Particle Flow Analysis of Macroscopic and Mesoscopic Failure Process of Salt Rock under High Temperature and Triaxial Stress

In order to reveal the mechanism of thermal-induced deformation and fracture development of salt rock under high temperature, the particle flow program PFC2D was used to study the triaxial compression failure process of salt rocks under different temperatures; at the same time, a combination model of Burge and Linearpbond was proposed to simulate plastic deformation and heat conduction of salt rock. Finally, the simulation results were compared with the experimental results to verify the validity of the conclusion. The simulation results show that the elastic limit points of rock gradually descend, the dilatancy points rise gradually, and the plastic deformation characteristics of salt rock become more obvious with the increase of temperature. Due to the damage of the sample, the strong chains break and disappear, increasing the proportion of the weak chains, and the high temperature intensifies the rupture of the contact between the particles in the salt rock. As the temperature increases from 50°C to 120°C, the strong chains in the rock sample decrease significantly, and the damage gradually increases; when the temperature is 150°C, the contact force decreases sharply, and the damage of salt rock is significant. According to the particle displacement cloud diagrams, it is found that the expansion direction from the middle part of the rock sample to the left and right ends is 12.08°, 9.55°, 8.2°, 6.33°, and 0°, respectively. The displacement directions of the rock sample show obvious radial expansion tendency, and the higher the temperature, the more obvious the “drum-shaped” failure phenomenon in the middle of the rock sample. During the heating process, the thermal cracks are mainly tensile cracks, and transverse cracks are gradually formed in the middle of the model. The cementation failure points at the top and bottom of the model expand in an oblique direction and form oblique cracks of about 45°. From the three different mathematical models of macroscopic and mesoscopic views, it is concluded that the effect of temperatures on salt rock is more significant after 90°C. This research is important for exploring the macroscopic and microscopic mechanics evolution of salt rock and provides a reference for determining the long-term mechanical strength of salt rock.

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Stress Drop as a Result of Splitting, Brittle and Transitional Faulting of Rock Samples in Uniaxial and Triaxial Compression Tests

Studia Geotechnica et Mechanica ◽

10.1515/sgem-2015-0003 ◽

2015 ◽

Vol 37 (1) ◽

pp. 17-23 ◽

Cited By ~ 2

Author(s):

Jerzy Cieślik

Keyword(s):

Stress Drop ◽

Rock Sample ◽

Triaxial Compression ◽

Failure Process ◽

Strength Loss ◽

Axial Stiffness ◽

Compression Tests ◽

Rock Samples ◽

Test Pressure ◽

Triaxial Compression Tests

Abstract Rock samples can behave brittle, transitional or ductile depending on test pressure, rate of loading and temperature. Axial stiffness and its changes, relative and absolute dilatancy, yield, and fracture thresholds, residual strength are strongly pressure dependent. In this paper the stress drop as an effect of rock sample strength loss due to failure was analyzed. Uniaxial and triaxial experiments on three types of rock were performed to investigate the stress drop phenomenon. The paper first introduces short background on rock behavior and parameters defining a failure process under uniaxial and triaxial loading conditions. Stress drop data collected with experiments are analyzed and its pressure dependence phenomenon is described. Two methods for evaluation of stress drop value are presented.

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Mechanical Properties of Bulk Glassy Metal after Deformation under High Temperature Conditions

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.340-341.113 ◽

2007 ◽

Vol 340-341 ◽

pp. 113-118

Author(s):

Takamasa Yoshikawa ◽

Masataka Tokuda ◽

Tadashi Inaba

Keyword(s):

