Mechanical behavior of strain-hardening geopolymer composites reinforced with natural and PVA fibers

2019 ◽  
Vol 8 ◽  
pp. 753-759
Author(s):  
Ana Carolina Constâncio Trindade ◽  
Paulo Henrique Ribeiro Borges ◽  
Flávio de Andrade Silva
Keyword(s):  
Mechanical Behavior ◽  
Strain Hardening ◽  
Geopolymer Composites

On the mechanical performance of K- and Na-based strain-hardening geopolymer composites (SHGC) reinforced with PVA fibers

2020 ◽  
Vol 248 ◽  
pp. 118558 ◽  
Author(s):  
Ana Carolina Constâncio Trindade ◽  
Iurie Curosu ◽  
Marco Liebscher ◽  
Viktor Mechtcherine ◽  
Flávio de Andrade Silva
Keyword(s):  
Strain Hardening ◽  
Mechanical Performance ◽  
Geopolymer Composites

Tensile behavior of strain-hardening geopolymer composites (SHGC) under impact loading

2020 ◽  
Vol 113 ◽  
pp. 103703 ◽  
Author(s):  
Ana Carolina Constâncio Trindade ◽  
Ali A. Heravi ◽  
Iurie Curosu ◽  
Marco Liebscher ◽  
Flávio de Andrade Silva ◽  
...  
Keyword(s):  
Strain Hardening ◽  
Impact Loading ◽  
Tensile Behavior ◽  
Geopolymer Composites

Strain Hardening of a Porous Limestone

1967 ◽  
Vol 7 (03) ◽  
pp. 229-234 ◽  
Author(s):  
J.B. Cheatham
Keyword(s):  
Yield Strength ◽  
Mechanical Behavior ◽  
Strain Hardening ◽  
Rock Mechanics ◽  
Mathematical Theory ◽  
Confining Pressure ◽  
Plasticity Theory ◽  
Single Type ◽  
Microscopic Structure ◽  
Theory Of Plasticity

Abstract Applications of the mathematical theory of plasticity promises to lead to the solution of many drilling and rock mechanics problems. Because of mathematical considerations, the inelastic behavior of rock has frequently been represented by a perfectly plastic model in conjunction with a yield criteria of the Coulomb or Mohr type. The totality of all stress states for which a solid ceases to behave elastically can be represented as a limit surface in stress space. Probing of such limit surfaces indicates details of strain hardening which are not provided by the standard triaxial testing procedure. Probing tests of the limit surfaces have been performed on Cordova Cream limestone to provide data for extending plasticity theory to cover situations in which consolidation and strain hardening are present. Test results indicate that this highly porous limestone undergoes a permanent volume decrease when it is subjected to hydrostatic pressures in excess of 3,500 psi. A virgin sample tested under a confining pressure of 1,500 psi has a yield strength of 1,700 psi; however, if the sample is subjected to a consolidation pressure of 5,000 psi, before testing at 1,500 psi, the yield strength is raised to 2,300 psi. Thus, both consolidation and strain hardening are important considerations in describing the mechanical behavior of this limestone. Tests conducted with the axis of the core having different orientations indicate that this rock is also anisotropic. Portions of the initial and subsequent limit surfaces are determined for samples loaded either perpendicular or parallel to the bedding planes. INTRODUCTION Previous experimental work in rock mechanics indicates that no mathematically tractable constitutive theory is inclusive enough to describe the mechanical behavior exhibited by all types of rocks under all conditions of stress and temperature. Indeed, the type of deformation encountered in a single type of rock is known to depend upon the stress and temperature conditions in the rock during deformation.1-5 Certain rocks and minerals, notably those minerals composed of ionic salts, have been shown to exhibit plastic deformation when tested under conditions of high confining pressure.2 Since the mathematical theory of plasticity provides simplifications over the theory of elasticity in certain types of problems, such as those in which limit analysis can be applied, it is of interest to know under what conditions plasticity theory may be applied to rock mechanics problems. The following factors determine the nature of the deformation a particular specimen will undergo:the microscopic structure of the rock, i.e., the structure visible under an optical microscope, including number of phases, porosity, distribution of phases,the mineralogical structure of the solid phases,the conditions of stress and the rate of change of stress andthe temperature. Extensive experiments on Yule marble, Carthage marble, Solenhofen limestone and other calcerous rocks indicate that these relatively nonporous rocks deform plastically under certain conditions of loading, and creep under other conditions of loading.1-3 This study is concerned with the behavior of Cordova Cream limestone (Austin chalk) which is also composed almost entirely of calcite and thus has the same mineralogical composition but, because of a rather large porosity, it possesses a different microscopic structure. This investigation was undertaken to learn if Cordova Cream limestone deforms plastically despite the embrittling effect of the pore spaces, and to provide data which can be used to determine whether the mathematical theory of plasticity can describe the mechanical behavior of Cordova Cream limestone.

