Noise , Vibration And Harshness Research Articles

Automotive powertrain electrification: system methodology to guarantee acoustic comfort

For the past few years, electrification has disrupted the automotive industry. Surprisingly, Noise Vibration and Harshness (NVH) became a major issue as it is located in high frequencies (1 to 5 kHz). The noise has 2 origins: the electromagnetic forces in the electric motor and the gear mesh forces in the reducer. The first part focuses on the methodology developed in collaboration with car-makers in order to integrate the powertrain in a satisfying way in the vehicle. First, this process is focused on the structure-borne noise. Attention is paid on rubber mounts and on their fixation points. Second, the airborne transfer may become an issue. Despite the acoustic power requirement provided, the final vehicle performance is not guaranteed. Examples will illustrate these important topics. The second part pays attention to the prediction of reducer noise. Automotive stakeholders are approaching the gear mesh source by approximate linear tools. Recent works have shown that this methodology has limitations and leads to inaccurate results. This may be a major concern. A few examples will illustrate this risk and show that further simulation developments are necessary.

Effect of Honeycomb Geometrical Parameters on Equivalent Radiated Power and Frequency Response of Motor Casing and Gearbox Surface of a Powertrain

ABSTRACTThe powertrain, as a central source of noise and vibration, is crucial in determining the overall NVH (noise, vibration and harshness) performance of vehicles, necessitating the optimisation of its structural components for improved durability and passenger comfort. This paper investigates the influence of key geometrical parameters—cell thickness, skin thickness and cell length—on the complex frequency modes of honeycomb and square sandwich structures using the Altair OptiStruct solver 2022 and fast Fourier transform analyser. The driven and non‐driven ends of a motor casing and a gearbox, represented by honeycomb structures and ribs, were subjected to an evaluation of equivalent radiated power (ERP). The results show that the square structure performs better at higher skin thickness when resisting severe lateral stresses than the honeycomb while being less stiff at higher cell thickness. Notably, smaller cell length had a substantial impact on the modes of the honeycomb structure, whereas larger cell length had an impact on the square structure. Response surface methodology was used to optimise the modal frequencies of both square and honeycomb panels simultaneously. An ideal cell length of 5.88 mm, skin thickness of 1.303 mm and cell thickness of 0.381 mm were found for the honeycomb construction, yielding a composite desirability of 0.981. On the other hand, with a cell length of 5.045 mm, skin thickness of 1.484 mm and cell thickness of 0.331 mm, the square structure achieved a composite desirability of 0.989. It is interesting to note that the driven end casing of the motor casing made more noise with the addition of ribs than the non‐driven end and gearbox. But compared to the original powertrain model, adding a honeycomb structure resulted in a noise reduction of about 10%.

Uncertainty Optimization of Vibration Characteristics of Automotive Micro-Motors Based on Pareto Elliptic Algorithm

The NVH (Noise, Vibration, and Harshness) characteristics of micro-motors used in vehicles directly affect the comfort of drivers and passengers. However, various factors influence the motor’s structural parameters, leading to uncertainties in its NVH performance. To improve the motor’s NVH characteristics, we propose a method for optimizing the structural parameters of automotive micro-motors under uncertain conditions. This method uses the motor’s maximum magnetic flux as a constraint and aims to reduce vibration at the commutation frequency. Firstly, we introduce the Pareto ellipsoid parameter method, which converts the uncertainty problem into a deterministic one, enabling the use of traditional optimization methods. To increase efficiency and reduce computational cost, we employed a data-driven method that uses the one-dimensional Inception module as the foundational model, replacing both numerical models and physical experiments. Simultaneously, the module’s underlying architecture was improved, increasing the surrogate model’s accuracy. Additionally, we propose an improved NSGA-III (Non-dominated Sorting Genetic Algorithm III) method that utilizes adaptive reference point updating, dividing the optimization process into exploration and refinement phases based on population matching error. Comparative experiments with traditional models demonstrate that this method enhances the overall quality of the solution set, effectively addresses parameter uncertainties in practical engineering scenarios, and significantly improves the vibration characteristics of the motor.

