Acoustic Emission Testing of Composite Materials Including Specimens Simulating the Embedded Sensors

Abstract

Composite materials including fiberglass and carbon fiber together with the necessary strength provide a sufficient saving the weight for structures of any shape and allow to realize unique characteristics due to their application are finding wider application in the creation of structures. This requires the development of a reliable non-destructive method for assessing their condition, including during operation, what is of no less importance since it allows to reject materials with defects even before structural elements are made of them. The evaluation of possibility to use the acoustic emission (AE) scanning method based on EMA type equipment for fiberglass specimens was conducted. Numerous experiments were performed on scanning specimens in the longitudinal direction, in which each of the AE sensors alternately acted as an emitter of test signals. Of the six specimens tested, three contained an integrated center element simulating an acoustic piezoelectric transducer. Tests have shown that with AE scanning it is possible to distinguish acoustic properties without loading specimens in the presence and absence of such an integrated concentrator and to quantitatively assess the damage for material with concentrator. Also, the unique for EMA systems automatic prediction of destructive loading for both materials were tested during specimens tension up to crash. The importance of the results obtained for creating a methodology of composites testing using AE scanning technology and providing clear criteria for assessing damage is noted.