scholarly journals Mechanical Behavior of Red Sandstone under Incremental Uniaxial Cyclical Compressive and Tensile Loading

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Baoyun Zhao ◽  
Dongyan Liu ◽  
Tianzhu Huang ◽  
Wei Huang ◽  
Wei Liu
Keyword(s):  
Energy Dissipation ◽  
Mechanical Behavior ◽  
Strain Curve ◽  
Tensile Loading ◽  
Creep Model ◽  
Short Term ◽  
Stress Strain ◽  
Cycle Number ◽  
Red Sandstone ◽  
Residual Strains

Uniaxial experiments were carried out on red sandstone specimens to investigate their short-term and creep mechanical behavior under incremental cyclic compressive and tensile loading. First, based on the results of short-term uniaxial incremental cyclic compressive and tensile loading experiments, deformation characteristics and energy dissipation were analyzed. The results show that the stress-strain curve of red sandstone has an obvious memory effect in the compressive and tensile loading stages. The strains at peak stresses and residual strains increase with the cycle number. Energy dissipation, defined as the area of the hysteresis loop in the stress-strain curves, increases nearly in a power function with the cycle number. Creep test of the red sandstone was also conducted. Results show that the creep curve under each compressive or tensile stress level can be divided into decay and steady stages, which cannot be described by the conventional Burgers model. Therefore, an improved Burgers creep model of rock material is constructed through viscoplastic mechanics, which agrees very well with the experimental results and can describe the creep behavior of red sandstone better than the Burgers creep model.

scholarly journals Mechanical Behavior of Shale Rock under Uniaxial Cyclic Loading and Unloading Condition

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Baoyun Zhao ◽  
Dongyan Liu ◽  
Ziyun Li ◽  
Wei Huang ◽  
Qian Dong
Keyword(s):  
Cyclic Loading ◽  
Mechanical Behavior ◽  
Creep Behavior ◽  
Peak Stress ◽  
Creep Model ◽  
Cycle Number ◽  
Shale Rock ◽  
Cyclic Loading And Unloading ◽  
Residual Strains ◽  
Loading And Unloading

In order to investigate the mechanical behavior of shale rock under cyclic loading and unloading condition, two kinds of incremental cyclic loading tests were conducted. Based on the result of the short-term uniaxial incremental cyclic loading test, the permanent residual strain, modulus, and damage evolution were analyzed firstly. Results showed that the relationship between the residual strains and the cycle number can be expressed by an exponential function. The deformation modulus E50 and elastic modulus ES first increased and then decreased with the peak stress under the loading condition, and both of them increased approximately linearly with the peak stress under the unloading condition. On the basis of the energy dissipation, the damage variables showed an exponential increasing with the strain at peak stress. The creep behavior of the shale rock was also analyzed. Results showed that there are obvious instantaneous strain, decay creep, and steady creep under each stress level and the specimen appears the accelerated creep stage under the 4th stress of 51.16 MPa. Based on the characteristics of the Burgers creep model, a viscoelastic-plastic creep model was proposed through viscoplastic mechanics, which agrees very well with the experimental results and can better describe the creep behavior of shale rock better than the Burgers creep model. Results can provide some mechanics reference evidence for shale gas development.

scholarly journals Prediction of Stress–Strain Curves Based on Hydric Non-Destructive Tests on Sandstones

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3366 ◽  
Author(s):  
Marco Ludovico-Marques ◽  
Carlos Chastre
Keyword(s):  
Physical Properties ◽  
Mechanical Behavior ◽  
Water Absorption ◽  
Analytical Model ◽  
Strain Curve ◽  
Low Pressure ◽  
Design Parameters ◽  
Compression Tests ◽  
Stress Strain ◽  
Non Destructive