Hands-on and Project based Learning in Noise, Vibration and Harshness (NVH) Course for the Undergraduate Students in Mechanical Engineering Program

The noise, vibration, and harshness (NVH) course is crucial for mechanical engineering undergraduate students since it covers a wide range of engineering applications. It makes students ready for their careers in the area of NVH which has received attention from industry. The traditional treatment in teaching the course is mathematically challenging and might not be helpful for some undergraduates who are kinaesthetic learners. The explanation of topics can be facilitated by modern computation tools with simulation and visual capabilities in NVH course. These contemporary simulation tools make it feasible to more effectively and engagingly teach mathematically complex subjects to students for better understanding. This paper describes teaching NVH course in the Mechanical Engineering department at the KLE Technological University. Course is taught in two parts at 5th and 6th semester level. The first course is Mechanical vibrations and the second one Noise, Vibration and Harshness (NVH). Hands-on lab sessions with the simulation tool are included in the second course to give student in-depth understanding of concepts. Keywords—Vibration; FEA; Course project.

A Methodology for Applying Skew in an Automotive Interior Permanent Magnet Rotor for Robust Electromagnetic and Noise, Vibration and Harshness Performance

Interior permanent magnet (IPM) motors in traction applications often employ discrete rotor skewing constructions to reduce torsional excitations and back-EMF harmonics. Although skewing is very effective in reducing cogging torque, the impact on torque ripple is not well understood and can vary significantly over the operating envelope of a motor. Skewing also leads to the creation of a non-zero axial force that may compromise the bearing life if not considered. This paper introduces a holistic methodology for analyzing the effect of skewing, aiming to minimize torsional excitations, axial forces and back-EMF harmonics whilst mitigating the impact on performance and costs. Firstly, analytical models are employed for calculating cogging torque, torque ripple and axial forces. Then, 2D and 3D finite element analysis are used to incorporate the influence of non-linear material behavior. A detailed structural model of the powertrain is employed to calculate the radiated noise and identify key areas allowing a motor designer to reduce noise, vibration and harshness (NVH). A meticulous selection process for the skewing angle, the number of skew stacks and the orientation of skew stacks is developed, giving particular attention to the effect of the selected pattern on NVH in both forward and reverse rotating directions.

Preface

About the conference International Conference for Acoustic and Vibration Engineers (NVHH 2023) is the first edition of the biennial NVHH conference series on acoustics, structural dynamics and NVH (Noise Vibration and Harshness) organized by the Budapest University of Technology and Economics, the University of Győr, and the Hungarian Chamber of Engineers in close cooperation with industrial partners. The goal of the conference is to provide an international forum for acoustic, vibration, and NVH engineers, researchers, and professionals to share their contributions in the fields of experimental as well as numerical acoustics, vibroacoustics, vehicle NVH, interior acoustics, and entertainment system development. The conference caters to both academicians and professionals, therefore state-of-the-art university research and cutting-edge industrial innovation will be presented side by side, followed by social gatherings that promote the exchange of information and nurture fruitful cooperations between the various fields of the profession. NVHH 2023 in numbers The conference hosted 112 participants from 9 European countries, presenting 38 technical or scientific papers in 8 sessions, complemented by 4 plenary lectures. 9 professional exhibitors contributed to the industrial relevance.List of Conference Chairs, Keynote and plenary lectures, Organizing Committee, Scientific Committee are available in this Pdf.

A method to investigate mid and high-frequency vibration energy transfer paths using the irrotational intensity

Structural intensity fields provide a clear understanding of the noise, vibration and harshness (NVH) behavior of complex structures by showing the vibration energy flow between zones of excitation and dissipation. The use of models with fine meshes for automotive structures has allowed structural intensity calculations to be performed at high frequencies. However, fields are difficult to understand at medium and high frequencies: the intensity field has a vortical character that hides the vibration energy flow in these frequency ranges. In this work, a methodology is presented to filter out vortices in the structural intensity field. The approach uses the Hodge–Helmholtz decomposition: the structural intensity field is decomposed into rotational, irrotational, and harmonic components. Among them, only the irrotational component is needed to describe the path of energy flow from sources to sinks. The proposed methodology involves calculating the dynamic response and solving a diffusion equation similar to the thermal conduction equation to obtain the irrotational field of interest. Plate examples are used to illustrate the efficiency of the method, which provides a better understanding of the mid- and high-frequency energy transmission paths.

