Allowance for the influence of the stress state on the mechanical characteristics and the coefficients of thermal expansion in Lamé’s problem for a graphite cylinder

2000 ◽  
Vol 41 (2) ◽  
pp. 71-72
Author(s):  
A. E. Zhidkov
Keyword(s):  
Thermal Expansion ◽  
Stress State ◽  
Mechanical Characteristics ◽  
Graphite Cylinder

Mechanical Characteristics of Soil Anchor under Combined Water and Ground Loads

2011 ◽  
Vol 243-249 ◽  
pp. 2915-2919
Author(s):  
Jian Bin Hao ◽  
Yu Ming Men
Keyword(s):  
Stress State ◽  
Model Test ◽  
Mechanical Characteristics ◽  
Axial Strain ◽  
External Factors ◽  
Soil Slope ◽  
Additional Load ◽  
Anchor System ◽  
State Of Tension ◽  
Ground Load

Gradually, anchor is in the working state of tension, but its stress becomes rather complicated when influenced by some external factors such as water, ground loads, etc. Aiming at the problems that ground additional load or coupling action of water and the additional load are forced on soil slope, the axial strain distributions of anchor tendons were obtained by model test. The change rules of axial strain at anchor head, near to slip plane, and end of the anchorage were analyzed respectively. The results show that under ground loads, the strain of anchor is biggest at the anchor head, and it gradually decreases from outer to inner. Under combined water and ground load, the stress state of the anchor system changes from tension to bending, and the upper anchors are most urgently affected. The experimental results can supply a reference for design and research of soil anchor with similar conditions.

scholarly journals Investigation of the fluids influence on change of sandstones collectors mechanical properties during saturation and degassing

2019 ◽  
Vol 109 ◽  
pp. 00103
Author(s):  
Serhii Tynyna ◽  
Vasyl Babenko
Keyword(s):  
Mechanical Properties ◽  
Stress State ◽  
Mechanical Characteristics ◽  
Partial Discharge ◽  
Laboratory Studies ◽  
Deformation Properties ◽  
Before And After ◽  
Surface Active ◽  
Sandstone Formation ◽  
State Of The Environment

The article discusses the effect of fluids on the properties of rocks. It is known that surface active environments, including gas, can significantly change the mechanical characteristics of solids. To establish the dependence of the effect of methane on the strength characteristics of rocks, the results of full-scale and laboratory studies are considered. The experiments were carried out on samples of outburst sandstone formation m3, taken at a depth of 915 m. Analysis of research results allowed to establish the effect of changes in gas saturation of rocks on their mechanical properties before and after degassing and partial discharge of experimental areas after they have been worked by lavas along m3 formation. It has been established that the reason for the increase in drillability and strength of sandstones was their degassing, and not a change in the stress state of the environment. This led to a change in the deformation properties of rocks in gas-saturated and degassed states.

scholarly journals Technological inheritance in metal forming

2020 ◽  
pp. 28-32
Author(s):  
V. А. Ogorodnikov ◽  
T. F. Arkhipova
Keyword(s):  
Stress State ◽  
Metal Forming ◽  
Mechanical Characteristics ◽  
Deformation Gradient ◽  
Practical Significance ◽  
Cold Plastic Deformation ◽  
Ultimate Deformation ◽  
Technological Inheritance ◽  
Technological Heredity ◽  
Stress States

Ogorodnikov V., Arkhipova T. Technological inheritance in metal forming. Material working by pressure. 2020. № 1 (50). Р. 28-32. Technological heredity in metal forming processes is accompanied by hardening, the appearance of residual stresses, a deformation gradient, residual plasticity and a number of other factors that determine the operational properties of the product. The influence of most factors of technological heredity on the mechanical properties of the material of products has been studied, however, the plasticity of a pre-deformed workpiece remains insufficiently studied. For a quantitative assessment, a calculation method is proposed, with the help of which it seems possible to determine the plasticity resource of pre-deformed blanks. The developed calculation apparatus is based on a fracture model based on a tensor description of damage accumulation. It allows for the known mechanical characteristics to predict the plasticity characteristics of pre-deformed blanks at any type of stress state. The proposed method assumes the use of plasticity diagrams, which describe the change in ultimate deformation depending on the stress state indicators. Plasticity diagrams are constructed for materials tested under conditions of linear or plane stress states (tension, compression, torsion). The practical significance of the results is evidenced by the assessment of the plasticity of steeply curved elbows obtained by the method of cold plastic deformation according to a combined scheme, including deforming pulling of a pre-willed workpiece. In this case, the workpiece in the form of a pipe was subjected to plastic bending. The proposed method makes it possible to assess the residual plasticity of the finished bend. A satisfactory convergence of the calculated and experimental data has been revealed.

