Analysis of Vehicle Interior Low-Frequency Noise Based on ATV

2014 ◽  
Vol 494-495 ◽  
pp. 78-81
Author(s):  
Long Ma ◽  
Wen Feng Xia
Keyword(s):  
Acoustic Pressure ◽  
Ride Comfort ◽  
Low Frequency ◽  
Coupled System ◽  
The Body ◽  
Frequency Noise ◽  
Vehicle Interior ◽  
Fem Model ◽  
Acoustic Structure ◽  
Acoustic Cavity

The FEM model of the body and acoustic cavity are created, and the acoustic-structure coupled system is built up,and the SPL(sound press level) of points corresponding to the drivers ear and passengers ears were calculated using software LMS.virtual.lab. And there are several relatively noticeable acoustic pressure peaks around 60Hz, 102Hz, 120Hz and 168Hz. The maximum noise value was calculated by using the method of ATV method, several suggestions are advised to decrease the vehicle interior noise so that the vehicle ride comfort could be improved.

scholarly journals The Relationship between Vibratory Sensation and Body Surface Vibration Induced by Low-Frequency Noise

2002 ◽  
Vol 21 (2) ◽  
pp. 87-100 ◽  
Author(s):  
Yukio Takahashi ◽  
Kazuo Kanada ◽  
Yoshiharu Yonekawa
Keyword(s):  
Body Surface ◽  
Mechanical Vibration ◽  
Low Frequency ◽  
The Body ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Vibration Acceleration ◽  
Surface Vibration ◽  
Human Body Surface ◽  
The Relationship

Human body surface vibration induced by low-frequency noise was measured at the forehead, the chest and the abdomen. At the same time, subjects rated their vibratory sensation at each of these locations. The relationship between the measured vibration on the body surface and the rated vibratory sensation was examined, revealing that the vibratory sensations perceived in the chest and abdomen correlated closely with the vibration acceleration levels of the body surface vibration. This suggested that a person exposed to low-frequency noise perceives vibration at the chest or abdomen by sensing the mechanical vibration that the noise induces in the body. At the head, on the other hand, it was found that the vibratory sensation correlated comparably with the vibration acceleration level of the body surface vibration and the sound pressure level of the noise stimulus. This finding suggested that the mechanism of perception of vibration in the head is different from that of the perception of vibratory sensation in the chest and the abdomen.

scholarly journals Study of a Nonlinear Membrane Absorber Applied to 3D Acoustic Cavity for Low Frequency Broadband Noise Control

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1138 ◽  
Author(s):  
Jianwang Shao ◽  
Tao Zeng ◽  
Xian Wu
Keyword(s):  
Degrees Of Freedom ◽  
Noise Control ◽  
Normal Modes ◽  
Low Frequency ◽  
Harmonic Balance Method ◽  
Nonlinear Normal Modes ◽  
Broadband Noise ◽  
Frequency Noise ◽  
Acoustic Cavity ◽  
Nonlinear Membrane

As a new approach to passive noise control in low frequency domain, the targeted energy transfer (TET) technique has been applied to the 3D fields of acoustics. The nonlinear membrane absorber based on the TET can reduce the low frequency noise inside the 3D acoustic cavity. The TET phenomenon inside the 3D acoustic cavity has firstly investigated by a two degrees-of-freedom (DOF) system, which is comprised by an acoustic mode and a nonlinear membrane without the pre-stress. In order to control the low frequency broadband noise inside 3D acoustic cavity and consider the influence of the pre-stress for the TET, a general model of the system with several acoustic modes of 3D acoustic cavity and one nonlinear membrane is built and studied in this paper. By using the harmonic balance method and the numerical method, the nonlinear normal modes and the forced responses are analyzed. Meanwhile, the influence of the pre-stress of the nonlinear membrane for the TET is investigated. The desired working zones of the nonlinear membrane absorber for the broadband noise are investigated. It can be helpful to design the nonlinear membrane according the dimension of 3D acoustic cavity to control the low frequency broadband noise.

