Experimental Study on Creep Characteristics of Coal under Uniaxial Compression

2012 ◽  
Vol 594-597 ◽  
pp. 290-293
Author(s):  
Yong Jie Yang ◽  
Ming Fu Guo ◽  
Dong Wei Chen
Keyword(s):  
Mechanical Test ◽  
Test System ◽  
Load Level ◽  
Creep Failure ◽  
Deep Mine ◽  
Creep Coefficient ◽  
Multi Stage ◽  
Creep Characteristics ◽  
Cubic Polynomial ◽  
Rock Mechanical Test

Generally surrounding rocks of deep mine show the typical creep characteristics and the multi stage loading creep test of coal was carried out by MTS815 rock mechanical test system in this paper. Compared to the creep coefficient of other rocks, creep coefficient of coal is relatively small. Coal creep failure changes obviously when load level is higher than the threshold stress. The constitutive characteristics of creep failure of coal can be fitted preferably by the Cubic Polynomial.

scholarly journals Experimental and Analytical Study on Creep Characteristics of Box Section Bamboo-Steel Composite Columns under Long-Term Loading

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 983
Author(s):  
Shixu Wu ◽  
Keting Tong ◽  
Jianmin Wang ◽  
Yushun Li
Keyword(s):  
Load Level ◽  
Experimental Results ◽  
Creep Model ◽  
Composite Column ◽  
Composite Columns ◽  
Creep Coefficient ◽  
Creep Characteristics ◽  
Section Size ◽  
Steel Composite

To expand the application of bamboo as a building material, a new type of box section composite column that combined bamboo and steel was considered in this paper. The creep characteristics of eight bamboo-steel composite columns with different parameters were tested to evaluate the effects of load level, section size and interface type under long-term loading. Then, the deformation development of the composite column under long-term loading was observed and analyzed. In addition, the creep-time relationship curve and the creep coefficient were created. Furthermore, the creep model of the composite column was proposed based on the relationship between the creep of the composite column and the creep of bamboo, and the calculated value of creep was compared with the experimental value. The experimental results showed that the creep development of the composite column was fast at first, and then became stable after about 90 days. The creep characteristics were mainly affected by long-term load level and section size. The creep coefficient was between 0.160 and 0.190. Moreover, the creep model proposed in this paper was applicable to predict the creep development of bamboo-steel composite columns. The calculation results were in good agreement with the experimental results.

Analysis on Bolt Supporting Mechanism for Roadways Driving along next Goaf Based on Triaxial Compression Test

2012 ◽  
Vol 594-597 ◽  
pp. 1159-1162
Author(s):  
Sheng Zhong ◽  
Yong Jie Yang ◽  
Min Wang
Keyword(s):  
Mechanical Test ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Test System ◽  
Deformation Characteristics ◽  
Compression Tests ◽  
Conventional Triaxial Compression ◽  
Strength And Deformation ◽  
Rock Mechanical Test ◽  
Triaxial Compression Tests

Conventional triaxial compression tests of coal specimens are carried out by MTS815 servo-controlled rock mechanical test system, and the strength and deformation characteristics of coal under different confining pressure are analyzed. On that basis, bolt supporting mechanism of surrounding rocks of roadways driving along next goaf is studied.

scholarly journals Experimental Study on the Creep Characteristics of Coal Measures Sandstone under Seepage Action

Processes ◽  
2018 ◽  
Vol 6 (8) ◽  
pp. 110 ◽  
Author(s):  
Ziheng Sha ◽  
Hai Pu ◽  
Ming Li ◽  
Lili Cao ◽  
Ding Liu ◽  
...  
Keyword(s):  
Creep Deformation ◽  
Deformation Rate ◽  
Confining Pressure ◽  
Test System ◽  
Stability Control ◽  
Surrounding Rock ◽  
Natural State ◽  
Saturation State ◽  
Creep Characteristics ◽  
Coal Measures

