Interior Noise Analysis Research Articles

Simulation and Optimization of Bus Interior Noise Based on Hybrid Method for Engine Vibration Load Identification

Buses are crucial for urban public transportation systems as they help reduce traffic congestion and promote environmental sustainability. The noise inside buses significantly affects the comfort and physical health of both drivers and passengers. Although numerous studies have focused on the interior noise of buses, few have explicitly addressed the methods of reducing bus noise through comprehensive bus simulation and testing. Challenges of the full bus simulation include obtaining accurate engine vibration loads and building the finite element model of the full bus. This study presents a comprehensive approach for analyzing and optimization bus interior noise caused by engine vibration excitation. A novel hybrid method is proposed to identify bus engine vibration load, combining experimental testing of engine cylinder pressure with multibody dynamics simulation. Structure–acoustic coupled simulations were conducted to predict bus interior noise based on a detailed finite element model of the full bus. The study demonstrates a strong correlation between simulation and experimental results, validating the accuracy and effectiveness of the proposed method. The primary causes of the interior booming noise were identified by simulation analysis and experimental diagnosis. Optimization analysis led to a notable noise reduction by adjusting the support stiffness of the drive shaft, body structure, and integrating rear leaf spring dampers. These processes contribute to the analysis and improvement of bus interior noise, ultimately enhancing bus ride comfort and promoting sustainable urban public transportation.

Squeak and Rattle Analysis of Automotive Interiors Considering Contact Nonlinearity

<div>In order to improve the squeak and rattle (S&R) performance level of automotive interiors, the contact nonlinear characteristics of structural components need to be considered when performing interior noise analysis. The finite element model of S&R analysis of the interior assembly is built, and the time-domain vibration characteristics of the contact points between the interior panels are analyzed by applying external forced excitation. The interaction force between contact points is obtained according to the contact equivalent model between interior materials. The external excitation and internal interaction force are analyzed as the total excitation to obtain the response results. Through experimental verification, compared with the S&R performance division method, the analysis results are consistent with the test results. Based on this model, S&R risk optimization is carried out, and the risk level is significantly reduced. The research shows that the level of S&R performance can be accurately predicted by considering the nonlinear contact problem of the contact point in the S&R analysis of interior assembly, which has important guiding significance for the forward development and optimization design of automobile S&R performance.</div>

Prediction and Aerodynamic Analysis of Interior Noise and Wind Drag Generated by the Outside Rear-View Mirror for Commercial Vehicles

The outside rear-view mirror (OSRVM) is installed on the vehicle’s surface, which causes unwanted aerodynamic noise and wind drag during driving. It is important to use simulation methods to predict the performance of aerodynamic noise and wind drag of commercial vehicles due to the OSRVM. Considering the wind drag of the OSRVM, a combinational simulation strategy is employed to calculate external flow and interior acoustic fields of commercial vehicles, respectively. The flow field is computed a priori with an incompressible flow solver. The acoustic field was then computed based on the information extracted from the CFD solver. To obtain the interior noise level at the driver’s ears, a vibroacoustic model is used to calculate the response of the window glass structure and interior cavities, where the unsteady aerodynamic pressure loading on the two side windows’ surface is treated as the acoustic source field. The paper provides flow field and acoustic simulations for three OSRVM configuration models. The results are compared to data obtained in road sliding test measurement on the commercial vehicle. The accuracy of the hybrid simulation method is proved, and the comparative analyses verify that the OSRVM B model dramatically reduces the interior noise and wind drag of commercial vehicles.

Mechanism of interior noise generation in high-speed vehicle based on anti-noise operational transfer path analysis

Owing to the continuous development of the automobile industry, increasingly stringent performance requirements for noise, vibration, and harshness of automobiles are being presented. Interior noise control in high-speed vehicles has not been adequately addressed, owing to the complex mechanism of noise generation. As simulations performed previously focused on vehicle wind noise and tyre noise cannot adequately predict the effect on passenger ear-side noise, these issues are investigated in this study. Their effects on passengers are investigated using transfer path analysis. An anti-noise operational transfer path analysis is proposed to study noise generated in high-speed vehicles. The established anti-noise operational transfer path analysis model can eliminate crosstalks between noise source signals of different transmission paths. The model is validated by comparing the measured and calculated values of the anti-noise operational transfer path analysis model. The coherence of the input noise signal and the ear-side noise signal of the passenger is assessed using coherence analysis. By calculating and categorising the contributions of different noise sources in different locations and types, the main noise sources affecting passenger comfort are determined. The result indicates that the main noise sources affecting the passenger’s ear-side noise change from engine noise to left-A wind noise and tyre radiation noise with increasing vehicle speed, in which the proportion also increase. The proposed anti-noise operational transfer path analysis is suitable for the interior-noise analysis of high-speed vehicles, and this study may serve as a reference for future studies regarding active and passive noise control in high-speed vehicles.

