Browse Topic: Noise, Vibration, and Harshness (NVH)

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Comparison of Wind Noise Quietness Metrics Using ISO 532-1 and ISO 532-32026-01-50769/17/2026
This study compares two international loudness standards—International Organization for Standardization (ISO) 532-1:2017 (Zwicker) and ISO 532-3:2023 (Moore–Glasberg–Schlittenlacher)—for assessing vehicle wind noise using wind tunnel measurement data. The two methods demonstrate good agreement in ranking wind noise quietness at typical highway speeds (120–140 km/h). However, discrepancies arise under specific conditions due to ISO 532-3’s binaural processing, which accounts for interaural inhibition effects. These differences are particularly pronounced in vehicles with asymmetric wind noise levels between the driver and passenger sides. Power-law regression analysis reveals that binaural loudness at the driver side (ISO 532-3) increases at a slower rate with wind speed compared to the monaural measurements [driver outboard ear (DOE)] of ISO 532-1. Under yaw angle conditions, the perceptual contribution of the driver inboard ear (DIE) introduces subtle metric-dependent variations. Contribution analyses further highlight method-specific sensitivities to noise source location and direction. Overall, this study provides a valuable reference for implementing loudness metrics in automotive wind noise engineering.
Hou, Hangsheng
A Study on the Development of Brake Moan Analysis for CTBA Vehicles Using Simulation2026-01-08149/14/2026
Moan noise is a low-frequency noise occurring in the 170–500 Hz frequency ranges. While it frequently appears in vehicles equipped with a rear Coupled Torsion Beam Axle (CTBA), the exact cause, generation mechanism and clear solutions remain unidentified. For those reasons, we have developed a moan noise analysis method capable of representing the moan noise phenomenon in vehicles with rear CTBA along with an automation tool. From these results, we can use moan analysis models to reduce real moan noise problems. Consequently, this not only enhances customer satisfaction and vehicle quality but also significantly increases the work efficiency of vehicle designers through design modification in the preliminary stages of vehicle development
Kim, Sungho, Kim, Jeongkyu, Hwang, Jaekeun, Kang, Donghoon
Influence of Ferritic Nitrocarburizing with Smart-ONC® on the Modal and Damping Behavior of Gray Cast Iron Brake Rotors2026-01-07989/14/2026
Ferritic nitrocarburizing (FNC) with in-process post-oxidation has been developed as a production-capable surface engineering solution for gray cast iron (GCI) brake rotors to meet the Euro 7 non-exhaust particulate emission limits. While prior investigations have demonstrated significant PM₁₀ reduction, improved corrosion resistance, and stable braking performance, the influence of FNC on noise, vibration, and harshness (NVH) performance requires systematic evaluation. This study quantified the relative contributions of the alloy composition, rotor geometry, and FNC treatment to the modal frequency and damping behavior. Seven ventilated disc types from multiple foundries were characterized to assess the composition-driven variability. In addition, 120 production discs (ventilated and solid) were measured before and after FNC processing to isolate the treatment effects. Modal properties were obtained using impulse-hammer testing under free–free boundary conditions in accordance with VDA 301, and damping was evaluated using the half-power bandwidth method (Q-factor). The results show that the natural frequency is governed primarily by geometric parameters, scaling with the friction-ring thickness and disc diameter. In contrast, the damping behavior is dominated by the alloy composition and graphite morphology. Variations in silicon, chromium, and carbon equivalent produced a 3–4× difference in the Q-factor across foundries. FNC treatment had a negligible effect on the natural frequency (<1%) but produced a measurable increase in the Q-factor, typically 7–10% for solid discs and 22–32% for ventilated discs. The findings establish a clear hierarchy of influence: composition controls the damping, geometry controls the frequency, and the FNC introduces a secondary shift. Within production-relevant composition windows, FNC + Smart-ONC® does not represent a limiting factor for the NVH performance of Euro 7–compliant brake systems.
Awe, Samuel Ayowole, Holly, Mike, Winter, Karl-Michael
Application of Electrochemical Noise Analysis for Rapid Assessment of Corrosion Resistance in Anodized AlSi Alloys2026-01-08039/14/2026
This study presents a rapid and fully quantitative method for evaluating the corrosion resistance of anodized Aluminum-Silicon (AlSi) alloys through Electrochemical Noise Measurement (ENM). Laboratory specimens and brake components of EN AC-45300 (AlSi5CuMg) are anodized and characterized using both ENM and Neutral Salt Spray (NSS) testing to establish a correlation between the two methodologies. The results reveal a clear and consistent relationship between the logarithm of the noise resistance (Log(Rn)) and the NSS exposure time, demonstrating that ENM captures the key electrochemical features governing corrosion initiation. By providing an objective and data-driven assessment based on measurements acquired within approximately 40 hours, ENM offers a significantly faster and more quantitative approach for predicting NSS performance, thereby reducing validation times of anodized AlSi components.
Abello, Mary Angel, Mezzomo, Lorenzo, Mataloni, Valentina, Bonfanti, Andrea, Bertasi, Federico
Further Investigation of Brake Squeal: Effect of (Inboard/Outboard) Pads Property Differential2026-01-07999/14/2026
It was reported earlier that the wear differential between the inboard pad and the outboard pad leads to brake squeal generation. The (inboard/outboard) pads wear differential can occur due to hardware issues such as brake pad drag and/or two different wear rates of the (I/O) pads, which is caused by two different material properties of the pads although the pad formula may be the same. It is found that (I/O) pads compressibility differential/hardness differential/friction differential are all interrelated and that they contribute to brake squeal generation in addition to the inboard pad tangential/radial taper wear. A method has been found to separate the inboard pad friction and the outboard pad friction and to estimate each friction coefficient.
Liu, Richard, Wu, Shane, Wu, Godot, Zou, Tianlang
A Study on Improvement of the Accuracy of Simulation for Squeal Noise Using Real Contact Friction Interface Model2026-01-08199/14/2026
The brake squeal noise arises from the complex phenomenon of the disc and the friction interface. In fact, even within the same shape of friction material, the noise characteristics vary based on the pattern of the friction interface. However, the current squeal noise simulation does not account for the effects of these friction interfaces; instead, it solely utilizes the friction coefficient and braking pressure to replicate the phenomenon. Consequently, the reliability of the complex eigenvalue analysis results is inevitably compromised. In this study, the complex eigenvalue analysis is conducted by incorporating the actual shape modeling technique of the friction interface, and the validity of the enhanced analysis method is validated through empirical testing. The friction surface modeling technique employed in this study is designed to randomly generate the friction interface of the analytical model by measuring the shape (form, waveform, roughness) of the actual friction surface. To accurately represent the actual friction surface shape in the analytical model, the size of the friction layer is also compactly constructed
Hwang, Jaekeun, Kim, Sungho, Kim, Jeongkyu, Kang, Donghoon
A Multi-Body Dynamic Analysis of Click Noise Generated in Rear Brake Caliper2026-01-08159/14/2026
As customer awareness of brake-related NVH (Noise, Vibration and Harshness) continues to increase across the automotive industry, noise originating from braking systems is increasingly regarded as important indicator of vehicle quality. Among these issues, intermittent click noise from rear brake caliper is commonly noticed during low-speed driving and initial brake application and is frequently associated with customer dissatisfaction. In the automotive industry, this noise has primarily been addressed through empirical design modifications and component-level testing. However, due to its low reproducibility and impulsive response characteristics, making quantitative prediction and root-cause identification during the design phase difficult. While most previous brake NVH research has mainly focused on continuous vibration phenomena such as squeal and groan, fewer studies have examined single-event impact noise related to pad-to-carrier clearances, contact transitions, and frictional nonlinearity from a simulation-based perspective. In this study, rear brake caliper click noise is defined as a dynamic phenomenon inherent to conventional caliper mechanical architecture. A Multi-Body-Dynamic model was developed using RecurDyn to reproduce the observed behavior incorporating pad-to-carrier clearance, friction characteristics, and component compliance. Brake dynamometer testing was conducted to measure acceleration and noise response, and correlation with simulation results was performed. Simulation and tests were carried out using a caliper geometry whose improvement effectiveness had been confirmed in prior applications, demonstrating that the applied approach can qualitatively and reproduce the occurrence tendencies and key characteristics of rear caliper click noise. The simulation-test integrated approach is applicable to early-stage NVH risk assessment and to the validation of countermeasures for click noise in production vehicles. Future work will focus on improving analytical modeling and prediction of click noise through development of a new model incorporating key design parameters.