The seepage action of underground water accelerates the deformation of roadway surrounding rock in deep mines. Therefore, the study of creep characteristics of surrounding rock under seepage action is the basis for the stability control of roadway surrounding rock in deep water-rich areas. In this paper, a seepage-creep coupling test system for complete rock samples was established. Combined with a scanning electron microscopy (SEM) test system, the seepage-creep law of coal measures sandstone and the damage mechanism were revealed. The study results showed that the maximum creep deformation of sandstone under natural and saturation state decreased gradually with the increase of confining pressure, and the maximum creep deformation under saturation state was greater than the corresponding value under natural state when the confining pressure was same. When the confining pressure was constant, the creep deformation, the constant creep deformation rate and the accelerated creep deformation rate of sandstone increased rapidly with the increase of infiltration pressure. With the change of time, the change of permeability parameters went through three cycles; each cycle was divided into two stages, slow change stage and rapid change stage, and the rate of variation increased with the increase of the seepage pressure. Based on the macroscopic and microscopic characteristics of sandstone rupture, the connection between macroscopic and microscopic mechanism on sandstone rupture was established. The results in this paper can provide a theoretical basis for stability control of roadway surrounding rock in water-rich areas.

scholarly journals Experimental Research on Creep Characteristics of Nansha Soft Soil

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Qingzi Luo ◽  
Xiaoping Chen
Keyword(s):  
Pearl River Delta ◽  
Soft Soil ◽  
Creep Damage ◽  
Pearl River ◽  
Test Results ◽  
Creep Failure ◽  
Consolidation Pressure ◽  
Creep Characteristics ◽  
Triaxial Creep ◽  
Shear Box

A series of tests were performed to investigate the creep characteristics of soil in interactive marine and terrestrial deposit of Pearl River Delta. The secondary consolidation test results show that the influence of consolidation pressure on coefficient of secondary consolidation is conditional, which is decided by the consolidation state. The ratio of coefficient of secondary consolidation and coefficient of compressibilityCa/Ccis almost a constant, and the value is 0.03. In the shear-box test, the direct sheer creep failure of soil is mainly controlled by shear stress rather than the accumulation of shear strain. The triaxial creep features are closely associated with the drainage conditions, and consolidation can weaken the effect of creep. When the soft soil has triaxial creep damage, the strain rate will increase sharply.

The Effects of Cooling Rate Upon Xdt m TiAl Weld Microstructure

1990 ◽  
Vol 194 ◽  
Author(s):  
Erica Robertson ◽  
Mary Ann Hill ◽  
Ricardo B. Schwarz
Keyword(s):  
Solid State ◽  
Cooling Rate ◽  
Volume Fraction ◽  
Mechanical Test ◽  
Test System ◽  
X Ray Diffraction ◽  
State Transformation ◽  
Solid State Transformation ◽  
X Ray ◽  
Weld Microstructure

AbstractFusion zone microstructures of an electron beam (EB) welded XDt m Ti–48at%Al + 6.5 vol% TiB2 alloy revealed plate-like precipitates which were absent in the base metal. The volume fraction of this phase increased with increasing cooling rate and correlated with increased weld cracking frequency. To determine whether this phase was a product of solidification from the melt or a product of a solid-state transformation, the microstructures of the welds were compared to those of samples cycled in a Gleeble 1500/20 Thermal-Mechanical Test System which was programmed to simulate the solid-state portion of the weld cooling rates (as predicted by a Rosenthal analysis). The microstructures were characterized by X-ray diffraction, optical and by scanning electron microscopy. The plate-like phase found in the weld microstructures was identified as TiB2 occurring upon rapid solidification of the melted weld metal.

Test Machine and Control System Interactions in the Evaluation of Rate-Dependent Metal Flow

1993 ◽  
Vol 115 (2) ◽  
pp. 179-186 ◽  
Author(s):  
S. B. Brown ◽  
V. R. Dave
Keyword(s):  
Control System ◽  
Dynamic Response ◽  
Mechanical Test ◽  
Metal Flow ◽  
Test System ◽  
Rate Change ◽  
Test Machine ◽  
Strain Rate Change ◽  
Rate Dependent ◽  
And Control

Although rate-change experiments are essential for characterizing rate-dependent flow, certain nonobvious aspects of test machine dynamic response and control system strategies can distort rate-change data. These distortions are large enough to cause rate-change experiments to characterize the test system dynamic response instead of the test material’s rate dependence. We demonstrate that both relaxation and strain rate change experiments exhibit this potential distortion of test data. Investigators performing these experiments must therefore examine control error carefully to assure that the experiments are valid. We demonstrate that the standard PID control modes normally used in servocontrolled mechanical test equipment will generate error. Either P or PD control modes are more appropriate for rate-change experiments.