Herringbone Buckling Patterns of Compressed Thin Films on Compliant Substrates

2004 ◽  
Vol 71 (5) ◽  
pp. 597-603 ◽  
Author(s):  
X. Chen ◽  
John W. Hutchinson
Keyword(s):  
Thin Films ◽  
Thermal Expansion ◽  
Stress State ◽  
Compressive Stress ◽  
Critical Stress ◽  
Metal Film ◽  
Minimum Energy ◽  
Thin Metal Film ◽  
Thermal Expansion Mismatch ◽  
Compliant Substrates

A thin metal film vapor deposited on thick elastomer substrate develops an equi-biaxial compressive stress state when the system is cooled due to the large thermal expansion mismatch between the elastomer and the metal. At a critical stress, the film undergoes buckling into a family of modes with short wavelengths characteristic of a thin plate on a compliant elastic foundation. As the system is further cooled, a highly ordered herringbone pattern has been observed to develop. Here it is shown that the herringbone mode constitutes a minimum energy configuration among a limited set of competing modes.

scholarly journals INFLUENCE OF ELEVATED TEMPERATURES ON MECHANICAL PROPERTIES OF CONCRETE

2018 ◽  
Vol 14 (1) ◽  
pp. 178-184 ◽  
Author(s):  
Vladimir I. Andreev ◽  
Lyudmila S. Polyakova
Keyword(s):  
Mechanical Properties ◽  
Thermal Expansion ◽  
Elastic Modulus ◽  
Shear Deformation ◽  
Mechanical Characteristics ◽  
Elevated Temperatures ◽  
Strength Functions ◽  
Deformation Coefficient

he paper considers the influence of elevated temperatures in the range from 20°C to 800°C in the mechanical properties of the concrete the thermal expansion, elastic modulus, shear deformation coefficient, strength. Functions describing the dependences of the mechanical characteristics of concrete on temperature as well as functions approximating the nonlinear diagram deformation of concrete at elevated temperatures are pro-posed.

scholarly journals Optimization and Mechanical Characteristics of Spatial Arc Antislide Pile

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
You-Sheng Deng ◽  
Cheng-Pu Peng ◽  
Jun-Cong Liu ◽  
Ling-Tao Li ◽  
Yun-Bo Fu
Keyword(s):  
Stress State ◽  
Mechanical Characteristics ◽  
Earth Pressure ◽  
Bending Moment ◽  
Test Results ◽  
Safety Factors ◽  
Supporting Structure ◽  
The Earth ◽  
Practical Engineering ◽  
Simulation Results

To improve the stress state of traditional antislide pile and utilize the stable soil on both sides of a landslide and slope foot, a spatial arc antislide pile supporting structure was proposed. Based on numerical calculation, a parametric study was conducted to assess the influence of the rise-span ratio on the stress state of the supporting structure, the displacement of the pile top, and the earth pressure in the front of the pile. The optimal rise-span ratio was 3-16 according to the numerical simulation results. An indoor model test at the optimal rise-span ratio was carried out, recording the pile strain and the earth pressure in front of the pile. The results showed that some indices increased with the increase in rise-span ratio, such as the load transferred to the pile at the arch foot, the bending moment of the piles, the displacement of the pile top, and the earth pressure; within a certain depth near the pile top, the soil in front of the pile is loose during the loading processes, and the earth pressure at the range was zero. The overall safety factors of the four supporting models were 2.42, 2.66, 2.78, and 2.84, respectively, which can satisfy the requirements for practical engineering. The test results verify the feasibility and rationality of the spatial arc antislide pile supporting structure, which can provide a new idea for landslide treatment.

