Noise, Vibration And Harshness Performance Research Articles

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.

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.

Nonintrusive parametric NVH study of a vehicle body structure

A reduced order model technique is presented to perform the parametric Noise, Vibration and Harshness (NVH) study of a vehicle body-in-white (BIW) structure characterized by material and shape design variables. The ultimate goal is to develop a methodology which allows to efficiently explore the variation in the design space of the BIW static and dynamic global stiffnesses, such that the NVH performance can be evaluated already in the preliminary phase of the development process. The proposed technique is based on the proper generalized decomposition (PGD) method. The obtained PGD solution presents an explicit dependency on the introduced design variables, which allows to obtain solutions in 0.1 milliseconds and therefore opens the door to fast optimization studies and real-time visualizations of the results in a pre-defined range of parameters. The method is nonintrusive, such that an interaction with commercial software is possible. A parametrized finite element (FE) model of the BIW is built by means of the ANSA CAE preprocessor software, which allows to account for material and geometric parameters. A comparison between the parametric NVH solutions and the full-order FE simulations is performed using the MSC-Nastran software, to validate the accuracy of the proposed method. In addition, an optimization study is presented to find the optimal materials and shape properties with respect to the NVH performance. Finally, in order to support the designers in the decision-making process, a graphical interface app is developed which allows to visualize in real-time how changes in the design variables affect pre-defined quantities of interest.

Modeling and analysis of nonlinear axial friction forces of tripod joints considering roughness characteristics of contact pairs

The nonlinear axial friction force (NAFF) induced by contact and friction between components of tripod joints constitutes an important dynamic characteristic of drive-shaft systems, which will lead to deterioration of the NVH (noise, vibration and harshness) performance of the vehicle. Based on the fractal theory, this paper proposes a novel modeling and analysis method for accurate estimation of NAFF considering micro contact and friction characteristics of contact pairs. An analytical model is developed for estimating the NAFF of tripod joints considering micro contact and friction characteristics of contact pairs. In the process of modeling, a modified distribution function is proposed to describe distributions of contact asperities between the curved surfaces to describe the contact and friction states between the rollers and the tracks inside tripod joints more accurately. The developed analytical model suggests that NAFF is related to the fractal parameters, the material parameters, the operating conditions and the distribution of asperities. The effectiveness of the analytical model is demonstrated by comparing the model-predicted NAFF with the measured data. Based on the developed model of NAFF, the influences of important input parameters on the magnitude of NAFF are qualitatively analyzed. Subsequently, Sobol' global sensitivity analysis method is used to further investigate the influences of important input parameters on the magnitude of NAFF. The results show that the proposed modeling and analysis method for estimating NAFF are essential to characterize relationships among NAFF and fractal parameters, material properties and distribution of asperities from a micro level, which could facilitate design optimization of the tripod joints.

Prediction of Crash Performance of Adhesively-Bonded Vehicle Front Rails

<div class="section abstract"><div class="htmlview paragraph">Adhesive bonding provides a versatile strategy for joining metallic as well as non-metallic substrates, and also offers the functionality for joining dissimilar materials. In the design of unibody vehicles for NVH (Noise, Vibration and Harshness) performance, adhesive bonding of sheet metal parts along flanges can provide enhanced stiffening of body-in-white (BIW) leading to superior vibration resistance at low frequencies and improved acoustics due to sealing of openings between flanges. However, due to the brittle nature of adhesives, they remain susceptible to failure under impact loading conditions. The viability of structural adhesives as a sole or predominant mode of joining stamped sheet metal panels into closed hollow sections such as hat-sections thus remains suspect and requires further investigation. As modern vehicle design is primarily driven by CAE (Computer-Aided Engineering), it is important to ensure that the experimental behaviors of adhesively-bonded components can be satisfactorily predicted. With the stated issues in mind i.e. gathering insight into the performance of adhesively-bonded steel hat-section components under impact loading and simulation of its behavior using an explicit FEA code such as LS-DYNA, a systematic experimental and numerical study is carried out comprising: (a) testing of single lap shear joints in a UTM and prediction of the average mechanical behavior of the joints till failure using a cohesive zone material modeling approach for the adhesive with independent Mode I and Mode II fracture criteria; (b) axial impact testing of double-hat section components with conventional spot welds, the same components with purely adhesively-bonded flanges in lieu of spot welds, and hybrid components with adhesive-bonding as well as sparse spot welds, and prediction of the detailed impact responses of the components mentioned; and (c) finally, implementation of the adhesive-based joining strategies in front rails of a validated finite element model of a commercially produced unibody passenger car and assessment of its performance vis-à-vis the baseline vehicle in full frontal NCAP test mode against a rigid barrier.</div></div>

