NDTnet 1998 Aug, Vol.3 No.8

Abstract

Lately, polymeric composite materials have found a wide application in industry thanks to their unique physical and mechanical properties. But a pronounced micro- and macro- nonhomogenuity of the structure, anisotropy of properties and diversity of models of the composite failure call for the use of efficient methods of the production process control to provide a sufficient reliability of the composite-based products. In this respect the acoustic emission (AE) method can be promising. It is based on recording the elastic waves of mechanical stress which are emissed from the failure sites under dynamic changes at all structural levels. Nevertheless, the use of the acoustic emission method in practice meets with a number of difficulties resulting from a high structural sensitivity of the method. Therefore, in every specific case of production use of the acoustic emission method the tentative studies are required to determine a functional connection between acoustic emission parameters and destructional process characteristics in structural materials. The present work was done to evaluate efficiency of the acoustic emission method use as a diagnostic tool for analysing the state of the YKH-5000 carbon plastic composite and its adhesive joints. A functional dependency between the character of the destructional and dissipative processes of the above materials was studied. A mechanism of deformation damage of the YKH-5000 carbon plastic was examined on the parameters of the acoustic emission . It was found that the carbon plastic load up to 0,4_B. stress is not critical with reference to residual strength. The shear strength () of the carbon plastic under study is found. It was found by means of the AE -method that the damage-free adhesive joints are acoustically little-active. A sharp increase in a number of pulses (by appr. a factor of 10) is seen at up to 70-80 % load. Appearance of high-amplitude pulses at 10-15% loads evidences about developing a dominant defect. Three diagnostical schemes (monotonous, two-multiple, step) of loading under AE examination of the YKH-5000 carbon plastics are tried out. A diagnostic criterion parameter, that is the accumulation coefficient correlating with the strength characteristics of the carbon plastic and its adhesive joints under study is found.

Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00

Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:

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