scholarly journals Compressive Test Characteristics and Constitutive Relationship of Wet Polypropylene Macrofiber-Reinforced Shotcrete

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Fenghui Li ◽  
Yunhai Cheng ◽  
Fei Wu ◽  
Chang Su ◽  
Gangwei Li
Keyword(s):  
Mechanical Response ◽  
Average Energy ◽  
Strain Curve ◽  
Peak Stress ◽  
Constitutive Relationship ◽  
Compression Tests ◽  
Response Characteristics ◽  
Test Characteristics ◽  
High Crack ◽  
Relationship Of

Shotcrete is often subject to poor ductility and cracking problems, particularly under high stresses. In order to deal with these issues, the feasibility of adding polypropylene macrofibers to shotcrete was verified. To ascertain the supporting effect, dry shotcrete, wet shotcrete, and wet polypropylene macrofiber-reinforced shotcrete (WPMS) were used as samples. Furthermore, the mechanical response characteristics thereof in uniaxial compression tests were compared and analyzed by acoustic emission (AE) monitoring. The results showed that the three materials were brittle, but the ductility, residual strength, and bearing capacity of polypropylene macrofiber-reinforced shotcrete were significantly enhanced. The energy absorption value of plain shotcrete was higher in the cracking stage, while that of polypropylene macrofiber-reinforced shotcrete was greater in the postpeak stage, which showed that the polypropylene macrofiber-reinforced shotcrete had the characteristics of a high crack-initiation strength and toughness. Besides, the energy release from fiber shotcrete occurred after the peak stress rather than near the peak stress. The average energy absorbed by polypropylene macrofiber-reinforced shotcrete was significantly higher than that in dry shotcrete and wet shotcrete, which implied that polypropylene macrofiber-reinforced shotcrete could mitigate the brittle instability of a shotcrete layer. A constitutive model of damage statistics was established based on the test data. The comparison between the experimental data and the fitting results can reflect the characteristics of the total stress-strain curve of such shotcrete. The results provide a basis for the optimization of polypropylene macrofiber-reinforced shotcrete layers.

scholarly journals Compressive Test Characteristics and Constitutive Relation of Wet Polypropylene Macrofibers Shotcrete

2020 ◽  
Author(s):  
Fenghui LI ◽  
Yunhai Cheng ◽  
Fei Wu ◽  
Chang Su ◽  
Gangwei Li
Keyword(s):  
Mechanical Response ◽  
Average Energy ◽  
Strain Curve ◽  
Peak Stress ◽  
Compression Tests ◽  
Compressive Test ◽  
Response Characteristics ◽  
Test Characteristics ◽  
High Crack ◽  
Supporting Effect

Abstract Shotcrete is often subject to poor ductility and cracking problems, particularly under high stresses. To address these issues, we investigated the feasibility of adding polypropylene macrofibres to shotcrete. To evaluate the supporting effect, we used dry shotcrete, wet shotcrete, and wet polypropylene macrofibre shotcrete as samples. We compared and analysed the mechanical response characteristics thereof in uniaxial compression tests by acoustic emission monitoring. The results showed that the three materials were brittle, but the ductility, residual strength, and bearing capacity of polypropylene macrofibre shotcrete were significantly enhanced. The energy absorption value of plain shotcrete was higher in the cracking stage, while that of polypropylene macrofibre shotcrete was higher in the post-peak stage, which indicated that the polypropylene macrofibre shotcrete had the characteristics of a high crack-initiation strength and toughness. Besides, the energy release from fibre shotcrete occurred after the peak stress rather than near the peak stress. The average energy absorbed by polypropylene macrofibre shotcrete was significantly higher than that in dry shotcrete and wet shotcrete, which suggested that polypropylene macrofibre shotcrete could mitigate the brittle instability of a shotcrete layer. Based on the test data, a constitutive model of damage statistics was established. The comparison between the experimental data and the fitting results could reflect the characteristics of the total stress-strain curve of such shotcrete. The results provide a basis for the optimisation of polypropylene macrofibre shotcrete layers.

