Nonuniversality of roughness exponent of quasistatic fracture surfaces

2012 ◽  
Vol 85 (2) ◽  
Author(s):  
Mehdi Ansari-Rad ◽  
S. Mehdi Vaez Allaei ◽  
Muhammad Sahimi
Keyword(s):  
Fracture Surfaces ◽  
Roughness Exponent ◽  
Quasistatic Fracture

Self-affine Fracture Surface Parameters and Their Relationship with Microstructure in a Cast Aluminum Alloy

2002 ◽  
Vol 17 (6) ◽  
pp. 1276-1282 ◽  
Author(s):  
M. Hinojosa ◽  
J. Aldaco
Keyword(s):  
Aluminum Alloy ◽  
Fracture Surface ◽  
The Self ◽  
Cast Aluminum Alloy ◽  
Cast Aluminum ◽  
Force Microscopy ◽  
Fracture Surfaces ◽  
Atomic Force ◽  
Roughness Exponent

The possible role of microstructural features in determining the self-affinity of the fracture surface of a cast aluminum alloy is explored in this work. Fracture surfaces generated both in tension and impact tests were topometrically analyzed by atomic force microscopy, scanning electron microscopy, and stylus profilometry. The roughness exponent exhibited the “universal” value ζ ≈ 0.78, and the correlation length ζ was of the order of the grain size. The brittle intermetallic compounds known to be important in crack initiation did not show any correlation with the self-affine parameters of the resulting fracture surfaces in this particular case.

Self-Affine Measurements on the Fracture Surface of Plastic Materials by AFM

1999 ◽  
Vol 578 ◽  
Author(s):  
E. Reyes ◽  
C. Guerrero ◽  
V. González ◽  
M. Hinojosa
Keyword(s):  
Plastic Material ◽  
Polymeric Materials ◽  
Operating Conditions ◽  
Average Roughness ◽  
Sem Images ◽  
Fracture Surfaces ◽  
Material Surfaces ◽  
Plastic Materials ◽  
Roughness Exponent ◽  
Good Agreement

AbstractThe self-aff'me behavior of fracture surfaces of polymeric materials was qualitatively and quantitatively studied. SEM images of fracture surfaces of both polypropylene and polystyrene show Chevron marks at several magnifications. In addition, for polystyrene the mirror and Hackle zones were also observed. For quantitative analysis, the average roughness exponent, ζ, of height profiles generated by AFM images, was estimated by applying the variable bandwidth method. Values of ζ=0.788 and ζ=0.810 were obtained for polypropylene and polystyrene, respectively. These results are in very good agreement with the claimed universal exponent of 0.8 reported in the literature for other non-polymeric materials. By choosing the AFM appropriate operating conditions, measurements of roughness on plastic material surfaces could be performed.

Self-Affine Quasi-Static Fracture of Soda-Lime Glass

2007 ◽  
Vol 560 ◽  
pp. 41-46 ◽  
Author(s):  
Claus Guerra-Amaro ◽  
M. Hinojosa ◽  
E. Reyes-Melo ◽  
V. González
Keyword(s):  
Soda Lime ◽  
The Self ◽  
Soda Lime Glass ◽  
Force Microscopy ◽  
Fracture Surfaces ◽  
Atomic Force ◽  
A Value ◽  
Roughness Exponent ◽  
Static Fracture ◽  
Static Conditions

In the present work we discuss the self-affine properties of the fracture surfaces of sodalime glass obtained under quasi-static conditions. The fracture surfaces are generated using a threepoint bending system in normal room conditions and under high humidity conditions. The surfaces were recorded both by Scanning Electron Microscopy and Atomic Force Microscopy, and their selfaffine properties are characterized using the Variable Bandwidth method. For both conditions it is observed that the major part of the fracture surface is occupied by the mirror zone. On the other hand, the self-affine analysis reveals that for both conditions the roughness exponent has values centred at around 0.58 with moderate dispersion, in agreement with previous results. Our findings support the hypothesis of the existence of a characteristic roughness exponent for quasi-static fracture with a value that is significantly lower than the value of 0.8 reported for rapid fracture conditions.

Fracture Surfaces in 3D Fuse Networks

1995 ◽  
Vol 409 ◽  
Author(s):  
V. I. Räisänen ◽  
M. J. Alava ◽  
R. M. Nieminen
Keyword(s):  
Fracture Surface ◽  
Fracture Process ◽  
Energy Surface ◽  
Minimum Energy ◽  
Quenched Disorder ◽  
Nanometer Scale ◽  
Directed Percolation ◽  
Fracture Surfaces ◽  
Final Fracture ◽  
Roughness Exponent

We study a 3D random fuse network model with computer simulations. The breaking thresholds are distributed randomly, corresponding to quenched disorder. We find for the roughness exponent of the final fracture surface ζ = 0.47 ± 0.19, which is close both the minimum energy surface value and the directed percolation depinning model value in 2+1 dimensions. It is also similar to results from measurements of fracture surfaces at nanometer scale, and from experiments in which the fracture process occurs slowly as in fatique. The traditional measure of damage, the number of broken bonds grows faster than the area effect (nb ˜ L2.28), with no signs of a trivally brittle regime.

