Dynamic shear band propagation and micro-structure of adiabatic shear band

Citation
Sf. Li et al., Dynamic shear band propagation and micro-structure of adiabatic shear band, COMPUT METH, 191(1-2), 2001, pp. 73-92
Citations number
52
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Mechanical Engineering
Journal title
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
ISSN journal
0045-7825 → ACNP
Volume
191
Issue
1-2
Year of publication
2001
Pages
73 - 92
Database
ISI
SICI code
0045-7825(2001)191:1-2<73:DSBPAM>2.0.ZU;2-O
Abstract
Meshfree Galerkin approximations in both two and three dimensions have been used in simulations of dynamic shear band propagation in an asymmetrically impact-loaded prenotched plate. Failure mode switching and failure mode tr ansitions, which have been reported experimentally, are replicated in numer ical computations, For intermediate impact speed (25 m/s < V less than or e qual to 30 m/s), the numerical results show that a cleavage crack initiates from the tip of the dynamic shear band, indicating a dominance of brittle failure mode, and a failure mode switch (ductile-to-brittle: shearband-to-c rack). For high impact velocities (V > 30 m/s), the numerical results show that a dynamic shear band penetrates through the specimen without trace of cleavage-type fracture, which is a ductile failure mode. Overall, with the increase of impact speed, the final failure mode of the impacted plate tran sits from brittle failure to ductile failure. By introducing a multi-physic s model to describe the stress collapse state of the shear band, it has bee n found that there is a non-uniform temperature distribution inside the adi abatic shear band. Strong evidences indicate that temperature distribution inside the shear band has periodic patterns in both space and time, confirm ing the latest experimental results of P. Guduru et al. [Mech. Mater. (2000 ), submitted]. This suggests that there may exist a thermal-mechanical inst ability within the adiabatic shear band, reminiscent of hydrodynamic instab ility due to viscous heating. (C) 2001 Elsevier Science B.V. All rights res erved.