Analysis and Control of the 1st Order Interior Noise and Vibration Induced by Driveline Imbalance for 4WD Vehicle

2016 ◽  
Author(s):  
Yuanfeng Xia ◽  
Jian Pang ◽  
Rui Liu ◽  
Wenjuan Li ◽  
Jianchun Xu
Keyword(s):  
The Body ◽  
Influence Coefficient ◽  
Vehicle Interior ◽  
Single Plane ◽  
Acoustic Cavity ◽  
Testing Method ◽  
Sensitivity Theory ◽  
Influence Coefficient Method ◽  
And Control ◽  
Coefficient Method

Based on the influence coefficient method of the single-plane and multi-plane imbalance, an experimental method of a 4WD driveline system imbalance is proposed. A sensitivity theory and a testing method of influence of the 4WD driveline system imbalance on the vehicle interior 1st order vibration and noise are proposed. According to the influence coefficient method of the single plane, this paper puts forward an imbalance separation method for the driveline components, especially the imbalance separation between the driveshaft and the axle. Based on the problems and phenomena of the 1st order interior vibration and noise induced by the driveline imbalance transferring through the body floor and the interior acoustic cavity, the driveline imbalance sensitivity, the dynamic imbalance of the driveshaft and the driveline system are analyzed separately. Finally, the control methods of the dynamic imbalance and sensitivity of the 4WD vehicle driveline system are provided.

scholarly journals AUTOMOBILE INTERNAL COMBUSTION ENGINE PRESSURE CHARGING AND GAS-GUIDE LOW FREQUENCY NOISE REDUCTION USING ACTIVE SOUND SOURCES

Akustika ◽  
2019 ◽  
Vol 34 ◽  
pp. 118-122
Author(s):  
Andrey Vasilyev
Keyword(s):  
Noise Reduction ◽  
Internal Combustion Engines ◽  
Acoustic Pressure ◽  
Combustion Engine ◽  
Low Frequency ◽  
Internal Combustion ◽  
Frequency Noise ◽  
Combustion Engines ◽  
Sound Sources ◽  
Automobile Engines

Pressure charging devices in different types of internal combustion engines is allowing to achieve a number of advantages: engine power and fuel effectiveness increasing, exhaust gases toxic reduction etc. Pressure charging systems may be classified by the different parameters. For the time being turbo-supercharger is the most popular unit of serial automobile engines pressure charging. But it has some negative properties. Therefore using of dynamic (acoustic) pressure charging devices is promising solution. Analysis of existing acoustic pressure charging systems is carried out. The perspectives of using of active sound emitters for acoustic pressure charging are described. Theoretical issues of automobile engines active acoustic charging are discussed. Construction of active charging system is suggested. Multifunctional approach to automobile internal combustion engines pressure charging and low frequency intake and exhaust noise reduction is suggested. The results described in this paper may be useful for further development and application of internal combustion engines with improved consumer’s and ecological characteristic.

Adaptive Active Control System of Vehicle Noise Design and Test

2014 ◽  
Vol 1028 ◽  
pp. 251-256 ◽  
Author(s):  
Ji Guang Jiang ◽  
Yue Zeng
Keyword(s):  
Active Noise Control ◽  
Low Frequency ◽  
Control Unit ◽  
Noise Signal ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Power Module ◽  
Vehicle Interior ◽  
Vehicle Noise ◽  
Active Noise

According to the vehicle interior low frequency noise existing, vehicle interior adaptive active noise control strategy is established based on the FXLMS algorithm, designed the core circuit module active noise controller, including the vehicle interior noise signal amplification module, a main control unit, audio power amplifier module and power module, completed development of the controller hardware, and programming the control software system; using this system, on vehicle driving conditions vice driver left ear position low frequency noise cancellation control in the steady state, the 8.5 dB (Lin) and 10.2dB (Lin) the amount of noise reduction.

