scholarly journals Tensile behavior of a Brazilian Disk Containing non-persistent Joint Sets Subjected to Diametral Loading: An Experimental Investigation

2021 ◽  
Author(s):  
Mostafa Asadizadeh ◽  
Jamshid Shakeri ◽  
Nima Babanouri ◽  
Mohammad Rezaei
Keyword(s):  
Tensile Strength ◽  
Tensile Stress ◽  
Failure Pattern ◽  
Structural Defects ◽  
Joint Spacing ◽  
Joint Continuity ◽  
Failure Patterns ◽  
Loading Direction ◽  
Joint Parameters ◽  
Strength And Stiffness

Abstract Structural defects are part of the inherent characteristics of rock masses. They can be found in the form of fishers, joints, and beddings and can be divided into persistent or non-persistent one. The coalescence of non-persistent cracks may lead to the formation of persistent joints under the tensile stress field, leading to instability of rock mass. The mechanical behavior of non-persistent jointed disks under tensile stress has essential implications for rock engineering structures. In this paper, concrete Brazilian disks containing open non-persistent joints were constructed and subjected to diametral loading to investigate the effect of this kind of joint parameters on the tensile strength and stiffness of disks. The effect of some parameters, such as joint continuity factor (the relationship between joint length and rock bridge length), bridge angle, joint spacing, and loading direction with respect to joint angle were investigated to estimate the tensile strength and stiffness as well as failure pattern. The results of experiments revealed that the tensile strength, stiffness, and failure pattern of Brazilian disks are highly affected by non-persistent pre-existing crack parameters. The increase of joint continuity factor and loading direction leads to an increase in tensile strength and a decrease in stiffness. However, when bridge angle and spacing increase tensile strength rises, and the former decreases stiffness while the latter results in its reduction. Finally, all the parameters significantly affect the failure pattern, and some failure patterns such as step-path failure, splitting, or sliding may occur as a function of non-persistent joint parameters.

scholarly journals Dynamic Fracturing Behavior of Layered Rock with Different Inclination Angles in SHPB Tests

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Jiadong Qiu ◽  
Diyuan Li ◽  
Xibing Li ◽  
Zilong Zhou
Keyword(s):  
Shear Stress ◽  
Tensile Stress ◽  
Split Hopkinson Pressure Bar ◽  
Impact Compression ◽  
Failure Patterns ◽  
Layered Rock ◽  
Bedding Planes ◽  
Loading Direction ◽  
Fracturing Process ◽  
Inclination Angles

The fracturing behavior of layered rocks is usually influenced by bedding planes. In this paper, five groups of bedded sandstones with different bedding inclination angles θ are used to carry out impact compression tests by split Hopkinson pressure bar. A high-speed camera is used to capture the fracturing process of specimens. Based on testing results, three failure patterns are identified and classified, including (A) splitting along bedding planes; (B) sliding failure along bedding planes; (C) fracturing across bedding planes. The failure pattern (C) can be further classified into three subcategories: (C1) fracturing oblique to loading direction; (C2) fracturing parallel to loading direction; (C3) mixed fracturing across bedding planes. Meanwhile, a numerical model of layered rock and SHPB system are established by particle flow code (PFC). The numerical results show that the shear stress is the main reason for inducing the damage along bedding plane at θ = 0°~75°. Both tensile stress and shear stress on bedding planes contribute to the splitting failure along bedding planes when the inclination angle is 90°. Besides, tensile stress is the main reason that leads to the damage in rock matrixes at θ = 0°~90°.

Experimental Study on the Stitching Reinforcement of Composite Member with a Circular Hole

2010 ◽  
Vol 152-153 ◽  
pp. 459-464
Author(s):  
Xi Ping Zhu ◽  
Zhang Xin Guo ◽  
Xiao Ang Cao ◽  
Xi Zhe Zhi
Keyword(s):  
Experimental Study ◽  
Tensile Strength ◽  
Circular Hole ◽  
Composite Laminates ◽  
Strain Distribution ◽  
Row Spacing ◽  
Loading Direction ◽  
Edge Distance ◽  
Edge Location ◽  
Strength And Stiffness

