Automobile Passenger Compartment Research Articles

Moment-Based Hybrid Polynomial Chaos Method for Interval and Random Uncertain Analysis of Periodical Composite Structural-Acoustic System with Multi-Scale Parameters

An interval and random moment-based arbitrary polynomial chaos method (IRMAPCM) is proposed in this paper for the analysis of periodical composite structural-acoustic systems with multi-scale uncertain-but-bounded parameters. In IRMAPCM, the response of structural-acoustic system is approximated as moment-based arbitrary polynomial chaos (maPC) expansion. IRMAPCM can construct the polynomial basis according to the moment of the random variable without knowing the Probability Density Function (PDF), which can avoid the errors introduced by estimating the PDF. Numerical examples of a hexahedral box and an automobile passenger compartment are given to investigate the effectiveness of IRMAPCM for the prediction of the sound pressure response of structural-acoustic systems.

Hybrid interval and random analysis for structural-acoustic systems including periodical composites and multi-scale bounded hybrid uncertain parameters

Abstract For the response analysis of periodical composite structural–acoustic systems with multi-scale uncertain-but-bounded parameters, a bounded hybrid uncertain model is introduced, in which the interval variables and the bounded random variables exist simultaneously. In the periodical composite structural–acoustic system, the equivalent macro constitutive matrix and average mass density of the microstructure are calculated through the homogenization method. On the basis of the conventional first-order Taylor series expansion, a homogenization-based hybrid stochastic interval perturbation method (HHSIPM) is developed for the prediction of periodical composite structural–acoustic systems with multi-scale bounded hybrid uncertain parameters. By incorporating the Gegenbauer polynomial approximation theory into the homogenization-based finite element method, a homogenization-based Gegenbauer polynomial expansion method (HGPEM) is also proposed to calculate the bounds of expectation and variance of the sound pressure response. Numerical examples of a hexahedral box and an automobile passenger compartment are given to investigate the effectiveness of the HHSIPM and HGPEM for the prediction of periodical composite structural–acoustic systems with multi-scale bounded hybrid uncertain parameters.

Microstructural topology optimization of structural-acoustic coupled systems for minimizing sound pressure level

The aim of this paper is to present a microstructural topology optimization methodology for the structural-acoustic coupled system. In the structural-acoustic system, the structure is considered to be a thin composite plate composed of periodic uniform microstructures. The discrete design variables are used in the microstructural topology optimization, and the constitutive matrix is interpolated by the power-law scheme at the micro scale. The equivalent macro material properties of the microstructure are computed through the homogenization method. The design objective is to minimize the sound pressure level (SPL) in an interior acoustic medium. The sensitivities of the SPL with respect to design variables are derived. The bi-directional evolutionary structural optimization (BESO) method is extended to solve the structural-acoustic coupled optimization problem to find the optimal material distribution of the microstructure. Numerical examples of a hexahedral box and an automobile passenger compartment are given to demonstrate the efficiency of the presented microstructural topology optimization method.

Homogenization-based interval analysis for structural-acoustic problem involving periodical composites and multi-scale uncertain-but-bounded parameters.

This paper presents a homogenization-based interval analysis method for the prediction of coupled structural-acoustic systems involving periodical composites and multi-scale uncertain-but-bounded parameters. In the structural-acoustic system, the macro plate structure is assumed to be composed of a periodically uniform microstructure. The equivalent macro material properties of the microstructure are computed using the homogenization method. By integrating the first-order Taylor expansion interval analysis method with the homogenization-based finite element method, a homogenization-based interval finite element method (HIFEM) is developed to solve a periodical composite structural-acoustic system with multi-scale uncertain-but-bounded parameters. The corresponding formulations of the HIFEM are deduced. A subinterval technique is also introduced into the HIFEM for higher accuracy. Numerical examples of a hexahedral box and an automobile passenger compartment are given to demonstrate the efficiency of the presented method for a periodical composite structural-acoustic system with multi-scale uncertain-but-bounded parameters.

Solution for Improvement the Thermal Comfort inside the Automobile Passenger Compartment

Raising the thermal comfort inside the car is a primary task of the car manufacturers and therefore the process of designing an optimal solution to improve the parameters of the thermal comfort is considered to have a tremendous importance. Considering this, in this paper we aim to adapt within the car a system of air conditioning which is used in the classical way, especially in the civil engineering industry. The proposed solution consists of designing a chamber used for the fluid preparation. The system includes some preset modules of the parameter values for the thermal comfort depending on climate and season, and also the possibility to customize the standard settings with the preferred ones of the vehicle occupants. This way it will be maintained a high level of thermal comfort and also the risks of accidents will be reduced (the driver can focus on the driving act instead of setting the parameters for thermal comfort). The paper also shows an experimental stand which can be used to study the thermal comfort parameters such as air temperature, humidity and air velocity and also to collect the results.

