T. Siegmund et A. Needleman, A NUMERICAL STUDY OF DYNAMIC CRACK-GROWTH IN ELASTIC-VISCOPLASTIC SOLIDS, International journal of solids and structures, 34(7), 1997, pp. 769-787
Dynamic crack growth is analyzed numerically for a plane strain block
with an initial central crack subject to impact tensile loading. The m
aterial is characterized as an isotropically hardening elastic-viscopl
astic solid. A cohesive surface constitutive relation is also specifie
d that relates the tractions and displacement jumps across the crack p
lane. In this formulation crack initiation, crack growth and crack arr
est emerge naturally as outcomes of the imposed loading, without any a
d hoc assumptions concerning crack growth criteria. Full transient ana
lyses are carried out using two characterizations of strain rate harde
ning; power law strain rate hardening and a combined power law-exponen
tial relation that gives rise to enhanced strain rate hardening at hig
h strain rates. The effects of the strain rate hardening characterizat
ion on crack initiation, crack growth and crack arrest are investigate
d. Enhanced strain rate hardening is found to lead to higher crack spe
eds, to lower toughness values and to crack tip fields that are more l
ike those of an elastic solid than for the power law rate hardening so
lid. Additionally, some parameter studies varying the cohesive surface
strength and the material flow strength are carried out. The effectiv
e stress intensity factor is found to increase dramatically at a certa
in value of the crack speed that depends on the cohesive surface stren
gth, the material Bow strength, the characterization of strain rate ha
rdening and the impact velocity, but there is a range where the crack
speed at which the increase in effective stress intensity factor occur
s is not very sensitive to impact velocity. (C) 1997 Elsevier Science
Ltd. All rights reserved.