Dynamic visualization of crack propagation and bridging stress using the mechano-luminescence of SrAl2O4: (Eu,Dy,Nd)

Abstract The goal of the present investigation was to visualize the propagating crack in a mechano-luminescence (ML) material to enable the measurement of instantaneous R-curves and directly observe the bridging (shielding) stress in a fast-propagating crack system. The well-known ML compound, SrAl 2 O 4 : Eu 2+ , was used as a model test material. Two additional trivalent rare earth elements, Dy and Nd, were introduced as co-dopants to improve the luminescent efficiency. The initiation and growth of a crack from the mechanically machined sharp notch tip in a disc shaped compact tension (CT) specimen at a relatively high loading rate were found to be associated with the extent of light emission around the crack. An in-situ measurement of crack length and applied load for 0.3 sec yielded an instantaneous R-curve at the conventional crack propagation speed.

[1]  K. Nonaka,et al.  Visualization of stress distribution using mechanoluminescence from Sr3Al2O6: Eu and the nature of the luminescence mechanism , 1999 .

[2]  M. Swain,et al.  Crack‐Tip‐Bridging Stresses in Ceramic Materials , 1991 .

[3]  K. White,et al.  Crack face bridging mechanisms in monolithic MgAl2O4 spinel microstructures , 1992 .

[4]  Laurent J. P. Guazzone,et al.  Elevated‐Temperature R‐Curve Behavior of a Polycrystalline Alumina , 1990 .

[5]  Y. Mai,et al.  Crack‐Interface Grain Bridging as a Fracture Resistance Mechanism in Ceramics: II, Theoretical Fracture Mechanics Model , 1987 .

[6]  R. Steinbrech,et al.  R‐Curve Behavior of Long Cracks in Alumina , 1990 .

[7]  K. White,et al.  Fatigue degradation of the crack wake zone in monolithic alumina , 1999 .

[8]  Chao-Nan Xu,et al.  Dynamic visualization of stress distribution by mechanoluminescence image , 2000 .

[9]  Dinesh K. Shetty,et al.  Rising Crack-Growth-Resistance (R-Curve) Behavior of Toughened Alumina and Silicon Nitride , 1991 .

[10]  Mohammad Taghi Kazemi,et al.  Size Effect in Fracture of Ceramics and Its Use To Determine Fracture Energy and Effective Process Zone Length , 1990 .

[11]  J. Rödel,et al.  In Situ Measurements of Bridged Crack Interfaces in the Scanning Electron Microscope , 1990 .

[12]  Michael G. Jenkins,et al.  Fracture Resistance of a Transparent Magnesium Aluminate Spinel , 1991 .

[13]  K. Sohn,et al.  Analysis of bridging stress effect of polycrystalline alumina using double cantilever beam method , 1997 .

[14]  Hidetoshi Nakano,et al.  Crack Measurements by Laser Ultrasonic at High Temperatures , 1993 .

[15]  K. Sohn,et al.  Analytical Modeling for Bridging Stress Function Involving Grain Size Distribution in a Polycrystalline Alumina , 1995 .

[16]  Richard J. Dewhurst,et al.  Surface‐breaking fatigue crack detection using laser ultrasound , 1993 .

[17]  Gilbert Fantozzi,et al.  R-curve evaluation and bridging stress determination in alumina by compliance analysis , 2003 .

[18]  Surendra P. Shah,et al.  Geometry‐Dependent R‐Curve for Quasi‐Brittle Materials , 1991 .

[19]  Chao-Nan Xu,et al.  Direct view of stress distribution in solid by mechanoluminescence , 1999 .

[20]  R. Steinbrech,et al.  Memory effect of crack resistance during slow crack growth in notched Al2O3 bend specimens , 1982 .

[21]  Kenneth W. White,et al.  Fracture mechanisms of a coarse-grained, transparent MgAl2O4 at elevated temperatures , 1992 .

[22]  K. Sohn,et al.  Direct observation of crack tip stress field using the mechanoluminescence of SrAl2O4:(Eu, Dy, Nd) , 2004 .

[23]  Dong-joo Lee,et al.  R‐Curve Behavior and Strength for In‐Situ Reinforced Silicon Nitrides with Different Microstructures , 1992 .

[24]  Detection of crack propagation in Si3N4/Si3N4-TiN laminated ceramics by electrical resistance , 2001 .

[25]  G. Pezzotti,et al.  Raman microprobe mapping of residual and bridging stress fields in AlN ceramics , 2002 .

[26]  Robert O. Ritchie,et al.  On the quantification of bridging tractions during subcritical crack growth under monotonic and cyclic fatigue loading in a grain-bridging silicon carbide ceramic , 1998 .

[27]  Kee-Sun Sohn,et al.  Search for Long Phosphorescence Materials by Combinatorial Chemistry Method , 2001 .

[28]  D. Munz,et al.  Evaluation of Bridging Parameters in Aluminas from R‐Curves by Use of the Fracture Mechanical Weight Function , 1995 .

[29]  K. White,et al.  Grain‐Bridging Mechanisms in Monolithic Alumina and Spinel , 1993 .