six-degree-of-freedom coupled machine–foundation system. Primary mass, stiffness, and damping are represented by lower and upper triangular membership functions, so uncertainty in both parameter values and membership widths is retained. At every α-plane, outer and inner vertex responses are propagated through the complex frequency-response matrix. A membership-weighted objective combines worst peak acceleration, broadband root-mean-square acceleration, footprint width, and a 16 mm relative-stroke constraint. Differential evolution determines nine absorber variables for a fixed 6% auxiliary-mass budget. The frequency-domain solver reproduces classical equal-peak tuning ratios to machine precision and absorber damping ratios within 0.20%. In 2,048 independent outer-support Sobol scenarios, the proposed design decreases the mean peak acceleration from 6.058 g to 1.262 g and the worst peak acceleration from 9.005 g to 1.682 g. The deterministic optimum attains a smaller mean peak of 1.112 g but violates the stroke constraint in 55.42% of the scenarios; the type-1 robust design violates it in 2.05%, whereas the proposed design has no violations and a maximum stroke of 15.992 mm. The results show that explicitly preserving membership-function uncertainty changes the mass allocation and first-mode detuning sufficiently to obtain a feasible broadband design without active control.

Open Access

Article

Article ID: 4624

A spectral-band estimation method of ground acoustic impedance for wind turbine sound propagation

by Chao Ma, Weifeng Yan, Shuyu Shen, Wenzhong Shen, Chang Xu

Sound & Vibration, Vol.60, No.6, 2026;

Accurate characterization of ground acoustic impedance is essential for reliable prediction of wind turbine sound propagation over natural and agricultural surfaces. In conventional indirect measurements, a loudspeaker and two microphones at different heights are used to estimate an equivalent flow resistivity by fitting the measured sound pressure level (SPL) differences with those calculated from an image-source propagation model and an acoustic impedance model. Because this fitting is generally carried out over a broad frequency range, the conventional approach is referred to here as the global-band method. However, a single full-band flow resistivity may not represent the frequency-dependent ground response with sufficient accuracy. To improve the spectral representation of the ground boundary condition, this paper proposes a spectral-band method for determining the ground impedance in individual 1/3-octave frequency bands. The method is intended to provide more accurate impedance inputs for wind turbine sound propagation models. The results show that the spectral-band method more accurately captures the frequency-dependent behavior of the effective flow resistivity and ground impedance, significantly reducing the discrepancy between calculated and measured SPL differences. In addition, an empirical formula is established to describe the relationship between the flow resistivity obtained using the global-band method and that obtained using the spectral-band method, so that the ground impedance can be more conveniently specified for simulations at individual frequency bands.

Open Access

Article

Article ID: 4701

Research on the characterization and optimization of the acoustic environment in command posts based on metamaterials and particle swarm algorithm

by Jiaojiao Zhang, TengYue Pan, Fei Yang, Wenqiang Peng, Xinmin Shen, Xiaonan Zhang

Sound & Vibration, Vol.60, No.6, 2026;

We investigated the acoustic environment of a military command post, focusing on two conflicting needs: protecting speech privacy while maintaining clear internal communication. A finite element model of a 248.17 m³ command post was built, combining geometric acoustics with ray tracing. To reduce diesel generator noise, we introduced parallel unequal-cavity acoustic metamaterials on both the source and the walls. Field measurements showed that enclosing the generator reduced its average sound pressure level from 90.4 dB to 73.8 dB. In simulations, applying the metamaterials to the walls shortened the reverberation time T60 from 0.81 s–2.13 s down to 0.4 s–1.6 s—but the improvement varied strongly with frequency. The largest drop occurred at 500 Hz (1.6 s to 0.4 s), with smaller reductions at 250 Hz and 1,000 Hz, and almost no change at 125 Hz or 8,000 Hz. Broadband speech transmission index (STI) improved from 0.44–0.69 to 0.52–0.95, averaging above 0.65. We then used particle swarm optimization to find the best source position within the already-optimized room. After 50 iterations, the 500 Hz equivalent per-band STI contributions exceeded 0.84 across most receivers and reached above 0.99 at several locations; other bands (250 Hz–4,000 Hz) stayed between 0.60 and 0.75. Overall, combining acoustic metamaterials with intelligent source placement appears to significantly improve the command post acoustic environment—a finding that may inform noise control strategies for similar military facilities.