Experimental Research on the Stress - Strain Curve of Regional Confined Concrete under Single Axial Press

2014 ◽  
Vol 584-586 ◽  
pp. 1289-1292
Author(s):  
Guo Liang Zhu
Keyword(s):  
Mechanical Properties ◽  
Theoretical Analysis ◽  
Constitutive Model ◽  
Theoretical Basis ◽  
Strain Curve ◽  
Confined Concrete ◽  
Constitutive Relationship ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Relationship Of

Regional confined concrete is base on confined concrete. It is the theory and application of a new attempt and development on confined concrete. To apply it to the actual project, we need to research mechanical properties and establish constitutive relationship of regional confined concrete. According to the research, we had carried on a series of tests, founded the stress-strain constitutive model of regional confined concrete under single axial press. The accuracy of theoretical analysis were more fully verified , and a theoretical basis for the application was provided.

A First Principles Study of Ultra-Thin (AIO)n Nanorods: Mechanical Behaviour Under Tension and Compression

2005 ◽  
Vol 219 (3) ◽  
pp. 123-130
Author(s):  
X Song ◽  
Q Ge ◽  
S. C. Yen ◽  
H-K Ching
Keyword(s):  
Mechanical Behaviour ◽  
First Principles ◽  
Density Functional ◽  
Mechanical Response ◽  
Minimum Energy ◽  
Strain Curve ◽  
Compression Tests ◽  
The Density Functional Theory ◽  
Tension And Compression ◽  
Energy Configurations

A first principles approach based on the density functional theory (DFT) was used to study the mechanical behaviour of the linear (Al-O) n nanorods with n spanned 1 to 10. The minimum-energy configurations for the nanostructures are first found by fully relaxing the coordinates of the atoms. Virtual tension and compression tests were then conducted by applying a series of tensile/compressive deformations to the relaxed structures and calculating the corresponding forces required to maintain the equilibrium of the deformed nanorods. A force-strain curve is then obtained for all the nanorods from these virtual tests. The mechanical response of the two shortest nanorods is similar to that of the ductile aluminium, but the longer nanorods deform in a similar manner to the brittle aluminium oxide. All the nanorods demonstrate a much higher compressive strength than tensile strength.

scholarly journals Dynamic Behavior and Fatigue Damage Evolution of Sandstone under Uniaxial Cyclic Loading

2020 ◽  
Vol 2020 ◽  
pp. 1-9 ◽  
Author(s):  
Yidan Sun ◽  
Yu Yang ◽  
Min Li
Keyword(s):  
Cyclic Loading ◽  
Fatigue Damage ◽  
Mechanical Response ◽  
Compressive Strain ◽  
Damage Model ◽  
Testing Machine ◽  
Strain Curve ◽  
Peak Stress ◽  
Creep Theory ◽  
Cycle Number

The mechanical response characteristics of sandstone specimens under different stress amplitudes and loading frequencies were tested by a TAW-2000 rock triaxial testing machine. The characteristics of the stress-strain curve and the evolution process of strain damage under cyclic loading are analyzed. Based on creep theory and the disturbance state concept, a theoretical model between the axial compressive strain, axial compressive stress, and cycle number is established. The results show that there exists an upper threshold value of stress in cyclic loading above which the specimen will be damaged. As peak stress increases, the energy loss and irreversible deformation caused by damage gradually increase. When loading to an unstable peak stress under cyclic loading, the fatigue damage of sandstone under cyclic loading undergoes three characteristic stages: the initial stage; the stable stage; and the accelerated failure stage. The parameters of the strain damage model based on the disturbance state concept of sandstone are identified by test data, and the rationality of the model is validated by comparing theoretical values with experimental measurements.

scholarly journals A Stress-Strain Model for Brick Prism under Uniaxial Compression

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Keun-Hyeok Yang ◽  
Yongjei Lee ◽  
Yong-Ha Hwang
Keyword(s):  
Strain Curve ◽  
Peak Stress ◽  
Test Results ◽  
Compression Tests ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Proposed Model ◽  
Relationship Model ◽  
Strain Relationship ◽  
Strain Model

This study proposes a simple and rational stress-strain relationship model applicable to brick masonry under compression. The brick prism compression tests were conducted with different mortar strengths and with constant brick strength. From the observation of the test results, shape of the stress-strain curve is assumed to be parabola. In developing the stress-strain model, the modulus of elasticity, the strain at peak stress, and the strain at 50% of the peak stress on the descending branch were formulated from regression analysis using test data. Numerical and statistical analyses were then performed to derive equations for the key parameter to determine the slopes at the ascending and descending branches of the stress-strain curve shape. The reliability of the proposed model was examined by comparisons with actual stress-strain curves obtained from the tests and the existing model. The proposed model in this study turned out to be more accurate and easier to handle than previous models so that it is expected to contribute towards the mathematical simplicity of analytical modeling.