Choi, Hyeontae, Kim, Sangbum, Park, Ilho, Kim, Taeuk, Kwon, Yongsik, Yang, Soonhong, Ma, Jaehyeon, Kim, Jinwook
Further Investigation of the Variables Affecting Brake Squeal: Dual-Piston and Single-Piston Calipers with NAO Pads2026-01-08259/14/2026
An earlier publication reported that brake squeal occurrence increases with increasing (inboard/outboard) pads wear rate difference in the case of a front dual-piston (twin-piston) caliper for a GVW vehicle of 2,510 kg fitted with Lowmet pads of straight chamfers and diamond chamfers. The current investigation was undertaken to find out if a front dual-piston caliper for a heavier vehicle (GVW 3,200 kg) fitted with NAO pads of straight chamfers, and a lighter single-piston caliper (GVW 2,100 kg) fitted with NAO pads of straight chamfers behave the same or not, using the SAE J2521 and Los Angeles City Traffic simulation procedures. In all cases, brake squeal is found to increase with increasing (inboard/outboard) pads wear rate differences (wear differentials); increasing pad radial taper is associated with increasing (I/O) pads wear differential; pad tangential taper lowers the (I/O) pads wear differential. Increasing friction coefficients do not relate to increasing squeal occurrences. To minimize brake squeal occurrence, caliper should be designed to minimize (I/O) pads wear differential.
Sriwiboon, Meechai, Rhee, Seong Kwan, Sukultanasorn, Jittrathep, Khathinhorm, Nicha, Kunthong, Jitpanu
Predicting Brake Squeal Occurrence Using Machine Learning with Temporal Feature Analysis of Braking-Torque Test Data2026-01-08129/14/2026
The automotive industry's paradigm shift toward autonomous driving and electrification has introduced new competitors threatening market dominance through differentiated value propositions. In this highly competitive landscape, delivering irreplaceable customer value requires providing sustainable and authentic luxury experiences. Quiet driving represents a tangible value that customers genuinely appreciate. Brake squeal—high-frequency noise arising from friction-induced vibration during braking—negatively impacts customer satisfaction and must be suppressed. Despite significant advances in brake squeal prediction modeling, the irregular nature of squeal generation mechanisms has prevented the development of a generalized predictive model applicable to product development processes. Development and verification remain largely experimental. This limitation constrains early-phase design validation, as brake squeal is highly sensitive to chassis and braking system design. When squeal issues emerge during post-design evaluation, fundamental improvements to pad materials become difficult. Consequently, damping characteristic tuning is employed for mitigation, incurring substantial development costs. This study addresses this challenge through systematic feature engineering of time-series braking data—brake torque, disc rotational speed, disc temperature, and brake pressure—collected during squeal evaluation tests. Based on the hypothesis that environmental conditions and brake system characteristics influence mechanical behavior, time-series features exhibiting strong predictive association with squeal occurrence were derived, and a machine learning model was developed to predict squeal occurrence probability using these features as input variables. The model's predictive performance was validated by comparing squeal probability predictions derived from independent torque performance evaluation data against actual squeal evaluation results. This validation confirms that the model successfully predicts squeal occurrence probability from dynamometer torque performance data alone. Consequently, this approach enables the prediction of squeal occurrence probability in early development phases before formal noise assessment is conducted, streamlining the development process and significantly reducing verification costs while contributing to quieter driving experiences.
Cho, Sunghyun, Yoon, Jungro, Kim, Yoon Cheol, Kim, Jeongkyu, Kim, Sungho, Baek, SongYi, Kim, Won Joon, Choi, Kyung Rok
Study on Nonlinear Dynamic Characteristics of High-Speed Train Braking Systems2026-99-11419/11/2026
To address the oversimplification in prior brake system models, this study develops a 10-degree-of-freedom (DOF) dynamic model of a disc brake system. A control-variable approach is employed to numerically simulate the effects of braking force, rotational inertia, brake pad tangential stiffness, suspension stiffness, and damping. The vibration responses under different braking conditions and in the presence of multi-parameter coupling are analyzed through bifurcation diagrams, phase trajectories, and Poincaré sections. The main findings indicate: (1) Increasing braking force induces a transition from period-1 to higher-order periodic motions (e.g., period-6), accompanied by significant vibration amplification; (2) Enhanced brake pad tangential stiffness suppresses vibration amplitude but extends the sticking phase duration; (3) Exceeding a critical primary suspension stiffness threshold triggers system instability. These results suggest that structural optimization of suspensions and reasonable selection of brake pad support stiffness are important measures to prevent stick-slip vibrations.
Li, Songge, Wang, Jingyue
Research on an Evaluation Method and Application of Autonomous Vehicles in Traffic Flow Environment2026-99-15629/11/2026
Traffic flow environment testing is indispensable in the research and evaluation process of intelligent vehicles. However, the current vehicle evaluation systems mostly focus on simple dynamic scenarios and lack a comprehensive assessment of vehicle performance in complex traffic flow environments. In view of this, this paper constructs a multi-dimensional comprehensive performance evaluation system for vehicles in traffic flow environments. Firstly, based on the randomness and dynamics of traffic flow, four core evaluation dimensions covering safety, comfort, efficiency, and economy are constructed. In terms of security, the collision time and Predicted Safety Metrics are adopted. This enables the dual quantification of immediate collision risks and dynamic obstacle avoidance capabilities. The comfort evaluation focuses on the impact of vibration frequency on the human body and constructs a graded quantitative index. Efficiency and economy evaluation models are built through time cost and energy consumption cost. The verification is carried out under different traffic flow scenarios, and the final results demonstrate the consistency between the evaluation method of this paper and the expert evaluation method, thereby verifying the rationality of the evaluation system presented in this paper.
Wang, Guangyu, Song, Shiping, Zhang, Cheng, Qu, Ge, Yu, Xiaojun
Experimental Study on Ultrasonic Drilling of CFRP Based on Ultrasonic Tools2026-99-14139/11/2026
To investigate the influence of laws of rotational speed, ultrasonic vibration, and feed speed on burr length, splitting length, and hole roundness of carbon fiber reinforced plastic (CFRP), drilling experiments using ultrasonic tools designed based on the dagger drill principle were carried out on CFRP materials. This study aims to explore methods for improving the hole-making quality of CFRP and further enhancing its hole-making efficiency. The results show that a high rotational speed can effectively reduce the burr length by 60% and the splitting length by 50%. Ultrasonic vibration can reduce the burr length and splitting length by about 70% and increase the hole roundness by about 10%. The higher the feed speed, the lower the hole-making quality, while an excessively low feed speed will impair the hole-making efficiency. In this study, the optimal hole-making quality was achieved when the rotational speed was set at 18500 r/min, ultrasonic vibration was activated, and the feed speed was controlled at 40 mm/min. The research results provide valuable references for the research, popularization, and application of ultrasonic tools and related technologies.
Xiang, Hui, Xiao, Liuwei, Song, Jinhui, Chen, Songlin, Liu, Zhichun, Liu, Yihong, Xiao, Huan, Zhang, Cheng, Ran, Qiuyue, Luo, Jiang
Optimized Design of Vibration Reduction for the Frame Structure of Metering, Considering Ground Impact Load2026-99-12339/4/2026
To effectively mitigate the adverse effects of impact loads on the operational quality of a planter, this paper focuses on precision metering with dual planting chambers, and a novel approach is proposed to concurrently consider static and impact loads in the design of the frame structure, aiming to achieve a balanced design that combines load-bearing capacity and vibration reduction effects. The methodology employs a dual-layer cyclic process, where the outer layer calculates equivalent static loads based on the structural nonlinear dynamic response, and the inner layer introduces these equivalent static loads into the objective function of the optimization model using a weight method. The design of the frame structure, which simultaneously accounts for static and impact loads, is established through a topology optimization model based on the parametric level-set method. The simulation-optimization results indicate that, within the two-dimensional plane, the optimized seed metering frame achieves a marked reduction in volume fraction while its compliance remains almost unchanged. When the solution is expanded from 2-D to 3-D, and the optimized volume is increased to match the original volume, the optimized stiffness becomes 1.92 times the initial stiffness. This demonstrates that the frame is substantially lightened yet its stiffness is effectively enhanced, confirming that the design concurrently offers improved vibration attenuation and load-bearing capacity. The proposed structural optimization method can provide a viable design for improving the quality of precision metering. Although physical tests are still lacking, the soundness and consistency of both the simulation outcomes and numerical analyses provide strong evidence for the feasibility of the proposed method. Future tests can further verify its effectiveness.
