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Showing 10 results for Subject: Vibration, noise, Acoustic

A. Fotouhi, M. Montazeri, M. Jannatipour,
Volume 1, Issue 1 (1-2011)

This paper presents the prediction of vehicle's velocity time series using neural networks. For this purpose, driving data is firstly collected in real world traffic conditions in the city of Tehran using advance vehicle location devices installed on private cars. A multi-layer perceptron network is then designed for driving time series forecasting. In addition, the results of this study are compared with the auto regressive (AR) method. The least root mean square error (RMSE) and median absolute percentage error (MDAPE) are utilized as two criteria for evaluation of predictions accuracy. The results demonstrate the effectiveness of the proposed approach for prediction of driving data time series.
Dr. Javad Marzbanrad, Mr Mohammad Hafezian, Mr Mehdi Mozaffarikhah,
Volume 9, Issue 1 (3-2019)

In this paper, the acoustic analysis of noise has been done in automotive cabin at high speed. High-frequency noise sources are applied separately to the roof and floor panels as well as to the windshield of the vehicle, which has been investigated at both the driver's and rear passenger's head. The most important panels that have the most noise emission are specified. In order to analyze high frequencies, the Statistical Energy Analysis (SEA) method has been used; also, the Response Surface Methodology (RSM) has been used to obtain optimized panel in terms of minimally weighing and maximum noise reduction. The results show that the proposed panels with unconstrained rubber layer can reduce the cabin interior aerodynamically generated noise more than %6.
Mrs Ghazal Etesami, Dr Mohammad Ebrahim Felezi, Prof Nader Nariman-Zadeh,
Volume 9, Issue 3 (9-2019)

The present paper aims to improve the dynamical balancing of a slider-crank mechanism. This mechanism has been widely used in internal combustion engines, especially vehicle engines; hence, its dynamical balancing is important significantly. To have a full balance mechanism, the shaking forces and shaking moment of foundations should be eliminated completely. However, this elimination is usually impossible. Hence, in the current study, a multi-objective optimization is carried out to maintain the optimal balance of mechanism. The vertical and horizontal components of shaking forces and shaking moment are considered as objective functions. Also, the design variables are included the mass, the moment of inertia and the mass center location of mechanism links. The length of mechanism links is also considered constant for achieving a fixed slider course. The four-objective optimization is applied using a differential evolution algorithm. The optimization results are presented in Pareto diagrams as suitable tools for selecting a mechanism with desired characteristics according to the importance of each objective function. The optimal mechanism is finally introduced by the mapping method. The comparison of optimized mechanisms and the original one indicates a significant reduction of shaking forces and shaking moment as well as the reduction of energy consumption.

Seyyed Hamed Tabatabaei, Saeed Moradi Haghighi, Amirhossein Kiani, Kasra Ghasemian,
Volume 11, Issue 2 (6-2021)

In this paper, an optimized insulator for sound packaging of the vehicle dash panel is proposed. The combination of the micro perforated panel and porous layers has been selected to insulate the dash panel of a vehicle.  The main advantages of the mentioned combination are light weight and various tunable parameters in comparison with other insulators. These provide significant flexibility to achieve an optimal performance for the noise attenuation of the vehicle cabin. Therefore, the parameters of the selected sound package have been optimized in order to achieve suitable sound absorption in a selected frequency range. Furthermore, the Genetic Algorithm (GA) is used to optimize the parameters. It can achieve more reliable and more accurate outcomes compared to the conventional method.  Full vehicle SEA (Statistical Energy Analysis) simulations are used to evaluate the optimized sound package. The results indicate that the optimized concept has maximum sound absorption capability.  Consequently, the proposed sound package improves the vehicle's engine noise reduction by 5 dB in comparison with un-optimized sample in mid and high frequency ranges.
Dr. Mohammad Salehpour, Dr. Ahmad Bagheri,
Volume 11, Issue 3 (9-2021)

In this study, a multi-objective differential evolution with fuzzy inference-based dynamic adaptable mutation factor with hybrid usage of non-dominated sorting and crowding distance (MODE-FM) is utilized for Pareto optimization of a 5-degree of freedom nonlinear vehicle vibration model considering the five conflicting functions simultaneously, under different road inputs. The significant conflicting objective functions that have been observed here are, namely, vertical seat acceleration, vertical forward tire velocity, vertical rear tire velocity, relative displacement between sprung mass and forward tire and relative displacement between sprung mass and rear tire. Different road inputs are, namely, double-bump, stationary random road and non-stationary random road. It is exhibited that the optimum solutions of 5-objective optimization contain those of 2-objective optimization and, as a result, this important matter creates more options for optimal design of nonlinear vehicle vibration model.
Mahsa Rahimbeigi, Dr. Abolfazl Khalkhali, Amirali Parivar,
Volume 11, Issue 4 (12-2021)