Open Access

Article

Article ID: 4502

Bridging surface engineering and vibration attenuation: A tribo‑dynamic perspective for manufactured mechanical systems

by Guibin Sun, Yirui Sun, Emil Abdraimov

Sound & Vibration, Vol.60, No.6, 2026;

The attenuation of vibration is one of the most important requirements in the manufacture of mechanical systems which are required to meet high speed, high load, light weight and precision control requirements. A traditional approach to vibration control is to redesign the structure, use passive damping or isolation systems, or use active control; the dynamic properties of the surface and interfaces are considered secondary. The aim of the present review is to adopt a surface-centered point of view by discussing how surface engineering can be used to achieve vibration attenuation by regulating the stiffness in contact, stabilizing the friction, damping at the interface, suppressing wear and enhancing the integrity of the surface. Functional coatings, solid lubricant films, viscoelastic layers, surface texturing, micro/nanopatterning, mechanical surface treatments, architectures for additive manufacturing (AM), and smart adaptive surfaces are critically discussed with regard to their vibration-control mechanisms and limitations. The focus is on tribo-dynamic coupling, i.e., coupling between friction, wear, lubrication and vibration, which can either dampen or amplify the dynamic response, depending on the feedback mechanisms between the components. The review also examines experimental characterization, multi-scale modelling, and applications in bearings, gears, machine tools, rotating machinery, automotive systems, aerospace components, robotics and biomedical devices. An integration of tribology, material science, manufacturing and structural dynamics is emphasized for effective vibration attenuation at surfaces. Standardized testing, predictive modeling, durability assessment, and system-level design frameworks are key to future progress. The surfaces of engineered systems should therefore be considered as more than just a physical barrier, but as a functional dynamic interface that can act as a quieter, more efficient, and more reliable mechanical system.

Open Access

Article

Article ID: 4615

Dynamic characterization and seismic performance evaluation of multi-span flyover bridge using ambient vibration testing and finite element modeling

by Arief Kusbiantoro, Rini Kusumawardani, Endah Kanti Pangestuti, Faridh Rizal Rivandhani, Anindya Cirila, Sri Sutrisni, Noorsuhada Md Nor

Sound & Vibration, Vol.60, No.6, 2026;

This study aims to evaluate the dynamic and seismic performance of an eight-span flyover bridge with a total length of 331 m using a combination of ambient vibration testing, finite element modeling, and non-linear seismic time-history analysis. The velocity data recorded during normal operation were evaluated using the Fast Fourier Transform to calculate the bridge's predominant natural frequency and validate a three-dimensional CSiBridge model. The natural frequencies obtained from the field measurement and numerical model were 3.670 Hz and 3.727 Hz, respectively, with a difference of 1.53%, which indicates reasonable agreement in the dominant frequency. The validated model was then analyzed by using artificial ground motions scaled to the required response spectrum with 5% damping. The seismic responses of the bridge piers were studied in terms of displacement, shear force, bending moment and axial force in the X and Y directions. The data suggest that the strongest seismic demands were focused at the middle piers, particularly at Pier 4. Furthermore, the comparison of the present bridge condition and the bridge with lead rubber bearings showed that the bearings reduced the displacement, shear force, and bending moment responses considerably. The results demonstrate that the model validation based on the vibration data provides a preliminary basis for subsequent seismic response analysis, and the lead rubber bearing can improve the seismic performance of multi-span flyover bridges efficiently.

Open Access

Article

Article ID: 4698

Wasserstein distributionally robust co-design of a fractional-order dual-resonator elastic metamaterial for broadband vibration attenuation

by Asokan  Vasudevan, Yogeesh Nijalingappa, Rashed Abu  Hammour, Poornachandran William, Suleiman Ibrahim  Mohammad, Torki M.  Al-Fawwaz

Sound & Vibration, Vol.60, No.6, 2026;

Locally resonant elastic metamaterials provide subwavelength attenuation but remain sensitive to uncertainty in stiffness, damping, and fractional order. This study develops a Wasserstein distributionally robust co-design framework that jointly selects the mass split, resonance tuning, loss scales, and fractional orders of a dual-resonator periodic cell. Bloch dispersion is condensed into a complex effective-mass model, and a feasibility-aware loss balances integrated attenuation, threshold coverage, internal-motion amplification, and resonance separation. Five bounded uncertainties in host stiffness, resonator stiffnesses, common loss scale, and fractional-order drift are represented in a finite 1-Wasserstein ambiguity set trained on 64 scrambled Sobol scenarios with 256 adversarial candidates. The proposed design is independently compared with equal-mass, nominal, and conditional-value-at-risk alternatives over 4,096 unseen scenarios. Across this validation set, the Wasserstein design reduced worst loss by 73.68% and increased fifth-percentile integrated attenuation by 32.50% relative to the equal-mass baseline while satisfying the internal-motion constraint. It allocated 56.03% of the resonator mass to the lower branch and selected tuning frequencies of 27.20 and 40.31 Hz. Exact antiresonance verification, uncertainty envelopes, finite-chain attenuation-equivalent insertion loss, and local sensitivity analysis support the numerical results. The framework provides a reproducible basis for robust broadband attenuation and subsequent specimen-level calibration and experimental validation.