Two kinds of elastic laws have been adopted by Gao (1990 and 1997) to analy
ze the deformation fields near a crack tip. One of them contains the respon
se to volume change and shape change; the other contains the response to ex
tension and compression. In this paper the two kinds of constitutive relati
ons are examined by typical large deformation, and the restrictions on cons
titutive parameters are discussed. (C) 1999 Elsevier Science Ltd. All right
s reserved.