NVH Performance Research Articles

A study on the effects of compression of the felt on flow resistance and acoustic characteristics

The sound absorbing materials used to reduce automobile interior noise are classified into Felt and PU Foam. Felt are widely used not only in internal combustion engine vehicles but also in Electric Vehicles because they are eco-friendly materials that can be recycled and relatively light. Automotive interior parts manufacture materials in various thicknesses depending on the shape of matched parts. The pressed material changes the density, flow resistance and affects the overall NVH performance of the vehicle. In this study we worked to confirm changes in flow resistance, sound absorption coefficient and sound transmission loss performance among acoustic characteristics based on the compress ratio of Felt. It was confirmed that the larger the compression of Felt, the larger the flow resistance value, thereby affecting the acoustic characteristic impedance, sound absorption coefficient and sound transmission loss.

Implementation of Laminate Structure in Car Hood and Study of its NVH Parameters

This paper examines the implementation of Laminate structure and aluminium panels in Hood in place of conventional steel hood. In laminate structure, 3 layers is considered with aluminum as a face material and PVC Solid as a core material which helps in efficient energy absorption and provide necessary stiffness for the panel. It has been observed that the natural frequency is improved over conventional steel bonnets with benefit of weight reduction in hood assembly. To validate its NVH performance static stiffness, natural frequency and torsional stiffness has been calculated and it has been found that Laminate structure Hood has better performance than steel hood with overall weight reduction of 41.36%.

Research on Improving NVH Performance of Automobile Side Door Glass in Use Based on 6 Sigma Method.

Automobile side door glass squeaks and rattles during use. This abnormal noise can make the driver and occupants irritable and reduce the comfort of the automobile. This reduces the sales of this automobile. This paper analyzes and determines the cause of squeak and rattle during the lifting and lowering process of the side door glass of an automobile. The noise is due to four reasons. One is that the distance between the inner waterproof belt and the automobile side door glass of the automobile is unreasonable, causing excessive friction between the automobile side door glass and the inner waterproof belt during the automobile side door glass up and down movement. Other factors affecting squeak and rattle may be the distance between the automobile side door sheet metal and the automobile side door glass, the thickness of the automobile side door glass and the characteristics of the inner waterproof belt. The first two dimensions are analyzed using the 6 sigma method, and the structure of the inner waterproof belt is improved and the flocking position is adjusted. The squeak and rattle phenomenon is explained using the implicit dynamic analysis method ABAQUS, and the compression load deflection after the installation of the inner waterproof belt is 3–9 N/100 mm. This research completely solves the squeak and rattle problem caused by the up and down movement of the side door glass of the automobile. This research has significance for solving practical engineering problems.

A size optimization procedure for irregularly spaced spot weld design of automotive structures

Spot weld layout design for body structures is of practical significance to both manufacturing cost control and performance improvement in the automotive industry. In this work, by using a typical thin-walled double-hat section beam as a proxy, a parametric study was first carried out to reveal the effects of spot weld layout design on the structural performances under both static and impact loading conditions. To overcome the limitation of traditional uniformly spaced spot weld configuration, an innovative size optimization based procedure was proposed for the spot weld layout design of automotive structures with irregular spacings. In this procedure, sampling points that satisfy both equality and inequality constraints are obtained by introducing the mixture design of experiment method. The leave-one-out cross validation strategy is used to bring the training samples into full play in building surrogate models for structural analyses with high accuracy. Moreover, the NSGA-II is incorporated to search the Pareto front of the multiobjective optimization problem. Application of the proposed procedure on the thin-walled double-hat beam resulted in 33.3% spot welds reduction from the uniformly spaced baseline design, without weakening the structural static and NVH performances by more than 3%. The reliability and effectiveness of the proposed procedure is thus proved.

Generating Component Designs for an Improved NVH Performance by Using an Artificial Neural Network as an Optimization Metamodel

In modern vehicle development, suspension components have to meet many boundary conditions. In noise, vibration, and harshness (NVH) development these are for example eigenfrequencies and frequency response function (FRF) amplitudes. Component geometry parameters, for example kinematic hard points, often affect multiple of these targets in a non intuitive way. In this article, we present a practical approach to find optimized parameters for a component design, which fulfills an FRF target curve. By morphing an initial component finite element model we create training data for an artificial neural network (ANN) which predicts FRFs from geometry parameter input. Then the ANN serves as a metamodel for an evolutionary algorithm optimizer which identifies fitting geometry parameter sets, meeting an FRF target curve. The methodology enables a component design which considers an FRF as a component target. In multiple simulation examples we demonstrate the capability of identifying component designs modifying specific eigenfrequency or amplitude features of the FRFs.