Effect of Reserved Texture on Mechanical Properties of Cold Drawn Pearlitic Steel Wire

2014 ◽  
Vol 936 ◽  
pp. 1948-1952 ◽  
Author(s):  
Li Chu Zhou ◽  
Yu Fei Zhao ◽  
Feng Fang
Keyword(s):  
Tensile Strength ◽  
Mechanical Test ◽  
Steel Wire ◽  
Pearlitic Steel ◽  
Test System ◽  
Fiber Texture ◽  
Experimental Result ◽  
Improve Working ◽  
The Wire ◽  
Scanning Electron

In this paper, pearlitic steel wire with/without reserved texture were investigated with the help of mechanical test system, scanning electron microscope (SEM) and XRD. Experimental result shows that: Tensile strength of two wire are almost same. After cold drawn tensile strength of wire with reserved texture are higher than tensile strength of the without one. Before cold drawn, two wires have same microstructure of isometric pearlite and after drawing the wire with reserved texture has less shear deformed pearlitic colony. Intensity of <110> fiber texture in the wire with reserved texture are stronger than the without one at all strains. The stronger <110> texture mean the orientation of α-ferrite lamella were more closely and improve working hardening rate of pearlitic wire.

Triaxial Failure of Aluminium Foams

Aerospace ◽  
2003 ◽  
Author(s):  
D. Ruan ◽  
G. Lu ◽  
B. Wang
Keyword(s):  
Yield Surface ◽  
Mechanical Test ◽  
Yield Criterion ◽  
Test System ◽  
Metallic Foam ◽  
Triaxial Tests ◽  
Strain Rates ◽  
Lightweight Structures ◽  
Stress States ◽  
Energy Absorbers

Aluminium foam is a type of cellular materials and offers potential for lightweight structures and energy absorbers in automotive and aerospace industries. They may be subject to multiaxial loads in these applications and it is essential to have a failure criterion in terms of the stresses which cause yield. Three criteria have been proposed so far. Gibson and Ashby deduced a yield surface by using dimentional arguments for ideal, isotropic, homogenous foams. Miller’s yield surface was based on the model of Drucker and Prager, which was originally proposed as a model for soil. It incorporated a linear and quadratic dependence on the pressure. Deshpande and Fleck modified the yield criterion of solid metals to account for the effect of porosity on the yield criterion for a metallic foam. In this paper, triaxial tests of CYMAT aluminium foams were conducted by using MTS (Mechanical Test System) with a Hoek Cell to investigate their yield surfaces experimentally. Five types of aluminium foams with nominal relative densities. of 5%, 10%, 15%, 17% and 20% were tested for a range of axisymmetric compressive stress states. Experimental results were compared with three theoretical criteria. Triaxial tests at various strain rates (from 10−4 to 10+1 s−1) were also performed in this paper to investigate the influence of strain rate on the yield surface.

Statistical Evaluation on Cumulative Damage Property of Aluminum Alloy Welded Joint under Multi-Stage Loading

2010 ◽  
Vol 118-120 ◽  
pp. 522-526
Author(s):  
Wei Li ◽  
Qiang Li ◽  
Ping Wang
Keyword(s):  
Aluminum Alloy ◽  
Test Data ◽  
Goodness Of Fit ◽  
Damage Model ◽  
Butt Joint ◽  
Load Level ◽  
Cumulative Damage ◽  
Goodness Of Fit Test ◽  
Multi Stage ◽  
Cumulative Damage Model

Two-stage loading tests corresponding to high-low loading and low-high loading were performed to clarify the cumulative damage properties of two kinds of aluminum alloy welded joints such as the corner joint and butt joint. As a result, the logarithmic value of cumulative damage can better be characterized by the normal distribution in accordance with the Komogorov-Smirnov goodness of fit test. The proposed linear cumulative damage model can better reflect the scatter characteristic of test data, as well as the newly developed nonlinear cumulative damage model can better characterize the effects of load sequence and load level on fatigue damage value, which was verified with the obtained test data.

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