Zhang, Wenpeng, Zeng, Shan, Zang, Ying, Wang, Yu
Study on the “Vibration-Differential Pressure” Coupled Environment Test Technology for Airborne Equipment Vibration Isolation Systems2026-99-12519/4/2026
The stable operation of airborne equipment determines the functionality and performance standards of aircraft. Installing vibration isolation systems on such equipment aims to improve its performance. With the advancement of aircraft capabilities, future evaluations of airborne equipment’s vibration isolation systems will require increasingly real-world experimental assessment. Achieving a ground-based simulation of the complex coupling environment encountered by airborne equipment at high altitudes presents a huge challenge. This paper proposes a method utilizing air springs to simulate differential pressure forces, successfully enabling ground-based testing of “vibration-differential pressure” coupled environments for airborne equipment. The results verify the effectiveness of this approach, and it can be used for this type of environmental testing.
Qin, Xiaomeng, Xing, Xiaoming, Mou, Haowen, Wang, Jianzhong
Comprehensive Analysis of Torsional Vibration Response in Marine Propulsion Shafting Systems2026-99-12749/4/2026
The marine propulsion shafting system serves as the core component of ship power transmission, wherein torsional vibrations can easily lead to shaft cracking and failure. Thus, avoiding shafting resonance is vital for ship safety. Previous research primarily focuses on a single vibration mechanism of diesel engine propulsion shafting systems, lacking a comprehensive analysis of modal characteristics, frequency, and transient responses. This paper systematically investigates the torsional vibration characteristics of shafting systems, constructs a mathematical model for torsional vibrations, deduces a method for solving natural frequencies, and establishes a frequency-domain transfer function matrix using the Laplace Transform to theoretically derive the transient response of damped forced vibrations. Taking the propulsion shafting system of a low-speed diesel engine in a 10,000-ton oil tanker as an example, a multi-condition analysis based on a simplified shafting model is conducted. This includes modal solution analysis, 0–2000 Hz frequency sweep tests, and comparative experiments on transient responses under different excitation frequencies with a 1000 Nm torque. The study reveals the influence mechanism of the coupling between excitation frequency and natural frequency on the dynamic characteristics of the shafting system. By investigating torsional vibration patterns, this research provides a theoretical basis for vibration reduction design and resonance avoidance in marine propulsion shafting systems.
Zhang, Jiayi
A Method of Hamiltonian System for the Vibration Problem of Cracked Plates with Piecewise Boundaries2026-99-12599/4/2026
This paper focuses on analytical solutions for studying the vibrations of partially cracked orthotropic plates with piecewise boundaries using the symplectic elasticity method. Crack compliance coefficients are derived from the line spring model and introduced into the governing equations. In this paper, by establishing the Hamiltonian system and solving the Hamiltonian canonical equations, the vibration problem of cracked plates with piecewise boundaries can be reduced to finding the symplectic eigenvalues and symplectic eigensolutions. In the Hamiltonian system, the problem is transformed into seeking the solution of an algebraic equation system by the aid of symplectic eigensolutions and the adjoint symplectic orthogonal relations between the eigensolutions. Thus, for orthotropic plates with cracks under piecewise boundary conditions, this work presents a set of analytical solutions. Specifically, expressions for the free vibration behavior are derived. Furthermore, the steady-state response is determined. Finally, the transient dynamic response is also formulated and solved. The numerical results show that this method is effective and the natural frequency obtained in this paper is consistent with experimental results. A parametric investigation is performed, with the aim of comprehensively investigating the dynamic behavior of cracked plates subjected to piecewise boundaries. Significant findings include how aspect ratio, piecewise boundary conditions, and crack length affect structural vibration characteristics. For the plates containing cracks under piecewise boundaries, the frequency-response and the time-history curves for the forced vibration are plotted. These curves clearly illustrate the corresponding vibration characteristics of the plates. Some of the results can provide benchmarks for validating numerical or approximate methods. The method presented in this paper can provide a pathway for solving similar problems in the field.
Qu, Jianlong, Yu, Qinyu, Jia, Jufang, Xu, Xinsheng
A Simultaneous Impulse and Oscillatory Component Decomposition Method for Fault Diagnosis of Rolling Bearings2026-99-12049/4/2026
Due to the interference of oscillatory components and noise, the periodic impulses associated with localized bearing faults become difficult to extract, leading to unreliable diagnostic performance. To solve this problem, the study proposes a simultaneous impulse and oscillatory component decomposition method (SIOCD). The method designs and solves a novel optimization model to decompose oscillatory components and fault impulse components from noisy vibration signals. To achieve component separation in the optimization model, distinct penalty functions are introduced for oscillatory and impulse components. For oscillatory components, a regularization term is applied to achieve their extraction by minimizing the component bandwidth in the frequency domain. For impulse components, a penalty function is designed to achieve their decomposition by enhancing both sparsity within groups (SWG) and sparsity across groups (SAG) in the time domain. Then, an iterative solver is derived using an alternating minimization framework and the majorization-minimization (MM) algorithm. Finally, the proposed method’s effectiveness is demonstrated through comprehensive simulation and experimental analyses, and the results demonstrate that it achieves superior performance over existing approaches in fault feature extraction and enhancement.
Sun, Haoran, Zhang, Jinduo, Han, Tianyu, Shi, Xi
Study on the Vehicle Unsteady Vibration Control with a Semi-Active Strut2026-99-12319/4/2026
Unsteady vibrations of vehicles, which can be easily perceived by the human body, may affect the driving experience and compromise driving comfort. However, the conventional three-point powertrain mounting system (PMS) often fails to offer a satisfactory solution. Here, a novel four-point PMS was proposed by introducing a semi-active strut (SAS), which can provide stronger damping in a low-frequency range to resolve this problem. Specifically, a thirteen degrees of freedom (DoFs) vehicle dynamic model (VDM) with four mounts was constructed, and the evaluation indices for unsteady vibration responses of the vehicle were determined and analyzed; Next, the PMS optimization design approach was employed to identify the proper position of installation and dynamic stiffness of the SAS, and meanwhile the 13 DoFs VDM and the force-sharing principle were used to identify the structural parameters of the strut; Last, comparative experiments were performed to analyze the effect of the strut on alleviating the unsteady vibration of the vehicle under varied unsteady vehicle states. The results showed that the SAS has significantly reduced the seat rail peak acceleration, verifying the effectiveness of our novel PMS in alleviating the unsteady vibration. The research provided a feasible solution to alleviate the unsteady vibration of vehicles and improve the driving experience.
Wang, Daoyong, Liu, Yongjiang, Ma, Bo
Dynamic Characteristics Analysis of Conical-Cylindrical Shell Structure2026-99-12789/4/2026
In the context of aerospace development towards lightweight, high reliability, and long life directions, such materials have become the core materials of key load-bearing structures for advanced aircraft, and their structural dynamic characteristics are directly related to the flight safety and service stability of the aircraft. This article uses uniform artificial springs to simulate the stiffness coupling effect and boundary conditions of the entire structure. In the stage of theoretical modeling, classical shell theory is used, and orthogonal polynomials are introduced as displacement functions. Is solved by the Lagrange energy equation. On this basis, the effect of external size parameters on structural vibration frequency is deeply discussed. With the change in structural natural frequency with the taper of the conical shell, the ratio of cylindrical shell length to diameter and the ratio of diameter to thickness are analyzed.
