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Journal Article

Uncertainty Analysis of High-Frequency Noise in Battery Electric Vehicle Based on Interval Model

Abstract The high-frequency noise issue is one of the most significant noise, vibration, and harshness problems, particularly in battery electric vehicles (BEVs). The sound package treatment is one of the most important approaches toward solving this problem. Owing to the limitations imposed by manufacturing error, assembly error, and the operating conditions, there is often a big difference between the actual values and the design values of the sound package components. Therefore, the sound package parameters include greater uncertainties. In this article, an uncertainty analysis method for BEV interior noise was developed based on an interval model to investigate the effect of sound package uncertainty on the interior noise of a BEV. An interval perturbation method was formulated to compute the uncertainty of the BEV’s interior noise.
Journal Article

Structural Optimization Techniques to Design Light Weight and Low Radiated Noise Components

Abstract Structural optimization evolved as a preferred technique across industries to develop lightweight products. One of the widely studied topics in structural optimization is to develop methods that reduce the radiated noise from a structure, where responses like Equivalent Radiated Power (ERP) and natural frequencies used to indirectly address the noise levels. This article compares freeform optimization with topology optimization technique and investigates their effectiveness for reducing radiated noise and weight. To illustrate the same, Finite Element Method (FEM) and Boundary Element Method (BEM) analysis are performed on a sheet metal flat plate (panel) as an example and correlated the same with experimental data. Further, different optimization problem formulations have been explored on those examples and results have been compared.
Journal Article

Resolution of HEV Battery Cooling System Inlet Noise Issue by Optimizing Duct Design and Fan Speed Control Strategy

Abstract The power battery cooling system of a hybrid electric vehicle is composed of a fan and duct assembly with its inlet positioned inside the vehicle cabin. For the prototype vehicle considered in this work, the air inlet is positioned on the package tray due to limited feasible choices. When the battery temperature is over rated limit, the cooling fan starts to operate to cool the battery system. Propelled by the fan in the cooling system, the air in the passenger compartment enters the duct inlet, and rushes through the air duct to reach the battery pack to fulfill the intended cooling function. In this case, the rear seat occupants could clearly perceive the existence of an annoying whirring noise. In this paper, the characteristics of the battery air cooling system and its working principles are briefly described. The air inlet noise generation mechanism and its frequency characteristics are then analyzed.
Journal Article

Influence of Rib Stiffener Design Parameters on the Noise Radiation of an Engine Block

Abstract Stiffener ribs are widely used to increase the stiffness of engine blocks, shifting the vibration modes to higher frequencies where excitation is weaker so that radiated noise can be reduced. The effect of different rib design parameters on the radiated noise emission of a diesel engine has been investigated considering its impact on block weight. A heavy-duty engine block was modeled using finite element method, multi-body dynamics approach was used to determine the excitation forces acting due to combustion pressure and inertias, and boundary element method was used to find the acoustic transfer vectors which give the relationship between engine surface velocities and sound pressure levels at predetermined microphone locations. Initially, the baseline analytical sound pressure level and surface velocity results for the engine without ribs were obtained. Two prototype engines, with and without stiffened ribs, were tested in an acoustic dynamometer in complete speed range.
Journal Article

Force Transmission Characteristics for a Loaded Structural-Acoustic Tire Model

Abstract Concerns about tire noise radiation arise partly from city traffic planning, environmental protection, and pedestrian safety standpoints, while from the vehicle passengers’ perspective, noise transmitted to the vehicle interior is more important. It is the latter concern that is addressed in this article. Sound-absorbing materials generally offer good absorption at higher frequencies, but the reduction of relatively low frequency, structure-borne tire noise is a continuing focus of many auto manufacturers. A tire’s internal, acoustic cavity resonance is a very strong contributing factor to tire-related structure-borne noise, and it can easily be perceived by passengers. Some reduction of vehicle cabin noise can be achieved through the insertion of sound-absorbing material in the tires. However, apart from the additional cost for such tires, there is also an increased complexity when repairing them because of the need to avoid damaging the sound-absorptive lining.
Journal Article

