In Situ Observation of Crack Propagation in Epoxy Composite Reinforced with Crushed Silica Particles

In-situ observation of fatigue crack growth of epoxy resin composite reinforced with crushed silica particle was carried out. The test was performed under constant ΔK condition. Based on the results, the crack propagation mechanism was discussed. The in-situ observation revealed that in front of the main crack, a microcrack was nucleated at the interface of matrix/particle and then coalesced with the main crack. At the same time, new microcracking occurred ahead of the crack tip and the crack propagated by repeating these processes. Retardation of crack growth rate was found to result from crack bridging induced by microcracking at silica particles and crack deflection.

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Fatigue Crack Growth Behaviour and Role of Roughness-Induced Crack Closure in CP Ti: Stress Amplitude Dependence

Metals ◽

10.3390/met11101656 ◽

2021 ◽

Vol 11 (10) ◽

pp. 1656

Author(s):

Mansur Ahmed ◽

Md. Saiful Islam ◽

Shuo Yin ◽

Richard Coull ◽

Dariusz Rozumek

Keyword(s):

Fatigue Crack ◽

Crack Propagation ◽

Crack Growth ◽

Crack Closure ◽

Fatigue Cracks ◽

Propagation Mechanism ◽

Amplitude Dependence ◽

Crack Growth Behaviour ◽

Crack Propagation Mechanism ◽

Cp Ti

This paper investigated the fatigue crack propagation mechanism of CP Ti at various stress amplitudes (175, 200, 227 MPa). One single crack at 175 MPa and three main cracks via sub-crack coalescence at 227 MPa were found to be responsible for fatigue failure. Crack deflection and crack branching that cause roughness-induced crack closure (RICC) appeared at all studied stress amplitudes; hence, RICC at various stages of crack propagation (100, 300 and 500 µm) could be quantitatively calculated. Noticeably, a lower RICC at higher stress amplitudes (227 MPa) for fatigue cracks longer than 100 µm was found than for those at 175 MPa. This caused the variation in crack growth rates in the studied conditions.

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Fracture in Bulk Amorphous Alloys

MRS Proceedings ◽

10.1557/proc-554-185 ◽

1998 ◽

Vol 554 ◽

Cited By ~ 5

Author(s):

J. A. Horton ◽

J. L. Wright ◽

J. H. Schneibel

Keyword(s):

Crack Propagation ◽

Crack Growth ◽

Shear Bands ◽

Bulk Amorphous Alloy ◽

In Situ Tem ◽

X Ray Diffraction ◽

Transmission Electron ◽

Crack Tips ◽

Temperature Fracture

AbstractThe fracture behavior of a Zr-based bulk amorphous alloy, Zr-10 Al-5 Ti-17.9 Cu-14.6Ni (at.%), was examined by transmission electron microscopy (TEM) and x-ray diffraction forany evidence of crystallization preceding crack propagation. No evidence for crystallizationwas found in shear bands in compression specimens or at the fracture surface in tensile specimens.In- situ TEM deformation experiments were performed to more closely examine actualcrack tip regions. During the in-situ deformation experiment, controlled crack growth occurredto the point where the specimen was approximately 20 μm thick at which point uncontrolledcrack growth occurred. No evidence of any crystallization was found at the crack tips or thecrack flanks. Subsequent scanning microscope examination showed that the uncontrolledcrack growth region exhibited ridges and veins that appeared to have resulted from melting. Performing the deformations, both bulk and in-situ TEM, at liquid nitrogen temperatures (LN2) resulted in an increase in the amount of controlled crack growth. The surface roughness of the bulk regions fractured at LN2 temperatures corresponded with the roughness of the crack propagation observed during the in-situ TEM experiment, suggesting that the smooth-appearing room temperature fracture surfaces may also be a result of localized melting.

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Influence of Hole Size on Crack Propagation Mechanism of Nano-Single Crystal Copper

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.328.679 ◽

2013 ◽

Vol 328 ◽

pp. 679-683

Author(s):

Ge Li ◽

Xian Qin Hou ◽

Zhi Min Liu

Keyword(s):

Molecular Dynamics ◽

Crack Propagation ◽

Hole Diameter ◽

Propagation Mechanism ◽

Hole Size ◽

Single Crystal Copper ◽

Dislocation Glide ◽

Hole Position ◽

Crack Propagation Mechanism ◽

Dynamics Method

By molecular dynamics method, the tensile processes of nanosingle crystal copper with the crack front existence hole were simulated, and the effect of different hole size on crack propagation mechanism was analyzed. The results indicate that as the hole position remain unchanged, the hole diameter was more bigger, the atomic staggered and the crack tip deactivation were more obvious under tensile loads caused more dislocation glide appeared, meanwhile the number of slide-line was more and the trend of crack branch extend to hole position was more obvious.

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