scholarly journals Fatigue Performance of Rubber Concrete in Hygrothermal Environment

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Yushan Liu ◽  
Jianyong Pang ◽  
Weijing Yao
Keyword(s):  
Plastic Strain ◽  
Elastic Strain ◽  
Relevant Literature ◽  
Strain Curve ◽  
Fatigue Performance ◽  
Loading Test ◽  
Loading Cycle ◽  
Different Temperatures ◽  
Hygrothermal Environment ◽  
Rubber Concrete

It is widely accepted that the rubber concrete (RC) originating from waste is a promising material that can contribute to the conservation and rational use of natural resources and the protection of the environment. However, the fatigue performance in a hygrothermal environment is a major concern because little pertinent information is available in the relevant literature. In this study, a cyclic loading test was carried out on RC subjected to different wet-dry cycles at different temperatures. The loading strain, plastic strain, and elastic strain of the concrete were compared and analyzed. The results revealed that the loading strain and plastic strain of the RC were obvious after the 1st loading cycle. As the number of loading cycles increased, the stress-strain curve became denser and the RC exhibited good elasticity. As the wet-dry cycles increased, the average plastic strain in the 10th–60th loading cycle increased while the elastic strain decreased. After 28 wet-dry cycles, the average plastic strain at 60°C increased by 42.31% compared with 20°C. In fact, as the temperature became higher, the plastic damage incurred by the RC became more severe. Finally, the damage variable was defined based on the elastic modulus and plastic strain to evaluate the fatigue performance of the RC in a hygrothermal environment. The findings of this study can provide a useful reference for RC applications.

Plastic Deformation in Microtomed Sections

1971 ◽  
Vol 29 ◽  
pp. 458-459
Author(s):  
J. Temple Black
Keyword(s):  
Plastic Deformation ◽  
Plastic Strain ◽  
Applied Stress ◽  
Elastic Strain ◽  
High Strain ◽  
Tool Material ◽  
Cutting Edge ◽  
Material Structure ◽  
Geometrical Constraints

The output of the ultramicrotomy process with its high strain levels is dependent upon the input, ie., the nature of the material being machined. Apart from the geometrical constraints offered by the rake and clearance faces of the tool, each material is free to deform in whatever manner necessary to satisfy its material structure and interatomic constraints. Noncrystalline materials appear to survive the process undamaged when observed in the TEM. As has been demonstrated however microtomed plastics do in fact suffer damage to the top and bottom surfaces of the section regardless of the sharpness of the cutting edge or the tool material. The energy required to seperate the section from the block is not easily propogated through the section because the material is amorphous in nature and has no preferred crystalline planes upon which defects can move large distances to relieve the applied stress. Thus, the cutting stresses are supported elastically in the internal or bulk and plastically in the surfaces. The elastic strain can be recovered while the plastic strain is not reversible and will remain in the section after cutting is complete.

Parameters Identification of Johnson-Cook Constitutive Equation for Aluminum Brass

2014 ◽  
Vol 887-888 ◽  
pp. 1032-1035 ◽  
Author(s):  
Chang Chun Di ◽  
Kai Bo Cui ◽  
Jun Qi Qin ◽  
Da Lin Wu
Keyword(s):  
Testing Machine ◽  
Strain Curve ◽  
High Strength ◽  
Dynamic Mechanical Properties ◽  
Model Parameters ◽  
Strain Rates ◽  
Stress Strain Curve ◽  
Method Of Least Squares ◽  
Different Temperatures ◽  
Split Hopkinson

Aluminum brass HAL66-6-3-2 is abrasion-resistant alloy with high strength, hardness and wear resistance, corrosion resistance is also well, commonly used in the field of marine and ordnance industry. The quasi static and dynamic mechanical properties were tested through the use of electronic universal testing machine and Split Hopkinson Tension Bar (SHTB). Meanwhile, the material stress-strain curve at different temperatures and different strain rates is also obtained. Based on Johnson-Cook constitutive model, using the method of least squares fitting the experimental data to determine the model parameters, fitting and experimental results agree well.

Research on Mechanical Properties of Crumb Rubber Concrete

2011 ◽  
Vol 477 ◽  
pp. 290-295 ◽  
Author(s):  
Li Bo Bian ◽  
Shao Min Song
Keyword(s):  
Mechanical Properties ◽  
Wear Resistance ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Apparent Density ◽  
Crumb Rubber ◽  
Fatigue Performance ◽  
Brittleness Index ◽  
Mixing Ratio ◽  
Rubber Concrete

Considering large number production of the abandoned tyres and the question of the concrete with mixture of crumb rubber，the mainly task of this paper is to study the mechanical properties of different mixing ratio concrete with vary volume of crumb rubber. The results showed that the workability, apparent density, compressive strength, flexural strength and brittleness index decrease as the increase of crumb rubber. While the anti-crack performance and anti-fatigue performance can be improved. The wear-resistance properties are a little lower than common concrete.

