If the crack can be assumed to be circular, one may take as the
`material coordinate' the coordinates of a
unit circle . Using the 6 shape parameters
() introduced in Nishimura & Kobayashi[30] one
describes **S** as

where the capital indices run from 1 to 2. Also, some of the formulae shown so far are simplified considerably. For example, (26) now reduces to

where the coordinate axis is chosen to align with .

Thu Feb 19 01:36:51 JST 1998