Optimal Stiffener Design for Interior Sound Reduction Using a Topology Optimization Based Approach

2003 ◽  
Vol 125 (3) ◽  
pp. 267-273 ◽  
Author(s):  
Jianhui Luo ◽  
Hae Chang Gea
Keyword(s):  
Topology Optimization ◽  
Optimization Problem ◽  
Low Frequency ◽  
Coupled System ◽  
Conservative System ◽  
Sound Level ◽  
Single Frequency ◽  
Frequency Noise ◽  
Topology Optimization Problem ◽  
Sound Reduction

A topology optimization based approach is proposed to study the optimal configuration of stiffeners for the interior sound reduction. Since our design target is aimed at reducing the low frequency noise, a coupled acoustic-structural conservative system without damping effect is considered. Modal analysis method is used to evaluate the interior sound level for this coupled system. To formulate the topology optimization problem, a recently introduced Microstructure-based Design Domain Method (MDDM) is employed. Using the MDDM, the optimal stiffener configurations problem is treated as a material distribution problem and sensitivity analysis of the coupled system is derived analytically. The norm of acoustic excitation is used as the indicator of the interior sound level. The optimal stiffener design is obtained by solving this topology optimization problem using a sequential convex approximation method. Examples of acoustic box under single frequency excitation and a band of low frequency excitations are presented and discussed.

scholarly journals The value of low-molecular-weight DNA of blood plasma in the diagnostic of the patological processes of different genesis

2013 ◽  
Vol 59 (3) ◽  
pp. 358-373 ◽  
Author(s):  
I.N. Vasilyeva ◽  
V.N. Zinkin
Keyword(s):  
Molecular Weight ◽  
Blood Plasma ◽  
Low Frequency ◽  
The Body ◽  
Chronic Obstructive ◽  
Low Molecular Weight ◽  
Frequency Noise ◽  
Obstructive Pulmonary Disease ◽  
Blood Concentrations ◽  
In Blood Plasma

The low-molecular-weight DNA appears in blood plasma of irradiated rats, and its content correlates directly with the irradiation dose. Cloning has shown, that enrichment of low-molecular-weight DNA with G+C content and features of its nucleotide sequences point to its ability to form rather stable nucleosomes. DNA obtained after irradiation of rats with principally different doses 8 and 100 Gy differed not only quantitatively, but also by content of the dinucleotides CpG and CpT; this suggests their origin from different sites of genome. For the first time it has been shown that exposure to low-frequency noise results in an increase of the contents of blood plasma low-molecular-weight DNA. In stroke patients blood concentrations of this DNA increased 3 days after the beginning of the acute period, and dynamics of its excretion differs in ischemic and hemorrhagic forms; in the case of ischemia low-molecular-weight DNA appears in cerebrospinal fluid. The chronic obstructive pulmonary disease in the state of remission is characterized by the decline of the level of low-molecular-weight DNA in the blood plasma unlike in the case of the chronic nonobstructive bronchitis. The clear dependence between formation and special features of the low-molecular-weight DNA fraction in blood plasma makes it possible to consider the low-molecular fraction as an universal index of apoptosis, which allows to distinguish basically different conditions of the body.

Vehicle Interior Low Frequency Noise Optimum Using Substructure Modal Synthesis Method

2011 ◽  
Vol 396-398 ◽  
pp. 2206-2212
Author(s):  
Er Bing Wang ◽  
Hong Zhou ◽  
Hai Qing Xu ◽  
Fang Zhang ◽  
Jing Wang
Keyword(s):  
Dynamic Model ◽  
Synthesis Method ◽  
Low Frequency ◽  
Element Model ◽  
Frequency Noise ◽  
Structural Noise ◽  
Vehicle Interior ◽  
Structural Dynamic ◽  
Modal Synthesis ◽  
Acoustic Contribution