Effects of Anisotropy on the Microstructural Characteristics and Mechanical Behavior of Shock-Loaded of AZ31 Alloy

2011 ◽  
Vol 284-286 ◽  
pp. 1537-1541 ◽  
Author(s):  
Min Hao ◽  
Fan Zhang ◽  
Cheng Wen Tan ◽  
Tie Jian Su ◽  
Xiao Dong Yu
Keyword(s):  
Mechanical Behavior ◽  
Strain Hardening ◽  
Electron Backscatter Diffraction ◽  
Az31 Alloy ◽  
Peak Strain ◽  
Compression Tests ◽  
Microstructural Characteristics ◽  
Post Shock ◽  
Backscatter Diffraction ◽  
Strain Hardening Rate

Effects of anisotropy on the microstructural characteristics and mechanical behavior of shock loaded of AZ31 magnesium alloy have been investigated. Using electron backscatter diffraction, tension twinning was observed in both shock loading directions along the normal (ND) and rolling directions (RD). Compression tests were carried out along ND and RD in both as-received and post-shock conditions. It indicated that the RD samples show a more notable hardening behavior compared to the as-received conditions. Moreover, it is postulated here that detwinningresults in a drop of strain-hardening rate for the ND samples under post shock reload conditions and tension twinning formed during the shock wave loading process leads to a significant moving left of the peak strain hardening rate for the RD samples under post shock reload conditions.

An Associative and Non-Associative Anisotropic Bounding Surface Model for Clay

2012 ◽  
Vol 79 (3) ◽  
Author(s):  
Jianhong Jiang ◽  
Hoe I. Ling ◽  
Victor N. Kaliakin
Keyword(s):  
Mechanical Behavior ◽  
Strain Hardening ◽  
Strain Softening ◽  
Surface Model ◽  
Flow Rule ◽  
Reasonable Accuracy ◽  
Bounding Surface ◽  
Softening Behavior ◽  
Different Types ◽  
Undrained Behavior

An anisotropic elastoplastic bounding surface model with non-associative flow rule is developed for simulating the mechanical behavior of different types of clays. The non-associative flow rule allows for the simulation of not only strain-hardening but also strain-softening response. The theoretical framework of the model is given, followed by the verification of the model as applied to the experimental results of a strain-hardening Kaolin tested under different undrained stress paths. The undrained behavior of Boston Blue clay, which exhibits a strain-softening behavior, is also simulated. It is shown that the non-associative nature of the model gives more accurate results than those of the same model employing an associative flow rule, especially for normally consolidated Kaolin specimens. The results show that the model is also capable of simulating the strain-softening behavior of Boston blue clay with reasonable accuracy.

Large Strain Mechanical Behavior of Poly(methyl methacrylate) (PMMA) Near the Glass Transition Temperature

2006 ◽  
Vol 128 (4) ◽  
pp. 559-563 ◽  
Author(s):  
G. Palm ◽  
R. B. Dupaix ◽  
J. Castro
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Methyl Methacrylate ◽  
Mechanical Behavior ◽  
Strain Hardening ◽  
Uniaxial Compression ◽  
Large Strain ◽  
Strain Rates ◽  
Poly Methyl Methacrylate

The mechanical behavior of amorphous thermoplastics, such as poly(methyl methacrylate) (PMMA), strongly depends on temperature and strain rate. Understanding these dependencies is critical for many polymer processing applications and, in particular, for those occurring near the glass transition temperature, such as hot embossing. In this study, the large strain mechanical behavior of PMMA is investigated using uniaxial compression tests at varying temperatures and strain rates. In this study we capture the temperature and rate of deformation dependence of PMMA, and results correlate well to previous experimental work found in the literature for similar temperatures and strain rates. A three-dimensional constitutive model previously used to describe the mechanical behavior of another amorphous polymer, poly(ethylene terephthalate)-glycol (PETG), is applied to model the observed behavior of PMMA. A comparison with the experimental results reveals that the model is able to successfully capture the observed stress-strain behavior of PMMA, including the initial elastic modulus, flow stress, initial strain hardening, and final dramatic strain hardening behavior in uniaxial compression near the glass transition temperature.

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