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Ensuring the robustness of vehicle systems and features is a key aspect of customer satisfaction and therefore is of vital importance to Original Equipment Manufacturers (OEMs). Both initial quality and quality over the life of the vehicle are important aspects to customers. Therefore, some features and systems require an active approach at monitoring system health. The intent of Active Noise Cancellation (ANC) systems in vehicles is to increase the customer’s perception of vehicle refinement and brand quality. Due to the nature of ANC system operation, it is critical that the system does not go divergent resulting in unwanted noise being heard by the customer. So, a method to monitor the ANC system operation and performance is required to ensure robustness. Despite tuning ANC systems considering expected vehicle build tolerances, vehicle aging and customer specific use cases, an ANC system can occasionally still go divergent in the field.

Community noise at vertiports is one of the most important questions related to upcoming urban air mobility (UAM) operations. While fixed-wing and/or fixed-rotor aircraft can mainly be treated by their changing operational parameters, such as rotor or propeller rpm, tilt-wing or tilt-engine configurations are more difficult to simulate because of their constantly changing noise emission and spatial radiation characteristics. The work presented in this paper is providing an overview of the noise situation at a virtual vertiport which is being approached and departed by a tilt-wing air-taxi in different ways. Several different departure procedures are simulated with the same generic air-taxi. For the noise emission semi-empiric methods were used. During the air-taxi’s descent and climb, different tilt configurations are included, mainly defined by the time dependent engine’s tilt-angle, but also related to different approach paths.

Helmholtz resonator is a very common anechoic measure, and it is widely used in pipe acoustic fields. Based on the enlightenment of the classic Helmholtz resonator, this paper proposes a headrest resonator model and extends it to the acoustic field of the passenger cabin to improve the road noise in the car. Firstly, through the theoretical model of Helmholtz resonator, the relationship between its resonance frequency and the geometric size of the resonator is clarified. Secondly, the influence of the headrest resonator on the acoustic field characteristics of the car is studied through finite element simulation analysis. It is demonstrated that the headrest resonator is placed in the car, and the sound pressure distribution characteristics of the passenger's inner ear near the resonance frequency change significantly. At the same time, through 3D printing, a sample of the headrest resonator is made.

In general, in-cabin booming noise is low frequency (20 Hz∼300 Hz) phenomenon which excites the cabin structure mainly due to excitations from the powertrain, exhaust system, road loads, etc. When a vehicle drives over road seams or a bumpy surface, low-frequency drumming noise is generated, causing driver discomfort. The generation of drumming noise is due to road irregularities, transferred and amplified through the vibration characteristics of the suspension, body frame, and body panels, as well as the acoustic characteristics of the vehicle interior. It is therefore difficult to take measures to get rid of drumming, after the basic vehicle construction has been finalized. The regular practice in vehicle development is finite element method (FEM) to obtain acoustical transfer functions of the body, and multi body simulation to get suspension load characteristics. The full vehicle simulation needs more time for analysis and extracting data.

There are two key factors driving the tyre manufacturers to increase their focus on improving the noise characteristics of the tyre: Strict homologation requirements for tyre and vehicle noise and the increasing prevalence of Electric vehicles. With developing infrastructure and vehicle technology, the tyre noise impact on overall vehicle noise is becoming more and more important. The principal focus of the study is to perform experimental analysis for understanding the effect of various operational parameters such as load, inflation pressure (IP) and speed on overall tyre noise in a semi-anechoic chamber under controlled conditions. To understand the impact of the operational parameters, five C1 class radial tyres with different rim sizes (14”-18”) and same tread patterns were used.

Disc brake squeal is always a challenging multidisciplinary problem in vehicle noise, vibration, and harshness (NVH) that has been extensively researched. Theoretical analysis has been done to understand the mechanism of disc brake squeal due to small disturbances. Most studies have used linear modal approaches for the harmonic vibration of large models. However, time-domain approaches have been limited, as they are restricted to specific friction models and vibration patterns and are computationally expensive. This research aims to use a time-domain approach to improve the modeling of brake squeal, as it is a dynamic instability issue with a time-dependent friction force. The time-domain approach has been successfully demonstrated through examples and data.

The automotive industry is evolving towards Electrified Vehicles (EV) in the recent years. Compared to the traditional ICE vehicles, tire noise induced by the tire-road interaction, is no longer masked by the internal combustion engine, and therefore becomes one of the most dominant sources of noise within the cabin and acoustic emission perceived by by-standers. Robust source characterization is one of the most important tasks for road noise prediction. The receiver-independent tire blocked forces are often used as ire-road source characteristics, which can be applied to any test-based or FE-based vehicle model to obtain the interior noise. They can be inversely identified from measurements on a tire test rig or on an in-situ vehicle. However, this inverse process needs to be repeated for different tires, roads and rolling speeds, which can become time-consuming and expensive.

