Toughness determination of zirconia toughened alumina ceramics from growth of indentation-induced cracks

1996 ◽  
Vol 11 (12) ◽  
pp. 3057-3063 ◽  
Author(s):  
D. Basu ◽  
B. K. Sarkar
Keyword(s):  
Stress Intensity ◽  
Crack Extension ◽  
Polished Surface ◽  
Surface Cracks ◽  
Transformation Toughening ◽  
Alumina Ceramics ◽  
Bend Tests ◽  
Point Bend ◽  
Zirconia Toughened Alumina

Short surface cracks were generated by Vickers indentation on the polished surface of alumina and different zirconia toughened alumina (ZTA) specimens, and their morphology was studied by serial sectioning. These cracks were grown in three-point bend tests under stepwise loading, and variation of toughness with crack extension was plotted to graphically separate the contributions from residual stress intensity and applied stress intensity factors. The plateau toughness determined from the intercept height of the crack extension plots exhibited an upward trend with zirconia content up to 15 vol % ZrO2 addition in the composition, which was proportional to the fraction of transformable tetragonal grains contributing to transformation toughening.

Initial Crack Extension in Two Intermediate-Strength Aluminum Alloys

1976 ◽  
Vol 98 (2) ◽  
pp. 152-158 ◽  
Author(s):  
C. A. Griffis ◽  
G. R. Yoder
Keyword(s):  
Aluminum Alloys ◽  
Crack Extension ◽  
Initial Crack ◽  
Thickness Variation ◽  
Linear Elastic ◽  
Geometry Dependence ◽  
Crack Movement ◽  
Resistance Curves ◽  
Point Bend

Three-point bend tests were conducted to examine the geometry dependence of JIc in two intermediate-strength aluminum alloys, 2024-T351 and 7005-T6351. The amounts of crack growth at selected points on the load-versus-deflection curves were delineated using a heat tinting technique. Resistance curves of J-versus-crack extension were constructed to facilitate determination of JIc at incipient crack movement. The through-thickness variation in fracture toughness of a 7.6-cm-thick plate of 7005 aluminum was determined and correlated with fractographic and metallographic observations. The current JIc measurements from subsized specimens of 7005 aluminum are compared with previous KIc characterizations using linear-elastic, full-thickness specimens.

scholarly journals Photoelastic Analysis of Cracked Thick Walled Cylinders

2017 ◽  
Vol 69 (1) ◽  
pp. 16-22
Author(s):  
Ştefan Dan Pastramă
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Internal Pressure ◽  
Crack Extension ◽  
Good Accuracy ◽  
Experimental Procedure ◽  
Photoelastic Analysis ◽  
Longitudinal Cracks

Abstract In this paper, the experimental determination of the stress intensity factor in thick walled cylinders subject to uniform internal pressure and having longitudinal non-penetrating cracks is presented. Photoelastic measurements were used together with the expressions of the stress field near the crack tip for Mode I crack extension and a specific methodology for stress intensity factor determination. Two types of longitudinal cracks - internal and external - were considered. Four plane models were manufactured and analyzed in a plane polariscope at different values of the applied internal pressure. The values of the normalized stress intensity factor were calculated and the results were compared to those reported by other authors. A good accuracy was noticed, showing the reliability of the experimental procedure.

Determination of Stress Intensity Factors for Interfacial Cracks in Bimaterial Systems

1990 ◽  
Vol 112 (2) ◽  
pp. 154-161 ◽  
Author(s):  
Yi-Hsin Pao ◽  
Tsung-Yu Pan
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Intensity Factors ◽  
Lap Shear ◽  
Interfacial Cracks ◽  
Shear Joint ◽  
Dcb Specimen ◽  
Wide Range ◽  
Point Bend

A relatively simple numerical method was developed to determine the stress intensity factors of interfacial cracks in bimaterial systems. The method is based on the evaluation of crack tip stress components using a p-version finite element method. Numerical experiments on a number of specimen geometries covering a wide range of material combination were performed. The geometries tested include a center-cracked panel (CCP), a single-lap shear joint (SLS) having two anti-symmetric cracks at the edges, a four-point bend specimen, and a bonded double-cantileverbeam (DCB) specimen. The numerical results agreed well with the analytical solutions and the experimental data of certain geometries. The range of integration distance over which accurate stress intensity factors can be determined was found to be within 10−5 and 10−3 of crack length and seems to be geometry independent.

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