UNSPECIFIED. (2004) The measurement of shear and compression waves in curing epoxy adhesives using ultrasonic reflection and transmission techniques simultaneously. MEASUREMENT SCIENCE & TECHNOLOGY, 15 (5). pp. 939-947. ISSN 0957-0233

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Abstract

Thin epoxy resin adhesive samples were ultrasonically measured during cure using normal incidence radially polarized shear wave electromagnetic acoustic transducers (EMATs). The EMATs used generated predominantly SH shear waves but they also generated/detected compression waves allowing the simultaneous measurement of shear and compression wave propagation through a curing epoxy in a non-contact regime. The source of the compression wave generation has been determined to be the in-plane shear Lorentz force. The adhesive thickness examined in the experiments was approximately I rum, which was optimal for experimental measurement using our apparatus: it temporally separated the ultrasonic waves of interest from others present in the pulse whilst remaining thin enough to be representative of a realistic adhesive layer. The rapid cure and standard or 'longer' cure epoxy adhesives described in this paper were supplied in a two-part cartridge form. The experiments show that there is a fundamental difference between the way that the elastic moduli develop in the rapid cure and the longer cure time epoxies. The rapid cure epoxy initially developed a shear elastic modulus at a fast rate, which suddenly decreased at approximately the same time that the temperature of the adhesive reached its maximum value during the exothermic reaction. The reflection measurements show that there was significant coupling of the shear wave into the adhesive even in its initial liquid-like state. The ultrasonic shear and compression wave velocities of the epoxy were calculated from the very outset of the cross-linking reaction using the reflection technique. A transmitted compression wave was visible from the outset of cure, and once a transmitted shear wave was detectable it was possible to measure attenuation for both; however, these data are not presented here as they are not key to the paper and they can be found in our previous publications that are referenced in this one.

Item Type:	Journal Article
Subjects:	T Technology > TA Engineering (General). Civil engineering (General)
Journal or Publication Title:	MEASUREMENT SCIENCE & TECHNOLOGY
Publisher:	IOP PUBLISHING LTD
ISSN:	0957-0233
Date:	May 2004
Volume:	15
Number:	5
Number of Pages:	9
Page Range:	pp. 939-947
Identification Number:	10.1088/0957-0233/15/5/023
Publication Status:	Published
URI:	http://wrap.warwick.ac.uk/id/eprint/8345

Data sourced from Thomson Reuters' Web of Knowledge

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