Determination of the Anand Viscoplasticity Model Constants for SnAgCu

2005 ◽  
Author(s):  
Bryan Rodgers ◽  
Ben Flood ◽  
Jeff Punch ◽  
Finbarr Waldron
Keyword(s):  
Fatigue Life ◽  
Plastic Strain ◽  
Test Specimen ◽  
Strain Curve ◽  
Temperature Cycling ◽  
Displacement Rate ◽  
Experimental Measurements ◽  
Strain Rates ◽  
Constant Displacement

The major focus of this work was the determination of the nine constants required for Anand’s viscoplastic constitutive model for a lead-free solder alloy, 95.5Sn3.8Ag0.7Cu and to compare them with those for SnPb. The test specimen was a cast dog bone shape based on ASTM E 8M-01, with a diameter of 4mm and a gauge length of 20mm. A series of tensile experiments were carried out: constant displacement tests ranging from 6.5 × 10−5/s to 1.0 × 10−3/s at temperatures of 20°C, 75°C, and 125°C; constant load tests at a range of loads from 10MPa to 65MPa, also at temperatures of 20°C, 75°C, and 125°C. A series of non-linear fitting processes was used to determine the model constants. Comparisons were then made with experimental measurements of the stress-plastic strain curves from constant displacement rate tests: it was found that the model matched the experimental data at low strain rates but did not capture the strain hardening effect, especially at high strain rates. A finite element model of the test was also constructed using ANSYS software. This software includes the Anand model as an option for its range of viscoplastic elements, requiring that the nine constants be input. In this case, an 8-noded axisymmetric element (VISCO108) was used to model the test specimen under constant displacement rate loading. The model was then used to predict the stress-plastic strain curve and this was compared to both the experimental measurements and the fitted Anand model. Reasonable agreement was found between the Anand model and the FE predictions at small strain rates. Finally, a BGA device was simulated under accelerated temperature cycling conditions using ANSYS with the fitted Anand for the SnAgCu solder joints. A Morrow-type fatigue life model was applied using empirical constants from two published sources and good agreement was found between experiment and predicted fatigue life.

A unified expression to estimate the stress-strain curve of polyamides at different temperatures

2018 ◽  
Vol 6 (1) ◽  
pp. 015304
Author(s):  
H S da Costa Mattos ◽  
J F S Brandão ◽  
F C Amorim ◽  
P V S Araújo ◽  
J M L Reis
Keyword(s):  
Strain Curve ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Different Temperatures

Microstructure Evolution and Mechanical Properties of Mg-Gd-Y-Zn-Zr Alloy during Compression

2021 ◽  
Vol 1035 ◽  
pp. 278-285
Author(s):  
Lei Chen Jia ◽  
Jian Min Yu ◽  
Guo Qin Wu ◽  
Wen Long Xu ◽  
Yong Gang Tian ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Plastic Strain ◽  
Microstructure Evolution ◽  
Large Angle ◽  
Compression Behavior ◽  
Kink Bands ◽  
Long Period ◽  
Different Temperatures ◽  
Compression Temperature ◽  
Zr Alloy

The compression behavior and mechanical properties of the Mg-13Gd-4Y-2Zn-0.5Zr (wt.%) alloy filled with intragranular long-period stacking ordered (LPSO) phases at different temperatures were investigated. The results showed that the higher the compression temperature, the smaller the plastic strain that the grains withstand. The grains changed from equiaxed to flat strips when compressed at 350°C, and the morphology of the grains did not change at 450°C. Due to the existence of DRX grains, compression at 450 °C didn’t cause large-angle kink, but the kink angle at 350°C was very large. DRX grains only appeared at the grain boundaries and around the intergranular LPSO phase at the beginning of compression, and only appear at the kink bands (KBs) after the lamellar LPSO phases begin to kink. DRX grains gradually increased with the KBs increasing.

Effect of Confining Layers of Steel Straps Confined High-Strength Concrete Cylinder under Uniaxial Cyclic Compression

2014 ◽  
Vol 70 (1) ◽  
Author(s):  
Hoong Pin Lee ◽  
Abdullah Zawawi Awang ◽  
Wahid Omar
Keyword(s):  
Plastic Strain ◽  
High Strength Concrete ◽  
Strain Curve ◽  
High Strength ◽  
Ultimate Capacity ◽  
Compression Loading ◽  
Strength Concrete ◽  
Concrete Cylinder ◽  
Loading Patterns ◽  
Confining Layers

The remarkable advantages and promising increment in concrete ultimate capacity as well as ductility by using steel straps as lateral confinement has brought the steel strapping tensioning technique (SSTT) as one of the most affordable confining technique in market. A number of studies have been reported the behaviour of SSTT-confined concrete under uniaxial monotonic compression loading but none of any study addressed the uniaxial cyclic response of such confinement. In this paper, twenty-one high-strength concrete cylinder specimens with diameter of 150 mm and 300 mm in height were cast, laterally pre-tensioned with steel strap in different confining layers and tested to failure under uniaxial cyclic and monotonic compression loading. A number of conclusions to be drawn from experimental results including the tangential validation of stress-strain curve for uniaxial monotonic and cyclic loading, independency of plastic strain to the amount of confining layers, the disagreement of uniqueness concept on the repeated uniaxial unloading and reloading cycles, and the promising effect of confining layers and loading patterns to the ultimate capacity of SSTT confinement. A plastic strain model is proposed and compared with existing plastic strain models. The result proved that SSTT confinement able to secure the lowest plastic strain among the others existing confinement method. 

