Dynamic shear bands: an investigation using high speed optical and infrared diagnostics

This paper presents an experimental investigation of the initiation and propagation characteristics of dynamic shear bands in C300 maraging steel. Pre-fatigued single edge notched specimens were impacted on the edge under the notch to produce shear dominated mixed mode stress fields. The optical technique of coherent gradient sensing (CGS) was employed to study the evolution of the mixed mode stress intensity factors. Simultaneously, a newly developed two-dimensional high speed infrared (IR) camera was employed to observe the temperature field evolution during the initiation and propagation of the shear bands. Possible criteria for failure mode selection are discussed. The IR images, for the first time, revealed the transition of crack tip plastic zone into a shear band and also captured the structure of the tip of a propagating shear band. These thermographs support the notion of a diffuse shear band tip and reveal “hot spots” distributed along the length of a well-developed shear band.

[1]  Ted Belytschko,et al.  Mesh-free Galerkin simulations of dynamic shear band propagation and failure mode transition , 2002 .

[2]  G. Ravichandran,et al.  Canonical aspects of adiabatic shear bands , 1997 .

[3]  T. Wright.  Scaling laws for adiabatic shear bands , 1995 .

[4]  R. Clifton,et al.  Shear band formation in thermal viscoplastic materials , 1989 .

[5]  U. S. Lindholm,et al.  Shock Wave and High-Strain-Rate Phenomena in Materials , 1992 .

[6]  R. Batra,et al.  Shear instability direction at a crack-tip in a thermoviscoplastic body , 1998 .

[7]  A. Rosakis,et al.  On the dependence of the dynamic crack tip temperature fields in metals upon crack tip velocity and material parameters , 1993 .

[8]  Ares J. Rosakis,et al.  Dynamically propagating shear bands in impact-loaded prenotched plates—I. Experimental investigations of temperature signatures and propagation speed , 1996 .

[9]  A. Molinari,et al.  Structures in shear zones due to thermal effects , 1991 .

[10]  A. Rosakis,et al.  Dynamic Crack Initiation in Ductile Steels , 1998 .

[11]  Ares J. Rosakis,et al.  Optical mapping of crack tip deformations using the methods of transmission and reflection coherent gradient sensing: a study of crack tip K-dominance , 1991, International Journal of Fracture.

[12]  P. Sukanek,et al.  The stability of plane Couette flow with viscous heating , 1973, Journal of Fluid Mechanics.

[13]  H. Ockendon,et al.  A model for fully formed shear bands , 1992 .

[14]  Michael Ortiz,et al.  The two-dimensional structure of dynamic boundary layers and shear bands in thermoviscoplastic solids , 1996 .

[15]  D. Grady.  Dissipation in adiabatic shear bands , 1994 .

[16]  B. Yang,et al.  Failure mode transitions in polymers under high strain rate loading , 2000 .

[17]  J. H. Hollomon,et al.  Effect of Strain Rate Upon Plastic Flow of Steel , 1944 .

[18]  Yi-long Bai.  Thermo-plastic instability in simple shear , 1982 .

[19]  A. Rosakis,et al.  Dynamically propagating shear bands in impact-loaded prenotched plates—II. Numerical simulations , 1996 .

[20]  J. Duffy,et al.  An experimental study of the formation process of adiabatic shear bands in a structural steel , 1988 .

[21]  Christopher S. Lynch,et al.  Mechanics of Materials and Mechanics of Materials , 1996 .

[22]  R. Pond,et al.  Inhomogeneous thermal changes in copper during plastic elongation , 1975 .

[23]  J. Duffy,et al.  On critical conditions for shear band formation at high strain rates , 1984 .

[24]  M. Meyers.  Dynamic Behavior of Materials , 1994 .

[25]  D. Grady.  Properties of an adiabatic shear-band process zone , 1992 .

[26]  T. Wright,et al.  Steady shearing in a viscoplastic solid , 1987 .

[27]  C. Weng,et al.  Linear stability analysis of plane Couette flow with viscous heating , 1996 .

[28]  A. Rosakis,et al.  The use of a coherent gradient sensor in dynamic mixed-mode fracture mechanics experiments , 1992 .

[29]  J. Lambros,et al.  Dynamic thermomechanical behavior of fiber reinforced composites , 2000 .

[30]  A. Molinari,et al.  Analytical Characterization of Shear Localization in Thermoviscoplastic Materials , 1987 .

[31]  A. Rosakis,et al.  Million frames per second infrared imaging system , 2000 .

[32]  J. S. Epstein,et al.  Experimental techniques in fracture , 1993 .

[33]  A. Needleman,et al.  Analysis of a brittle-ductile transition under dynamic shear loading , 1995 .

[34]  G. Moss.  Shear Strains, Strain Rates and Temperature Changes in Adiabatic Shear Bands , 1981 .

[35]  Romesh C. Batra,et al.  Analysis of material instability at an impact loaded crack tip , 1998 .

[36]  J. Duffy,et al.  Measurement of the temperature profile during shear band formation in steels deforming at high strain rates , 1987 .

[37]  H. Rogers.  Adiabatic Plastic Deformation , 1979 .

[38]  Alan T. Zehnder,et al.  STONE IMPACT DAMAGE TO AUTOMOTIVE PAINT FINISHES: MEASUREMENT OF TEMPERATURE RISE DUE TO IMPACT , 1993 .

[39]  A. Zehnder,et al.  Measurement of the temperature field induced by dynamic crack growth in Beta-C titanium , 1994 .

[40]  J. Mason,et al.  Adiabatic shear localization in the impact of edge-notched specimens , 1998 .

[41]  R. Recht.  Catastrophic Thermoplastic Shear , 1964 .

[42]  K. Ravi-Chandar.  On the failure mode transitions in polycarbonate under dynamic mixed-mode loading , 1995 .

[43]  J. Hutchinson,et al.  Kinking of A Crack Out of AN Interface , 1989 .

[44]  L. B. Freund,et al.  Deformation trapping due to thermoplastic instability in one-dimensional wave propagation , 1984 .

[45]  Ares J. Rosakis,et al.  Partition of plastic work into heat and stored energy in metals , 2000 .

[46]  Wing Kam Liu,et al.  Dynamic shear band propagation and micro-structure of adiabatic shear band , 2001 .

[47]  D. Rittel,et al.  Mode-mixity and dynamic failure mode transitions in polycarbonate , 1998 .

[48]  Ares J. Rosakis,et al.  On the temperature distribution at the vicinity of dynamically propagating cracks in 4340 steel , 1991 .

[49]  L. B. Freund,et al.  Fracture Initiation Due to Asymmetric Impact Loading of an Edge Cracked Plate , 1990 .

[50]  Ares J. Rosakis,et al.  A coherent gradient sensor for crack tip deformation measurements: analysis and experimental results , 1991 .

[51]  Yi-long Bai,et al.  Adiabatic Shear Localization: Occurrence, Theories and Applications , 1992 .