Zhao, Yunhao, Chen, Jie
Research on Online Zero-Point Calibration Technique for Ω-Shaped Coriolis Flowmeters in CCUS Applications2026-99-12379/4/2026
The Ω-shaped Coriolis flowmeter, owing to its suitability for high-pressure and wide-temperature conditions, has become the preferred device for CO2 metering in CCUS-EOR projects. In practical applications, however, the volatile nature of operating pressures and temperatures triggers a persistent zero-point drift. This instability creates a ripple effect: it not only degrades metering precision but also fundamentally undermines the equitable basis of carbon trading markets. This study, through theoretical analysis, fluid-structure coupling simulation, and experiments, deeply investigates the patterns of zero-point drift in Ω-shaped Coriolis flowmeters and corresponding correction methods. The research reveals that the asymmetry of the measuring tube structure is the primary cause of zero-point drift, with changes in the vibration frequency of the measuring tube directly influencing the zero-point value, leading to the establishment of a related zero-point drift model. Based on the asymmetric structure of a DN15 Ω-shaped Coriolis flowmeter, simulations were performed to model the zero-point variation patterns under different pressures and temperatures using CO2 as the fluid, thereby verifying the effectiveness of the zero-point drift model. To validate our approach, we executed targeted zero-point experiments, employing the proposed model to predict zero-point shifts across a broad spectrum of pressures and temperatures. By integrating these predictions into a refined correction framework, we successfully neutralized drift-induced errors. These findings offer both a robust theoretical pillar and a practical toolkit for high-precision CO2 accounting, ultimately safeguarding the economic integrity of carbon trading within CCUS-EOR initiatives.
Yu, Haobo, Hua, Chenquan, Yu, Wenxin, Zhao, Zerun
A Study on the Dynamic Characteristics of Long-Span Single Conductors Using Meshfree Methods2026-99-04248/28/2026
The free vibration characteristics of long-span transmission conductors form the fundamental basis for vibration control design, as their natural frequencies and mode shapes directly affect line safety and the selection of vibration suppression devices. In this study, the three-dimensional linear free vibration governing equations were derived through functional integration of the kinetic and potential energies by using Hamilton’s variational principle. Compared with the conventional integral transform method, an improved meshfree discretization strategy is proposed: the shape functions are constructed using the moving least squares (MLS) method, while the boundary conditions are treated with a fully transformed approach, thereby converting the partial differential equations into ordinary differential equations. Subsequently, a corresponding eigenvalue problem is solved to calculate the first few frequencies of the system, and the effect of conductor natural parameters on these frequencies for the transmission conductor is investigated. The results indicate that the natural frequency decreases when the conductor length becomes larger, and the rate of decrease becomes more gradual as the length increases; it decreases with increasing cross-sectional diameter; it decreases linearly with increasing material density; and it increases linearly with increasing elastic modulus. These findings demonstrate that conductor length, cross-sectional diameter, material density, and elastic modulus all have significant effects on the natural frequency. Among them, length and diameter affect the frequency by altering the conductor’s inertia and structural characteristics, whereas density and elastic modulus govern the frequency from the perspectives of inertia and stiffness, respectively.
Li, Chen, Cheng, Yongfeng, Li, Danyu, Qiu, Gang
Objective Quantification of Harmonic Impulsive Sounds and Interval Prediction of Sound Quality in Hybrid Vehicle Engines10-11-01-00038/28/2026
Steady advancement is observed in global research on eco-friendly and sustainable transportation. Rapid technological evolution of hybrid electric vehicles (HEVs) is documented. Lower overall noise output and more compact structures are achieved in HEV engines relative to conventional internal combustion engines. The perceptibility of harmonic impulsive sounds is significantly enhanced by these design characteristics. A close correlation is observed between these acoustic phenomena and negative human auditory perceptions. These events are treated as a core focus for HEV noise, vibration, and harshness optimization. Accurate quantification of harmonic impulsive sounds is not achieved by conventional objective indicators. A favorable balance between reliability and accuracy is not established by existing subjective prediction models. Practical engineering applications of these methods are severely restricted. A novel objective quantification method for harmonic impulsive sounds is proposed in this study. The method is established based on time–frequency masking theory and tonal strength. Bench tests in a semi-anechoic chamber and subjective evaluation experiments with standardized rating scales are performed for data collection. Collected sound signals are decomposed through an integrated approach of wavelet transform and variational mode decomposition. Targeted feature extraction is completed for harmonic impulsive sounds. A quantitative index incorporating human auditory temporal and frequency masking effects is developed. The proposed index exhibits a significantly stronger correlation with subjective evaluation results than traditional objective metrics, confirming its superior ability to reflect actual perceived sound quality. An interval prediction model for sound quality evaluation is established based on support vector machines and kernel density estimation. Traditional objective metrics and the proposed index are introduced as key input parameters. Effective and reliable prediction of HEV engine noise subjective satisfaction is achieved by the model.
Lin, Xu, Liang, Xingyu, Shi, Zhiyuan
Vibration Simulation of Guide Mechanism Based on Rigid-Flexible Coupling Dynamics2026-99-03108/14/2026
For vibration issues induced by coupling effects between flexible barrel guide mechanisms and moving bodies in high-speed dynamic systems, this study investigated their interaction mechanism using flexible multibody dynamics principles. A solid model was developed in 3D CAD software. The modal neutral file (MNF) of the guide mechanism was generated in ABAQUS, and its contact dynamics with the moving body were simulated in ADAMS via flexible contact theory and the modal superposition method. Comparative simulations revealed that incorporating structural flexibility yielded smoother fluctuations in the moving body’s axis inclination angle, providing more accurate system behaviour characterization. Exit velocity and spin rate errors remained below 5% against theoretical values, demonstrating model reliability.
Zhu, Qing, Cheng, Zixiang, Zhuo, Changfei
Structural Optimization Design and Experimental Study of a Shipboard Cabinet2026-99-09018/7/2026
The shipboard cabinet is an important carrier of radar equipment. It is necessary to ensure a good working environment and provide maximum support and protection for the internal equipment. In this paper, a shipboard cabinet that can realize a parallel heat dissipation architecture was taken as the object. The natural frequency and mode were used to find the area where the cabinet was prone to high-frequency vibration under impact excitation. The response characteristics of the cabinet under strong impact conditions were studied using a nonlinear transient dynamic analysis method. The weak links in the cabinet structure were identified, and the structural reinforcement design was carried out. After optimization, the maximum stress value of the cabinet was significantly reduced, and the safety factor was greater than 1.5. Finally, the effectiveness of the structural optimization was verified through experiments. The cabinet vibration isolation system was optimized and selected to ensure that it has good vibration isolation characteristics and impact response. The vibration isolation performance of the wire mesh isolator and the non-resonant peak isolator in the shipboard vibration and impact environment was verified by experiments. The impact transmissibility is less than 0.3, and the vibration transmissibility is less than 1.5, which can further improve the vibration and impact resistance of the shipboard cabinet.
Ni, Xiaokang, Jiang, Bo, Zhang, Liangjuan, Wu, Jingkai
Analysis of the Impact on Ride Comfort from Splitting the Unsprung Mass in Vehicle Modeling2026-01-50578/6/2026
The study was conducted to investigate the differences in ride comfort analysis between treating the unsprung mass as a whole and modeling it separately. A classical two-degrees-of-freedom single-wheel vehicle vibration model and a three-degrees-of-freedom single-wheel vehicle vibration model with split unsprung mass were established, with their state-space descriptions determined. The fundamental vibration response quantities of both models were identified, and time-domain simulations under random road excitation were performed using MATLAB/Simulink. The results indicate that the two modeling approaches exhibit minimal differences in ride comfort analysis for the sprung mass, but there are certain differences for the unsprung mass. Additionally, for the three-degrees-of-freedom single-wheel vehicle vibration model with split unsprung mass, the axle-to-wheel mass ratio was introduced to analyze the changes in the fundamental vibration response quantities when the unsprung mass increases by a fixed value and is distributed differently between the axle and the wheel. The results show that variations in the axle-to-wheel mass ratio have no significant impact on the vibration characteristics of the sprung mass. Reducing the mass ratio, i.e., transferring part of the unsprung mass to the wheel, can somewhat reduce the vertical acceleration of the unsprung mass, but it will slightly increase the relative dynamic load on the wheel. Finally, the other two models were simplified by combining the two masses connected by the bearings.
