Modeling of phase interfaces during pre-critical crack growth in concrete

2011 ◽  
Vol 33 (9) ◽  
pp. 966-977 ◽  
Author(s):  
D. Asahina ◽  
E.N. Landis ◽  
J.E. Bolander
Keyword(s):  
Crack Growth ◽  
Critical Crack

Sub-Critical Crack Growth Behavior of a Low-Temperature Co-Fired Ceramic

2007 ◽  
Vol 90 (5) ◽  
pp. 1527-1533 ◽  
Author(s):  
Rajan Tandon ◽  
Clay S. Newton ◽  
Saundra L. Monroe ◽  
S. Jill Glass ◽  
Christine J. Roth
Keyword(s):  
Low Temperature ◽  
Crack Growth ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Critical Crack

scholarly journals Subcritical crack growth parameters in glass as a function of environmental conditions

2020 ◽  
Author(s):  
Christopher Brokmann ◽  
Stefan Kolling ◽  
Jens Schneider
Keyword(s):  
Crack Growth ◽  
Environmental Conditions ◽  
Subcritical Crack Growth ◽  
Growth Parameters ◽  
Crack Depth ◽  
Indentation Test ◽  
Soda Lime ◽  
Initial Crack ◽  
Chemical Compositions ◽  
Critical Crack

Abstract In the present work, subcritical crack growth in soda–lime silicate glass is investigated under different environmental conditions. Crack growth parameters as a function of temperature and humidity were determined by dynamic fatigue tests, which has been verified by using the in-situ method of filming crack growth during experiments. The specimens were pre-damaged for constant initial crack lengths in all specimens using the Vickers indentation test. The determined parameters were compared with those from literature in order to discuss existing deviations of sub-critical crack growth parameters in literature. These deviations may be caused by environmental conditions and different chemical compositions of the glass. Arrest lines were used to determine the ratio of crack width to crack depth in Vickers indented specimens. For the initial crack depth, images of fracture surfaces were taken using an scanning electron microscope. Furthermore, the influence of humidity and temperature on the failure stress of unindented specimens with a constant initial crack length was simulated.

scholarly journals The Impact of surface perturbations on snow-slope stability

1998 ◽  
Vol 26 ◽  
pp. 307-312 ◽  
Author(s):  
H. Conway
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Slope Stability ◽  
Crack Growth ◽  
Basal Layer ◽  
Field Measurements ◽  
Critical Crack ◽  
Small Surface ◽  
Weak Layer ◽  
The Impact

Measurements and observations by others indicate that a potential slab avalanche consists of a relatively cohesive slab of snow overlying a thin weak layer that coniains flaws where locally the shear stress from the overburden is not fully supported. Under favorable conditions, snow will shear strain-soften, which provides the basis for applying a slip-weakening model to examine the size of flaw needed to initiate sub-critical crack propagation along the weak layer. Using typical values for snow properties, the model predicts sub-critical crack growth can initiate from a relatively small flaw well before the shear stress from the overburden approaches the peak shear strength at tin-bed. The occurrence of small flaws or imperfections in the basal layer would explain field measurements which usually indicate that avalanching occurs before the applied shear stress exceeds the shear strength at the basal layer.Widespread slab-avalanche activity often increases significantly soon after the onset of rain on new snow. Measurements of temperature and mechanical properties show that only the upper 0.15 m or less of the slab has been altered at the time of avalanching; alterations at the sliding layer have not yet been detected. Results from the slip-weakening model indicate that the rain-induced alterations would reduce the size of flaw needed to initiate sub-critical crack growth by 10–20%. The observations and model results show clearly the importance of the slab properties; it is evident that both the slab and the weak layer act together to control slope stability. A further implication is that the stability of freshly deposited snow is often close to critical, because a relatively small surface perturbation is often sufficient to cause avalanching. This is not surprising, because it is well known from field observations that new snow on slopes should be treated with caution.

Sub-critical crack growth in some phosphate glasses

2008 ◽  
Vol 354 (2-9) ◽  
pp. 580-586 ◽  
Author(s):  
S. Etter ◽  
F. Despetis ◽  
P. Etienne
Keyword(s):  
Crack Growth ◽  
Phosphate Glasses ◽  
Critical Crack
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