Analysis and Optimization of Low‐Speed Road Noise in Electric Vehicles

When a certain electric vehicle is driving at a constant speed of 40 km/h on the rough asphalt road, the rear passenger can obviously feel the ear pressure, which seriously affects the comfort. Through the analysis of objective data, it was found that the problem was caused by the road excitation, which leads to the coupling between the mode of the backup door and the mode of the acoustic cavity, and causes the resonance of the car cavity, thus causing the ear pressure sensation. To solve this problem, this paper optimizes the backup door by means of experiment and simulation, increases the dynamic vibration absorber, makes its modal frequency avoid the acoustic cavity modal frequency, and achieves the purpose of reducing the interior noise. After optimization, the vehicle noise is reduced by 8 dBA at 42 Hz under 40 km/h working condition of rough road surface, and the ear pressure sensation is reduced at the same time, thus improving the NVH (noise, vibration, and harshness) performance of the vehicle.

Multi-objective optimization of magneto-rheological mount structure based on vehicle vibration control

Considering the influence of mount structure parameters on the quality of vehicle noise, vibration and harshness (NVH), a multi-objective optimization method of the magneto-rheological (MR) mount based on vehicle vibration control was proposed. A lumped parameter model was used to establish the relationship between the structure parameters of the MR mount and the NVH performance of the vehicle. Considering the influence of current on the magneto-rheological fluid viscosity and flow rate in damping channel, the dynamic characteristics of MR mount was obtained by the lumped parameter model. Then, a 10 degrees of freedom (DOF) vehicle model with MR mounting system was established. Finally, a co-simulation optimal platform was developed by the ISIGHT, MATLAB, and ANSYS software, and the non-dominated sorting genetic algorithm II was used to optimize the design of the mount magnetic circuit with the goal of improving the quality of vehicle NVH. The results showed that under the start/stop and the constant speed conditions, the root mean square values of vibration acceleration of the driver’s seat rail of the vehicle with the optimal design magneto-rheological mount decreases by 31.6% and 7.8%, respectively compared with the initial design mount, improved the ride comfort of the vehicle.

Two-step dynamics of a semiactive hydraulic engine mount with four-chamber and three-fluid-channel

Semiactive hydraulic engine mounts (HEMs) offer better noise, vibration and harshness (NVH) performance in a wider frequency band than passive HEMs and provide acoustic and vibrational comfort for passenger cars that rivals that of active engine mounts (AEMs); these advantages lead to the wider use of HEMs than AEMs. In limited control modes, broadening the vibration isolation band as much as possible is the fundamental purpose of semiactive HEMs. This paper focuses on an analytical and experimental study of a unique semiactive HEM with four-chamber and three-fluid-channel whose lengths shorten successively while the cross-sectional areas increase successively. The semiactive HEM presents dynamic characteristics in a two-step style and thus can offer good NVH performance in a relatively wider band. The first step is induced by the resonance of the longest fluid channel, and the second step is induced by the resonance of the shortest fluid channel corresponding to a separate decoupling membrane (DM) fluid chamber. The relationship of bulk stiffness between the DM and the main rubber spring is switched from an in-series connection for the first step to an in-parallel connection for the second step, which is an intrinsic reason for effectively widening the vibration isolation band. To better clarify the two-step dynamics, the influence of the DM is further investigated by introducing frequency-dependent bulk stiffness in-series and in-parallel. Moreover, two additional HEMs and their experimental two-step dynamics are illustrated to validate the frequency-dependent bulk stiffness. The ideal control strategies for semiactive HEMs with four-chamber and three-fluid-channel are developed and numerically verified by minimizing the force transmissibility in a wider frequency band. The findings of this paper can facilitate the design of dynamics for HEMs with a DM. Proper matching and relationship switching of the bulk stiffness between the DM and the main rubber spring can effectively improve NVH performance for passenger cars.