scholarly journals Mineral Composition, Pore Structure, and Mechanical Characteristics of Pyroxene Granite Exposed to Heat Treatments

Minerals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 553 ◽  
Author(s):  
Shang ◽  
Zhang ◽  
Xu ◽  
Liu ◽  
Xing
Keyword(s):  
Thermal Expansion ◽  
Elastic Modulus ◽  
High Temperature ◽  
Pore Structure ◽  
Failure Mechanism ◽  
Mineral Composition ◽  
Mechanical Characteristics ◽  
P Wave ◽  
Rock Porosity ◽  
Granite Samples

In deep geoengineering, including geothermal development, deep mining, and nuclear waste geological disposal, high temperature significantly affects the mineral properties of rocks, thereby changing their porous and mechanical characteristics. This paper experimentally studied the changes in mineral composition, pore structure, and mechanical characteristics of pyroxene granite heated to high temperature (from 25 °C to 1200 °C). The results concluded that (1) the high-temperature effect can be roughly identified as three stages: 25–500 °C, 500–800 °C, 800–1200 °C. (2) Below 500 °C, the maximum diffracted intensities of the essential minerals are comparatively stable and the porous and mechanical characteristics of granite samples change slightly, mainly due to mineral dehydration and uncoordinated thermal expansion; additionally, the failure mechanism of granite is brittle. (3) In 500–800 °C, the diffraction angles of the minerals become wider, pyroxene and quartz undergo phase transitions, and the difference in thermal expansion among minerals reaches a peak; the rock porosity increases rapidly by 1.95 times, and the newly created pores caused by high heat treatment are mainly medium ones with radii between 1 μm and 10 μm; the P-wave velocity and the elastic modulus decrease by 62.5% and 34.6%, respectively, and the peak strain increases greatly by 105.7%, indicating the failure mode changes from brittle to quasi-brittle. (4) In 800–1200 °C, illite and quartz react chemically to produce mullite and the crystal state of the minerals deteriorate dramatically; the porous and mechanical parameters of granite samples all change significantly and the P-wave, the uniaxial compressive strength (UCS), and the elastic modulus decrease by 81.30%, 81.20%, and 92.52%, while the rock porosity and the shear-slip strain increase by 4.10 times and 11.37 times, respectively; the failure mechanism of granite samples transforms from quasi-brittle to plastic, which also was confirmed with scanning electron microscopy (SEM).

scholarly journals Experimental Study on Thermal Expansion Behavior of Concrete under Three-Dimensional Stress

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Zhipeng Yu ◽  
Fan Zhang ◽  
Xiao Ma ◽  
Fujian Yang ◽  
Dawei Hu ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Stress State ◽  
Coefficient Of Thermal Expansion ◽  
Three Dimensional ◽  
Test System ◽  
True Triaxial Test ◽  
Underground Engineering ◽  
Thermal Expansion Behavior ◽  
Expansion Behavior

Concrete is widely used in underground engineering and bears three-dimensional stress transmitted by overlying load. When a fire occurs, the thermal expansion of concrete structure under such stress state is different from that under stress-free state. For this purpose, a self-developed real-time high-temperature true triaxial test system was applied to investigate the thermal expansion behavior of concrete under three-dimensional stress state. The thermal expansion strain of concrete under the three-dimensional stress undergoes strain increasing and strain stabilizing stages. At 600°C, the maximum thermal expansion strain of concrete under the three-dimensional stress is 0.75%. The average coefficient of thermal expansion of concrete under three-dimensional stress condition was then calculated, and its value reaches the minimum of 8.68 × 10−6/°C at 200°C and the maximum of 13.41 × 10−6/°C at 500°C. Comparing the coefficient of thermal expansion of concrete under stress-free condition given by Eurocode, it is found that the three-dimensional stress has an obvious restraint on the thermal expansion of concrete. The research results can provide theoretical basis for the stability analysis of underground engineering concrete structures under high-temperature environment.

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