Development of a novel hybrid method to evaluate driving comfort in an all-terrain vehicle using transfer path analysis and transfer function analysis

Vehicle comfort has become a buzzword in the automobile sector and continuous research is going on in this domain. Every automobile manufacturer would like to take the lead in vehicle comfort so as to attract more customers. Noise, vibration and harshness (NVH) testing is very important for improving the driving comfort of a vehicle. Driving comfort is directly related to the driving ability and health of the driver. Many international organisations have laid down guidelines for measuring driving comfort and categorise it in a range from comfortable to extremely uncomfortable. The present study adopts an experimental approach to determine the driving comfort in all-terrain vehicles (ATVs) by measuring frequency-weighted root-mean-square (RMS) accelerations at all the driver contact points in three mutually perpendicular directions as per the guidelines laid down in ISO 2631-1:1997 and ISO 5349-1:2001. The low-amplitude high-frequency engine vibrations are attenuated by performing transfer path analysis (TPA) of the vehicle roll cage before and after design modifications. The performance of the engine isolator mount is evaluated by carrying out transfer function analysis (TFA) of the active and passive engine mount vibrations. A novel hybrid approach comprising the TPA and TFA methods is used to attenuate the engine vibrations. The test result shows the effectiveness of the design modifications at the footrest, whereas there is moderate to low effectiveness at the steering and seat, respectively.

A New Method for Controlling Vibration in Automotive Applications: Circular Force Generator Technology

Automotive Noise Vibration and Harshness (NVH) continues to be critical to address in passenger vehicles, especially as new vehicles today emphasize the use of lighter weight materials that create even more challenging NVH issues. NVH can negatively impact drivability and comfort, as well as perceived vehicle quality. Moreover, with the development of increased driver ergonomic technologies and capabilities (audible or otherwise), NVH continues to be key in allowing these technologies to be fully effective. Both passive and active control technologies are used extensively to improve automotive NVH. The use of active noise and vibration control has become a standard solution approach in vehicles, especially to mitigate low-frequency noise and vibration inside the vehicle. Linear actuators have been used in active engine mounts as well as frame vibration control to mitigate passenger cabin NVH. This paper introduces a new lightweight approach for active vibration control for automotive applications. Controllable Circular Force Generator (CFG) technology is introduced to displace the use of larger, heavy linear electromagnetic technology, and is shown to provide improved performance with lower weight and cost.

A Lightweight Multilayer Dissipative Material with High Acoustic Performance

A multilayer acoustic treatment constructed of fibrous acoustic absorption material combined with dissipative acoustic material achieves a low profile and is lightweight and multi-functional, with properties that are desirable for NVH (noise, vibration, and harshness) treatments. The dissipative material consists of microfibers and acoustically active particles; this material was introduced in the last SAE NVH conference: A Novel Dissipative Acoustic Material [1]. In this paper, the acoustic performance of the multilayer treatment was evaluated by using random incidence absorption and transmission loss measurements, as well as in-vehicle experiments. Absorption and transmission loss were additionally modeled using the transmission matrix method (TMM). In the in-vehicle test, an OEM wheelhouse liner with Trim, for an SUV, was evaluated utilizing this new multilayer 3M treatment.

