Acoustic and Eddy Current Methods of Nondestructive Testing of Thermally Expanded Graphite Sheets

The widespread use of polyolefin foams in strategically important industries is due to their high thermal, sound and vibration insulation properties. The aim of the work was to evaluate the non-uniformity of elastic properties over the area of sheets of polyolefin foams of various types using the acoustic non-contact shadow amplitude method of testing and confirmation by the structural analysis method.The article presents the developed installation and a new method of non-contact acoustic testing of sheets made of closed-cell polyolefin foams based on recording the amplitude of the pulse that passed through the sheet and allowing to assess to the unevenness of its elastic properties during scanning. Studies of uneven elastic properties were carried out on sheets of closed-cell polyolefin foams of the ISOLON 500 and ISOLON 300 brands which differ in material and manufacturing technology (technique of cross-linking, method and multiplicity of foaming).It is shown that the absolute amplitude of the signal and its spread relative to the average value is affected by the structure of the foam polyolefin material and its heterogeneity over the area of the studied sheet determined by the production technology which is confirmed visually using microscopy.Studies have shown the effect on the indications unevenness of the method of obtaining and the apparent density of the material. It is shown that the most uneven elastic properties and structure belong to sheets of polyolefin foam obtained by chemical cross-linking technology (the unevenness of Δ was 6.5 %). Among the physically cross-linked sheets of polyolefin foam the most uniform in structure and elastic properties are samples made of ethylene vinyl acetate with Δ = 3.8 %, as well as sheets with a high foaming rate (Δ = 3.9 %). The unevenness of structure of the studied sheets of polyolefin foams was confirmed by optical microscopy of sections in two mutually perpendicular directions.

show abstract

Density study of thermoexpanded graphite samples by acoustic amplitude-shadow method

Bogdan,

Muraveva,

Blinova

et al. 2023

Defektoskopiâ

View full text Add to dashboard Cite

The paper presents the results of the study of sensitivity of the acoustic method of density control for samples of expanded graphite based on registration of changes in the amplitude of the signal passed through the sample due to density changes. The results have shown that the limiting sensitivity of the method is commensurable with an error of density measurement by direct weight method and mass and equal to 26 kg/m3 and 0.02 g. The unevenness of the density distribution over the area of TEG samples of different thickness was evaluated, and the amplitude excursion of the signal transmitted through the sample, proportional to the density deviation, for some sheets reached up to 50%, for mats - 30%, and the smallest did not exceed 10%. In the process of scanning, an inversely proportional dependence of the amplitude of the passed acoustic signal on the average density of the samples was revealed, which is most expressed for small thicknesses of TEG mats and sheets.

show abstract

scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.

Contact Info

customersupport@researchsolutions.com

10624 S. Eastern Ave., Ste. A-614

Henderson, NV 89052, USA

Blog Terms and Conditions API Terms Privacy Policy Contact Cookie Preferences Do Not Sell or Share My Personal Information

Made with 💙 for researchers

Part of the Research Solutions Family.

Acoustic and Eddy Current Methods of Nondestructive Testing of Thermally Expanded Graphite Sheets

Cited by 3 publications

References 11 publications

Investigation of Density of Samples Made of Thermally Expanded Graphite by Acoustic Amplitude-Shadow Method

Investigation of Density of Samples Made of Thermally Expanded Graphite by Acoustic Amplitude-Shadow Method

Evaluation of Nonuniformity of Elastic Properties of Sheets Made from Closed-Сell Polyolefin Foams by Acoustic Method

Density study of thermoexpanded graphite samples by acoustic amplitude-shadow method

Contact Info

Product

Resources

About