A harmonic injection method for improving NVH performance of permanent magnet synchronous motor

A harmonic injection method is proposed for reduce permanent magnet synchronous motor torque ripple and noise, which is based on harmonic model of PMSM. The effectiveness of the method is verified by simulation and experiment. It is proved that this method can significantly improve NVH performance of the motor.

Analysis and optimization of idle noise caused by canister purge solenoid valve

In the development process of a certain CHINA VI proprietary brand car model, there exists the problem of intermittent “dada” sound in the cockpit during idling. After investigation, it’s determined that the air pulse noise generated when the canister purge solenoid valve is working, it is transmitted to the car panels through the pipeline, and then to the cockpit, which would cause a “dada” sound. By adding expansion chamber in the desorption pipe and designing part of the pipeline which fixed in the clamp as rubber pipe, the intensity of air pulse can be effectively reduced and the transmission path of air pulse vibration can be blocked. Through objective testing and subjective evaluation, the scheme can greatly reduce the idle noise of the cockpit, thus improving the NVH performance of the vehicle and bringing comfortable riding environment to the passengers.

On shale shaker’s structural optimization and performance improvement

Recent trends, predictions [1] and overall assessments [2] in extractive industries show there will be changes in many aspects of business, varying from geopolitical issues up to the optimization of working processes and machines. In severe conditions of drilling stations usually based quite a way off to cities and are difficult to access, it is important for all the equipment and machines to operate without failure and provide forecasted level of durability, because unexpected shutdown may lead to halting of production and economic losses. This article is focused on investigation of shale shaker primary characteristics and its behavior during operational loads. In the result of the work an optimization has been performed on the basis of kinematic, strength and NVH performance. Special emphasis was put on the value of vibrational acceleration which reflects an overall possibility of a shale shaker to sift drilling mud. It is a widespread practice to implement optimization tools into different fields. The methods of usage topology optimization can follow the same ideas as it is done in automotive [3] or agricultural industries [4]. Advantage of this paper based on intense cooperation between manufacturing department of the customer and CAE engineers which is the basis of a good design process [5] and overall approach to successful development [6], that includes manufacturing restrictions and that allowed to prove sustainability of the models through validation phases, in the beginning of the project for the initial structure and in the middle of the project for several newly assembled prototypes. So the results of the work have been confirmed by real experiments. Another strong point was a possibility to obtain a feedback right from drilling stations about the condition of optimized shale shaker after it started to work under common operational loads. Constant monitoring, predicting systems and other methods to evaluate overall condition of the machines under operational loads or drilling fluids [7] during the extraction process are important measures in order to prevent unexpected failures. Process and result of this work can be assembled in a step-by-step method for simplified evaluation of shale shakers with vibrators of different amounts and powers. Such method allowed to obtain an overall glimpse on main characteristics, performance, to locate durability weak zones and shows potential for possible structural optimization. The new approach has been used in this research by using the CML-Bench platform, which is a system for managing the simulation driven design projects field of digital design and modeling [8]. This system allows tracking and observing all necessary variables, simulation history and mutual influence of different parameters on different structural changes. Such a method for design engineering allows easily carrying out multidisciplinary optimization of the objects and always being aware of the performance state of the whole system [9].

Evaluation Index for Sporty Engine Sound Reflecting Evaluators’ Tastes, Developed Using K-means Cluster Analysis

Developments in vehicle technology and accompanying improvements in NVH performance have led to increased consumer demand for high sound quality, such as a “sporty” engine sound. As sporty sound is subjective, this study sought to express its meaning quantitatively and to develop a model that accommodates the differences in individuals’ tastes. Engine sounds of four vehicles at wide-open throttle were recorded and the signal was modulated via filtering. Acoustic and psychoacoustic parameters of the samples produced were calculated, and the preferences for sportiness were identified through jury testing. Using K-means clustering, factor analysis, and multiple linear regression, a sound quality index and a model reflecting differences in evaluators’ tastes were developed. The index was retested using new evaluators and new samples, demonstrating its reliability by high correlation. This sound quality evaluation index is useful for producing highly accurate results and reflecting the opinions of groups expressing a variety of commonalities.