Mechanical Properties ◽

Plastic Deformation ◽

High Temperature ◽

Room Temperature ◽

Tensile Load ◽

Experimental Result ◽

Uniaxial Tensile ◽

Heating Process ◽

Plastic Behavior ◽

Temperature Conditions

Bulk glassy metal is an alloy with the vitreous amorphous structure. Because of various excellent properties, this material is expected to use as an alternative structural material for several engineering applications very well. Although bulk glassy metal is very little deformed plastically in the room temperature, it shows the huge super-plastic behavior over the high temperature. However, there is not many reports mentioned about the mechanical properties of bulk glassy metal after plastic deformation under high temperature condition. From the above point of view, in this study, we have investigated the lower bound of temperature at which Zr55Cu30Al10Ni5 bulk glassy metal can be plastically deformed in uniaxial tensile load. Furthermore, it is focused on the strength property of bulk glassy metal in the room temperature after deformed under various high-temperature conditions. In the experimental result, when this material was heated at temperature of 685[K] or higher, this material crystallized and the mechanical strength in room temperature drastically decreased to 200[MPa], although this material as cast had the strength over 1500[MPa]. However, this material showed sufficiently the plastic deformation at temperatures of 643[K] and the strength in room temperature after cooling was equal to as cast. It is supposed that the strength depend on its atomic structure, i.e., amorphous or crystalline, and the change of its structure is affected strongly by heating process.

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Infrared Thermal Image Study on Failure of Granite with Hole

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.353-358.2313 ◽

2007 ◽

Vol 353-358 ◽

pp. 2313-2316 ◽

Cited By ~ 3

Author(s):

Zhi Hong Tan ◽

Chun An Tang ◽

Wan Cheng Zhu

Keyword(s):

High Temperature ◽

Thermal Effects ◽

Rock Sample ◽

Failure Process ◽

Close Relation ◽

Local Area ◽

Thermal Image ◽

Image Study ◽

Granite Sample ◽

Infrared Thermal Images

The changing behavior for infrared thermal image omen of the rock with fracture is essential for the geotechnical engineering. In order to study the behavior, the infrared thermal images for the failure process of rock with hole are carried out. The size of the rock sample is 20cm×10cm×2cm with hole at the center of the sample and the diameter of the hole is 1cm. Considering the fact that sample will effect the results of the observation for infrared thermal image during the experiment, the laminated granite sample was used to replace the cylinder or cuboid sample. The achieved results under uniaxial compression indicate that intensity of the micro ruptures have a close relation with the thermal effects. When the main fractures happen, there is a strip of high temperature that will appear at the destructed local area. During loading process, the abnormity of infrared temperature has two kinds of behaviors as follows: (1) temperature rises and falls alternately, rises before the fracture; (2) temperature falls slowly at beginning, and then rises slowly, then rises quickly before the fracture appears. Even for the same rock sample, the behaviors of the infrared phenomenon may be different during failure.

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The influence of high temperature plastic deformation on the kinetics of graphitization of pyrolytic carbons

Journal de Chimie Physique ◽

10.1051/jcp/196966s1121 ◽

1969 ◽

Vol 66 ◽

pp. 121-128 ◽

Cited By ~ 4

Author(s):

D. B. Fischbach

Keyword(s):

Plastic Deformation ◽

High Temperature ◽

Kinetics Of

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Structural Transformations and Mechanical Properties of Metastable Austenitic Steel under High Temperature Thermomechanical Treatment

Metals ◽

10.3390/met11040645 ◽

2021 ◽

Vol 11 (4) ◽

pp. 645

Author(s):

Igor Litovchenko ◽

Sergey Akkuzin ◽

Nadezhda Polekhina ◽

Kseniya Almaeva ◽

Evgeny Moskvichev

Keyword(s):

Plastic Deformation ◽

Grain Size ◽

High Temperature ◽

Austenitic Steel ◽

Structural Transformations ◽

Initial State ◽

Twin Boundaries ◽

Metastable Austenitic Steel ◽

Average Grain Size ◽

Heating Up

The effect of high-temperature thermomechanical treatment on the structural transformations and mechanical properties of metastable austenitic steel of the AISI 321 type is investigated. The features of the grain and defect microstructure of steel were studied by scanning electron microscopy with electron back-scatter diffraction (SEM EBSD) and transmission electron microscopy (TEM). It is shown that in the initial state after solution treatment the average grain size is 18 μm. A high (≈50%) fraction of twin boundaries (annealing twins) was found. In the course of hot (with heating up to 1100 °C) plastic deformation by rolling to moderate strain (e = 1.6, where e is true strain) the grain structure undergoes fragmentation, which gives rise to grain refining (the average grain size is 8 μm). Partial recovery and recrystallization also occur. The fraction of low-angle misorientation boundaries increases up to ≈46%, and that of twin boundaries decreases to ≈25%, compared to the initial state. The yield strength after this treatment reaches up to 477 MPa with elongation-to-failure of 26%. The combination of plastic deformation with heating up to 1100 °C (e = 0.8) and subsequent deformation with heating up to 600 °C (e = 0.7) reduces the average grain size to 1.4 μm and forms submicrocrystalline fragments. The fraction of low-angle misorientation boundaries is ≈60%, and that of twin boundaries is ≈3%. The structural states formed after this treatment provide an increase in the strength properties of steel (yield strength reaches up to 677 MPa) with ductility values of 12%. The mechanisms of plastic deformation and strengthening of metastable austenitic steel under the above high-temperature thermomechanical treatments are discussed.

