Effects of Temperature and Humidity on the Sound Absorption of Automotive Sound Absorbing Materials

ASME 2008 Noise Control and Acoustics Division Conference ◽

10.1115/ncad2008-73025 ◽

2008 ◽

Author(s):

Edward R. Green ◽

Andrea L. Zent

Keyword(s):

Automotive Industry ◽

Sound Absorption ◽

Temperature Changes ◽

Highly Sensitive ◽

Target Values ◽

Temperature And Humidity ◽

Humidity Measurements ◽

Effects Of Temperature ◽

Materials Used ◽

Absorption Measurements

Normally, small differences in day-to-day and laboratory-to-laboratory sound absorption measurements do not have large consequences because most noise control applications are not highly sensitive to small changes in sound absorption. However, in the automotive industry, materials are not purchased unless they meet strict sound absorption targets. As a result, decisions worth millions of U.S. dollars are made based on acoustic measurements. As material sound absorption moves closer to target values, the consequences of small measurement variations, such as those which might be caused by changes in ambient temperature and humidity during the course of a test, become more critical. The purpose of the work presented in this paper is to investigate which materials used for vehicle sound absorption are sensitive to temperature and humidity. Measurements are made using an impedance tube. It is discovered that typical materials used as absorbers in automotive applications are not sensitive to small temperature changes, and only a few materials are sensitive to changes in humidity.

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An optimization method for reverberation room design

INTER-NOISE and NOISE-CON Congress and Conference Proceedings ◽

10.3397/in-2021-2118 ◽

2021 ◽

Vol 263 (4) ◽

pp. 2360-2371

Author(s):

Paul Didier ◽

Cédric Van hoorickx ◽

Edwin Reynders

Keyword(s):

Sound Absorption ◽

Sound Field ◽

Optimization Procedure ◽

Optimization Method ◽

Finite Sample ◽

Low Frequencies ◽

Room Design ◽

Target Values ◽

Measured Absorption ◽

Absorption Measurements

The ISO 354:2003 standard relating to sound absorption measurements is currently under revision to improve the reproducibility of the procedure it describes. Round robin tests conducted across various reverberation rooms indeed revealed significant disparities between sound absorption measurements of the same sample. One of the reasons is that, at low frequencies, the sound field in a single laboratory cannot be considered fully diffuse. However, the average sound field across different laboratories may be considered diffuse if the interaction between the finite sample and the diffuse field is duly accounted for and the direct field close to the absorber is disregarded. In this work, a method is developed for optimizing reverberation room design such that measured absorption values are as close as possible to ensemble average diffuse values. The reverberation room is modelled using the finite element method and standardized measurements of an absorptive sample are simulated. The distance between resulting absorption coefficients and diffuse target values is minimized in an optimization procedure having the geometrical characteristics of the model as input parameters. The results are anticipated to participate to the revised ISO 354 as guidelines for the construction of new reverberation rooms or the improvement of existing ones.

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Cryo-TEM of amphiphilic polymer and amphiphile/polymer solutions

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100150216 ◽

1993 ◽

Vol 51 ◽

pp. 876-877

Author(s):

Yeshayahu Talmon

Keyword(s):

Microstructural Characterization ◽

Building Blocks ◽

Quantitative Information ◽

Physical Models ◽

Specimen Preparation ◽

Time Resolved ◽

Temperature Changes ◽

Temperature And Humidity ◽

Microstructured Fluids ◽

Air Streams

To achieve complete microstructural characterization of self-aggregating systems, one needs direct images in addition to quantitative information from non-imaging, e.g., scattering or Theological measurements, techniques. Cryo-TEM enables us to image fluid microstructures at better than one nanometer resolution, with minimal specimen preparation artifacts. Direct images are used to determine the “building blocks” of the fluid microstructure; these are used to build reliable physical models with which quantitative information from techniques such as small-angle x-ray or neutron scattering can be analyzed.To prepare vitrified specimens of microstructured fluids, we have developed the Controlled Environment Vitrification System (CEVS), that enables us to prepare samples under controlled temperature and humidity conditions, thus minimizing microstructural rearrangement due to volatile evaporation or temperature changes. The CEVS may be used to trigger on-the-grid processes to induce formation of new phases, or to study intermediate, transient structures during change of phase (“time-resolved cryo-TEM”). Recently we have developed a new CEVS, where temperature and humidity are controlled by continuous flow of a mixture of humidified and dry air streams.

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Rolling Resistance Calculation Procedure Using the Finite Element Method

Tire Science and Technology ◽

10.2346/tire.19.170158 ◽

2019 ◽

Vol 48 (3) ◽

pp. 224-248

Author(s):

Pablo N. Zitelli ◽

Gabriel N. Curtosi ◽

Jorge Kuster

Keyword(s):

Finite Element ◽

Energy Dissipation ◽

Rolling Resistance ◽

Element Model ◽

The Finite Element Method ◽

Temperature Changes ◽

Rubber Compounds ◽

Different Temperatures ◽

Materials Used ◽

Account Temperature

ABSTRACT Tire engineers are interested in predicting rolling resistance using tools such as numerical simulation and tests. When a car is driven along, its tires are subjected to repeated deformation, leading to energy dissipation as heat. Each point of a loaded tire is deformed as the tire completes a revolution. Most energy dissipation comes from the cyclic loading of the tire, which causes the rolling resistance in addition to the friction force in the contact patch between the tire and road. Rolling resistance mainly depends on the dissipation of viscoelastic energy of the rubber materials used to manufacture the tires. To obtain a good rolling resistance, the calculation method of the tire finite element model must take into account temperature changes. It is mandatory to calibrate all of the rubber compounds of the tire at different temperatures and strain frequencies. Linear viscoelasticity is used to model the materials properties and is found to be a suitable approach to tackle energy dissipation due to hysteresis for rolling resistance calculation.

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