Study on abnormal noise of leather of car shift mask based on FAT

Shift cover problem is one of the hot issues of car interior trim. Based on the theory of fault tree analysis, a fault tree model of a family car was established, and various influencing factors were analyzed in detail. By optimizing the leather production process, the NVH performance of the whole vehicle is improved, which provides a reference basis for solving similar problems in engineering.

Analysis of the control strategy of range extender system on the vehicle NVH performance

With focus on NVH performance, this paper studies the range extender system control strategy such as the initial start speed, operating points, speed up and down control method between operating points of the range extender, etc. At the same time, the confirmation of the operating points of the range extender based on the full vehicle frequency distribution and vibration and noise level of key points (seat rail, driver’s inner ear) was performed. Finally, we conducted objective test and compared the test data with benchmark vehicles.

Robust Development of Electric Powertrain NVH for Compact Electric SUV

<div class="section abstract"><div class="htmlview paragraph">Electric vehicles (EV’s) present new challenges to achieving the required noise, vibration & harshness performance (NVH) compared with conventional vehicles. Specifically, high-frequency noise and unexpected noise phenomenon, previously masked by the internal combustion engine can cause annoyance in an EV. Electric motor (E-motor) whine noise caused by electromagnetic excitation during E-motor operation is caused by torque ripple and radial excitation. Under high speed and high load operating conditions, the overall sound level may be low, however high frequency whine noise can impair the vehicle level NVH performance. An example of a previously masked unexpected noise phenomenon is a droning noise that can be caused by manufacturing quality variation of the spline coupling between the rotor shaft of the E-motor and the input shaft of the reducer. It is dominated by multiple higher orders of the E-motor rotation frequency.</div><div class="htmlview paragraph">In this study, the high speed and high load condition whine noise problem was reproduced through electromagnetic and structural analysis. The countermeasures (E-motor geometry refinements to reduce the excitations and mechanical system transfer path modifications to reduce the vibration response) were defined and the effects investigated. Mechanical system modification to improve NVH performance without increasing the mass is challenging. However, E-motor air-gap geometry optimization, such as slot opening modulation and rotor notch modifications achieved significant noise reduction without critical trade-off of other performance.</div><div class="htmlview paragraph">This paper also describes the basic improvement plan proposed through the simulation of the droning noise behavior. The main two manufacturing errors (pitch error in the spline coupling and the alignment error between the rotor and the gearbox shafts) that are responsible for the unexpected droning noise were identified. Using simulation it was shown that the droning noise can be reduced through improved quality control and tolerance design optimization of factors such as axis self-alignment and spline gear tooth quality.</div></div>

Identification of Contact Stiffness between Brake Disc and Brake Pads Using Modal Frequency Analysis

The contact stiffness between brake disc and brake pads is a vital parameter that affects brake NVH performance through increasing the system stiffness and modal frequencies. In order to establish accurate contact behavior between brake parts for further research on precise modeling of disc brakes, a method of identifying the normal contact stiffness of a floating caliper disc brake was developed in this study based on modal frequency testing and finite element analysis. The results showed that contact stiffness increases with brake pressure due to compression of the friction material and increases with the disc mode order at lower-order modes but almost stays invariant at higher-order ones due to contact area variation.

NVH 시뮬레이터 기반 흡기 소음 시뮬레이션에 관한 연구

Noise, vibration, and harshness (NVH) simulators enable the subjective evaluation of vehicle interior noise and improvement of the NVH performance. To achieve a powerful and sporty engine sound, several original equipment manufacturers of automobile parts introduce the engine intake noise into the vehicle cabin through pipe systems that reinforce the low-frequency engine noise components. The present study proposes an intake-noise module that simulates an intake-noise reinforcing system and can be integrated with the previously developed NVH simulator. The intake- noise simulation module is based on the intake noise source model, pipe system model, and room impulse response model. The pipe system is modeled by the transfer-matrix method (TMM), and the room impulse response is modeled using the image-source method. The intake noise source is time variant because the noise source depends on the rotational speed of the engine and the crankshaft angle. TMM is also time variant because the noise propagation characteristics in TMM vary with the throttle valve angle. Intake noise source and TMM are designed in the frequency domain. In two cases of intake-noise reinforcing system, the loudness and sharpness (which are known to be correlated with a sporty engine noise) are calculated for the simulated data. The developed NVH simulator can assist the design of intake-noise reinforcing systems that reach the targeted sound quality.