Elastomeric engine mounts are being used in heavy vehicles as well as passenger cars to absorb the vibrations of the engine, carry its weight and reduce its movement while driving. The aim of this research is some studies that have been done to find the components of the elastomeric compound. Moreover, the feasibility study of constructing three different specimens with different percentages of soot and oil has been carried out in order to achieve the desired characteristics in the heavy vehicle engine mount. A rheometric test was then performed to determine the temperature and time of sintering. The tensile strength test has been used to determine the elasticity of the rubber specimens and to achieve high damping coefficients. Also the tensile strength test was performed with the aim of obtaining a specimen with a suitable stress-strain relationship and comparing the results with the reference engine mount. Consequently, the elastomeric compound is used to make the elastomeric engine mount of heavy duty vehicle in the form of rubber and reverse engineering.
Yavar Nourollahi Golouje, Seyyed Mahdi Abtahi, Majid Majidi,
Volume 12, Issue 2 (6-2022)

In this paper, analysis and control of the chaotic vibrations in bounce dynamic of vehicle have been studied according to the comparison of controller based on the nonlinear control and chaos controller on the basis of the chaotic system properties. After modeling the vehicle dynamic, the chaotic behavior of the uncontrolled system was determined using combination of the numerical analysis including bifurcation diagrams and max Lyapunov exponent. The system parameters values were then identified in the quasi-periodic and chaotic behavior system. In order to eliminate the chaotic vibrations, the control signal was first developed using a nonlinear fast-terminal sliding mode control algorithm that its control gains are estimated online by fuzzy logic which was designed for vehicle vertical dynamics. Then the delayed feedback control was designed based on the development of Pyragas algorithm to control the system based on the properties of the chaotic system and generation of a small control signal. Comparison of the feedback system depicts priority of the Fuzzy-Pyragas controller in less energy consumption and better behavior.
Dr Eric Amoah Asante, Mr Randy Amuaku,
Volume 12, Issue 4 (12-2022)

Due to increase in the number of goods carrying tricycles, the amount of noise and pollution on our roads has increased. To optimize the control of the engine noise emission for tricycle, different absorptive material liners have been introduced into muffler design. In this study, the performance of Aerogel, Ceramic, Kenaf fibre, Polyester and Rockwool as absorptive material liners on the transmission loss under 20 ℃, 60 ℃, 100 ℃, 150 ℃ and 200 ℃ temperature treatment for goods carrying tricycle was evaluated. The analysis averaged over all temperature treatments showed that introducing absorptive materials into the muffler improved the performance by 71.56 %, 84.12 %, 86.31 %, 89.37 % and 93.99 % for Aerogel, Rockwool, Ceramic, Polyester and Kenaf fibre respectively. Similarly, analysis averaged over all absorptive material treatments disclosed that the muffler with absorptive material liner under 60 ℃, 100 ℃, 150 ℃ and 200 ℃ temperature treatment improved the performance over the muffler without a liner by 85.1 %, 80.8 %, 87.5 % and 92.3 % respectively. The flow resistivity values for the absorptive material liners used was inversely proportional to the transmission loss except the Kenaf fibre which had the highest transmission loss though with second highest flow resistivity. PLSR analysis showed that Aerogel, Rockwool, Ceramic, Polyester and Kenaf fibre yielded better prediction accuracy than the No liner by 33.88%, 32.75%, 30.45%, 30.41% and 22.35% respectively. The study has confirmed that introducing absorptive material liners in mufflers used by goods carrying tricycles can optimize the performance.
Hamidreza Ebrahimi, Mohammadhassan Shojaeifard, Salman Ebrahimi-Nejad,
Volume 13, Issue 2 (6-2023)

The present study aims to optimize a two-chamber muffler’s geometry and improve its acoustic performance. Mufflers with a circular cross-section are used in this study and then underwent the vibroacoustic analysis using COMSOL Multiphysics software. Several geometries, including a reference model and new ones, are designed and their geometry is optimized by Parametric and grid optimization methods, which are the software’s optimization methods. First, the reference paper is validated to ensure the simulation produces the least error. The results obtained in this study have a good match with those of the reference. Then, by changing dimensions such as length, diameter, and inner design of the mufflers, the best geometry in terms of transmission loss and bandwidth was selected and compared with the results acquired by the reference model. It was found that the acoustic performance of the optimized design (two-chamber muffler with four inner tubes) outperforms the model used in the reference. That is, the results indicate that the optimized design is able to attenuate sound up to 78dB in the range of 0 to 500Hz, 45dB higher than that of the conventional model. Further, the muffler’s weight is reduced by a quarter, using a 0.9mm thickness.

Mr Arash Darvish Damavandi, Dr Behrooz Mashhdi, Dr Masoud Masih-Tehrani,
Volume 13, Issue 3 (9-2023)

This paper investigates the performance of the hydraulically interconnected suspension system with the full vehicle model of ride and handling. A sensitivity analysis has been performed by changing the coefficients of the cylinder and accumulator valves and the initial conditions of the accumulators in the default hydraulic circuits to determine the effect on the frequency and damping of the system response such as roll, pitch, and bounce. This study highlights the importance of the influence of all system parameters to investigate vehicle vibration characteristics. The results provide valuable insights for designers and engineers working on improving automotive suspension system performance. Damping and frequency of modes change up to 179% with the change of cylinder valves and 141% with the change of accumulator valves and 74% for the initial pressure of accumulators change in mentioned range.

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