scholarly journals A Thermal Damage Constitutive Model for Oil Shale Based on Weibull Statistical Theory

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Guijie Zhao ◽  
Chen Chen ◽  
Huan Yan
Keyword(s):  
High Temperature ◽  
Constitutive Model ◽  
Oil Shale ◽  
Thermal Damage ◽  
Triaxial Compression ◽  
Strain Curve ◽  
Practical Significance ◽  
Compression Tests ◽  
Different Temperatures ◽  
Damage Constitutive Model

In this work, we first studied the thermal damage to typical rocks, assuming that the strength of thermally damaged rock microelements obeys a Weibull distribution and considering the influence of temperature on rock mechanical parameters; under the condition that microelement failure conforms to the Drucker–Prager criterion, the statistical thermal damage constitutive model of rocks after high-temperature exposure was established. On this basis, conventional triaxial compression tests were carried out on oil shale specimens heated to different temperatures, and according to the results of these tests, the relationship between the temperature and parameters in the statistical thermal damage constitutive model was determined, and the thermal damage constitutive model for oil shale was established. The results show that the thermal damage in oil shale increases with the increase of temperature; the damage variable is largest at 700°C, reaching 0.636; from room temperature to 700°C, the elastic modulus and Poisson’s ratio decrease by 62.66% and 64.57%, respectively; the theoretical stress-strain curve obtained from the model is in good agreement with the measured curves; the maximum difference between the two curves before peak strength is only 5 × 10−4; the model accurately reflects the deformation characteristics of oil shale at high temperature. The research results are of practical significance to the underground in situ thermal processing of oil shale.

scholarly journals The Porosity Dynamic Model of the Compacted Broken Coal

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Xuefeng Han ◽  
Tingxiang Chu ◽  
Minggao Yu ◽  
Jiangkun Chao ◽  
Zhihui Ma ◽  
...  
Keyword(s):  
Spontaneous Combustion ◽  
Axial Stress ◽  
Fractal Theory ◽  
Dynamic Change ◽  
Strain Curve ◽  
Fractal Model ◽  
Evolution Model ◽  
Dynamic Evolution ◽  
Permeability Evolution ◽  
Loading Test

In order to study the dynamic change law of the porosity of the compacted broken coal under different axial stress loading, based on the environment of the broken and compacted coal in the gob, aiming at the influence of the porosity on the spontaneous combustion of the coal, combined with the fractal theory, the fractal model of the porosity of the broken coal is established. A self-designed “testing device for permeability evolution and spontaneous combustion characteristics of crushed coal under pressure” is used to carry out axial loading test on selected coal samples in the gob. By comparing and analyzing the calculated results of void dynamic evolution model and experimental data, it is found that the relative error of void dynamic evolution model is between 2.8% and 6.2%, which meets the engineering needs. According to the stress-strain curve, initial accumulation state parameters, fractal dimension of initial crushing, and particle size distribution, the change of porosity under different compacted conditions can be predicted by the model, which has certain significance for identifying the change of compacted broken coal porosity and analyzing the process of coal spontaneous combustion and oxidation.

Hardening of the Porcine Thoracic Aorta Subjected to Freezing and Thawing: Experimental Evaluation and Mathematical Modeling

2008 ◽  
Author(s):  
Hiroshi Yamada ◽  
Kousuke Yasuno ◽  
Kensuke Fujisaki ◽  
Hiroshi Ishiguro
Keyword(s):  
Cooling Rate ◽  
Physiological Stress ◽  
Strain Curve ◽  
Fluid Phase ◽  
Collagen Fibers ◽  
Uniaxial Tensile ◽  
Freezing And Thawing ◽  
Loading Test ◽  
Stress Strain ◽  
Collagen Molecules

Identifying changes in the mechanical behavior of blood vessels subjected to freezing and thawing, such as occur with cryopreservation, are of key importance. Excising pairs of fresh ring specimens from identical porcine thoracic aortas (n = 8 for each cooling rate), we carried out uniaxial tensile loading and unloading tests over the physiological stress range (first and second tests) and performed a loading test until the breaking point within the range of a load cell (third test). After the first test, one specimen of the pair was frozen at −80°C at a cooling rate of −1°C or −50°C/min and thawed, while the other was held at 5°C as a control. At both cooling rates, for the specimens subjected to freezing, the ratios of the tangential modulus in the stress-strain curve (between 130 and 150 kPa) in the second test to that in the first test differed significantly (p < 0.01) from the respective ratios of the control specimens. We formulated a mathematical model of the stress–strain relationship considering elastic and collagen fibers and an incompressible fluid phase. We evaluated the working hypothesis that collagen fibers reduce their extensibility either by hardening as a mechanical change or by shortening as a geometric change. We attributed this response to the formation of dehydration-induced cross-linking in collagen molecules at the microscopic level.

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