With electromobility, vehicles are becoming quieter due to the presence of electric motors that replace internal combustion engines. The interior cabin noise of electric vehicles is characterized by high-frequency components that can be annoying and unpleasant. Therefore, it is essential to analyse the NVH behaviour of e-powertrains early in the design-phase. However, this induces inherent uncertainties during the design process related to the operating conditions, geometrical parameters, measurement techniques, etc. that need to be quantified with fast and comprehensive stochastic models. In this work, we first present a deterministic framework to provide first-order estimations of the e-powertrain’s interior whining noises, combining both the airborne & structure-borne contribution with data-driven NVH transfers meta-models.

The study of electronics, motors and mechanical noise and vibration have often been treated as separate fields in R&D, Production, and test/validation. In electric powertrains, the electric and mechanical must be designed and tested in parallel to really understand the machine operation. This paper will highlight an existing link between the electrical and mechanical noise in electric powertrains and what measurement/analysis tools are available for performing an NVH analysis including electrical measurements.

Fast NVH analysis from the start of the motor design is important to speed up product development by avoiding major NVH issues later. In this paper, different methods for electric motor noise and vibration predictions are proposed for different stages in the design process. The results are compared to previous experimental validation [1]. The first method combines electromagnetic finite element analysis to calculate the forces, with analytical models for the stator vibration and acoustic response [2]. This requires minimal structural design data, and can be carried out rapidly, allowing the exploration of many design possibilities in the early design stage, and is implemented in Ansys Motor-CAD. This is compared with the full structural finite element analysis (FEA) [1]. It is shown that the fast analytical NVH process provides a good prediction for the motor noise level early in the design process.

Pass-by noise measurement is mandatory for automotive manufacturers for conformity of production. With evolving of pass-by noise requirements (under 68 dB in 2024), all the stakeholders should be able to comply with this criterion. OEMs, suppliers of passive acoustic treatments, road manufacturers and tire manufacturers are concerned and should deploy efforts to provide solutions for control of exterior noise. In this regard, simulations are preferable over measurement campaigns as they can provide fast feedback on passive exterior treatments for exterior noise control. In the particular case of Lightyear vehicles, the main contributors to pass-by noise are tires and in-wheel motors. Considering that, a contribution of each of these two sources of noise to pass-by noise will be described. Tire noise sources and motor noise sources will be replaced by simple monopole sources. The best monopole source location for both tires and motors is discussed.

Electric and Hybrid vehicles have standards for emitting enough noise to reduce danger and risk to pedestrians when operating at low speeds. Simulation can help to support development and deployment of these systems while avoiding a time-consuming, test-based approach to design these AVAS (Acoustic Vehicle Alerting System) warning systems. Traditionally, deterministic simulation methods such as Finite Element Method (FEM) and Boundary Element Method (BEM) are used at low frequencies and statistical, energy-based methods such as Statistical Energy Analysis (SEA) are used at high frequencies. The deterministic methods are accurate, but computationally inefficient, particularly when the frequency increases. SEA is computationally efficient but does not capture well the physics of exterior acoustic propagation. An alternative method commonly used in room acoustics, based on geometrical or ray acoustics, is “Ray Tracing” and can be used for sound field prediction.

Vehicle Acoustic Prototyping in the mid to high frequency range is challenging with numerical models only. To overcome this challenge, over the past decade, experimental techniques were developed that allow the engineer to incorporate Test-Based models in their (numerical) simulation as well. Using Virtual Point Technology these Test-Based models serve well to describe, for example, the complex dynamics of the vehicle body Noise Transfer Functions. Here the high modal density and damping characteristics are simply measured on a mule or prototype vehicle and coupled to numerical models of the drivetrain using Dynamic Substructuring. As such accurate predictions and/or risk assessments can be made much earlier in the mid and high frequency range during the vehicle development stage. While test-based models serve well to describe the coupled vehicle dynamics, loads to compute actual vehicle responses are needed as well.

This paper presents an experimental method for measuring transmission paths from the exterior to the interior of a passenger vehicle using a reciprocal approach: A production vehicle was placed in a semi-anechoic environment; artificial noise sources were placed at the location of the occupant’s ear(s) inside the vehicle and beamforming arrays with a total of more than 300 microphones were used to observe apparent noise sources on the vehicle exterior resulting from transmission paths. This makes it possible to quickly measure transmission paths over the whole vehicle body. One of the motivations for this work is the monitoring of sealing quality on production vehicles. Artificial seal breaches were introduced on the vehicle and a number of excitation signals were assessed to develop a method to detect and localise leakage noise sources.