The study of the mechanical behavior of building stones is traditionally supported by destructive compression tests carried out on representative specimens. However, in order to respect the monuments’ integrity, the study of the mechanical behavior of stones can be based mostly on physical properties obtained from non-destructive tests (NDT). For this study, a simple and cheap NDT—water absorption under low pressure—was used to carry out fast surveys and to predict the most important design parameters of loadbearing masonry, among which are the compressive strength, strain at failure, and even elastic modulus on monument blocks. The paper presents the results of the experimental work conducted to obtain the physical properties and stress–strain curves of the sandstones tested. Supported by these results, it was possible to correlate the various parameters and develop an analytical model that predicts the stress–strain curve of the sandstones based on water absorption under low pressure tests. A good agreement is observed between the analytical model and the experimental tests.

scholarly journals An in situ synchrotron study of the localized B2↔B19′ phase transformation in an Ni–Ti alloy subjected to uniaxial cyclic loading–unloading with incremental strains

2020 ◽  
Vol 53 (2) ◽  
pp. 335-348
Author(s):  
Xiaohui Bian ◽  
Ahmed A. Saleh ◽  
Peter A. Lynch ◽  
Christopher H. J. Davies ◽  
Azdiar A. Gazder ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Cyclic Loading ◽  
Plastic Strain ◽  
Strain Curve ◽  
Transformation Strain ◽  
Gauge Length ◽  
Stress Strain ◽  
Macroscopic Stress ◽  
Residual Strains

High-resolution in situ synchrotron X-ray diffraction was applied to study a cold-drawn and solution-treated 56Ni–44Ti wt% alloy subjected to uniaxial cyclic loading–unloading with incremental strains. The micro-mechanical behaviour associated with the partial and repeated B2↔B19′ phase transformation at the centre of the sample gauge length was studied with respect to the macroscopic stress–strain response. The lattice strains of the (110)B2 and different B19′ grain families are affected by (i) the transformation strain, the load-bearing capacity of both phases and the strain continuity maintained at/near the B2–B19′ interfaces at the centre of the gauge length, and (ii) the extent of transformation along the gauge length. With cycling and incremental strains (i) the elastic lattice strain and plastic strain in the remnant (110)B2 grain family gradually saturate at early cycles, whereas the plastic strain in the B19′ phase continues to increase. This contributes to accumulation of residual strains (degradation in superelasticity), greater non-linearity and change in the shape of the macroscopic stress–strain curve from plateau type to curvilinear elastic. (ii) The initial 〈111〉B2 fibre texture transforms to [120]B19′, [130]B19′, [150]B19′ and [010]B19′ orientations. Further increase in the applied strain with cycling results in the development of [130]B19′, [102]B19′, [102]B19′, [100]B19′ and [100]B19′ orientations.

Mechanical Behavior of Materials under Tensile Loads

2004 ◽  
pp. 13-31
Keyword(s):  
Tensile Test ◽  
Mechanical Behavior ◽  
Tensile Deformation ◽  
True Strain ◽  
Strain Curve ◽  
Tensile Specimen ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Mathematical Expressions ◽  
Reduction In Area

Abstract This chapter focuses on mechanical behavior under conditions of uniaxial tension during tensile testing. It begins with a discussion on the parameters that are used to describe the engineering stress-strain curve of a metal, namely, tensile strength, yield strength or yield point, percent elongation, and reduction in area. This is followed by a section describing the parameters determined from the true stress-true strain curve. The chapter then presents the mathematical expressions for the flow curve. Next, it reviews the effect of strain rate and temperature on the stress-strain curve. The chapter then describes the instability in tensile deformation and stress distribution at the neck in the tensile specimen. It discusses the processes involved in ductility measurement and notch tensile test in tensile specimens. The parameter that is commonly used to characterize the anisotropy of sheet metal is covered. Finally, the chapter covers the characterization of fractures in tensile test specimens.