Research on interior noise optimization of minibus based on vibration transfer path analysis using super element method

In this paper, aiming at the problem of excessive low-frequency noise in a minibus, the SEM (Super Element Method) was applied to the NVH (Noise, Vibration and Harshness) dynamics simulation analysis of the vehicle, and the vibration and noise control schemes were proposed from the aspect of vibration transfer path to improve NVH performance. First, the relationship and difference between SEM and LFEM (Legacy Finite Element Method) were elaborated theoretically. Afterward, the legacy finite element model of the full vehicle, which comprehensively considered all related components such as BIW (Body In White), chassis, door covers, body accessories and interior and exterior trims, was established based on LFEM. Furthermore, the subsystems of legacy finite element model of the vehicle were divided into super elements based on SEM, and the differences between SEM and LFEM in model processing were discussed in detail. In addition, the modal analysis and frequency response analysis of the full vehicle were carried out by LFEM and SEM respectively, and the computational results were compared with the testing results to verify the simulation accuracy and feasibility of the SEM in solving the vehicle body dynamics problems. Meanwhile, through the comparison of simulation analysis process of SEM and LFEM in practical case, the advantages of SEM compared with LFEM were discussed in terms of computational efficiency and storage space occupied. Finally, the stiffness optimization schemes of rubber bushing in the middle of driveshaft were proposed to improve vibration and noise from the aspect of vibration transfer path, and the testing results verified the effectiveness of the optimization schemes in reducing the low frequency noise inside the vehicle. The study concluded that SEM had obvious advantages over LFEM in terms of computational efficiency and storage space occupied, while ensuring the computational accuracy basically consistent with that of LFEM.

Study on interior noise control of minibus based on structural acoustic radiation

Aiming at the problem of excessive low-frequency noise inside a minibus, the interior noise control scheme was studied to improve the NVH (Noise, Vibration, and Harshness) performance of the vehicle based on the characteristics of the structural acoustic radiation. With acoustic contribution as the evaluation index, the ability of the structure to radiate noise to the vehicle was studied from the perspective of modal participation and panel contribution. In this study, the legacy finite element model of the vehicle was firstly established, and the model was validated through the modal test of the BIW (Body in White), and the noise transfer function analysis was carried out to identify the critical frequency points. Furthermore, the improved super element method (SEM) was used to establish the super element simulation model of the vehicle, the simulation analysis of the modal contribution and panel contribution was carried out for the critical frequency points, and the panels that provide the main contribution were determined. In addition, a single-factor experimental study was carried out on the position of the critical panel by using the dynamic vibration absorbers with different performance parameters, so as to verify the accuracy of the simulation results of the panel acoustic contribution for the critical frequency. Finally, the structural optimization schemes of the critical panels were designed and verified by experiments. It was indicated that optimizing the acoustic radiation characteristics of the structure by improving the body panel structure to reduce interior noise was feasible.

High-Fidelity Analysis With Multiphysics Simulation for Performance Evaluation of Electric Motors Used in Traction Applications

A Multi-physics simulation workflow encompassing soft-coupling of electromagnetic, thermal, and NVH (noise, vibration, and harshness) for performance evaluation of the traction drive is proposed in the paper. This study focuses on modeling of the electrical components of the drive unit that includes battery, inverter, and the electric machine. Further, a high-fidelity electric machine model is presented considering the non-idealities introduced by temperature variation, manufacturing process and phase current harmonics. The high-fidelity model is used to simulate electric motors like the ones used in the Tesla Model 3, Jaguar I-Pace and Chevy Bolt battery electric vehicles. Moreover, an in-house design is built and tested to validate the fidelity of the workflow.

Laboratory Test of a Vehicle Active Noise-Control System Based on an Adaptive Step Size Algorithm

NVH (noise, vibration, and harshness) is a key factor affecting vehicle comfort. Compared with traditional sound absorption and isolation methods, active noise control (ANC) offers a significant advantage in solving the problem of low- and medium-frequency noise from road surfaces. However, the classic filtered-x least mean squares (FxLMS) algorithm is ineffective in terms of adapting to different road noises to ensure a stable noise reduction effect when facing the complex and changeable noise environment of moving vehicles. Therefore, an adaptive step size algorithm (ASSFxLMS) is proposed in this paper, which can adjust the step size according to the size of the reference signal to ensure the stability of the adaptive process. In order to improve the performance of the algorithm, a particle swarm optimization algorithm is also used to automatically adjust the parameters, so that the step size of the adaptive algorithm always maintains a relatively ideal size. The simulated pulse noise of standard SαS distribution was used as the reference signal for the simulation. The simulation results show that compared with other algorithms, the proposed algorithm under different degrees of pulse noise conditions, noise reduction stability, and noise reduction amplitude are improved. In order to further verify the feasibility of the algorithm in vehicle road noise reduction, this paper also conducted a hardware-in-the-loop noise reduction experiment in the laboratory, employing the road noise data collected by the real vehicle. Under different interior noise conditions, the proposed active noise-control system has a maximum noise reduction effect of 12 dB for low-frequency noise below 100 Hz.