Transfer Path Analysis of Interior Noise above Bogie Area of High-speed Train

Transfer Path Analysis of Interior Noise above Bogie Area of High-speed Train

Analysis of Urban Bus Body Vibration and Coupling Interior Noise

Bus body vibration and interior noise caused by vibration directly affect the ride comfort, cause driving fatigue, discomfort, and bring to the urban environmental noise pollution at the same time. Based on urban bus as the research object in the paper, the modal analyses of body structure, interior spoke and solid coupling model have been carried out by LMS. Virtual Lab software, and compared with the results of modal experiment results on body. The interior sound pressure response has been calculated under the engine incentive by using the boundary element method, and the sound pressure response curves for low frequency have been gotten. Finally, the local structure of body has been improved, and this method reaches the purpose of noise reduction by the simulation calculation. At the same time, references have been provided for improving vehicle vibration and noise.

Prediction and energy contribution analysis of interior noise in a high-speed train based on modified energy finite element analysis

Abstract Compared with traditional finite element analysis and statistical energy analysis, the energy finite element analysis (EFEA) has the advantages of small computations and solving local responses in large-scale complex structures. In this paper, the structural sound insulation effect is introduced to EFEA for predicting and analyzing interior noise responses of extruded structures in a high-speed train. Firstly, the carriage structure and cavity models are established based on EFEA theory, and model parameters are obtained through experiments and effective simulations. Mechanical and acoustic excitation sources of the high-speed train are extracted through multi-body dynamic simulation, acoustic finite element method and nonlinear acoustic solution. The reliability of predicted excitations is validated by verifying the amplitude peak frequency bands. The interior noise responses at several observations are obtained and in good agreement with on-site test results, and the EFEA prediction model of interior noise is verified accurately. Secondly, the energy contribution of exterior excitation sources to interior noise responses is analyzed based on EFEA model. The results indicate that acoustic excitations dominate the acoustic energy in the frequency bands above 800 Hz, and the energy contribution of mechanical excitations and acoustic excitations is relatively close in the frequency bands below 600 Hz. The contribution of aerodynamic noise excitations is predominantly concentrated in the frequency bands below 500 Hz, while that of wheel-rail noise excitations is concentrated in the frequency bands above 800 Hz. In the frequency bands below 1250 Hz, the energy contribution of rail noise excitations is much more important than that of wheel noise excitations, while their contribution gets gradually close in the frequency bands above 1600 Hz. Besides, the acoustic excitations at the bottom of the carriage are quite important sources. Finally, wheel-rail noise excitations are optimized with spoke-shielding damping wheels and dynamic vibration absorbers, and the sound pressure level in the amplitude peak bands is reduced by about 8 dB. The interior noise responses are reduced by about 3–5 dB in the frequency bands above 800 Hz, and total loudness, sharpness and roughness at different locations are decreasing by more than 1 sone, 0.05 acum and 0.03 asper respectively. Therefore, wheel-rail noise optimizations have good reduction effects on interior noise responses in the high frequency bands.

Interior Noise Analysis in the Compartment of a New Type Sleeping EMU Based on Psychoacoustic Parameters

Interior Noise Analysis in the Compartment of a New Type Sleeping EMU Based on Psychoacoustic Parameters

A Systematic Approach to Identify Sources of Abnormal Interior Noise for a High‐Speed Train

A systematic approach to identify sources of abnormal interior noise occurring in a high‐speed train is presented and applied in this paper to resolve a particular noise issue. This approach is developed based on a number of previous dealings with similar noise problems. The particular noise issue occurs in a Chinese high‐speed train. It is measured that there is a difference of 7 dB(A) in overall Sound Pressure Level (SPL) between two nominally identical VIP cabins at 250 km/h. The systematic approach is applied to identify the root cause of the 7 dB(A) difference. Well planned measurements are performed in both the VIP cabins. Sound pressure contributions, either in terms of frequency band or in terms of facing area, are analyzed. Order analysis is also carried out. Based on these analyses, it is found that the problematic frequency is the sleeper passing frequency of the train, and an area on the roof contributes the most. In order to determine what causes that area to be the main contributor without disassembling the structure of the roof, measured noise and vibration data for different train speeds are further analyzed. It is then reasoned that roof is the main contributor caused by sound pressure behind the panel. Up to this point, panels of the roof are removed, revealing that a hole of 300 cm2 for running cables is presented behind the red area without proper sound insulation. This study can provide a basis for abnormal interior noise analysis and control of high‐speed trains.