A coupled smoothed finite element method (S-FEM) for structural-acoustic analysis of shells

In this paper, a coupled smoothed finite element method (S-FEM) is developed to deal with the structural-acoustic problems consisting of a shell configuration interacting with the fluid medium. Three-node triangular elements and four-node tetrahedral elements that can be generated automatically for any complicated geometries are adopted to discretize the problem domain. A gradient smoothing technique (GST) is introduced to perform the strain smoothing operation. The discretized system equations are obtained using the smoothed Galerkin weakform, and the numerical integration is applied over the further formed edge-based and face-based smoothing domains, respectively. To extend the edge-based smoothing operation from plate structure to shell structure, an edge coordinate system is defined local on the edges of the triangular element. Numerical examples of a cylinder cavity attached to a flexible shell and an automobile passenger compartment have been conducted to illustrate the effectiveness and accuracy of the coupled S-FEM for structural-acoustic problems.

A new random interval method for response analysis of structural–acoustic system with interval random variables

For the response analysis of the structural–acoustic system without sufficient information, an interval random model is introduced. In the interval random model, the uncertain parameters are assumed as random variables, while some probability distribution parameters of random variables are modeled as interval parameters instead of precise values. Based on the interval random model, the interval random dynamic equation is constructed and a new random interval method named as the random moment – change of variable interval stochastic perturbation method (RM-CVISPM) is proposed. In RM-CVISPM, the response of the structural–acoustic system is approximated as a linear function of interval random variables based on the first-order stochastic perturbation analysis. Then, the expectation and variance of the obtained response are calculated by the random moment method. The probability density of the obtained response is yielded by the change of variable technique. Finally, the intervals of expectation, variance and probability density of response are estimated by an interval perturbation method. Numerical results on a shell structural–acoustic model and an automobile passenger compartment with flexible front panel verify the effectiveness and efficiency of RM-CVISPM.

Research on the Relation between Automotive Air Conditioning Supply-Air Direction and Cooling Efficiency about Thermal Field of the Passenger Compartment

The cooling process of unsteady temperature field in the automobile passenger compartment is simulated , making use of computational fluid dynamics software FLUENT and the algorithm of PBCS ,and two equation model is replaced with the three-dimensional turbulence model. And then the workflow is established, which includes DOE, optimization algorithm, approximate model and the numerical simulation. Numerical simulations uses experimental design method to collect data for analysis into the relations and trends of the supply-air direction and the cooling efficiency.The sample points train approximation model, using radial basis function (RBF) neural network approximation model instead of the high cost of the simulation calculation. Multi-island GA is chosen to optimize the supply-air direction. The supply-air direction optimized and the supply-air direction vertical surface of inlet tuyere are calculated by simulation software respectively.Results show that the optimized direction making the car chamber cooling effect is remarkable, by the analysis of the heat flow value and temperature contours of before and after optimization.

An interval random perturbation method for structural‐acoustic system with hybrid uncertain parameters

SUMMARYAn interval random model is introduced for the response analysis of structural‐acoustic systems that lack sufficient information to construct the precise probability distributions of uncertain parameters. In the interval random model, the uncertain parameters are treated as random variables, whereas some distribution parameters of random variables with limited information are expressed as interval variables instead of precise values. On the basis of the interval random model, the interval random structural‐acoustic finite element equation is constructed, and an interval random perturbation method for solving this interval random equation is proposed. In the proposed method, the interval random matrix and vector are expanded by the first‐order Taylor series, and the response vector of the structural‐acoustic system is calculated by the matrix perturbation method. According to the linear monotonicity of the response vector, the lower and upper bounds of the response vector are calculated by the vertex method. On the basis of the lower and upper bounds, the intervals of expectation and standard variance of the response vector are obtained by the random interval moment method. The numerical results on a shell structural‐acoustic model and an automobile passenger compartment with flexible front panel demonstrate the effectiveness and efficiency of the proposed method. Copyright © 2013 John Wiley & Sons, Ltd.

