| Autor: |
Ducret, D., El Guerjouma, R., Jayet, Y., Baboux, J. C. |
| Předmět: |
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| Zdroj: |
AIP Conference Proceedings; 2000, Vol. 509 Issue 1, p1199, 8p, 4 Diagrams, 2 Charts, 5 Graphs |
| Abstrakt: |
Ultrasonics is a suitable technique for nondestructive evaluation of structural materials degradation. Although the most common objective of ultrasonic testing is the detection and location of overt flaws, ultrasonics can be used to identify microstructural factors that alter strength and performance. However, while single large defects can be individually detected and characterized, widely dispersed discontinuities are impossible to resolve and only their global effects on bulk properties can be observed and measured. The aim of this paper is, using an immersion technique, to characterize damage progression of a glass fiber epoxy matrix composite during hygrothermal aging by means of attenuation frequency-dependence measured in normal incidence and longitudinal and transversal ultrasonic velocities measured as function of the propagation direction. The anisotropic elastic constants of the material are recovered from the ultrasonic velocities using an optimization process. Effects of hygrothermal aging on the attenuation dispersion, longitudinal and transversal ultrasonic velocities angular dependence and on the elastic properties are discussed. Anisotropic damage is assessed in terms of loss of stiffness. We show that, these macroscopic effects of damage result from located fiber/matrix interface decohesion. A microscopic investigation conducted using scanning electronic microscopy (SEM) on the damaged sample confirms this assumption and shows an important debonding at the fiber-matrix interface mostly located at the pole of the fibers in the thickness direction. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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