Identification and contribution analysis of vehicle interior noise based on acoustic array technology

This article proposes an advanced far-field acoustic hologram for vehicle sound source identification and investigates a method of performing contribution analyses in the far field. The hologram is applied for statistically optimized near-field acoustic holography used to identify vehicle sound sources (internal and external). An advanced far-field acoustic hologram is first proposed to improve the spatial resolution of low-frequency sound source locations in the far field. In addition, an acoustic contribution analysis based on near-field acoustic holography is used to provide a direction for low-noise optimization design. Next, a new sound source identification and low-noise technology is explored via the aforementioned methods and applied for sound source identification and acoustic contribution analyses for a vehicle. The analysis results showed that in the process of sound source identification, the contribution of each sound source can be simultaneously sorted, and this finding can help guide research on the low-noise control of a vehicle.

Contribution analysis of interior noise and floor vibration in high-speed trains by operational transfer path analysis

A study on the contribution analysis of interior noise and floor vibration in high-speed trains was conducted using operational transfer path analysis. Initially, noise and vibration measurement at...

A full-spectrum analysis of high-speed train interior noise under multi-physical-field coupling excitations

High-speed-railway-train interior noise at low, medium, and high frequencies could be simulated by finite element analysis (FEA) or boundary element analysis (BEA), hybrid finite element analysis–statistical energy analysis (FEA–SEA) and statistical energy analysis (SEA), respectively. First, a new method named statistical acoustic energy flow (SAEF) is proposed, which can be applied to the full-spectrum HST interior noise simulation (including low, medium, and high frequencies) with only one model. In an SAEF model, the corresponding multi-physical-field coupling excitations are firstly fully considered and coupled to excite the interior noise. The interior noise attenuated by sound insulation panels of carriage is simulated through modeling the inflow acoustic energy from the exterior excitations into the interior acoustic cavities. Rigid multi-body dynamics, fast multi-pole BEA, and large-eddy simulation with indirect boundary element analysis are first employed to extract the multi-physical-field excitations, which include the wheel–rail interaction forces/secondary suspension forces, the wheel–rail rolling noise, and aerodynamic noise, respectively. All the peak values and their frequency bands of the simulated acoustic excitations are validated with those from the noise source identification test. Besides, the measured equipment noise inside equipment compartment is used as one of the excitation sources which contribute to the interior noise. Second, a full-trimmed FE carriage model is firstly constructed, and the simulated modal shapes and frequencies agree well with the measured ones, which has validated the global FE carriage model as well as the local FE models of the aluminum alloy–trim composite panel. Thus, the sound transmission loss model of any composite panel has indirectly been validated. Finally, the SAEF model of the carriage is constructed based on the accurate FE model and stimulated by the multi-physical-field excitations. The results show that the trend of the simulated 1/3 octave band sound pressure spectrum agrees well with that of the on-site-measured one. The deviation between the simulated and measured overall sound pressure level (SPL) is 2.6dB(A) and well controlled below the engineering tolerance limit, which has validated the SAEF model in the full-spectrum analysis of the high speed train interior noise.

Active control analysis of passenger vehicle interior noise produced from tyre/road interaction

Active noise control (ANC) system is a possible solution for reducing the overall vehicle interior noise and minimising the noise annoyance experienced by the driver and passengers. ANC systems can be installed in vehicles in order to adapt the road noise to customer preferences and expectations. They bring human perception criteria other than loudness into the control design. However, the analysis in this paper deals with applying ANC technology to the tyre/road noise in a vehicle enclosure. In the automotive industry, both cost/weight requirements and increasing comfort demands explain the interest shown at the moment for ANC. In consideration of requirements of quietness, improvement and reduction of weight, an ANC system is based on vibration measurement (reference) at the driver's legs region and sound pressure level at the driver's head position. The neuro-fuzzy technique identifies a specified desired output from two input parameters. The results obtained indicate the feasibility of applying the methodology in this instance. Moreover, it has been verified that a good noise reduction performance can be obtained at the driver's head position over frequencies up to 400 Hz.

Coupled analysis of engine noise and interior noise of an automobile

The coupled model of a four-cylinder internal combustion engine and a dash panel was constructed to analyze the relationship between the engine noise and interior noise of an automobile. Finite element analysis, flexible multi-body dynamics, and boundary element analysis were integrated to obtain the tetrahedron-element models, structural vibration response, and radiated noise, respectively. The accuracy of the finite-element model of the engine was validated by modal analysis via single-input multi-output technology, while the dash panel was validated by sound transmission loss experiment. The block was optimized to reduce the radiated acoustic power from the engine surface. The acoustic transfer path between the engine cabin and passenger compartment was then established. The coupled analysis results reveal that the interior noise is optimized due to the engine noise reduction.