Experiment studies are carried out on the stitching reinforcement of composite laminates containing a circular hole. The tensile strength and stiffness are measured, and their dependence on stitching parameters such as stitching needle distance, row spacing, edge distance and stitching type (i.e. single stitching or double stitching) are analyzed. The strain distribution is investigated experimentally for different stitching parameters, external load and edge location of the hole. It is shown that the results of stitching reinforcement are quite different for composite laminates with a circular hole, which could provide proper stitching parameters for designers. The analysis for different failure samples are made. Reinforced by stitching, the failure section is mainly perpendicular to loading direction. It can be seen that the capacity of load bearing rises when the composite components are reinforced by stitching the hole.

Molecular dynamics study on the mechanical response and failure behaviour of graphene: performance enhancement via 5–7–7–5 defects

RSC Advances ◽  
2016 ◽  
Vol 6 (31) ◽  
pp. 26361-26373 ◽  
Author(s):  
G. Rajasekaran ◽  
Avinash Parashar
Keyword(s):  
Molecular Dynamics ◽  
Tensile Strength ◽  
Structural Properties ◽  
Elastic Moduli ◽  
Mechanical Response ◽  
Performance Enhancement ◽  
Structural Defects ◽  
Thick Sheet ◽  
Failure Behaviour ◽  
Production Techniques

A one atom-thick sheet of carbon exhibits outstanding elastic moduli and tensile strength in its pristine form but structural defects which are inevitable in graphene due to its production techniques can alter its structural properties.

Numerical Simulation on Failure Patterns of Rock Discs and Rings Subject to Diametral Line Loads

2004 ◽  
Vol 261-263 ◽  
pp. 1517-1522 ◽  
Author(s):  
Wan Cheng Zhu ◽  
K.T. Chau ◽  
Chun An Tang
Keyword(s):  
Tensile Strength ◽  
Standardized Test ◽  
Process Analysis ◽  
Failure Process ◽  
Brazilian Test ◽  
Rock Failure ◽  
Numerical Code ◽  
Failure Patterns ◽  
Rock Failure Process ◽  
Indirect Tensile

Brazilian test is a standardized test for measuring indirect tensile strength of rock and concrete disc (or cylinder). Similar test called indirect tensile test has also been used for other geomaterials. Although splitting of the disc into two halves is the expected failure mode, other rupture modes had also been observed. More importantly, the splitting tensile strength of rock can vary significantly with the specimen geometry and loading condition. In this study, a numerical code called RFPA2D (abbreviated from Rock Failure Process Analysis) is used to simulate the failure process of disc and ring specimens subject to Brazilian test. The failure patterns and splitting tensile strengths of specimens with different size and loading-strip-width are simulated and compared with existing experimental results. In addition, two distinct failure patterns observed in ring tests have been simulated using RFPA2D and thus this verifies the applicability of RFPA2D in simulating rock failure process under static loads.

Wear Out Failure Patterns and Their Interpretation

1980 ◽  
Vol 22 (3) ◽  
pp. 143-151 ◽  
Author(s):  
A. D. S. Carter
Keyword(s):  
Fatigue Strength ◽  
Failure Rate ◽  
Initial Period ◽  
Failure Pattern ◽  
Weibull Distributions ◽  
Increasing Failure Rate ◽  
Failure Patterns ◽  
Loss Of Strength ◽  
Continuous Loss

It is shown theoretically that fatigue of a component will result in a failure pattern which consists of an initial period of intrinsic reliability, or near zero failures, followed by a rapid increase in failure rate when loss of fatigue strength becomes operative, to be followed in turn by a period during which the failure rate decreases with time or maybe remains constant. By contrast other wear-out modes involving a continuous loss of strength give rise to a steadily increasing failure rate after the period of intrinsic reliability has expired. Practical examples of each type are quoted to substantiate the theoretical deductions. The interpretation of wear out characteristics by Weibull distributions is discussed.

