Rock Brittleness Evaluation Method Based on the Complete Stress-Strain Curve

Abstract Brittleness is a crucial parameter of rock mass and the key indicator in rock engineerings, such as rockburst prediction, tunnelling machine borehole drilling, and hydraulic fracturing. To solve the problem of using present brittleness indexes, the existing rock brittleness indexes were firstly summarised in this paper. Then, a brittleness index (BL), which considers the ratio of stress drop rate and stress increase rate and the peak stress, was proposed. This new index has the advantage of simplifying the acquisition of key parameters and avoiding dimensional problems, as well as taking the complete stress-strain curves into account. While applying the BL, the peak strain is used to describe the difficulty of brittle failure before the peak point, and the ratio of stress drop to strain increase can reflect the stress drop rate without dimension problem. In order to verify the applicability of BL, through the PFC2D, the microparameters and confining pressure were changed to model different types of rock numerical specimens and different stress condition. The results show that the BL can well reflect and classify the brittleness characteristics of different rock types and characterise the constraint of confining pressure on rock brittleness. Moreover, the influence of microparameter on macroparameter was studied. In order to further verify the reliability of the brittleness index (BL), this study conducted uniaxial and triaxial compression tests (30 MPa) on marble, sandstone, limestone, and granite under different confining pressure.

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A New Rock Brittleness Evaluation Index Based on the Internal Friction Angle and Class I Stress–Strain Curve

Rock Mechanics and Rock Engineering ◽

10.1007/s00603-018-1487-0 ◽

2018 ◽

Vol 51 (7) ◽

pp. 2309-2316 ◽

Cited By ~ 7

Author(s):

Hui Zhou ◽

Jun Chen ◽

Jingjing Lu ◽

Yue Jiang ◽

Fanzhen Meng

Keyword(s):

Internal Friction ◽

Strain Curve ◽

Friction Angle ◽

Internal Friction Angle ◽

Class I ◽

Evaluation Index ◽

Stress Strain Curve ◽

Stress Strain ◽

Rock Brittleness

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Stress-strain Curve Estimation Procedure for Large Strain Including Post-necking Strain

JOURNAL OF THE JAPAN WELDING SOCIETY ◽

10.2207/jjws.88.621 ◽

2019 ◽

Vol 88 (8) ◽

pp. 621-623

Author(s):

Masayuki KAMAYA

Keyword(s):

Large Strain ◽

Strain Curve ◽

Estimation Procedure ◽

Stress Strain Curve ◽

Stress Strain ◽

Curve Estimation

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A modified version of MATLAB application window for predicting the weld bead profile and stress–strain plot of AA5052 CMT weldment using ER4043

SIMULATION ◽

10.1177/00375497211031522 ◽

2021 ◽

pp. 003754972110315

Author(s):

B Girinath ◽

N Siva Shanmugam

Keyword(s):

Strain Curve ◽

Weld Bead ◽

Welding Parameters ◽

Bead Geometry ◽

Hybrid Technique ◽

Stress Strain Curve ◽

Stress Strain ◽

Weld Bead Geometry ◽

Inference System ◽

Engineering Stress

The present study deals with the extended version of our previous research work. In this article, for predicting the entire weld bead geometry and engineering stress–strain curve of the cold metal transfer (CMT) weldment, a MATLAB based application window (second version) is developed with certain modifications. In the first version, for predicting the entire weld bead geometry, apart from weld bead characteristics, x and y coordinates (24 from each) of the extracted points are considered. Finally, in the first version, 53 output values (five for weld bead characteristics and 48 for x and y coordinates) are predicted using both multiple regression analysis (MRA) and adaptive neuro fuzzy inference system (ANFIS) technique to get an idea related to the complete weld bead geometry without performing the actual welding process. The obtained weld bead shapes using both the techniques are compared with the experimentally obtained bead shapes. Based on the results obtained from the first version and the knowledge acquired from literature, the complete shape of weld bead obtained using ANFIS is in good agreement with the experimentally obtained weld bead shape. This motivated us to adopt a hybrid technique known as ANFIS (combined artificial neural network and fuzzy features) alone in this paper for predicting the weld bead shape and engineering stress–strain curve of the welded joint. In the present study, an attempt is made to evaluate the accuracy of the prediction when the number of trials is reduced to half and increasing the number of data points from the macrograph to twice. Complete weld bead geometry and the engineering stress–strain curves were predicted against the input welding parameters (welding current and welding speed), fed by the user in the MATLAB application window. Finally, the entire weld bead geometries were predicted by both the first and the second version are compared and validated with the experimentally obtained weld bead shapes. The similar procedure was followed for predicting the engineering stress–strain curve to compare with experimental outcomes.

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Driving-stress waveform and the determination of rock internal friction by the stress--strain curve method

Geophysical Journal International ◽

10.1111/j.1365-246x.1980.tb02638.x ◽

1980 ◽

Vol 63 (2) ◽

pp. 567-572 ◽

Cited By ~ 2

Author(s):

H.-P. Liu

Keyword(s):

Internal Friction ◽

Strain Curve ◽

Stress Strain Curve ◽

Stress Strain ◽

Curve Method

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Stress-strain curve of paper revisited

Nordic Pulp & Paper Research Journal ◽

10.3183/npprj-2012-27-02-p318-328 ◽

2012 ◽

Vol 27 (2) ◽

pp. 318-328 ◽

Cited By ~ 37

Author(s):

Svetlana Borodulina ◽

Artem Kulachenko ◽

Mikael Nygårds ◽

Sylvain Galland

Keyword(s):

Three Dimensional ◽

Strain Curve ◽

Failure Behavior ◽

Three Dimensional Model ◽

Stress Strain Curve ◽

Stress Strain ◽

Fiber Network ◽

Bonding Parameters ◽

Particle Level ◽

The Impact

Abstract We have investigated a relation between micromechanical processes and the stress-strain curve of a dry fiber network during tensile loading. By using a detailed particle-level simulation tool we investigate, among other things, the impact of “non-traditional” bonding parameters, such as compliance of bonding regions, work of separation and the actual number of effective bonds. This is probably the first three-dimensional model which is capable of simulating the fracture process of paper accounting for nonlinearities at the fiber level and bond failures. The failure behavior of the network considered in the study could be changed significantly by relatively small changes in bond strength, as compared to the scatter in bonding data found in the literature. We have identified that compliance of the bonding regions has a significant impact on network strength. By comparing networks with weak and strong bonds, we concluded that large local strains are the precursors of bond failures and not the other way around.

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Definition of the yield point in plasticity and its effect on the shape of the yield locus

Journal of Strain Analysis ◽

10.1243/03093247v014331 ◽

1966 ◽

Vol 1 (4) ◽

pp. 331-338 ◽

Cited By ~ 13

Author(s):

T C Hsu

Keyword(s):

Yield Point ◽

Experimental Work ◽

Strain Curve ◽

Yield Locus ◽

Experimental Results ◽

Stress Strain Curve ◽

Proportional Limit ◽

Stress Strain ◽

Small Section ◽

Definition Of

Three different definitions of the yield point have been used in experimental work on the yield locus: proportional limit, proof strain and the ‘yield point’ by backward extrapolation. The theoretical implications of the ‘yield point’ by backward extrapolation are examined in an analysis of the loading and re-loading stress paths. It is shown, in connection with experimental results by Miastkowski and Szczepinski, that the proportional limit found by inspection is in fact a point located by backward extrapolation based on a small section of the stress-strain curve, near the elastic portion of the curve. The effect of different definitions of the yield point on the shape of the yield locus and some considerations for the choice between them are discussed.

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