Jie, Li, Wei, Deng, Chengyu, Li
Multi-Objective Optimization Design of Ship Propulsion Shaft System in Ice Area Based on NSWOA Algorithm2026-99-01527/31/2026
Ship propulsion shaft systems are subjected to ice load excitation when ships are navigating in polar ice regions. Compared to conventional hydrodynamic effects, the ice load imposes higher requirements on the shaft system’s ability to withstand torsional stresses. To improve the power of the ship propulsion system when sailing in ice areas and reduce the power loss of the shaft system, while considering the vibration performance. In this paper, a multi-objective optimal design of the shaft system is carried out using the Non-dominated Sorted Whale Optimization Algorithm (NSWOA) to reduce stresses on both the motor shaft and the intermediate shaft. The coupled system model of motor-shaft system-propeller structural components is established, and the system dynamics response model is obtained by solving using the Newmark-β method. Based on the response model, a multi-objective whale optimization algorithm is used to optimize the power and vibration performance of the shaft system simultaneously. The optimized results show that the shaft system transfer efficiency is improved by 0.27%, and the stress at the shaft end is reduced by 11.8% and 12.3% respectively.
Hu, Chuanxi, Li, Yao, Pan, Shuxian, Liu, Zhiyong, Xie, Yuteng, Ye, Jun, Zhou, Ruiping
Research on Sealing and Vibration Reduction Performance of Large Sized Packaging Box2026-99-02027/31/2026
With the continuous development of large precision equipment, the reliability requirement for long-distance transportation is also constantly increasing. Large packaging box with sealing and vibration reduction performance is crucial during transportation. This article introduces the sealing measures for large-sized packaging box, as well as the sealing structure design methods for key parts, vibration reduction measures and the selection and design of vibration dampers. The designed packaging box has been used for long-distance transportation of various types of equipment and the reliability of sealing and vibration reduction performance has been verified in practical applications, providing reference for the design of similar packaging boxes.
Zhang, Ruoyu, Jiang, Shouli
Enhanced Vibration Damping Properties of Novel Mn-Cu Alloy for Ship Structural Applications2026-99-02367/31/2026
Low-frequency vibrations in ships have detrimental effects on the lifespan of onboard equipment and the comfort of crew members, thereby highlighting the importance of developing efficient vibration-damping materials as a critical research area. This study investigates the application of Mn-Cu damping alloys for mitigating vibrations within the 0–1000 Hz frequency range, which is typical of ship environments. The vibration-damping characteristics of the material were examined through a combination of experimental and numerical simulations. A numerical simulation framework was developed to predict the vibration response of manganese-copper damping alloys, incorporating a frequency-dependent damping ratio model derived from experimental characterization. Comparative analyses validated the accuracy of vibration simulations that incorporate frequency-dependent damping ratios and demonstrated the superior vibration attenuation performance of the Mn-Cu damping alloy across the 0-1000 Hz frequency band. Deck application analysis revealed that manganese-copper damping devices reduced the root mean square (RMS) vibration acceleration of the ship deck by up to 17.5% in the 0-1000 Hz frequency range compared to aluminum alloy counterparts. The damping effect was particularly significant in the 400–1000 Hz range, where vibration energy dissipation was most effective due to the material's intrinsic damping mechanisms. Additional engineering evaluation confirmed that the Mn-Cu alloy components maintain structural integrity while providing enhanced damping performance under typical marine environmental conditions. This study establishes a theoretical foundation for the design of ship vibration-damping materials, expands the potential applications of damping alloys in marine engineering, and provides valuable reference data for material selection and vibration control design in shipbuilding and offshore engineering applications.
Yao, Sitong, Tian, Ali, Zhao, Xianghua
Study on Energy-related Mechanisms of Aeroelastic Instability of Ultra-Long Flexible Wind Turbine Blades Under Various Working Conditions2026-99-01347/31/2026
With the continuous increase in wind turbine power capacity, ultra-long flexible blades face intensified aeroelastic instability risks due to reduced structural stiffness, enhanced modal coupling, and aerodynamic nonlinearity. In addition to the analysis of basic vibration characteristics, this study focuses on energy-related mechanisms of aeroelastic instability under various working conditions. Using a numerical model integrating Dynamic Blade Element Momentum Theory (DBEMT) and Geometrically Exact Beam Theory (GEBT), over 400 time-domain simulations were conducted to characterize instability onset and development. Results reveal four distinct aeroelastic instability regions, each dominated by specific modes. In Region A, flutter dominated by the 2nd flapwise mode is observed. In Region B, flutter dominated by the 1st edgewise mode is observed. In Region C, flutter dominated by the 2nd edgewise mode is observed. While in Region D, where the medial angle of attack (AoA) of the blade has exceeded the stall angle, stall-induced vibration dominated by the 1st flapwise mode is observed. Energy analysis shows aerodynamic work concentration near the blade tip drives instability, with diverse energy exchange patterns across regions. Except for some operating conditions in region C, where instability is dominated by edgewise energy absorption, most aeroelastic instability conditions are dominated by flapwise energy absorption. Torsional degree of freedom contributes minimally to aerodynamic work, but the torsional vibration exerts a notable influence on the AoA. This, in turn, changes the comprehensive aerodynamic forces impacting the blade as well as the general aeroelastic stability. This study clarifies the relationship between operating conditions and energy-driven instability, offering some reference values for the design work and safety assurance of ultra-long flexible blades of the wind turbine.
Wang, Su, Chen, Jiajia, Zhou, Le, Shen, Xin, Li, Chun, Du, Zhaohui
Analysis of the Cause of Knocking Noise in a Marine Dual-Power Dual-Branch Transmission Gear System2026-99-16507/24/2026
This study investigates the knocking noise phenomenon in a marine dual-power dual-branch transmission gear system. Vibration mechanisms are analyzed, and potential failure modes are assessed. System vibration data were evaluated using time-domain and frequency-domain methods. Results show that overall vibration levels remained within acceptable limits, with no indication of imminent failure. Physical inspection confirmed that the shaft, gears, bearings, housing, and installation met specifications, with no observed performance degradation or structural damage. By correlating noise occurrence with vessel loading conditions, a strong relationship was identified among gear transmission torque, the power distribution ratio between high-and low-pressure turbines, and the onset of knocking. Specifically, under low-load conditions, uneven power and torque distribution among the four gear branches led to insufficient loading on the low-pressure side. This light-load state induced instability in the low-pressure gears, resulting in periodic tooth disengagement or back-side tooth contact, which is established as the root cause of the knocking noise.
Gu, Chengzhong, Xu, Hanwei, Luo, Rirong, Ren, Fushan
Fatigue Life Analysis of Diesel Engine Filter Seat under Random Vibration Condition2026-99-16567/24/2026
The filter seat of diesel engine fuel filters is a key load-bearing component in the engine fuel system. Its structural integrity directly affects the reliability and safety of fuel delivery. In actual operation, the filter seat is subjected to random vibration loads generated by engine operation and vehicle dynamics, which may cause fatigue failure over time, even when static stresses are below the yield strength. This study employs finite element modeling (FEM) to investigate the structural strength and fatigue life of the diesel engine filter seat under random vibration conditions. The CAD model is simplified and meshed to reflect the main load paths, and boundary conditions, including bolt preload, gravity, and measured vibration PSD spectra are applied. Modal and harmonic response analyses are performed using Abaqus, and the Tovo-Benasciutti frequency-domain method is used in fe-safe to predict fatigue life. The results identify the most fatigue-sensitive areas and reveal that the minimum fatigue life is 10^3.067 cycles under realistic conditions, with the most critical regions located near the bolt connection. The simulation methodology and results provide a reliable basis for structural optimization and life prediction of similar components under random vibration environments.