Structural-Acoustic Analysis of Automobile Passenger Compartment

Besides the performances of handling, stability, ride comfort, power and fuel economy, the sound pressure levels in the automobile passenger compartments heavily influence the customer’s purchasing decision. The interior acoustics of automobile passenger compartment was analyzed in this paper. The frequency response analysis was performed on the vehicle body due to road roughness. The frequency response of vehicle body’s output spectrum, nodes’ velocity is used as the boundary condition of the acoustic cavity. With boundary element method and acoustic transfer vector method, the panel acoustic contribution was analyzed. By modifying the stiffness, damping or mass of the corresponding panel, the acoustic pressure levels at the driver’s and passenger’s ear were decreased.

Experimental investigation of different active noise control concepts applied to a passenger car equipped with an active windshield

The main purpose of this work is the implementation and experimental investigation of different active structural acoustic control (ASAC) concepts for the reduction of interior noise in an automobile passenger compartment. For the control experiments, a medium-class test car was used, which had been equipped with an active windshield. The active windshield consists of the serial-production laminated glass pane augmented with piezoceramic patch-transducers applied to the blackened rim of the windshield. A multi-reference test provided measurement data for the identification of a local discrete-time state-space model (SSM). The subsequent acquisition of frequency response functions (FRF) by way of using the same actuators but measuring on a much finer grid provided the database for the formulation of a least-squares problem to derive a global system model. Based on the local and global discrete-time SSMs, different controllers were designed and experimentally realized. The comparison of the vibration levels in open- and closed-loop showed a global reduction of 5–7dB in the acoustically relevant frequency band containing the second and third structural resonance of the windshield system. The occurrence of complex operational deflection shapes (ODS) was identified as the main limitation concerning the disturbance rejection of the active system. The acoustic performance of the ASAC system is reflected in a reduction up to 15dB in sound pressure level (SPL).

Modeling of temperature and humidity ratio in an automobile passenger compartment for automobile air conditioning systems

This study investigates thermal dynamic modeling of a passenger compartment in an air conditioned automobile equipped with HVAC (heating, ventilation, and air conditioning). In particular, dynamics of temperature and humidity ratio, both critical to passenger comfort, in the passenger compartment are examined. By analyzing enthalpy change during an automobile air conditioning circulation cycle on a psychrometric chart, heat exchange between outside environment and the passenger compartment can be modeled as functions of operation settings of the HVAC. With enthalpy content decomposed into sensible heat and latent heat, changes in heat content can be attributed to the changes in the corresponding temperature and humidity ratio, respectively. Consequently, impacts resulting from the mismatch between two heat characteristics on temperature and humidity ratio can be formulated accordingly: room sensible heat factor (RSHF) of the passenger compartment and apparatus sensible heat factor (ASHF) of the HVAC. A Matlab/Simulink simulation is implemented to verify the proposed model under several control policies that either maintain constant enthalpy or maintain constant temperature in the passenger compartment. With these two temperature and humidity ratio models derived, further research on designing control policies to achieve better passenger comfort for general automobile air conditioning systems can be derived and tested.

Panel contribution analysis for the interior region of a complex structure using the Helmholtz equation least squares method.

The paper presents an experimental study on using Helmholtz equation least squares based nearfield acoustic holography to perform panel contribution analysis inside a complex structure with overall dimensions of 21 × 14 × 14 in.3 in the shape of an automobile passenger compartment. A point random force was used to excite this structure. The radiated acoustic pressures were measured by a linear array of 13 microphones scanning over the interior surface at close distances, resulting in 520 measurement points. These measured acoustic pressures were used to reconstruct the vibro-acoustic responses, including the normal surface velocity (NSV) and surface acoustic pressures (SAPs) of the cabin. Next, the reconstructed NSV and SAP are used to determine the normal-component of the time-averaged acoustic intensity on the surface, which was then correlated to the sound pressure level at any field point, say, at the driver ear position inside the cavity. The relative contributions from individual panels toward a specific field point are calculated by summing the acoustic power flow from individual panels, and their ranking is determined. The major advantage of this approach is that panel contributions toward any number of field points can be determined based on a single set of measurements.

自動車室内における乗員への車室内長波放射と日射の影響

We discuss the dynamical simulation model of thermal environment for automobile passenger compartments with passengers that is useful for the development of automobile air-conditioning systems. In our previous research, we proposed the model of this type with the consideration of accuracy and computation complexity, however, proposed model was insufficient to simulate the influence of emission and insolation on the thermal environment of the automobile passenger compartment with passengers.In this paper, we focus on the emission and the insolation, and try to model the influence of those on the thermal environment of the automobile passenger compartments with passengers. For the emission analysis, we compute view factors based on the 3D model of automobile and human body (passenger), and adopt Gebhart’s method to consider the absorption and the reflection of the emission at the surface of the automobile passenger compartment and the passengers. While, for the insolation, we compute the spectral insolation based on date, time, location, and attitude of the automobile by using solar geometry algorithm and spectral insolation model (SPECTRAL2), and evaluate the effect of the insolation on the thermal environment of the automobile passenger compartment with passenger by Gebhart’s method.