Application and optimization of damping pad to a body-in-white of a vehicle for improved road noise, vibration and harshness performance

Road noise is expected to become even more important in the vehicle product development cycle due to electrification and challenging lightweight/emission targets. In this study, a topology optimization algorithm is applied to determine the damping pad layout on the roof and floor panels of a Body-in-White (BIW), being the dominant contributors on road noise, vibration and harshness (NVH) performance of an automotive. Optimization algorithm yields the prescribed % of the surface area of these panels where the damping pad should be distributed set by the automotive Original Equipment Manufacturers (OEMs). The objective function is the minimization of the overall acceleration of these panels for the frequencies up to 200 Hz, while the weight of the BIW is considered as the optimization constraint. The results of the optimization are compared with the road NVH performance of panels with full damping and no damping. The optimization results indicate that by using 25% of the damping pad on the roof and floor panels improve the vibration performance especially in the frequency range of 80 Hz to 150 Hz significantly compared to bare BIW panels. Besides, the performance of the 25% damping is almost same as the application of full damping pad for frequencies between 90 Hz to 110 Hz. The results show that the methodology is able to address the trade-offs between road NVH and weight targets effectively.

Study on Radiated Noise of a Panel under Fluctuating Surface Pressure Due to an Idealized Side Mirror

As traditional automobiles develop towards new energy vehicles, the noise, vibration and harshness (NVH) performance of automobiles is facing new challenges. Without the cover of the traditional engine noise and inlet and exhaust noise, the high-speed wind noise becomes more prominent. Thus, research on the calculation method of vehicle interior noise in high-speed driving condition is needed. However, vehicle body structure is complex, and the external excitation components are complicated. In order to analyze the method of predicting the vehicle interior noise at high speed, an idealized side mirror model is taken as the research object in this paper and the radiated noise of a panel under the fluctuating surface pressure (FSP) due to the idealized side mirror is studied. The FSP of the panel is first studied by the numerical simulations of incompressible and compressible flow field. For the incompressible flow field, the Corcos turbulent boundary layer (TBL) model is established to simulate the convective component and the boundary element method (BEM) is used to extract the acoustic component. Subsequently, the Corcos model coupling BEM method, the random modal force coupling BEM method and the deterministic modal force coupling BEM method are used separately to calculate the noise of the panel under the FSP. For the compressible flow field, the convective and acoustic component in the fluctuating pressure are separated by the wavenumber-frequency spectrum (WFS) method. The radiated noise of the panel under the FSP is calculated again by using the WFS, the method of random modal force and the method of deterministic modal force, respectively. Then, the computational time of the six methods of incompressible and compressible calculation is compared. Finally, a fast and accurate method of calculating the panel radiated noise under FSP is obtained by comparing the computational accuracy with the experimental results and combining the computational time: the method of incompressible random modal force. This method can be used to quickly and accurately analyze the vehicle interior noise at high speed, and to optimize the exterior protrusions and the vehicle sound package for improving the vehicle NVH performance at high speed.

Experimental and numerical techniques for lightweight vehicle sound package development

The use of lightweight structural materials poses great challenge to noise control of a vehicle. A new approach to sound package design in lightweight vehicles was developed to reduce vehicle interior noise level without addition of weight. This new approach relies on lightweight acoustical materials that provide superior sound absorption performance to reduce noise level at the source, e.g., inside engine compartment and near the tires. Vehicle NVH finite element analysis (FEA) models were used to develop the lightweight vehicle’s structural design to bring the lightweight vehicle’s low and mid frequency responses closer the baseline vehicle’s performance. Full vehicle SEA (statistical energy analysis) model was developed to evaluate the high frequency NVH (noise, vibration, and harshness) performance of a vehicle. This correlated SEA model was used for the vehicle sound package optimization studies to develop sound package design to improve lightweight vehicle’s acoustic performance. In this paper, the use of NVH CAE (computer aided engineering) simulations for lightweight vehicle design is presented to highlight the limitation and use of FEA and SEA in lightweight vehicle development.

