scholarly journals Compressive Fracture of Brittle Geomaterial: Fractal Features of Compression-Induced Fracture Surfaces and Failure Mechanism

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
L. Ren ◽  
L. Z. Xie ◽  
C. B. Li ◽  
J. Wang
Keyword(s):  
Failure Mechanism ◽  
Fractal Dimensions ◽  
Contrastive Analysis ◽  
Mode Fracture ◽  
Compressive Fracture ◽  
Fracture Surfaces ◽  
Failure Patterns ◽  
Rough Fracture ◽  
Fracture Tests ◽  
Tension Fracture

Compressive fracture is one of the most common failure patterns in geotechnical engineering. For better understanding of the local failure mechanism of compressive fractures of brittle geomaterials, three compressive fracture tests were conducted on sandstone. Edge cracked semicircular bend specimens were used and, consequently, fresh and unfilled compressive fracture surfaces were obtained. A laser profilometer was employed to measure the topography of each rough fracture surface, followed by fractal analysis of the irregularities of the obtained compression-induced fracture surfaces using the cubic cover method. To carry out a contrastive analysis with the results of compressive fracture tests, three tension mode fracture tests were also conducted and the fractal features of the obtained fracture surfaces were determined. The obtained average result of the fractal dimensions of the compression-induced surfaces was 2.070, whereas the average result was 2.067 for the tension-induced fracture surfaces. No remarkable differences between the fractal dimensions of the compression-induced and tension-induced fracture surfaces may indicate that compressive fracture may occur, at least on the investigative scale of this work, in a similar manner to tension fracture.

Roughness and fractality of fracture surfaces as indicators of mechanical quantities of porous solids

Open Physics ◽  
2011 ◽  
Vol 9 (6) ◽  
Author(s):  
Tomáš Ficker ◽  
Dalibor Martišek
Keyword(s):  
Mechanical Properties ◽  
Fractal Dimension ◽  
Fractal Dimensions ◽  
Point Of View ◽  
Porous Solids ◽  
Surface Parameter ◽  
Cement Pastes ◽  
Fracture Surfaces ◽  
Profile Parameter ◽  
3D Profile

AbstractThe 3D profile surface parameter H q and fractal dimension D were tested as indicators of mechanical properties inferred from fracture surfaces of porous solids. High porous hydrated cement pastes were used as prototypes of porous materials. Both the profile parameter H q and the fractal dimension D showed capability to assess compressive strength from the fracture surfaces of hydrated pastes. From a practical point of view the 3D profile parameter H q seems to be more convenient as an indicator of mechanical properties, as its values suffer much less from statistical scatter than those of fractal dimensions.

Failure mechanism and failure patterns of SCS composite beams with steel-fiber-reinforced UHPC

2020 ◽  
Vol 211 ◽  
pp. 110471 ◽  
Author(s):  
Youzhu Lin ◽  
Jiachuan Yan ◽  
Zefang Wang ◽  
Feng Fan ◽  
Yue Yang ◽  
...  
Keyword(s):  
Failure Mechanism ◽  
Steel Fiber ◽  
Composite Beams ◽  
Fiber Reinforced ◽  
Failure Patterns

ON THE APPLICATION OF METHODS USED TO CALCULATE THE FRACTAL DIMENSION OF FRACTURE SURFACES

Fractals ◽  
2001 ◽  
Vol 09 (01) ◽  
pp. 105-128 ◽  
Author(s):  
TAYFUN BABADAGLI ◽  
KAYHAN DEVELI
Keyword(s):  
Fractal Dimension ◽  
Fractal Dimensions ◽  
Natural Fracture ◽  
Data Sets ◽  
Data Set ◽  
Fracture Surfaces ◽  
Power Spectral ◽  
Data Points ◽  
2D Data ◽  
Fracturing Mechanism

This paper presents an evaluation of the methods applied to calculate the fractal dimension of fracture surfaces. Variogram (applicable to 1D self-affine sets) and power spectral density analyses (applicable to 2D self-affine sets) are selected to calculate the fractal dimension of synthetic 2D data sets generated using fractional Brownian motion (fBm). Then, the calculated values are compared with the actual fractal dimensions assigned in the generation of the synthetic surfaces. The main factor considered is the size of the 2D data set (number of data points). The critical sample size that yields the best agreement between the calculated and actual values is defined for each method. Limitations and the proper use of each method are clarified after an extensive analysis. The two methods are also applied to synthetically and naturally developed fracture surfaces of different types of rocks. The methods yield inconsistent fractal dimensions for natural fracture surfaces and the reasons of this are discussed. The anisotropic feature of fractal dimension that may lead to a correlation of fracturing mechanism and multifractality of the fracture surfaces is also addressed.