Gu, Kexuan, Zhu, Yi, Xie, Liang, Wang, Wei
Parameter Identification of Projectiles Based on an Improved Butterfly Algorithm Optimizing a Mixed Kernel Extreme Learning Machine2026-99-16167/24/2026
Accurate projectile dynamic modelling requires identifying aerodynamic parameters. The traditional methods for identifying aerodynamic parameters of missiles suffer from significant modeling errors. Therefore, this study proposes an improved butterfly-shaped optimization hybrid extreme learning machine algorithm. It combines the butterfly algorithm with a hybrid extreme learning machine, Cauchy mutation, and adaptive weight. The search ability of the Butterfly algorithm is enhanced by introducing the Cauchy distribution function and adaptive weighting factors. In addition, to balance the weights of searches and to optimize the regularization coefficients and kernel function parameters, the dynamic switching probability p is introduced. The identification accuracy of four different algorithms was compared under noise-free conditions. The feasibility of the improved butterfly-optimized hybrid extreme learning machine was verified. When there is noise, the strength of the algorithm is confirmed by comparing the effect of different noise levels on how well it can identify things. The simulation results show that the improved butterfly optimization hybrid extreme learning machine algorithm has higher accuracy and better robustness in identifying projectile aerodynamic parameters. The simulation results show that the improved butterfly optimization hybrid extreme learning machine algorithm has higher accuracy and better robustness in identifying projectile aerodynamic parameters.
Wang, Qianqian, Wang, Kangjian, Jiao, Wenjie, Yi, Wenjun, Chen, Jintong
Optimization of Turbine Discrete Noise by Non-Uniformly Distributed Blade Design2026-99-16177/24/2026
The Mellin non-uniformly distributed moving blade method was adopted to conduct CFD numerical analysis and sample experimental tests on the axial-flow turbines before and after optimization using the uniformly distributed and non-uniformly distributed design methods, respectively. In the original design, five blades were evenly distributed in the 360° circumferential direction, and the non-uniformly distributed angles were 46°, 102°, 46°, 83°, and 83°. CFD numerical analysis shows that due to the low rotational speed of the turbine and the absence of a sealing structure at the blade tip, factors such as tip noise leakage and backflow have little impact, and the flow field pulsation is mainly caused by the blades themselves. The non-uniformly distributed design can significantly enhance the work-doing capacity of the blades. At 90% of the blade height, the torque can be increased by up to 60%, but at the same time, the axial force on the blades also increases accordingly. Near 80% - 90% of the blade height, the axial force increases by 33%. The flow rate performance of the non-uniformly distributed design is slightly inferior to that of the uniformly distributed design, but the overall noise is better than that of the uniformly distributed design, with maximum optimization of 0.48 dB (A); the maximum values of the first three orders of discrete noise are significantly improved, with a maximum improvement of 0.75 dB (A), and the discrete noise orders of the non-uniformly distributed turbine can avoid blade - related factors and disperse the energy to nearby orders.
Wu, Aiping, Ma, Tianli, Wang, Shiming, Ding, Chengling
Research on Ground-based Testing of Optimized Engine-Driven Pumps for Civil Aircraft2026-99-18247/17/2026
This study focuses on the ground testing of an optimized engine-driven pump system for civil aircraft. It proposes the test methods for the pressure pulsation at the pump outlet, the stress and vibration of the pipeline, and the cabin noise level on board. These tests are designed to determine whether the function and performance of the optimized engine-driven pump meet the intended improvement objectives. This paper elaborates on the test objectives of the pressure pulsation test, pipeline stress test, pipeline vibration test, and noise test on ground-based testing of civil aircraft. It proposes corresponding testing methodologies, summarizes the technical specification requirements for selecting different types of test sensors, outlines the principles for selecting test points during the testing process, and presents methods for processing the collected test data. By conducting tests on a specific model of civil aircraft and coupling with comparative analysis of test data, it was found that the pressure pulsation level, pipeline vibration level, and cabin noise level on board the optimized engine-driven pump have been significantly improved compared with the original design. At the same time, it is concluded that the stress level of the optimized engine-driven pump outlet pipeline remained within the allowable fatigue limits of the material.
Li, Ying, Qi, Xiaoyan
Analysis and Improvement of Rattle Noise in Manual Transmission2026-99-05277/10/2026
In response to the problem of manual transmission rattle noise in the acceleration process of a truck, the mechanism of the problem is analysed, and the scheme is developed and verified from two aspects: reducing the torsional vibration of the system and reducing the response of the transmission gear. The results show that, on the one hand, reducing the clutch stiffness and optimizing the torsional vibration of the system can reduce the rattle noise of the transmission; On the other hand, it can also reduce the rattle noise of transmission gears by improving the engagement precision of transmission gears and reducing the gear clearance. Considering the improvement effect, cost, and influence on other performance of the two schemes, the appropriate engineering scheme is selected to effectively solve the problem and improve the riding comfort of the product.
Yang, Zhijie, Xu, Binghua
A Novel Rotating Component Comprehensive Diagnostic Network Based on Stacked Auto Encoders and Sparse Filter Combined with Generative Adversarial Network2026-99-05347/10/2026
Nowadays, the majority of intelligent fault diagnosis approaches are still centered on individual faulty components, while only a limited number of models are capable of performing integrated diagnosis for rotating systems that consist of shafts, bearings, and gears. Under variable-speed operating conditions, the large scale of vibration data further complicates the process of effective feature extraction. To improve these challenges, this study develops a comprehensive diagnostic framework for rotating components, termed WGAN-SAFC. The proposed architecture integrates a Wasserstein Generative Adversarial Network (WGAN) with a hybrid structure of stacked autoencoders and sparse filtering (SAFC). SAFC integrates the feature-learning capability of SAE and the sparsity-driven representation of SF, while incorporating adversarial data generation to address sample imbalance and enhance fault diagnosis performance. Experimental verification on collected vibration datasets demonstrates that WGAN-SAFC achieves superior diagnostic accuracy and robustness compared with existing methods.
Li, Shunming, Feng, Mengqi
Design and Testing of a Quasi-Zero-Stiffness Vehicle-Mounted Isolation System with Additional Inerter2026-99-05207/10/2026
Vehicle vibrations during precision instrument transport can cause damage and failure. Existing vibration isolators often lack reliability, mass production feasibility, and easy maintenance. In this paper, we design and analyze a quasi-zero-stiffness vehicle-mounted isolator with an inerter, decreasing dynamic stiffness while raising the effective mass. Theoretical, simulation, and experimental results show improved isolation performance, lower isolation frequency, and a broader isolation bandwidth.
Li, Kai, Lv, Sibo, Sun, Ning, Dai, Shijie
Aircraft Noise Event Identification Technology Based on Single Acoustic Vector Sensor2026-99-05917/10/2026
With the rapid development of China’s civil aviation industry, the problem of airport noise has attracted widespread social attention. The requirement for the real-time monitoring and evaluation of acoustic environment around airports is becoming more and more intense. The identification of aircraft noise events in the complex acoustic environment surrounding the airport is the most critical technical problem in airport noise monitoring. However, the traditional noise source identification technology is difficult to be widely used in real-time monitoring system due to its large errors and complex deployment conditions. This paper presented an aircraft noise source identification technique based on a single acoustic vector sensor. The azimuth parameters of the noise source were estimated by the three-dimensional spatial positioning algorithm of sound pressure and particle vibration velocity combined with information processing, and the three-dimensional footprint of the noise event in the complex acoustic environment was described. Finally, the event was judged as an aircraft noise event by matching the noise footprint with the aircraft flight path. By monitored and analyzed the actual noise events of aircraft departure, the results show that this method can only use a single acoustic vector sensor to locate the aircraft noise source and distinguish the aircraft noise event from the background noise event, which provide a new lightweight method for the real-time airport noise monitoring system to locate the noise source and identify the aircraft noise event
Hou, Jiayu, He, Tianlun, Zhu, Lin, Chen, Ying, Liu, Yinhui, Lv, Lei, Wang, Yuhao, Chen, Da
Measurement of Exhaust Sound Levels of Stationary SnowmobilesJ2567_202607 (Current)7/6/2026
This SAE Standard establishes the test procedure, environment, and instrumentation for determining the sound levels of snowmobiles in the stationary test mode. This test method is intended to provide an accurate measurement of exhaust and other engine noise and may be used to evaluate new and in-use snowmobiles to determine compliance with noise control regulations. Sound level measurements obtained with this test method are not intended as an engineering determination of overall machine noise. For this purpose, the use of SAE J192 is recommended.
