The Behavior of Short Interface Edge-Cracks in Bonded Bimaterial Layers

The initiation of surface and interface edge cracks in functionally graded ceramic thermal barrier coatings resulting from the application of a thermal load is studied. For a given specimen configuration, the singular behavior of the thermal stresses is analytically determined in terms of a singularity power β and pseudo-stress intensity factors K1 and K2. Crack initiation at the surface at the interface is related to the surface temperature and the temperature difference between the surface of the coating and the substrate. The experimental results are used to provide Weibull curves for the probability of survival of plasma sprayed mullite and CoCrAlY coating systems.

Download Full-text

A fully parametric weight function for inclined edge cracks with a kink

Engineering Fracture Mechanics ◽

10.1016/j.engfracmech.2015.01.029 ◽

2015 ◽

Vol 136 ◽

pp. 195-212 ◽

Cited By ~ 5

Author(s):

M. Benedetti ◽

V. Fontanari ◽

B.D. Monelli ◽

M. Beghini

Keyword(s):

Weight Function ◽

Edge Cracks

Download Full-text

Morphology of Edge Cracks of Rolled Magnesium Alloy Sheet

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.922.469 ◽

2014 ◽

Vol 922 ◽

pp. 469-474 ◽

Cited By ~ 3

Author(s):

Sho Manabe ◽

Hiroshi Utsunomiya ◽

Tetsuo Sakai ◽

Ryo Matsumoto

Keyword(s):

Magnesium Alloy ◽

Magnesium Alloys ◽

High Speed ◽

Heating Temperature ◽

Thin Sheet ◽

Contact Length ◽

Alloy Sheet ◽

Different Temperatures ◽

Edge Cracks ◽

Critical Reduction

Magnesium alloys show low deformability at low temperature because of hcp structure and inactiveness of basal slip. Manufacturing of thin sheet is difficult in industries. Some approaches, such as small-draft multi-pass rolling, intermediate annealing, isothermal rolling and high-speed rolling were proposed to overcome the deformability. However, small edge cracks are still formed on the sheet. In this study, rolling speed of 1000m/min was employed to warm-roll AZ31B magnesium alloy in a single pass at different temperatures. The edge cracks formed after the rolling were classified into three main groups: minor, regular and zigzag edge cracks. ‘Crack contact length’ are introduced to explain the morphology of edge cracks. The results show that the critical reduction for crack initiation depends on the pre-heating temperature. The spacing between edge cracks increases linearly with the crack contact length regardless of roll diameter, speed and reduction. It is suggested that this approach is useful to understand the formation mechanism of edge cracks and to evaluate the rollability of magnesium alloys.

Download Full-text