Combined with the structural dynamic model of a car set up with the substructure modal synthesis method, body panels acoustic contribution was analyzed to reduce the in-car structural noise in low frequency range. The driver-right-ear position was selected as acoustic response point, with the operational vibration response of the dynamic model as boundary condition for acoustic BEM (boundary element model), the panels that attribute most to the in-car noise were located according to ATV (acoustic transfer vector) results. After the vibrational restraint of the crucial panels by corresponding experimental measurement, in idling, the most decrease of main peaks is 5.7dB; the overall level of in-car noise is reduced by 3.89dB. It indicates that the substructure mode synthesis method can provide proper suggestion for optimizing in-car structural noise.

scholarly journals Full Vehicle Vibration and Noise Analysis Based on Substructure Power Flow

2017 ◽  
Vol 2017 ◽  
pp. 1-17 ◽  
Author(s):  
Zhien Liu ◽  
Shuai Yuan ◽  
Shenghao Xiao ◽  
Songze Du ◽  
Yan Zhang ◽  
...  
Keyword(s):  
Finite Element ◽  
Power Flow ◽  
Vibration Isolation ◽  
Noise Analysis ◽  
Solution Process ◽  
Low Frequency ◽  
Vehicle Body ◽  
Frequency Noise ◽  
Vehicle Interior ◽  
Computation Efficiency

Combining substructure and power flow theory, in this paper an external program is written to control MSC. Nastran solution process and the substructure frequency response are also formulated accordingly. Based on a simple vehicle model, characteristics of vibration, noise, and power flow are studied, respectively. After being compared with the result of conventional FEM (finite element method), the new method is confirmed to be feasible. When it comes to a vehicle with the problem of low-frequency noise, finite element models of substructures for vehicle body and chassis are established, respectively. In addition, substructure power flow method is also employed to examine the transfer characteristics of multidimensional vibration energy for the whole vehicle system. By virtue of the adjustment stiffness of drive shaft support and bushes at rear suspension lower arm, the vehicle interior noise is decreased by about 3 dB when the engine speed is near 1050 rpm and 1650 rpm in experiment. At the same time, this method can increase the computation efficiency by 78%, 38%, and 98% when it comes to the optimization of chassis structure, body structure, and vibration isolation components, respectively.

Numerical and experimental research on flow and aerodynamic noise characteristics of coach

2020 ◽  
pp. 095440702097381
Author(s):  
Yifei Chang ◽  
Zhigang Yang ◽  
Qiliang Li
Keyword(s):  
Flow Field ◽  
Acoustic Pressure ◽  
Low Frequency ◽  
The Body ◽  
Scale Model ◽  
Aerodynamic Noise ◽  
Band Pass Filter ◽  
Eddy Simulation ◽  
Noise Characteristics ◽  
Turbulent Pressure

The researches on flow and aerodynamic noise characteristics of coaches are urgently needed to improve with the rapid development of new energy coaches. In this paper, tests in model wind tunnel and numerical calculations were carried out to study the phenomenon of flow and aero-noise on 1:25 scale model coach. Based on large eddy simulation (LES) and detached eddy simulation (DES), reliable numerical calculation method of flow and aero-noise on coach was established and verified. It is found that the maximum difference on turbulent pressure between test and LES is less than 10 dB(A) while that of DES is about 20 dB(A). Due to the results got from 1:25 scale model, the W_LES_HOA model is used to obtain the flow field and sound field information outside the coach. To find out the different propagation characteristics of turbulent pressure pulsation and acoustic pressure, proper orthogonal decomposition (POD) and band-pass filter analysis are used for further analysis. For rearview mirror, the energy of first mode is 6.1%, and only the first nine modes have an energy for more than 3.0%. By the reconstruction of first four modes, it can be seen that the complicated transverse vortex shedding couples with A pillar vortex and reaches the body surface. However, the coupling of turbulent pressure can only be seen clearly under low frequency around 250 Hz while the coupling of acoustic pressure can be seen under 750 Hz. Meanwhile, with the analysis of low frequency round 250 Hz and 500 Hz, the change of flow field generated by airflow impingement on the windward surface and A pillar makes the front of the coach becomes the main sources of aerodynamic sound sources.

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