Mixed Mode Fracture Tests on Concrete

1989 ◽  
pp. 117-130 ◽  
Author(s):  
H. W. Reinhardt ◽  
H. A. W. Cornelissen ◽  
D. A. Hordijk
Keyword(s):  
Mixed Mode ◽  
Mixed Mode Fracture ◽  
Mode Fracture ◽  
Fracture Tests

Numerical Investigation of Adhesively Bonded Joints

2013 ◽  
Vol 392 ◽  
pp. 105-109
Author(s):  
Mahmood Mokhtari Hasan Abad ◽  
Reza Bakhtiari ◽  
Naghdali Choupani
Keyword(s):  
Mixed Mode ◽  
Fracture Behaviour ◽  
Mixed Mode Fracture ◽  
Bonded Joints ◽  
Adhesively Bonded ◽  
Adhesively Bonded Joints ◽  
Mode Fracture ◽  
Aerospace Material ◽  
Numerical Studies ◽  
Fracture Tests

The study focuses on using fracture mechanics to evaluate mixed-mode fracture properties of adhesively bonded aerospace material systems. As a part of experimental efforts, mixed-mode fracture tests were performed using modified Arcan specimens consisting of several combinations of adhesive, composite and metallic adherends using a special loading device. Experimental and numerical studies of mixed-mode fracture behaviour of adhesively bonded aluminum and steel were also performed using an adhesive in the aerospace industry. Finite element analyses were carried out on specimens with different adherends. Based on those analyses, many fundamental numerical results were obtained.

Image Reconstruction and Analysis of Three-Dimensional Fracture Surfaces Based on the Stereo Matching Method

2004 ◽  
Vol 261-263 ◽  
pp. 1593-1598
Author(s):  
M. Tanaka ◽  
Y. Kimura ◽  
A. Kayama ◽  
L. Chouanine ◽  
Reiko Kato ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Image Reconstruction ◽  
Fracture Surface ◽  
Fractal Analysis ◽  
Stereo Matching ◽  
Three Dimensional ◽  
Fractal Dimensions ◽  
Matching Method ◽  
Fracture Surfaces ◽  
Box Counting Method

A computer program of the fractal analysis by the box-counting method was developed for the estimation of the fractal dimension of the three-dimensional fracture surface reconstructed by the stereo matching method. The image reconstruction and fractal analysis were then made on the fracture surfaces of materials created by different mechanisms. There was a correlation between the fractal dimension of the three-dimensional fracture surface and the fractal dimensions evaluated by other methods on ceramics and metals. The effects of microstructures on the fractal dimension were also experimentally discussed.

Numerical study of heat transfer across rough fracture surfaces

2020 ◽  
Author(s):  
Thomas Heinze
Keyword(s):  
Heat Transfer ◽  
Laboratory Experiments ◽  
Numerical Study ◽  
Three Dimensional ◽  
Fracture Morphology ◽  
Geothermal Systems ◽  
Fracture Surfaces ◽  
Rough Fracture ◽  
Transfer Processes ◽  
Fracture Morphologies

<p>Maximizing heat exploitation in geothermal systems is crucial for the economic efficiency of many geothermal systems. As the hydraulic flow in most geothermal systems is primarily due to fracture flow, heat transfer processes along the fracture surfaces are essential. However, while flow and mass transport in a single fracture have been studied experimentally and theoretically to a great extent, heat transfer processes have been rarely investigated. Laboratory experiments show the influence of the fracture surface morphology on flow and heat transfer processes, though a physical interpretation has been missing so far. Further, in many geothermal systems but also in many natural hydrothermal systems, the solid and fluid phases are not in local thermal equilibrium. Parameterization of local thermal non-equilibrium models was originally developed for porous media and adoptions to fractures have been cumbersome. In this work, I present a numerical study on heat transfer processes across rough fracture surfaces. Using a three-dimensional steady-state flow model, heat transfer across the fracture surface is studied for both scenarios: assuming and neglecting a thermal equilibrium across phase boundaries. Also, separate fracture morphologies have been studied using natural sandstone probes as well as synthetically generated fractures. The numerical simulations results are compared to laboratory experiments using artificially generated and 3D-printed fracture surfaces of various fracture morphologies for code validation. The full three-dimensional simulations reveal the role of flow channeling effects on the heat transfer taking place along rough surfaces, which is not captured by simulations with reduced spatial dimensions. The simulations results suggest a re-examination of the effective heat transfer coefficient for fractured reservoirs under local thermal non-equilibrium conditions incorporating characteristics of fracture morphology. The simulations results can also be linked to thermal stress generation and possibly explaining the deformations of fracture surfaces observed in the laboratory. However, parameterization of surface roughness is neither distinct nor trivial. Various parameters exist, such as the joint roughness coefficient, Hurst exponent or statistical descriptions, but none has been successfully linked to flow, transport or transfer characteristics. Relating fracture morphology with results of numerical simulations and laboratory findings regarding transfer and transport processes indicate a shortfall of conventional roughness parameterizations to sufficiently describe the observed variation in heat transfer parameters.</p>

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