Snowmobile Technical Committee
A Multiphysics Approach to Mitigate Pulse-Width-Modulation-Induced Acoustic Noise in Permanent Magnet Synchronous Motor Drives for Electric Vehicles14-15-03-00147/3/2026
This article investigates high-frequency noise in permanent magnet synchronous motors (PMSMs) for electric vehicles, originating from pulse width modulation (PWM). A theoretical model is developed to formulate the phase voltage under space vector PWM (SVPWM), explicitly accounting for the additional harmonic components generated by the discrete-time voltage update in digital control systems. This derived voltage waveform serves as the excitation source in an electromagnetic finite-element model, from which the PWM current harmonics and their resulting high-frequency electromagnetic forces are computed. Critical components of the electromagnetic force are then extracted through two-dimensional Fourier transform. A structural model of the motor, incorporating practical assembly constraints, is established and validated by experimental modal tests on a fully assembled motor unit. To enable rapid noise prediction over the wide speed range, vibro-acoustic transfer functions are introduced. The predicted noise shows good agreement with experimental data. Leveraging this multiphysics model, the influence of switching frequency on noise characteristics is analyzed. The study identifies that avoiding excitation of the motor’s zero-order mode is critical for noise suppression. Accordingly, an optimal frequency-hopping strategy is proposed. Experimental validation confirms the strategy’s effectiveness in reducing noise over the wide speed range.
Lin, Fu, Chen, Yihui
Optimization of a Halbach array as NVH Mitigation Technique in a Yokeless and Segmented Armature Axial Flux Machine2026-01-07547/1/2026
This paper presents the optimization of a Halbach magnet array applied to an axial flux machine (AFM) in a 12-pole, 18-slots yokeless and segmented armature (YASA) topology, evaluated in the torque–speed characteristics diagram. AFMs offer significant advantages in terms of compact design and high torque density compared to other permanent magnet machine topologies. However, noise, vibration, and harshness (NVH) performance is strongly influenced by cogging torque, electromagnetic torque ripple, and tooth forces. While Halbach magnet arrays are well established in high-performance radial flux machines, only limited research has investigated their influence in AFMs. A Halbach array concentrates magnetic flux on one side of the magnet arrangement, leading to increased air gap flux density and a strongly reduced need of a back iron yoke under the magnets. By using a Halbach array, the magnetic field distribution in the air gap becomes more sinusoidal, thereby reducing harmonic components. Previous studies have primarily focused on further torque enhancement or mass reduction through the elimination of back iron. Given that AFMs already exhibit high torque and power density, the objective of this paper is the reduction of NVH factors such as cogging torque, torque ripple amplitudes and tooth forces while minimizing the required magnet mass and maintaining the specified performance criteria. In the optimization process, in addition to the segmentation of the pole and transition magnets, the magnet height as well as the required thickness of the back iron yoke are optimized. For the design and optimization of the Halbach array, two-dimensional (2D) and three-dimensional (3D) finite-element (FE) models are combined with surrogate modeling techniques. In addition to the impact on torque ripple, further potential benefits of the Halbach configuration, including improvements in efficiency and reductions in overall motor weight, are analyzed and discussed.
Müller, Karsten, Schulz, Fabian, Bremer, Martin, Burkhardt, Yves, De Gersem, Herbert
Evaluation of Helicopter Turbine Engine Linear Vibration EnvironmentAIR1289A (Current)6/29/2026
This SAE Aerospace Information Report (AIR) outlines a recommended procedure for evaluation of the vibration environment to which the gas turbine engine powerplant is subjected in the helicopter installation. This analysis of engine vibration is normally demonstrated on a one-time basis upon initial certification, or after a major modification, of an engine/helicopter configuration. This AIR deals with linear vibration as measured on the basic case structure of the engine and not, for example, torsional vibration in drive shafting or vibration of a component within the engine such as a compressor or turbine airfoil. In summary, this AIR discusses the engine manufacturer’s "Installation Test Code" aspects of engine vibration and proposes an appropriate measurement method.
S-12 Powered Lift Propulsion Committee
A Contribution to the Probabilistic Road Noise Simulation Using Non-Parametric Variability Modeling Abstract2026-01-07116/20/2026
An application of a Non-Parametric Variability Modeling (NPVM), as introduced by Pr. Soize, of a full vehicle road noise simulation, is an opportunity to highlight some applicative issues of such a stochastic approach. First, the convergence of the stochastic computations is considered by introducing the probabilistic modal density of the considered model as an indicator of the system intrinsic dynamic behavior. Since the probabilistic model induces a spread of modal frequencies, the upper range shows a lack of modes, deviating from the actual system modal density. The study of this deviation leads to the modal truncation criterion required to achieve a relevant probabilistic modal density in a targeted frequency range. The required margin in order to achieve a proper convergence of the probabilistic problems appears larger than expected. Then, using appropriate parameters, road noise simulation is investigated in the framework of the stochastic modeling. After the capability of the NPVM to handle the random loads requested for road noise, an FRF Based Sub-structuring approach is used to investigate different options for the loads application. Indeed, the complex behavior of the rotating tire/wheel system with the road is often handled by computing (or measuring) blocked forces or interface forces of a source sub-system (chassis) applied to a receiving sub-system (trimmed body). Cases where the receiving subsystems variability only, or both subsystems variability are considered, are investigated. It appears that, when variability applies to the full vehicle, using deterministic blocked forces may lead to erroneous results. When the trimmed body only is subject to uncertainties, deterministic interfaces forces lead to a reasonable approximation of probabilistic results. In both parts, theoretical derivations are illustrated by the results obtained from actual industrial models.
Gagliardini, Laurent, Glandier, Christian, Bauer, Eric, Straka, Andreas, Fiedler, Uwe
The Influence of Interior Noise on Just-Noticeable Speed Differences in Conventional and Electric Vehicles2026-01-06716/20/2026
Electric vehicles (EVs) and internal-combustion-engine vehicles (ICEVs) differ fundamentally in their in-cabin acoustics, notably the attenuation or absence of engine-order content. Prior work reports associations between reduced engine sound, speed underestimation, and poorer speed maintenance; however, research on how EVs’ new sound affects speed perception and control is scarce, and most newer studies focus on comfort and subjective pleasantness rather than speed perception. Addressing this gap, the present study uses a two-interval, two-alternative forced-choice (2AFC) paradigm to directly measure just-noticeable differences (JNDs) in speed under ICEV, EV, and silent conditions. Thirty participants performed a 2AFC task in which, on each trial, they viewed two first-person highway clips (reference vs. comparison) and indicated which appeared faster. Results from ANOVA and post-hoc tests indicate that at the 40 km/h reference speed participants showed no clear differences across sound conditions, whereas at 100 km/h there were marked differences in JND: mean values were 1.93 km/h (ICEV), 3.48 km/h (EV), and 5.15 km/h (silence). A psychoacoustic parameter analysis suggests that this effect is not explained by speed-dependent changes in loudness or sharpness; we interpret that RPM-related, clearly audible frequency shifts in ICEV provide the primary contributory cue. For EV NVH or artificial sound design, enhancing speed-contingent, trackable spectral cues while respecting comfort may help maintain drivers’ ability to discriminate speed differences.
Li, Zhenxian, Parizet, Etienne, Colangeli, Claudio
Rib Design of Electric Drive Unit Housings for Reduced Noise Radiation2026-01-06876/20/2026
Although propulsion noise often constitutes a minority of the overall noise in electric vehicles, it remains an important quality indicator due to its high-frequency tonal character, which is undesirable even at low levels. There are many factors that influence the interior car levels of propulsion noise, i.e. gear whine and electric motor whine. The primary ones to consider are the electric drive units (EDU) internal forces, but also secondary properties such as EDU housing design and encapsulation, vehicle sound pack and mount isolation play important roles. This work focuses on EDU housing design and more particularly on the housing ribs that enables attachment point stiffness and housing strength, but which can also cause problems in terms of noise radiation. Numerical parameter studies on geometrical properties such as length dimensions, thickness and curvature were performed on single ribs of different types. For each design iteration, the key performance indicators radiated sound power, squared velocity and radiation efficiency were studied. The outcome of this work provides insights into which characteristics of ribs that are central for radiated noise. For instance, it was proven that a rather small curvature of the outer edge of a rib can decrease the radiated noise but also that certain rib dimensions can result in extensive noise due to the interaction of the first bending mode with the peak in radiation efficiency.