Research on tire model parameter identification strategy based on CDTire/3D

High accuracy tire modeling is essential to study the automotive fatigue-durability, handling-stability, and NVH performance in the virtual proving ground. Compared with other tire models, CDTire/3D can be directly used in multi-body dynamics simulation, and its linearized version can be adopted in road noise analysis. In consideration of its high generality for cost saving, CDTire/3D has an extensive engineering application prospective in the automotive industry. It is the critical technique to accomplish high-efficiency and high-precision CDTire/3D modeling by investigating the mechanical mechanism of tire and the influence of parameters on all test conditions, based on which a parameter identification strategy is conducted in this paper. The effectiveness of the strategy is verified by a tire modeling case.

Research on Improvement Methods of Automotive NVH Performance

The performance of automotive NVH will directly affect the production and sales of automobiles. This article summarizes the generation and control of the main NVH problems in automobiles, and discusses the methods to improve the NVH performance of the vehicle from three aspects: free damping treatment of the body structure, analysis of the contribution of body panels, and analysis of key hard-point forces of the vehicle steering system.

Ride comfort enhancement for passenger vehicles using the structure-immittance approach

This paper presents a novel approach to identify inerter-based suspension struts, which can provide significant performance enhancement for passenger vehicles. The inerter has been used on Formula 1 racing cars, and several beneficial devices incorporating inerters have also been identified for ride comfort enhancement. However, previous investigations either were limited to simple network configurations with moderate performance improvement, or resulted in complicated configurations with a large number of elements which are impractical for real-life applications. In addition, some important practical performance constraints have not been taken into consideration, such as high-frequency dynamic stiffness which influences the NVH performance, and frequency content consideration of the sprung mass acceleration which more directly relates to passenger perception. In this paper, a quarter-car model including top mount is studied, with the performance of a conventional suspension strut presented as baseline. The structure-immittance approach, which can cover all networks with pre-determined numbers of each element type, is adopted for the identification of the optimal suspension configurations. Several configurations with up to a performance improvement are identified with all other practical performance indices to be no worse than the baseline. The suspension devices proposed in previous works are also considered for a sake of comparison, demonstrating significant advantages of the structure-immittance approach. Subsequently, a sensitivity analysis against the sprung and unsprung mass changes is carried out, which represents cargo and tyre weight variations, respectively. Time domain response and other reality checks are then conducted for the out-performing configurations, which reconfirm the ride comfort enhancement and ensure no unexpected behaviour occurs.

Finite Element Analysis of Origin Dynamic Stiffness and Vibration Sensitivity of BIW

In this paper, Hyperworks software is used for geometric cleaning, meshing and grid quality checking of the BIW model. The BIW model is assembled with solder joint units, and then the dynamic stiffness of the joints is analyzed. The acceleration frequency response function (IPI) curve is obtained by simulating the body with the method of origin admittance. The dynamic stiffness deficiency is found by comparing with the dynamic stiffness curve of the target value. Vibration transfer function of the body is obtained by vibration sensitivity analysis, and the sensitive parts of the body under excitation are located more accurately. Some corresponding suggestions and optimization are put forward to improve the NVH performance of the body.

A Study on Simulation Based Validation of Optimized Design of High Precision Rotating Unit for Processing Machinery

With the rapid development of processing technology, the demand for precision, durability and NVH performance of processing machinery has also increased. This paper presents an optimally designed gear train composed of a set each of spiral bevel gears and spur gears to serve as a high precision rotating unit for processing machinery. The safety of each component used in the rotating unit gear train was verified using the geometry method and empirical formulae. The load contact pattern and PPTE value, which is an important indicator of the gear whine characteristic, were optimized using micro geometry modifications. In addition, the transfer efficiency of the entire gear train was determined and a novel dynamic analysis based on the comparison of the dynamic transmission error and the modal flexibility was performed to verify the correctness of the geometry design.

Novel Glass Laminates for Improved Acoustic Performance

<div class="section abstract"><div class="htmlview paragraph">Noise, Vibration, and Harshness (NVH) performance of vehicles is an all-encompassing study of hearing and feeling vibration as it relates to end user experience. The collection of glass in a vehicle can represent a large surface area, and can have a significant effect on NVH performance. Some of the most important glazing positions in relationship to the driver are the front doors, due to the proximity to the driver. Novel glass laminate constructions can provide acoustic improvement for these body positions over typically used standard glazings. The performance of these constructions will be discussed in terms of: acoustics, glass closing and door slam survivability, and solar performance.</div></div>