A novel decoupling control method based on neural network for EV’s Driving PMSM

Permanent Magnet Synchronous Motor (PMSM) is often used in Electrified Vehicle (EV), while its Id (direct-axis current) and Iq (quadrature-axis current) are coupled. Traditional FOC (Field Oriented Control) method can’t get an accurate decoupling control of them when the motor speed changed with the vehicle’s driving condition, especially at high speed. This coupling issue leads an unstable torque output. And further, it deteriorates the NVH (noise vibration and harshness) performance of EV. This paper focuses on the decoupling solution and puts forward a new control strategy which combines the neural network control idea with FOC method. The novel method gives a neural network controller based on four single neuron PID controllers, which its function is to realize the d-q axis interacted adjustment and decoupling. Four single neurons PID controllers achieve the negative feedback control of Id to Ud (direct-axis voltage), Iq to Ud, Iq to Uq (quadrature-axis voltage), and Id to Uq respectively. Creatively, it takes PMSM speed as one of the neuron inputs to adjust the feedback weight of Id and Iq dynamically. A comparing simulation which is set up in the Simulink platform is given in this paper. Simulation results show that this method gives a good self-adaptiveness and decouples the influence of Id and Iq, as well as improve the motor control quality at high speed.

An investigation on interior noise reduction using 2D locally resonant phononic crystal with point defect on car ceiling

Interior noise, as one of the indicators of automotive NVH (noise, vibration and harshness) performance, has been associated with an increasing importance in ride comfort evaluation. This paper presents a new method of interior noise reduction based on phononic crystal theory. Considering the lightweight requirement, the car ceiling plate is divided into nine regions to determine where the phononic oscillators should be mounted. By leveraging the acoustic contribution analysis of each region, the phononic crystal is arranged in the region that contributes the most to interior noise, bringing out the best attenuation effect in its bandgap. However, it is noted that at certain frequencies, the vibration of the ceiling plate or other body plates, which exhibits negative contribution to interior noise, should not be attenuated due to their beneficial effects. Thus in this paper, a point defect is employed for the design of a two-dimensional (2D) phononic crystal structure to preserve the negative contribution part of the plate’s vibration at specific frequencies. The validity of the proposed method in interior noise reduction is verified by simulation. Moreover, the error analysis is implemented and an optimization scheme is proposed.

A negative Poisson's ratio suspension jounce bumper

Jounce bumpers in automotive suspension can absorb impact energy and improve Noise, Vibration and Harshness (NVH) performance of entire vehicle. In this paper, a negative Poisson's ratio (NPR) structure was introduced and applied on the jounce bumper. The NPR jounce bumper can be primarily described by few parameters and is convenient for design, analysis and optimization. Three NPR jounce bumper prototypes were manufactured and tested. The test results of prototype 1 indicated that the NPR jounce bumpers had excellent viscoelasticity characteristic to absorb impact energy owing to its high damping. Compared with traditional jounce bumper, the NPR jounce bumper can achieve similar mechanical behavior but with a smoother load-displacement curve, which is beneficial to the NVH performance. Moreover, numerical calculation was conducted. Its results were fairly reliable for the prediction of mechanical behavior of NPR jounce bumper. The numerical results implied the stress concentration areas and the displacement of failure. The deformation shapes of NPR jounce bumper were also discussed. Finally, prototypes 2 and 3 manufactured from 3D printing technology were tested to explore the possibility of the application of 3D printing technology on NPR structures.

