Interior Vibration Research Articles

Effective low noise rumble strip design and performance

The purpose of the NCHRP 15-68 Effective Low Noise Rumble Strips project was to develop and recommend a rumble strip design capable of minimizing the exterior noise that can impact residences along a roadway while producing sufficient noise and vibration inside the vehicle to alert the operator of lane departure. A review of the previous research indicated that this could best be accomplished with a rumble strip of a sinusoidal profile. Twenty sinusoidal test sites were installed in Washington State, varying the wavelength from 12 to 24 inches, the peak-to-peak amplitude from 5/16 to 1/2 inch, and the recess from 0 to 1/8 inch. Each of the test sites were evaluated using the recommended test procedure developed during Phase I of the NCHRP project, which included a primary interior noise measurement, a primary interior vibration measurement, and an exterior pass-by measurement. Based on the accepted interior noise and vibration standard of 10 dB or more difference on and off the strips and the design goal used in this research of 5 dB or less at the pass-by location, the recommended rumble strip design is a sinusoidal profile with a 15-inch wavelength, a 7/16- to 1/2-inch peak-to-peak amplitude, and a 0-inch recess.

Application of machine learning on complete vehicle data for interior vibration prediction based on transfer paths in narrowband spectrum

Interior noise and vibration are critical quality criteria for vehicles in the automotive sector. The latter is essential in driving comfort, where many development resources are used for the design and the evaluation. As a result, testing the entire vehicle is very important to assess vibration and ride comfort. The assembly of the entire vehicle is carried out virtually using transfer functions derived either from simulations or from measurements. Since simulations of a complete vehicle are still challenging,transfer functions are usually measured with considerable effort. Therefore, limiting the necessary measurements to specific components is desirable to be efficient and to save costs. In this work, the authors use an artificial neural network to predict the interior vibration profiles of a complete vehicle based on full test drives at different speeds and road conditions. Triaxial acceleration measurements serve as the database. In addition, a criterion is proposed to select essential sensors for the learning process. The results show that if the data is handled carefully, many sensors can be discarded, and the network can predict accurate acceleration spectra for virtual sensors at various test conditions.

Tire and Engine Sources Contribution to Vehicle Interior Noise and Vibration Exposure Levels

The main objective of the research presented in this paper is to enhance driver-passengers comfort of a vehicle that in turn leads to better vehicle safety and stability. The focus was put on studying the interior vibration and noise contributions originated from tire-road and engine-transmission subsystems, due to their significant impact on the dynamic performance of the vehicle. The noise and vibration measurements were recorded at the driver’s head position and on the driver legs room. Furthermore, the influence of different tire types and road surface textures on the vehicle interior noise and vibration were considered. The results indicate that the widely used conventional engine mounts and tires in commercial vehicles cannot fulfill the conflicting requirements for the best isolation concerning both road surface and engine-transmission induced excitations. The values of driver’s head position sound pressure level and floor vibration acceleration broadband averages originate for engine-transmission are lower than that for tire-road interaction. Furthermore, the values of RMS, crest factor, kurtosis and IRI for the vehicle waveform were estimated for vehicle speeds, tire types and road surface textures. Moreover, the percentage contribution for both interior noise and vibration originated from tire-road interaction is higher than the one from vehicle engine-transmission system in all the vehicle speed range, tire type and road surface texture considered.

A Smartphone-Enabled IoT System for Vibration and Noise Monitoring of Rail Transit

With the development of the urban rail transit system, the ride comfort of trains in operation has been emphasized by passengers and railroad operators alike. The monitoring of interior vibration and noise levels of trains provides an efficient way to guarantee ride comfort. Traditional monitoring equipment has numerous disadvantages, such as high cost, poor mobility, and lack of real-time evaluation functions. To solve these problems, this study explored the utilization of smartphones to measure vibration and noise and diagnose human comfort levels. A smartphone application has been developed based on the Internet of Things (IoT) concept. The smartphone device not only realizes data sensing, visualization, and transmission, but also fulfills edge-computing functions to process sensing data and evaluate vibration and noise impact in real time. The design principle and major components of the developed application are elaborated. In situ experiments were conducted on the Hong Kong Mass Transit Railway, which provides valuable experiences for applying IoT monitoring technology in the rail transit systems and enables the realization of citizen sensing in the future.