Interior noise analysis based on acoustic excitation tests

This paper describes a method for analysing the low–frequency structure and airborne sound of a fully trimmed vehicle on the basis of acoustic excitation tests. In experimental analyses of structure–borne sound, there are times when the coupled modes of the vehicle cannot be identified by direct measurement. It is shown that, in such cases, it is necessary to use the vibration distribution obtained reciprocally by acoustic excitation from a loudspeaker located at the passenger's ear position. It is also shown that the use of direct and reciprocal measurements in analyses of airborne sound yields valuable information for reducing the interior noise level.

An Experimental Analysis of Interior Noise in an Ambulance and Noise Reduction with Damping Materials

To solve the problem of an ambulance interior noise, a multi-input and single-output linear system model is established based on the partial coherence analysis method. In this model, vibration acceleration signals of panels are treated as input, sound pressure signals is treated as output. The relevant influence among the system inputs are ruled out and the partial coherence function value is considered as an indicator to estimate the panels’ acoustic contribution to the field point. On the basis of analysis, the structural modification with damping materials is performed on the panels with greater contribution. The results show that panels’ acoustic contribution can be analyzed by partial coherence analysis method effectively and structural modification with damping materials based on the method has significant effect on reducing the vehicle interior noise and decreasing additional mass.

Simulation and Optimization to Vehicle Interior Noise in Mid and High Frequency Using VAone

Finite Element-Statistical Energy Analysis (FE-SEA) hybrid method is better than SEA method for vehicle interior noise analysis in mid frequency. The noise predictions using FE-SEA in mid and SEA in high frequency are good in consistent with the experiments, so the computer-aided simulation using above two methods is a good alternative to experiments. The results shows that the Poly Methyl Meth Acrylate (PMMA) instead of glass as the windshield material can reduce the interior noise at the driver’s ear in mid frequency, also lighten the body weight. The results shows the new polymer transparent material can looked as a good new way for vehicle interior noise reduction and body lightweighting.

부산도시철도 3호선 실내소음 및 저주파 소음 특성

This paper deals with the analysis of interior noise and low frequency noise characteristic for the Busan citizens to use public transport, Busan Metro Line 3. The interior noise evaluation index, articulation index(AI) is evaluated the lower value about average 22 % in a whole range, this is difficult to have a conversation. Also, noise criteria(NC) curve is partially evaluated as NC-65 below 2000 Hz, space type is evaluated as factories. Another of interior noise evaluation index, preferred speech interference level(PSIL) is evaluated the upper value about average 66 dB(A) in a whole range, this is evaluated to be interrupted. In the case of low frequency noise(20~200 Hz), the measurement of low frequency noise is assessed largely beyond noise criteria of ISO 226. The low frequency noise should be reduced because low frequency noise affects on psychological stress and displeasure although low frequency noise is not recognized by auditory sense. The low frequency noise criteria and guideline will be enacted from now on in Korea.

Simulation on a car interior aerodynamic noise control based on statistical energy analysis

How to simulate interior aerodynamic noise accurately is an important question of a car interior noise reduction. The unsteady aerodynamic pressure on body surfaces is proved to be the key effect factor of car interior aerodynamic noise control in high frequency on high speed. In this paper, a detail statistical energy analysis (SEA) model is built. And the vibra-acoustic power inputs are loaded on the model for the valid result of car interior noise analysis. The model is the solid foundation for further optimization on car interior noise control. After the most sensitive subsystems for the power contribution to car interior noise are pointed by SEA comprehensive analysis, the sound pressure level of car interior aerodynamic noise can be reduced by improving their sound and damping characteristics. The further vehicle testing results show that it is available to improve the interior acoustic performance by using detailed SEA model, which comprised by more than 80 subsystems, with the unsteady aerodynamic pressure calculation on body surfaces and the materials improvement of sound/damping properties. It is able to acquire more than 2 dB reduction on the central frequency in the spectrum over 800 Hz. The proposed optimization method can be looked as a reference of car interior aerodynamic noise control by the detail SEA model integrated unsteady computational fluid dynamics (CFD) and sensitivity analysis of acoustic contribution.

SOUND QUALITY ANALYSIS AND PREDICTION OF VEHICLE INTERIOR NOISE BASED ON GREY SYSTEM THEORY

This paper presents a novel effective methodology for sound quality analysis and prediction of vehicle interior noise using gray system theory. Four objective psychoacoustic parameters selected to evaluate acoustic performance of vehicle interior environment are loudness, sharpness, roughness, and fluctuation. Subjective evaluation is presented using paired comparison method, and Bradley–Terry model is also created. The relationship between subjective evaluation and psychoacoustic parameters is determined by using gray relational analysis. Meanwhile, the correlation among psychoacoustic parameters is also revealed. Sound quality prediction models are created based on GM (0, N) and GM (1, N) model. The prediction results show that GM (1, N) model is more capable than GM (0, N) model for prediction of sound quality. Thus, the analysis and prediction results confirm that the proposed method in this study can be a useful tool to analyze and predict sound quality of the vehicle interior noise.