Residual Stress Distribution in Pure Bending Beam Subjected to Tensile Failure on One Side

2006 ◽  
Vol 524-525 ◽  
pp. 253-258
Author(s):  
X.B. Wang
Keyword(s):  
Residual Stress ◽  
Tensile Strength ◽  
Stress Distribution ◽  
Tensile Stress ◽  
Strain Localization ◽  
Tensile Strain ◽  
Residual Stress Distribution ◽  
Neutral Axis ◽  
Residual Tensile Stress ◽  
Pure Bending

The stress distribution on the midsection of a pure bending beam where tensile strain localization band initiates on the tensile side of the beam and propagates within the beam is analyzed. Using the static equilibrium condition on the section of the midspan of the beam and the assumption of plane section as well as the linear softening constitutive relation beyond the tensile strength, the expressions for the length of tensile strain localization band and the distance from the tip of the band to the neutral axis are derived. After superimposing a linear unloading stress distribution over the initial stress distribution, the residual stress distribution on the midsection of the beam is investigated. In the process of strain localization band’s propagation, strain-softening behavior of the band occurs and neutral axis will shift. When the unloading moment is lower, the length of tensile strain localization band remains a constant since the stress on the base side of the beam is tensile stress. While, for larger unloading moment, with an increase of unloading moment, the length of tensile strain localization band decreases and the distance from the initial neutral axis to the unloading neutral axis increases. The neutral axis of midsection of the beam will shift in the unloading process. The present analysis is applicable to some metal materials and many quasi-brittle geomaterials (rocks and concrete, etc) in which tensile strength is lower than compressive strength. The present investigation is limited to the case of no real crack. Moreover, the present investigation is limited to the case that the length of strain localization band before unloading is less than half of depth of the beam. Otherwise, the residual tensile stress above the elastic neutral axis will be greater than the tensile strength, leading to the further development of tensile strain localization band in the unloading process.

In Situ Formation of Poly(ethylene naphthalate) Microfibres in Polyethylene and Polypropylene during Extrusion

2007 ◽  
Vol 334-335 ◽  
pp. 161-164 ◽  
Author(s):  
Ka Lok Leung ◽  
Allan J. Easteal ◽  
Debes Bhattacharyya
Keyword(s):  
Tensile Strength ◽  
Scanning Electron Micrographs ◽  
Polyolefin Blends ◽  
Extrusion Die ◽  
Order Of Magnitude ◽  
Poly Ethylene ◽  
Strength And Stiffness ◽  
The Relationship ◽  
Fibre Morphology

Tensile properties and morphology of poly(ethylene naphthalate)/polyolefin blends and the relationship with the extrusion die size were investigated. Scanning electron micrographs of the blends reveal that the fibre morphology is developed during extrusion through the die. Skin-core morphology has been observed. As die diameter decreases, a droplet-to-fibre transition in morphology increases tensile strength and stiffness. After microfibrillization, up to 100% increase in the tensile stiffness was observed and the tensile strength could increase by one order of magnitude.

Development of poplar glued–laminated timber. I: Tensile strength and stiffness of poplar laminating stock

1986 ◽  
Vol 13 (4) ◽  
pp. 445-459 ◽  
Author(s):  
M. M. Lepper ◽  
F. J. Keenan
Keyword(s):  
Tensile Strength ◽  
Volume Effect ◽  
The Other ◽  
Regression Analyses ◽  
Frequency Data ◽  
Glulam Beam ◽  
Full Size ◽  
Glued Laminated Timber ◽  
Strength And Stiffness ◽  
General Slope

The tensile strength and stiffness of 263 full-size pieces of 38 × 80 mm in-grade poplar lumber from two mills in Ontario were determined. Prior to testing, complete maps of all grade-related defects in each piece were made; these defects included general slope of grain, centre knots, and edge knots. Specific gravity and moisture content were also recorded for each piece. After testing, the defects that triggered each piece's failure were noted. This information led, through regression analyses and the assumption of a Weibull distribution, to models for tensile strength and stiffness. The models were developed for the pieces from one mill and were tested against the results obtained from pieces from the other mill; agreement was very good. The knot frequency and slope frequency data were used in a modified form of the Foschi and Barrett glulam beam simulation model to predict the fifth fractile value of a population of poplar glulam beams. Taking the volume effect into account, the predicted beam strengths and stiffnesses are close to those of glulam beams of stress grade 20f–E.

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