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Verification of electric steel punching simulation results using microhardness

The International Journal of Advanced Manufacturing Technology ◽

10.1007/s00170-020-06500-6 ◽

2021 ◽

Author(s):

Sampsa Vili Antero Laakso ◽

Ugur Aydin ◽

Peter Krajnik

Keyword(s):

Plastic Deformation ◽

High Speed ◽

Steel Sheet ◽

Electrical Steel ◽

High Speed Steel ◽

Experimental Methods ◽

Fem Simulations ◽

Iron Losses ◽

Simulation Results ◽

Electrical Steel Sheet

AbstractOne of the most dominant manufacturing methods in the production of electromechanical devices from sheet metal is punching. In punching, the material undergoes plastic deformation and finally fracture. Punching of an electrical steel sheet causes plastic deformation on the edges of the part, which affects the magnetic properties of the material, i.e., increases iron losses in the material, which in turn has a negative effect on the performance of the electromagnetic devices in the final product. Therefore, punching-induced iron losses decrease the energy efficiency of the device. FEM simulations of punching have shown significantly increased plastic deformation on the workpiece edges with increasing tool wear. In order to identify the critical tool wear, after which the iron losses have increased beyond acceptable limits, the simulation results must be verified with experimental methods. The acceptable limits are pushed further in the standards by the International Electrotechnical Commission (IEC). The new standard (IEC TS 60034-30-2:2016) has much stricter limits regarding the energy efficiency of electromechanical machines, with an IE5 class efficiency that exceeds the previous IE4 class (IEC 60034-30-1:2014) requirements by 30%. The simulations are done using Scientific Forming Technologies Corporation Deform, a finite element software for material processing simulations. The electrical steel used is M400-50A, and the tool material is Vanadis 23, a powder-based high-speed steel. Vanadis 23 is a high alloyed powder metallurgical high-speed steel with a high abrasive wear resistance and a high compressive strength. It is suitable for cold work processing like punching. In the existing literature, FEM simulations and experimental methods have been incorporated for investigating the edge deformation properties of sheared surfaces, but there is a research gap in verifying the simulation results with the experimental methods. In this paper, FEM simulation of the punching process is verified using an electrical steel sheet from real production environment and measuring the deformation of the edges using microhardness measurements. The simulations show high plastic deformation 50 μm into the workpiece edge, a result that is shown to be in good agreement with the experimental results.

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Effect of CO2 on Anti-Corrosion Property of a Polyurea Coating Modified with Organosilicone

Materials Science Forum ◽

10.4028/www.scientific.net/msf.789.466 ◽

2014 ◽

Vol 789 ◽

pp. 466-470

Author(s):

Qing Hao Shi ◽

Bing Ying Wang ◽

Bin Zhao

Keyword(s):

High Temperature ◽

Partial Pressure ◽

Composite Coating ◽

Corrosion Test ◽

Electrochemical Impedance ◽

Failure Process ◽

Corrosion Property ◽

Corrosion Mechanism ◽

Partial Pressures ◽

High Temperature High Pressure

The corrosion mechanism of organic silicon modified polyurea composite coating under different CO2 partial pressures was studied using high-temperature autoclave, combined with scanning electron microscopy (SEM), adhesion tests and electrochemical impedance spectroscopy (EIS) technology. The experimental results showed that: there was no corrosion product formed on the surface of coating sample after high-temperature high-pressure corrosion test, and with the increasing of CO2 partial pressure, the coating adhesion and impedance values decline increases. Moreover CO2 partial pressure increases accelerated the failure process of polyurea composite coating system.

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