Research on the Design Method of Pure Electric Vehicle Acceleration Motion Sense Sound Simulation System

Due to the emerging trend of energy conservation and emission reduction around the world, the new energy vehicle industry has achieved rapid development. However, there are new challenges regarding vehicle NVH(noise, vibration, and harshness). When a pure electric vehicle is being driven, the inside of the vehicle is relatively quiet, which cannot bring the driver sound feedback reflecting the change of the vehicle state. In order to solve this problem, this paper studies the design method of a sound simulation system for acceleration motion in pure electric vehicles. In this paper, the motion characteristics of automobile engine acceleration sound, sound signal analysis and processing, subjective evaluation of sound quality, and sound synthesis strategy are studied. By reading the vehicle running state data on the CAN bus of pure electric vehicles, the goal of engine motion sense sound simulation during vehicle acceleration is achieved. This helps to enhance driving feedback and improve user driving experience.

Vehicular Electronic Image Stabilization System Based on a Gasoline Model Car Platform

Noise, vibration and harshness (NVH) problems in vehicle engineering are always challenging in both traditional vehicles and intelligent vehicles. Although high accuracy manufacturing, modern structural roads and advanced suspension technology have already significantly reduced NVH problems and their impacts; off-road condition, obstacles and extreme operating condition could still trigger NVH problems unexpectedly. This paper proposes a vehicular electronic image stabilization (EIS) system to solve the vibration problem of the camera and ensure the environment perceptive function of vehicles. Firstly, feature point detection and matching based on an oriented FAST and rotated BRIEF (ORB) algorithm are implemented to match images in the process of EIS. Furthermore, a novel improved random sampling consensus algorithm (i-RANSAC) is proposed to eliminate mismatched feature points and increase the matching accuracy significantly. And an adaptive Kalman filter (AKF) is applied to improve the adaptability of the vehicular EIS. Finally, an experimental platform based on a gasoline model car was established to validate its performance. The experimental results show that the proposed EIS system can satisfy vehicular performance requirements even under off-road condition with obvious obstacles.

The study of the possibility of the pumping unit optimization for two operation modes, different from the optimal one

BACKGROUND: The study of factors affecting the vibroacoustic characteristics of pumps is one of the main areas of development in the current pump industry. Improvement of these characteristics allows to extend the service life of pumps by means of vibration levels reduction as well as to decrease the noise level.
 AIMS: In this study, the attempt to optimize the flow part of a multi-stage pump was made in order to obtain acceptable noise, vibration and harshness (NVH) characteristics in two operation modes that are different front the optimal one.
 METHODS: As the result of the study, it was found that changing these parameters in favour of NVH has a negative impact on the pump efficiency and vice versa. Thereby the optimal balance between these parameters should be found. The optimization was performed with the method of research of the parameter space with use of LP-tau sequences. The following elements were chosen as the optimization parameters: the area at the entrance to downstream, the angle of guide vanes at the entrance to the downstream, the width of rotor at the outlet, the angle of rotor vanes at the inlet and the outlet, the wrap angle of rotor vane. Decrease of the area of the graph of pressure pulsation spectrum was chosen as the optimization criteria. The mathematical model was verified with two designs of the flow part produced and tested earlier. The first sample has an overstated rate of the NVH spectrum in the area of high frequencies, the second sample has an overstated rate of the NVH spectrum in the area of low frequencies.
 RESULTS: The compiled mathematical model proved its good quality, showing the same results, which allows to speak about the admissibility of its use for optimization of the flow parts of pumps.
 CONCLUSIONS: This study will be useful for specialists in the field of vane hydraulic machines design.

