Quasi-dynamic visualization of crack propagation and bridging evolution in Si3N4 and SiC ceramics by mechano-luminescence |
| |
Authors: | Ji Sik Kim Kevin Kibble Mark Stanford Yong Nam Kwon Kee-Sun Sohn |
| |
Affiliation: | (1) Structural Testing, Institute for Materials Testing, IMS, Bulevar vojvode Misica 43, 11000 Belgrade, Serbia;(2) Istituto per la Valorizzazione del Legno e delle Specie Arboree (CNR-IVALSA), Consiglio Nazionale delle Ricerche, San Michele all’Adige, 38010 Trento, Italy |
| |
Abstract: | The propagations of macro-scale cracks were visualized in Si3N4 and SiC ceramics using a mechano-luminescence (ML) of SrAl2O4:Eu,Dy. The bridging zones behind the crack tip were also clearly detected in the crack path within realistic time frames.
The ML made it possible to detect cracks propagating within a speed range of 200 m/s to 250 m/s, thereby realizing so-called
quasi-dynamic R-curves. The magnitudes and shapes of the bridging stress distributions were found to change with the advancing
cracks, continuing to change as the applied load changes, even after the cessation of crack propagation. The effective toughening
then commenced and the applied stress intensity factors increased dramatically up to ∼120 MPa√m in Si3N4 and 150 MPa√m in SiC. The KTip values expected on the basis of the instantaneous bridging stress distributions obtained from ML observations deviated greatly
from those measured using the conventional crack tip lengths; rather, the values support the results obtained by using bridging
tips in quasi-dynamic crack propagations. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|