where A and n are constants. Thouless et al. [13] derived a model based on buckling of an edge flake that predicted n = 3, but their loading geometry was somewhat different than the usual edge chipping procedures with pointed indenters. (The forces in their model and experiments were applied in a distributed fashion parallel to the edge and at a location between the crack and the side surface.) They obtained:
where λ is a constant, E is the elastic modulus, cf is the critical crack length at instability. An indentation fracture mechanics model for edge chipping by Chai and Lawn [14] for edge chip resistance supports the power law Eq. (2), but only for the case of n = 1.5. Although some of our data in Part 1 [1] and earlier work [11] matched the power law with n = 1.5, much of the data did not. Our exponents ranged from as small as 1 to as large as 2.
Madrix 214d Crack
DOWNLOAD: https://byltly.com/2vHGut
where γf is the fracture surface energy. The actual total fracture energy should also include the additional fracture energy associated with the array of short starburst cracks emanating from the initial indentation and the microfracturing immediately underneath the indentation, but these contributions may scale with the indentation and chip size. So since c, C, and D are proportional to the edge distance, d, the energy of fracture in the formation of chip is proportional to d2, which matches the a1 first term on the right of Eq. (11). 2ff7e9595c
Comments