Dynamic response control of centrifugal pendulum vibration absorber with motion-limiting device during startup in gravity field

The dynamic performance of a vertically rotating centrifugal pendulum vibration absorber (CPVA) during engine start-up was investigated. The equations of motion were established using a Lagrange equation of the second kind containing terms for gravity and the motion-limiting device of the absorber, respectively. The optimal positioning of the motion-limiting device was determined from the perspective of CPVA stability and damping capability, and the terminology for the CPVA damping quality factor was defined to evaluate the damping capability of the absorber. Simulink models were established to simulate the behaviour of the absorbers at different speeds during engine initiation and assess the impact between the absorber and motion-limiting device during engine start. Based on the results, the concept of knocking power was proposed, and it was shown that resonance occurring during engine start worsens the noise, vibration and harshness (NVH) performance of the system. It was further shown that the initial position of the absorber at the moment of engine start to turn affects the knocking power and, as a result, the startup noise of the CPVA. The study also finds that the transient position of the absorber at the engine ignition time affects the knocking power. The responses of CPVA under different working conditions were tested on an electric bench and compared with simulation results. Based on our results, we propose several measures to control absorber behaviour and reduce knocking power.

Vehicle vibro-acoustical comfort optimization using a multi-objective interval analysis method

Vehicle interior vibro-acoustical comfort, i.e., noise, vibration and harshness (NVH), is important to consumers and automotive manufacturers because it affects the physical and mental health of passengers and impacts the reputations of automotive manufacturers. Although simulations can predict vehicle interior noise and vibration, acoustic treatment and resulting uncertainty may generate considerable errors between the simulation and actual measurement results. Meanwhile, the recursive invocation of a complex simulation model in an optimization leads to a very time-consuming calculation process. These problems make the optimization of vehicle interior vibro-acoustical comfort a challenge for the automotive industry. In this paper, a new method, the multiobjective interval analysis method, was proposed to solve these problems. To implement this method, we carried out a vehicle road test instead of a complicated simulation model to collect data. The vehicle interior noise and vibration were recorded, and the interior sound pressure level (SPL) and total weighted acceleration root mean square (TWA-RMS) values were calculated and used as objectives. Then, a multiobjective interval analysis method was proposed to compute the midpoint and radius of the objective functions under different uncertainties. The preferred average performance and robustness of the vehicle vibro-acoustical comfort was adjusted by tuning the weighting factor. To accelerate the calculation process, a neural network model was developed as an approximate model to construct the numerical relation between the dynamic parameters and the vibro-acoustic metrics. Finally, the effectiveness and accuracy of the proposed method were verified with experimental results.

Method to investigate the short-term effects of vibration on the output performance of the proton exchange membrane fuel cell in fuel cell vehicles

The proton exchange membrane fuel cell (PEMFC) in fuel cell (FC) vehicles (FCVs) is always operating in a vibration environment, which can affect the FC output performance. This effect will bring new challenges in terms of NVH (Noise, Vibration and Harshness) and should be investigated during the development of FCVs. This paper proposes an investigation method for the short-term effect of vibration on the output performance of the FC in FCVs. The method is generalized as a procedure with four stages. Firstly, the vibrations of powertrain components and FC are measured by performing measurements on overall FCV, considering different driving maneuvers and environments. The characteristics of components’ vibrations are then identified and the vibration environment of the FC in the FCV is investigated by conducting vibration and contribution analysis. The analysis results are used to derive the vibration cases for the in-situ FC vibration test in the last stage to investigate the vibration effect on the FC performance. In general, vibration reduces the output power of FC by about 2% compared to the case without vibration. The fluctuation of FC power under vibration is also increased. Different FC orientations can also affect its performance, and this effect can be enlarged when vibrations are introduced. In the worst case, vibration can cause a power reduction of more than 9%. In addition, the sensitivity of the FC output power to different types of excitation varies. The knowledge obtained during the investigation provides the basis for the NVH development and optimization with the aim of improving FC output performance.