Spiral bevel gears are commonly used in heavy-duty trucks and buses. An integrated dynamic model of the spiral bevel gears with mixed elastohydrodynamic lubrication is proposed in this study. First, loaded tooth contact analysis was performed to evaluate the kinematic parameters and calculate the mesh force variation for one mesh cycle. These kinematic quantities are used in the mixed elastohydrodynamic lubrication (EHL) calculation to determine the EHL parameters such as pressure, film thickness, and shear distribution considering the surface roughness profile of the spiral bevel gears. Then, the EHL pressure and film thickness are used in the calculation of the coefficient of friction, damping, and oil film elastohydrodynamic lubrication stiffness. Last, these tribological parameters are used in the dynamic calculation of the spiral bevel gears.

The tooth surface error will affect the contact pattern and transmission error of the hypoid gear, which may result in an unfavorable dynamic response. The tooth surface error can be generated by machine tool errors, such as blade wear. The most common forms of blade wear are the positive cutter radius and the positive blade angle error. In addition, in the cutting process of face-hobbed hypoid gear, the continuous indexing motion will aggravate the blade wear due to the alternating cutting force. Most previous studies on the influence of hypoid gear tool errors only focus on the contact pattern and static transmission error. However, there are very few studies about the effect of tool errors on hypoid gear dynamic responses. In this paper, a hypoid gear tooth surface, mesh, and linear dynamic model with tool errors were established. The tooth surface deviation distribution of different tool errors was analyzed.

This paper describes a simulation methodology developed for gear rattle severity evaluation and drivetrain architecture optimization. The noise generated by gear rattle is one of the main contributors towards customer’s overall NVH perception. This study adopts a model-based design approach to simulate the tendency of gear rattle in neutral and drive conditions. Gear rattle simulation model for Tractor driveline developed in 1-D environment and correlated with test data acquired on tractor drivelines for multiple field applications. This analytical physics-based model includes engine torsional signature, clutch damper torsional characteristic and dynamics of traction and PTO driveline. This dynamic simulation model helps to understand and predict the gear rattle severity of various drivetrain architecture early in the product development cycle and assess & Optimize driveline NVH performance.

The fast-growing automotive industry and rapid development of new E-drive technology nowadays brings about higher gear design requirements. E-motor applications challenge gear performance due to their higher load and speed levels compared to traditional internal combustion engines (ICE). The advantages of using asymmetric gears include lower stress, higher efficiency, better bending and contact strength, increased durability, etc. However, asymmetric gear dynamics are not well understood or analyzed. This paper performs extensive study on the effect of asymmetric gears on NVH performance of compound gear transmissions. The parametric study covers different combinations of pressure angles and root fillet settings on the drive and coast sides of the gear. The analysis is focused on the sensitivity of gear transmission error (TE) towards different symmetric and asymmetric gear designs.

NVH (Noise, Vibration and Harshness) of the electric drive axle (EDA) is a key attribute in electric-vehicle development. The NVH attributes of the EDA directly determines the driving comfort and customer feeling of the vehicle. Especially in pure electric working condition, the EDA noise is more perceptible by people without the engine noise masking. This paper investigates the abnormal noise in the vehicle caused by EDA. First, the filtered playback method is used to identify abnormal noise frequency between 330Hz and 430Hz.Adopted modal analysis, MASTA simulation, modulation noise analysis to identify problematic critical parts. The validity of the results is verified using the DOE method by part exchange, and finally locked to the source of gear parameters Rs and Fr. By adjusting the production process of gear and the second shaft, the assembly process error was avoided, and the gear parameter targets are formulated.

Encapsulation of electric powertrains is a booming topic with the electrification of vehicles. It is an efficient way of reducing noise radiated by the machines even in later stages of the design and without altering the electromagnetic performance. However, it is still difficult to define the best possible treatment. The locations, thicknesses and material compositions need to be optimized within given constraints to reach maximum noise reduction while keeping added mass and cost at minimum. In this paper, a methodology to design the encapsulation based on numerical vibro-acoustic simulations is presented. In a first step, the covered areas are identified through post-processing of a finite element acoustic radiation model of the bare powertrain. In a second step, a design of experiment is performed to assess the influence of various cover parameters on the acoustic radiation results.