Experimental Study on Mechanical Characteristics of Deformation of Red Sandstone

2011 ◽  
Vol 261-263 ◽  
pp. 1234-1238
Author(s):  
Rui Hong Wang ◽  
Yu Zhou Jiang ◽  
Jing Guo ◽  
Shi Yi Wen
Keyword(s):  
Rock Mass ◽  
Elastic Modulus ◽  
Mechanical Characteristics ◽  
Deformation Modulus ◽  
Strain Curve ◽  
Confining Pressure ◽  
Peak Strain ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Red Sandstone

For geotechnical engineering, it has great significance to research the mechanical characteristics of rock mass under three dimensional stresses. Through triaxial compression failure test, the characteristics of stress-strain curve and deformation of red sandstone from Sichuan under different confining pressures has been analyzed. The results show that: with the increment of confining pressure, the failure mode of rock mass changes from brittle failure to ductile failure gradually, and an obvious yield platform appears near the peak strength of stress-strain curve; the elastic modulus, deformation modulus, peak strain and residual strain of rock sample increase with the increment of confining pressure, the elastic modulus and deformation modulus are not a fixed value, and the relation between deformation parameter and confining pressure can be fit through quadratic curve.

scholarly journals Feasibility of a Two-Stage Forming Process of 316L Austenitic Stainless Steels with Rapid Electrically Assisted Annealing

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 815 ◽  
Author(s):  
Viet Luu ◽  
Thi Nguyen ◽  
Sung-Tae Hong ◽  
Hye-Jin Jeong ◽  
Heung Han
Keyword(s):  
Mechanical Behavior ◽  
Electric Current ◽  
Strain Curve ◽  
Single Pulse ◽  
Stress Strain Curve ◽  
Forming Process ◽  
Stress Strain ◽  
Two Stage ◽  
Post Annealing ◽  
Electrically Assisted

The post-annealing mechanical behavior of 316L austenitic stainless steel (SUS316L) after electrically assisted (EA) annealing with a single pulse of electric current is experimentally investigated to evaluate the feasibility of a two-stage forming process of the selected SUS316L with rapid EA annealing. A tensile specimen is deformed to a specific prestrain and then annealed by applying a single pulse of electric current with a short duration less than 1 s. Finally, the specimen is reloaded until fracture. The stress-strain curve during reloading shows that the flow stress of the SUS316L significantly decreases, which indicates the occurrence of EA annealing. The electric current also increases the maximum achievable elongation of the SUS316L during reloading. The stress-strain curve during reloading and the microstructural observation suggest that the effects of EA annealing on the post-annealing mechanical behavior and microstructure strongly depend on both the applied electric current density (electric current per unit cross-sectional area) and the given prestrain. The results of the present study suggest that the EA annealing technique could be effectively used to improve the formability of SUS316L when manufacturing complex parts.

Layered fracture prediction of QStE700 medium-thickness steel plate under tensile loading

2020 ◽  
pp. 095440542097803
Author(s):  
Chuanmin Zhu ◽  
Peng Gu ◽  
Yiqing Yu ◽  
Zhan Tao ◽  
Heng Zhang
Keyword(s):  
Steel Plate ◽  
Strain Curve ◽  
Tensile Loading ◽  
Equivalent Strain ◽  
True Stress ◽  
Image Correlation ◽  
Correlation Technique ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Medium Thickness

Layered fracture frequently occurs in the deforming process of QStE700 medium-thickness steel plates under tensile loading. In this study, the morphology of a layered fracture was observed via scanning electron microscopy, and the mechanism of the layered fracture was also analyzed. Based on the three-dimensional digital image correlation technique, a section analysis method was adopted for determining the true stress–strain curve including the necking process. A modified Bridgeman’s equation was adopted to transform the true stress–strain curve into the equivalent stress–strain curve. At the time of layered fracture occurrence, the equivalent strain and stress triaxiality of differently shaped specimens were obtained and fitted to a linear exponential relationship equation. The equation was the layered fracture criterion function and combined with the finite element method (FEM) simulations for determining the damage criterion of the layered fracture of a certain specimen. The FEM-simulated equivalent strain was consistent with the experimental equivalent strain of the layered fracture. Summarizing, the proposed method to predict the layered fracture of a QStE700 medium-thickness steel plate is effective and can be adopted in the study and control of layered fracture.

scholarly journals A 3-D finite element modeling for the textile-reinforced concrete plates under tensile load using a non-linear behaviour for cementitious matrix