Microstructure and Self-Affine Fracture Surface Parameters in Steel

2006 ◽  
Vol 509 ◽  
pp. 43-48 ◽  
Author(s):  
J. Niño ◽  
M. Hinojosa ◽  
V. González
Keyword(s):  
Fracture Surface ◽  
Impact Test ◽  
Surface Parameters ◽  
Force Microscopy ◽  
Fracture Surfaces ◽  
Grain Sizes ◽  
Atomic Force ◽  
A Value ◽  
Roughness Exponent ◽  
Microstructural Condition

The fracture surfaces of SAE-1018 steel tension and impact test specimens with different grain sizes are analyzed in order to explore the possible relations between the microstructure and the self-affine fracture surface parameters such as the roughness exponent, ζ, and the correlation length, ξ. The topography of the fracture surfaces was observed and quantified by means of scanning electron microscopy, atomic force microscopy, optical microscopy and optical digitizer. It is confirmed that the fracture surfaces exhibit a self-affine behavior extending over six decades of length scale, from nanometers up to a few millimeters. The roughness exponent exhibits a value of ζ∼0.82 for all the cases regardless of the microstructural condition.

STATISTICS OF FRACTURE SURFACES

Fractals ◽  
1993 ◽  
Vol 01 (04) ◽  
pp. 1059-1067 ◽  
Author(s):  
J. PLANÈS ◽  
E. BOUCHAUD ◽  
G. LAPASSET
Keyword(s):  
Aluminium Alloy ◽  
Power Law ◽  
Fracture Mode ◽  
Experimental Measurements ◽  
Height Distribution ◽  
Gaussian Distributions ◽  
Fracture Surfaces ◽  
Roughness Exponent ◽  
Theoretical Predictions ◽  
Branched Structures

Experimental measurements of the roughness exponent ζ of some fracture surfaces are reported. Whatever the fracture mode, for unbranched (aluminium alloy) or branched (Ni3Al) surfaces, ζ is found quite close to 0.8, in accordance with other experimental determinations, but not with theoretical predictions of standard 3-d models. The complete height distribution for the complex branched structures is shown to slowly decrease with increasing altitude. It implies a power-law behavior for the low order moments which is experimentally recovered. Exponents reveal different from that of gaussian distributions.

New Dimensions in Freeze-Etching

1969 ◽  
Vol 27 ◽  
pp. 202-203 ◽  
Author(s):  
Russell L. Steere ◽  
Michael Moseley
Keyword(s):  
Fracture Surfaces ◽  
Aluminum Specimen ◽  
Specimen Holder ◽  
Freeze Etching ◽  
The Right

A redesigned specimen holder and cap have made possible the freeze-etching of both fracture surfaces of a frozen fractured specimen. In principal, the procedure involves freezing a specimen between two specimen holders (as shown in A, Fig. 1, and the left side of Fig. 2). The aluminum specimen holders and brass cap are constructed so that the upper specimen holder can be forced loose, turned over, and pressed down firmly against the specimen stage to a position represented by B, Fig. 1, and the right side of Fig. 2.

Locating Al in the DABCO catalyst before and after Al extraction

1990 ◽  
Vol 48 (4) ◽  
pp. 265-267
Author(s):  
Kathleen B. Reuter
Keyword(s):  
Active Site ◽  
Inverse Relationship ◽  
Transverse Direction ◽  
Reaction Rate ◽  
Acid Phosphate ◽  
Fracture Surfaces ◽  
Al Content ◽  
Before And After ◽  
Relationship Of

The reaction rate and efficiency of piperazine to 1,4-diazabicyclo-octane (DABCO) depends on the Si/Al ratio of the MFI topology catalysts. The Al was shown to be the active site, however, in the Si/Al range of 30-200 the reaction rate increases as the Si/Al ratio increases. The objective of this work was to determine the location and concentration of Al to explain this inverse relationship of Al content with reaction rate.Two silicalite catalysts in the form of 1/16 inch SiO2/Al2O3 bonded extrudates were examined: catalyst A with a Si/Al of 83; and catalyst B, the acid/phosphate Al extracted form of catalyst A, with a Si/Al of 175. Five extrudates from each catalyst were fractured in the transverse direction and particles were obtained from the fracture surfaces near the center of the extrudate diameter. Particles were also obtained from the outside surfaces of five extrudates.

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