Experimental and Computational Model for a Neonatal Incubator with Thermoelectric Conditioning System

This work describes the design, construction and testing of a thermo-electric conditioning device installed in a neonatal incubator with the aim of improving the precision in the regulation of the interior air temperature, reducing noise and interior vibration, and improving the life of the neonate. A simplified one-dimensional thermal model has been developed, made up of resistances and thermal capacities that simulate the thermal behaviour of all the elements of the system from end to end. All the equations of the model are obtained in a nodal way, allowing the mathematical relationship between the input and output to be known. This model makes it possible to improve temperature control, avoiding the deviations that occur in the traditional model controlled by sensors at both ends. The computational model allows to predict the variation of temperatures in transient and permanent regime. This model allows the design and sizing of the thermoelectric system for different outdoor environmental conditions and the selection of the number of Peltier modules needed to satisfy the heating demand of other incubators with different geometry and capacity. The results of the computational model show good agreement with the experimental tests, despite being a simplified 1D nodal model. The results obtained show a coefficient of operation (COP) of 1.38, achieving higher performance than the current traditional electrical resistance system (COP = 1). In addition, a CFD study has been carried out to check the air patterns, to see the temperature uniformity and to estimate the number of air changes per hour (HVAC) inside the incubator.

Vehicle interior noise and vibration prediction by combination analyses of Component and Operational TPA

In this study, we propose an analytical method consisting of Operational TPA (OTPA) and Component TPA (CTPA) to predict the vehicle interior noise and vibration without the vehicle operational test in case the noise source such as engine was modified. In the proposed method, the blocked force of the noise source was obtained at a test bench and the vibration at the source attachment point on the vehicle was calculated by CTPA. After then, the response point signal (interior noise / vibration) is estimated from several reference point signals including the calculated vibration by OTPA. For the verification of this method, a simple vehicle model which is composed of four tires and a motor was prepared in addition to a test bench. OTPA was firstly applied to the vehicle model to analyze the contribution from tires and a motor to the body vibration (response point). The blocked force of a modified motor was obtained by CTPA at the test bench and the force was used to predict the response point by OTPA. Finally, the estimated interior vibration was compared with the actual measured response point vibration when the motor was replaced on the vehicle model and the accuracy was verified.

RETRACTED ARTICLE: Research on the virtual reality of vibration characteristics in vehicle cabin based on neural networks

A finite element model of commercial vehicles was firstly built in the paper to study the virtual reality of vibration characteristics, and the top 6-order modal was then computed and compared with the experimental results to verify the reliability of the computational model. Then, a neural network model of the cabin was built. Through road tests, the excitation signal at the cabin suspension point and the response signal of interior vibration noise were measured under the idle condition and constant speed condition. The measured excitation signal was applied to the prediction model for frequency response analysis, in order to compute the interior noise within the range 20–200 Hz. The obtained simulation result of the vibration noise was compared with the experimental result and analyzed. As indicated from the analysis, the influence of excitation spectrum and the model can be reflected by the simulation response spectrum, which is consistent with the experimental result. The higher precision can be also obtained when the model is applied to predict the interior noise.

Research on the vibration characteristics of the commercial-vehicle cabin based on experimental design and genetic algorithm

Most of the published researches on the vibration isolation performance of the commercial vehicle focus on the suspension system and the power-train system, and few of them focus on the cabin. Moreover, the researches on the cabin mostly focus on how to reduce the interior noise, and the interior vibration characteristics have not received adequate attention. Therefore, this paper tries to research the vibration characteristics of the commercial-vehicle cabin in order to improve ride comfort. Firstly, the vibration characteristic of the cabin was tested on the actual road. Then, the rigid-flexible coupling dynamic model of the commercial vehicle was built, and the computational results were compared with the experimental results. It was found that the results were consistent with each other, which showed that the computational model was reliable. Finally, based on the verified computation model, some parameters that influenced the vibration characteristic of the cabin were explored. As a result, the influencing tendency of each parameter to the cabin vibration under each working condition was obtained, but influencing levels of each parameter cannot be analyzed quantitatively. In order to research the contribution degree of each parameter to the vibration in cabin, DOE (Design of Experiment) method was used for the analysis to provide references for the optimal matching of a cabin suspension system. Then, the vibration in the cabin was optimized based on genetic algorithm to obtain the optimal performance. This research can provide a reference for the other researches on the reduction vibration for the cabin.

The relationship of vibration and groundborne/structureborne noise in buildings relative to vibration in the ground from exterior sources

Ground vibration generated by roadway traffic, rail, and transit systems can be transmitted into buildings were it can either be perceived as feelable vibration or as sound radiated from the interior building surfaces, i.e., floors, walls, and ceilings. The amount of vibration that is transmitted into a building is affected by a reduction as the vibration is transmitted from the ground to the foundation of the building (i.e., coupling loss) and amplification due to resonances within the building structure. This paper will discuss these effects and measurements that have been conducted to quantify the effects for common residential building construction adjacent to rail lines. A brief discussion regarding the relationship of groundborne/structureborne noise to interior vibration from exterior sources of ground vibration will be included.