Lennström, David, Malm, Oskar, wurzinger, Jakob, Cederlund, Johan
Application of Tone-to-Noise Ratio for Early Diagnosis and Control of Electric Drive Whine2026-01-06866/20/2026
High-frequency whine from electric drive systems has become a critical issue restricting the improvement of vehicle sound quality. Traditional evaluation methods struggle to accurately identify masked whine risks in the early research and development (R&D) phase, due to incomplete hardware of prototype vehicles and high interior background noise. This often leads to problems being delayed until the mass production stage, resulting in high rectification costs. To address this issue, this paper proposes and validates an early risk assessment method based on the Tone-to-Noise Ratio (TNR). First, the generation mechanism of Electric Drive (E-Drive) whine is systematically analyzed, identifying the electromagnetic noise of the electric motor and the gear whine of the reducer as the two dominant noise sources. To address this bottleneck, the TNR psychoacoustic metric is introduced to quantify the perceptual salience of tonal noise relative to background noise, which effectively mitigates the masking effect caused by high background noise in early prototype vehicles. Combined with an engineering case of a Plug-in Hybrid Electric Vehicle (PHEV), the study confirms that the TNR method can accurately identify potential high-risk whine orders in the Verification Prototype (VP) phase and enable reliable forward prediction of risks in the Mass Production (MP) stage. On this basis, a multi-dimensional noise reduction strategy covering harmonic current injection, gear microgeometry optimization, and transfer path optimization is developed for the identified risk orders. Full vehicle validation shows that the noise of key whine orders is reduced by 5–10 dB(A) after optimization, while the TNR value decreases significantly, and the vehicle NVH performance reaches industry-leading levels. This research forms a complete technical path from TNR-based early identification to targeted closed-loop control, providing a theoretical basis and practical engineering example for the proactive management and efficient solution of E-Drive whine risks in various new energy vehicles.
Yun, Zhao, Hui, Hui, Gao, Pan, Xiao, Zhongdi, Zan, Chen, Teng, Charlie
NVH Aspects of DC Charging2026-01-07036/20/2026
The deployment of high-power DC charging infrastructure for electric vehicles introduces new challenges in managing noise, particularly in public environments where acoustic comfort and regulatory compliance are essential. Noise emissions from both charging stations and vehicles during charging are a concern for operators of charging parks regarding customer experience and noise immission regulations. AVL employed a structured three-step approach to develop a non-expert tool for assessing the noise radiation of charging stations and vehicles during the charging phase. In a first step, AVL characterized the noise emissions with sound power measurements. Secondly, the measurement results were transferred to the virtual domain. To achieve this, the vehicles and charging station were characterized in the simulation with multiple monopole sources supported by transfer function measurements. This simulation model was validated against the sound power measurement results. After successful correlation of the simulation model, AVL implemented a user-friendly noise mapping tool for predictive planning of charging parks moving from a 3D FEM simulation approach to a simplified noise radiation model according to ISO 9613. Measurements were conducted on a representative high-power DC charging station and two electric vehicles. The vehicle cooling fan was identified as the dominant noise source on the vehicle side, while internal cooling fans of the charging station were the primary contributors to the noise radiated by the charger. Noise emissions were found to increase with higher charging currents, indicating a strong dependency on thermal load. The project established a reusable workflow for acoustic source identification enabling the creation of a scalable database. The noise mapping tool allows easy prediction of noise radiation from multiple charging stations and vehicles during the planning phase of charging parks and supports the design of countermeasures to meet regulatory requirements.
Gojo, Josef, Polanz, Markus, Graf, Bernhard, Langjahr, Paco, Mehrgou, Mehdi
Towards Realistic Stick-Slip Testing: Efficiently Mapping Material Behavior across a wide Range of Loading Conditions2026-01-07136/20/2026
To minimize noise caused by interior components rubbing against each other, automotive materials are usually tested in advance with the established stick-slip method according to VDA standard 230-206. This procedure is widely used for soft materials, upholstery and plastics. However, it is limited to constant climatic and selected loading conditions. Contrary, in real application, changing climates and dynamic excitations can nevertheless trigger noise issues even in materials rated as suitable in the prior tests. To address this gap, a new test method has been developed that evaluates the stick-slip behavior of material combinations for a wide range of loading and climatic conditions. Conducted in a climate chamber with a standard stick-slip test bench, the procedure applies sinusoidal excitations, dynamic climatic shifts and advanced data analysis. In addition to the usual results the new method also evaluates realistic scenarios such as starting a vehicle in different seasons or sudden jolting movements with high excitation speeds. The result is a detailed map of stick-slip behavior as a function of excitation speed and climate. While requiring a similar level of effort as the traditional test, this approach delivers far greater insight. It enables a more reliable optimization of materials and facilitates targeted material selection for specific applications. In this manner, it can not only contribute to improve product quality but also to achieve quiet interiors and customer satisfaction.
Fritz, Susanne, Strangfeld, Martin
Automating Component NVH Characterization: A Systematic Approach for Component Test Bench Characterization2026-01-07046/20/2026
Vehicle electrification and accelerated development cycles create a need for virtual Noise, Vibration and Harshness (NVH) development tools which are fast, precise and, seamlessly interchangeable between development sites, suppliers and OEMs. Component-based Transfer Path Analysis (C-TPA), standardized in ISO 20270:2019, enables independent component characterization and integration with virtual models to predict sound and vibration in new assemblies, referred to as Virtual Prototype Assemblies (VPA). However, conventional measurements are labor-intensive, typically restricted to a small number of samples, and overlook production variability. This paper introduces a fully automated, ISO 20270-compliant C-TPA system for non-rigid test benches, featuring a pre-instrumented test fixture with multiple vibration shakers and sensors automatically linked to a data acquisition system for immediate processing. Components can be characterized within minutes, with blocked forces directly integrated into a VPA workflow, replacing time-intensive in-vehicle testing with a repeatable, operator-independent bench procedure. A case study on an automotive steering system demonstrates the method’s accuracy, repeatability, and efficiency, along with its ability to predict realistic interior sound pressure levels and capture production variability, enabling robust virtual NVH evaluation early in the development cycle.
Sturm, Michael, Wienen, Kevin, Brandstetter, Markus, Sorber, Eric, Corbeels, Patrick, Verrecas, Bart, Gonçalves, Vinícius
Investigation of Spline-Induced Excitation Forces in Electric Drive Units via Flexible Multibody Dynamic Simulation2026-01-06926/20/2026
This study investigates the NVH characteristics of the spline coupling that connects the motor and reducer shafts in an electric drive unit, using flexible multibody dynamics simulations. Focusing on the source stage of the NVH analysis process, the excitation force magnitude and spline trajectory are examined under various spline design conditions. The study compares spline fit types (side fit vs. major fit), clearance vs. interference conditions, and variations in tooth number and module size. This study analyzes the overall behavior of spline excitation forces under various design conditions, complementing prior research focused mainly on specific causes or manufacturing improvements. Side fit splines exhibit lower first-order excitation forces compared to major fit splines, but significantly higher excitation forces at higher orders. This leads to increased spline trajectory amplitude and amplified whirling of the input shaft. Since the input gear is directly coupled to the input shaft, this whirling behavior increases the gear center-distance variation, which in turn amplifies the cumulative pitch error. In particular, clearance fit conditions result in greater higher-order excitation forces and gear eccentricity than interference fits. Major fit splines, on the other hand, show more stable trajectories and lower higher-order excitation forces, minimizing their impact on the overall system. The analysis of tooth number variation reveals that increasing the number of teeth reduces first-order excitation forces while increasing higher-order components, indicating that force distribution within the spline can be tuned. Tooth number adjustment does not affect the rest of the system, suggesting it is a practical strategy for achieving desired NVH characteristics. In conclusion, spline design parameters such as fit type and tooth number significantly influence the magnitude and directional behavior of excitation force, leading to system-level phenomena.
Kim, Dong-Jun, Hwang, Seung Gyu, Kim, Donghee, Kim, Seon Hyeong, Lee, SangHan, Grant, George, Halse, Christopher
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