2021 ◽  
Vol 15 (1) ◽  
pp. 67-78
Author(s):  
Tran Manh Tien ◽  
Xuan Hong Vu ◽  
Dao Phuc Lam ◽  
Pham Duc Tho
Keyword(s):  
Reinforced Concrete ◽  
Mechanical Behavior ◽  
Tensile Load ◽  
Strain Curve ◽  
Numerical Results ◽  
Textile Reinforced Concrete ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Cementitious Matrix ◽  
Non Linear

A big question in the numerical approaches for the mechanical behavior of the textile-reinforced concrete (TRC) composite under tensile loading is how to model the cracking of the cementitious matrix. This paper presents numerical results of 3-D modeling of TRC composite in which the non-linear behavior model was used by considering the cracking for the cementitious matrix. The input data based on the experimental results in the literature. As numerical results, the TRC composite provides a strain-hardening behavior with three phases in which the second one is characterized by the drops in stress on the stress-strain curve. Furthermore, this model could show the failure mode of the TRC specimen with the multi-cracking on its surface after the numerical tests. From this model, the development of a crack from micro-crack to macro at a cross-section was highlighted. The stress jumps in reinforcement textile after each crack was also observed and analyzed. In comparison with the experiment, a good agreement between both results was found for all cases of this study. A parametric study could show the effect of the length and position of the measurement zone on the stress-strain curve of TRC’s mechanical behavior. Keywords: textile reinforced concrete (TRC); cementitious matrix; textile reinforcement; mechanical behaviour; numerical modeling.

The Mechanical Behavior and Martensitic Transformation of Porous NiTi Alloys Based on Geometrical Reconstruction

2017 ◽  
Vol 09 (03) ◽  
pp. 1750038 ◽  
Author(s):  
Xiaofeng Lu ◽  
Chaojie Wang ◽  
Gang Li ◽  
Yang Liu ◽  
Xiaolei Zhu ◽  
...  
Keyword(s):  
Finite Element ◽  
Mechanical Behavior ◽  
Strain Curve ◽  
Element Model ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Element Analysis ◽  
The Real ◽  
Porous Niti ◽  
Niti Shape Memory Alloys

The finite element analysis (FEA) of porous NiTi shape memory alloys (SMAs) remains a challenge due to irregularity and complexity of pore structure. In this paper, the real finite element model (FEM) is established based on the geometrical reconstruction. Through a SMA constitutive model, the mechanical behavior and stress-induced martensitic (SIM) phase transformation are analyzed with the real FEM. The results show that the stress–strain curve of FEA is in good agreement with the experimental curve and the calculation can reflect the mechanical behavior well in the compressive process. With the increase of load, the SIM first appears pore walls or weak parts of struts, then spreads to the center of matrix, and finally happens to most of matrix. When the slope of the stress–strain curve shows obvious changes, the SIM has happened in quite a part of matrix.

Comparison of the Experimental Behavior of a Shape Memory Alloy in Compression and Tension

Aerospace ◽  
2003 ◽  
Author(s):  
Tobias Hesse ◽  
Mehrdaad Ghorashi ◽  
Daniel J. Inman
Keyword(s):  
Shape Memory Alloy ◽  
Mechanical Behavior ◽  
Shape Memory ◽  
Material Properties ◽  
Tensile Loading ◽  
Theoretical Models ◽  
Compression Tests ◽  
Stress Strain ◽  
Tensile Forces ◽  
Tension And Compression

The concept of Shape Memory Alloy (SMA) has been a subject of extensive research in the recent few years. In many SMA applications, wire elements have been used in order to control structural specifications like shape and stiffness. Since a wire can only be subjected to tensile forces, the available theoretical models for DMA discuss only the tensile loading. The present paper is an endeavor to overcome this shortcoming. It gives experimental resluts for tension and compression tests on specimens (having different geometries) made of an identical shape memory alloy. The corresponding results are compared with each other. Using stress-strain diagrams, several important material properties are obtained. These parameters can then be implemented in SMA models in order to analyze and predict the mechanical behavior of SMA elements subjected to compression.

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