Vibration Transfer Path Analysis and Path Ranking for NVH Optimization of a Vehicle Interior

By new advancements in vehicle manufacturing, evaluation of vehicle quality assurance has got a more critical issue. Today noise and vibration generated inside and outside the vehicles are more important factors for customers than before. So far several researchers have focused on interior noise transfer path analysis and the results have been published in related papers but each method has its own limitations. In present work, the vibration transfer path analysis and vibration path ranking of a car interior have been performed. As interior vibration is a source of structural borne noise problem, thus, the results of this research can be used to present the structural borne noise state in a vehicle. The proposed method in this paper does not need to disassemble the powertrain from the chassis. The procedure shows a good ability of vibration path ranking in a vehicle and is an effective tool to diagnose the vibration problem inside the vehicle. The simulated vibration spectrums in different speeds of the engine have a good compliance with the tested results; however, some incompatibilities exist and have been discussed in detail. The simulated results show the strength of the method in engine mount optimization.

Study on High-speed Train Abnormal Interior Vibration and Noise Related to Wheel Roughness

Based on field tests of high-speed coaches X and Y, the characteristics and mechanisms of the abnormal interior noise and vibration occurred in the type X coach are investigated. In the field tests, the test coaches are running at the same operation speed and similar exterior air turbulence and track excitation. The two types of coaches are contiguously marshaled in the adjacent positions of a same train, both of which are motors. A long-term monitoring and analysis of the wheel wear status and the interior vibration-noise of coaches X and Y marshaled in trains are conducted focusing on the relationship between the interior abnormal noise and the non-circular wear of wheels. The test results shows that the type X coach generates higher abnormal vibration and noise than type Y coach. The abnormal vibration and noise are sensitive to the high-order polygonal wear of the coach wheels. It is also found that the higher vibration and noise on type X coach is related to its special interior structural.

Analysis of Tire Tread Pattern’s Impact on Interior Vibration and Noise Based on Wavelet Transform

The path of tire pattern’s impact on interior noise and vibration was analyzed. The same type tires with six kinds of different tread pattern were selected as the investigating subjects, and the interior measuring points’ vibration and noise signals of different tires were measured under full load condition. The basic theory of Wavelet Transform (WT) and its signal reconstruction principle were researched, and 1/3 octave Morlet wavelet was induced and analyzed. The vibration and noise signals of measuring points were transformed by using 1/3 octave Morlet wavelet, distribution features of vibration and noise signals of six tires with different tread pattern were made a comparison in time domain and frequency domain, and the distinct results of different tires were achieved. The advantage of WT in the aspect of time-frequency analysis for time domain signal is revealed.

Investigation on Technology of Automobile Vibration and Noise Reduction Based on Body-In-White Structure

The automotive body system is not only a source for directly radiating noise into the vehicle interior space, but also a key component for transmitting various vibrations and noise. The optimization of the modes for body-in-white has significant meanings for improving the reliability and NVH (Noise, Vibration and Harshness) performance of the whole vehicle. Based on the current situation that there is more severe interior vibration and noise problem occurring in driving for a light passenger vehicle, a hybrid modal analysis method combined with experiment and simulation methods is applied to investigate the vibration and noise characteristics of the whole vehicle body. By performing such modal analysis, the modal frequencies of the auto-body are improved effectively by strengthening the vibration sensitive regions in the body structure. The experiment for measuring interior vibration and noise levels under cruise condition is conducted to validate that the structural optimization for body-in-white has significant contribution for improving the whole vehicle NVH performance.

267有限要素法を援用した構造体の振動インテンシティ計測

Many studies about structural intensity (SI) measurement, which is useful to know transmission paths of the vibration energy in a body, have been reported. Most of the works, however, have been done only for thin bodies, such as beams or plates because of the difficulty in measuring interior vibration distribution in thick structures. In this paper, a new SI measurement method applicable to thick bodies is proposed. In the method, the entire vibration distribution in the structure is estimated form limited number of the measured partial surface vibration data with the aid of dynamic analysis of finite element method (FEM). The entire SI distribution is calculated using the estimated vibration and stress distributions. Several SI measurements for thick vibrating bodies have been successfully carried out by the proposed method.

FEM aided structural intensity measurement method for thick body

Many studies about structural intensity(SI) measurement, which is useful to know transmission paths of the vibration energy in a body, have been reported. Most of the works, however, have been done only for thin bodies, such as beams or plates because of the difficulty in measuring interior vibration distribution in thick structures. In this paper, a new SI measurement method applicable to thick bodies is proposed. The entire vibration distribution in the structure is calculated by dynamic analysis of the finite element method (FEM) from the partial surface vibration data if the elastic parameters, the sound velocity, sizes of a body under study, and the locations of excitation and absorption are given a priori. The entire SI distribution can be estimated using the results. Based on this method, several SI measurements for thick vibrating bodies have been successfully carried. The merits of this method are as follows. (1) Only surface vibration data of the structure is needed to estimate the entire SI distribution. (2) It is applicable for arbitrary 3-D structures if the conditions mentioned above are satisfied a priori. The principle and the experimental results are described in the report.