Helmholtz equation least squares based panel contribution analysis.

This paper presents a methodology for analyzing relative contributions from individual panels toward the sound pressure field inside a large enclosure, for example, an aircraft cabin, automobile passenger compartment, etc., due to sound transmission from external acoustic sources, structural vibrations, or their combinations. In this approach, the field acoustic pressure is correlated directly to the normal component of the time‐averaged surface acoustic intensity, which is reconstructed based on acoustic pressures measured by microphones in the near field of a structure using Helmholtz equation least squares method. The normal surface acoustic intensities are calculated on individual panels; therefore their relative contributions toward sound radiation at any field point can be evaluated and ranked. This approach is advantageous over those based on a reciprocally measured transfer function [Hald et al., Internoise (2006); Wolff, Internoise (2007)] in that panel contributions are done by taking a single set of measurements, and results are valid for all interior points. To validate this methodology, numerical simulations are conducted for a spherical enclosure for which the analytic solutions are readily available. Specific examples of numerical simulations include a dilating spherical and a partially vibrating sphere. Finally, experimental results using this methodology for a full‐size vehicle are demonstrated.

An Equivalent-Acoustic Finite Element Method for Modeling Sound Absorbing Materials

An equivalent-acoustic finite element method is developed for modeling sound absorbing materials, such as seats and interior trim in the automobile passenger compartment. The equivalent-acoustic method represents the sound absorbing material using acoustic finite elements with frequency-dependent material properties determined from the measured acoustic impedance of sound absorbing material samples. Solution of the equivalent-acoustic model within the Nastran computer capability and coupling of the model with an acoustic finite element model of a surrounding enclosure, such as the passenger compartment, are developed. The accuracy of the equivalent-acoustic method is assessed for modeling a sound absorbing material in a one-dimensional impedance tube, a foam layer in a rectangular box enclosure, and an automotive seat in a semi-reverberant enclosure.

Acoustic optimisation design for suspension characteristics based on the method of dynamic subsystem modification

Based on the finite element technique on the structure-acoustic coupling analysis, a dynamic subsystem modification method for the acoustic-vibration characteristic of an elastic thin-walled cavity is introduced in this paper. It is directly applied to the dynamic modification of an automobile's passenger compartment and then supports the Noise, Vibration and Harshness (NVH) performance analysis on the suspension system. The design objective is minimising the sound pressure level of the interior noise of the passenger compartment and the design variables are the stiffness and the damping of suspension system. Finally, the effect of the optimisation design is validated through a calculating example.

外部環境，乗員および空調の影響を考慮した自動車室内温度の区分モデルに基づく動的シミュレーション―実験による検証

The objective of this paper is to discuss the temperature environment model of automobile's passenger compartments for the analysis of comfortableness and the design of air-conditioning control. To consider the comfortableness, it is necessary to model the distribution of the temperature since almost all the people do not feel the uniform temperature environment to be comfortable. In this paper, we construct the dynamical model of the temperature environment by piecewise modeling technique in which the passenger compartment is divided into plural areas to consider the temperature distribution. And then we verify the performance of the model by comparing the simulation results of the model with experimental results.

Evaluation of asthmatic volunteers' pulmonary responses to effluents from automotive airbags

Deploying automotive airbags release potential respiratory irritants at high concentrations. We evaluated the respiratory irritancy of six contemporary prototype driver/passenger airbag systems, using a previously established USA auto industry protocol for human testing. For each system, ten volunteers with asthma were exposed individually inside an automobile passenger compartment, during deployment and for 20 minutes afterwards. Symptoms and lung function were monitored for two hours after exposure. All airbag systems fulfilled the established standard of no more than three in ten subjects with positive response (defined as clinically meaningful lung function disturbance plus increased asthma symptoms). Three systems evoked no positive responses. Statistically significant (P<0.005) differences in lung function and symptom responses between systems were not accurately predictable from measured pollutant concentrations. Conclusions: contemporary airbag designs vary appreciably in their potential to provoke asthma. Airbag testing with potentially susceptible human subjects can be useful in pre-market evaluation.

Prediction method of passenger's thermal sensation by numerical simulation of air flow in an automobile passenger compartment

Prediction method of passenger's thermal sensation by numerical simulation of air flow in an automobile passenger compartment