Comparative Study of Interior Permanent Magnet, Induction, and Switched Reluctance Motor Drives for EV and HEV Applications

With rapid electrification of transportation, it is becoming increasingly important to have a comprehensive understanding of criteria used in motor selection. This paper presents the design and comparative evaluation for an interior permanent magnet synchronous motor (IPMSM) with distributed winding and concentrated winding, induction motor (IM), and switched reluctance motor (SRM) for an electric vehicle (EV) or hybrid electric vehicle (HEV) application. A fast finite element analysis (FEA) modeling approach is addressed for IM design. To account for highly nonlinear motor parameters and achieve high motor efficiency, optimal current trajectories are obtained by extensive mapping for IPMSMs and IM. Optimal turn- on and turn- off angles with current chopping control and angular position control are found for SRM. Additional comparison including noise vibration and harshness (NVH) is also highlighted. Simulation and analytical results show that each motor topology demonstrates its own unique characteristic for EVs/HEVs. Each motor’s highest efficiency region is located at different torque-speed regions for the criteria defined. Stator geometry, pole/slot combination, and control strategy differentiate NVH performance.

Technique for Hanger Location of Vehicle Exhaust System Using Finite Element Method

A simulation technique using a finite element method (FEM) model for predicting, reducing and optimizing vibrations of the exhaust system was developed in this paper. This paper postulates the first stage in the design analysis of an exhaust system. Under excitation of the engine and road surface, the vibration energy of the exhaust system will result in the vibration of the body and produce structure noise transfers to the body from the hanger. These problems will effect or compromise noise, vibration and harshness (NVH) performance of the vehicle. A method called averaged driving DOF displacement (ADDOFD) is used to determine and optimize the exhaust hanger locations in this paper. Based on a sample vehicle, the HyperMesh and MSC Nastran software are adopted for meshing and calculation in the FEM modeling and vibration modal analysis of the exhaust system. Exhaust system’s free-free mode and sum of its eigenvectors are solved using MSC Nastran. Hanger locations are recommended at the position where the ADDOFD is relatively lower. Then static analysis and dynamic analysis of the exhaust system are performed, and finally hanger locations of the exhaust system are selected. When reasonable hanger positions have been decided, the vibration level of the body and the internal noise would have been decreased. This method can effectively select better NVH performance hanger locations in the earlier vehicle development process and can be extended to other types of vehicle, thus is effective for saving both the time and the cost of operation.

Vibro-Acoustic Characterization and Optimization of Periodic Cellular Material Structures (PCMS) for NVH Applications

NVH (Noise, vibration, and harshness) performance has been identified as having a significant influence in the purchase considerations of most automobile purchasers. Periodic cellular material structures (PCMS) are recently introduced multi-functional structures, commonly in sandwich form, that facilitate a wide variety of engineering purposes. Although literature concerning many PCMS properties is abundant, information about their vibration and acoustic responses is scanty, to the best knowledge of the present authors. This article documents a basic investigation of the vibration and acoustic behaviors of some PCMS through practical, analytical and numerical approaches, in order to evaluate the possibilities for minimizing, the transmission of noise and vibration. Some of these materials were made and investigated over frequency ranges which include several commonly-encountered vibration and acoustic frequencies of automotive and some other structures. Observations from this work are therefore expected to contribute towards design inputs to obtain better performances. A novel investigation of the effects upon vibration response of even slight inaccuracies of cutting out samples from larger blanks of such materials has also been made.

Systematic Fea Study of Vehicle Exhaust System Hanger Location Using Addofd Method

Under excitation of the engine and road surface, the vibration energy of the exhaust system which will result in the vibration of the body and produce the structure noise transfers to the body from the hanger. In view of these problems will cause noise, vibration and harshness (NVH) performance of the vehicle. A method called averaged driving DOF displacement (ADDOFD) is used to determine and optimize the exhaust hanger locations in this paper. Based on a sample vehicle, the Hyper Mesh and MSC. Nastrans oftware are adopted for meshing and calculation in the FEM modeling and vibration modal analysis of the exhaust system. Exhaust systems free-free mode and sum of its eigenvectors are offered using MSC. Nastran. Hanger locations are recommended at the position where the ADDOFD is relatively lower. Then static analysis and dynamic analysis of the exhaust system are done, and finally hanger locations of the exhaust system are selected. When the reasonable hanger positions have been decided, the vibration level of the body and the internal noise would have been decreased. This method can effectively select better NVH performance hanger locations in the earlier vehicle development process and can be extended to other types of vehicle, thus is instructive for saving both the time and the cost of operation.