Feature-Based Response Classification in Nonlinear Structural Design Simulations

Abstract An applied system design analysis approach for automated processing and classification of simulated structural responses is presented. Deterministic and nonlinear dynamics are studied under ideal loading and low noise conditions to determine fundamental system properties, how they vary and possibly interact. Using powerful computer resources, large amounts of simulated raw data can be produced in a short period of time. Efficient tools for data processing and interpretation are then needed, but existing ones often require much manual preparation and direct human judgement. Thus, there is a need to develop techniques that help to treat more virtual prototype variants and efficiently extract useful information from them. For this, time signals are evaluated by methods commonly used within structural dynamics and statistical learning. A multi-level multi-frequency stimulus function is constructed and simulated response signals are combined into frequency domain functions.
Journal Article

Explanation for Variability in Lower Frequency Structure-Borne Noise and Vibration: Roles of Rear Subframe Dynamics and Right-Left Spindle Phasing

Abstract This investigation focuses on a class of rear suspension systems that contain both direct and intersecting structural paths from the tire contact patches to the vehicle body. The structural paths intersect through a dynamically active rear subframe structure. New experiments and computational models are developed and analyzed in this article to investigate the variability of structure-borne noise and vibration due to tire/road interactions in the lower- to mid-frequency regimes. Controlled operational experiments are conducted with a mass-production minivan on a chassis dynamometer equipped with rough road shells. Unlike prior literature, the controlled experiments are analyzed for run-run variations in the structure-borne noise up to 300 Hz in a single vehicle to evaluate the nature of excitations at the spindle as the key source of variation in the absence of significant manufacturing, assembly and instrumentation errors.
Journal Article

Direct Versus Indirect Acting Piezoelectric CR Injectors: Comparison of Hydraulic Performance, Pollutant Emissions, Combustion Noise, and Fuel Consumption

Abstract A comprehensive comparison between a direct acting and an indirect acting piezoelectric injector has been carried out both at the hydraulic rig and at the dynamometer cell. The working principle of these injector typologies is illustrated, and their hydraulic performance has been analyzed and discussed on the basis of experimental data collected at a hydraulic test rig. The injector characteristics, nozzle opening and closure delays, injector leakages, injected flow-rate profiles, injector-to-injector variability in the injected mass, injected volume fluctuations with the dwell time (DT), and minimum DT for fusion-free multiple injections have been compared in order to evaluate the impact of the injector driving system on the injection apparatus performance. The direct acting and indirect acting piezoelectric injectors have been installed on a Euro 5 diesel engine, which has been tested at a dynamometer cell.
Journal Article

Application of Multi-Attribute Weighted Gray Target Decision in Automobile Noise Reduction Scheme Evaluation

Abstract In the selection of automobile noise reduction schemes, the lack of comprehensive quantitative index system and objective evaluation method is a serious problem. In this article, the methods of analytic hierarchy process (AHP) and gray target decision were used to solve the problem. Firstly, AHP and gray target decision method were introduced respectively in detail. Secondly, three automobile noise reduction schemes were illustrated. Four types of data were selected as the decision indexes, and the weight coefficients of all the decision indexes were calculated using the AHP. Then multi-attribute mixed weighted gray target decision model was established. The optimum scheme was obtained by the calculation of the off-target distance and the sorting of the calculation results. The proposed method can quantify the evaluation process and overcome the disadvantages of the traditional analogy method. The example shows that the method is feasible.
Journal Article

A Review on Physical Mechanisms of Tire-Pavement Interaction Noise

Abstract Tire-pavement interaction noise (TPIN) dominates for passenger cars above 40 km/h and trucks above 70 km/h. Numerous studies have attempted to uncover and distinguish the basic mechanisms of TPIN. However, intense debate is still ongoing about the validity of these mechanisms. In this work, the physical mechanisms proposed in the literature were reviewed and divided into three categories: generation mechanisms, amplification mechanisms, and attenuation mechanisms. The purpose of this article is to gather the published general opinions for further open discussions.