Dynamic Recrystallization Behavior of High Carbon Chromium Bearing Steel

2014 ◽  
Vol 584-586 ◽  
pp. 1011-1016
Author(s):  
Xiao Lei Zhang ◽  
Hui Li ◽  
Shi Xin Xu ◽  
Zhi Chao Li ◽  
Zhen Li Mi
Keyword(s):  
Flow Stress ◽  
Dynamic Recrystallization ◽  
Peak Stress ◽  
Bearing Steel ◽  
Peak Strain ◽  
Compression Tests ◽  
Gcr15 Bearing Steel ◽  
Dynamic Recrystallization Behavior ◽  
Gleeble 3500 ◽  
Relationship Of

The effect of process parameters on dynamic recrystallization of GCr15 bearing steel was investigated by a single-pass compression tests using Gleeble-3500 thermal simulator. The results indicate that the flow stress decreases with the increasing of temperature and the decreasing of strain rate. The dynamic recrystallization rate increases with the increasing of deformation temperature. By regression analysis, the mean activation energy and the stress exponent are determined to be 435.1KJ/mol-1and 5.0505 respectively. Meanwhile, the kinetic mathematical model of dynamic recrystallization and constitutive equation are established.The relationship of peak stress, peak strain and Z parameters is founded by using the data of flow stress curves.

The Study on BFRP Binding Force of Secondary Compression Tests of Concrete Short Columns

2011 ◽  
Vol 418-420 ◽  
pp. 116-120
Author(s):  
Wei Ha Ma
Keyword(s):  
Initial Stress ◽  
Strain Curve ◽  
Peak Stress ◽  
Stress And Strain ◽  
Compression Tests ◽  
Secondary Stress ◽  
Stress Strain Curve ◽  
Binding Force ◽  
Short Columns ◽  
Strength And Deformation

This article has test researched on the BFRP constraint compression of the concrete short columns secondary stress axial compression , got C20, C25 reinforced concrete specimens of stress-strain curve test, studies show that strengthened specimens of strength and deformation of the increased significantly, and the degree of improve related with the size of initial stress. Through testing the processing and analysis of data, concludes that the calculation formula of peak stress and strain of the strengthening specimens under the secondary stress and can reflect the influence of different condition of initial stress .

scholarly journals Nonlinear Dynamic Constitutive Model of Frozen Sandstone Based on Weibull Distribution

2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
Lei Wang ◽  
Hongming Su ◽  
Shiguan Chen ◽  
Yue Qin
Keyword(s):  
Elastic Modulus ◽  
Constitutive Model ◽  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Soft Rock ◽  
Strain Curve ◽  
Peak Stress ◽  
Experimental Results ◽  
Compression Tests ◽  
Hopkinson Pressure Bar

To obtain the dynamic mechanical properties of frozen sandstone at different temperatures (i.e., 20°C, −10°C, −20°C, and −30°C), dynamic uniaxial compression tests of saturated sandstone are conducted using a split-Hopkinson pressure bar. The experimental results demonstrated that the brittleness of the saturated sandstone increased and its plasticity weakened with a decrease in temperature. The peak strength and dynamic elastic modulus of the sandstone were positively correlated with its strain rate. The peak stress was most sensitive to the strain rate at −10°C, and the elastic modulus was most sensitive to the strain rate at −30°C. According to the evident segmentation characteristics of the obtained stress-strain curve, a viscoelastic dynamic constitutive model considering the strain rate effect and temperature effect is developed; this model combines a nonlinear (or linear) body and a Maxwell body in parallel with a damage body. The applicability of the constitutive model is also verified using experimental data. The fitting results were demonstrated to be in good agreement with the experimental results. Furthermore, the fitting results serve as reference for the study of the constitutive model of weakly cemented soft rock and the construction of roadway freezing methods.

Constitutive relationship of IN690 superalloy by using uniaxial compression tests

Rare Metals ◽  
2011 ◽  
Vol 30 (1) ◽  
pp. 81-86 ◽  
Author(s):  
Chaoyang Sun ◽  
Jinrong Liu ◽  
Rui Li ◽  
Qingdong Zhang ◽  
Jianxin Dong
Keyword(s):  
Uniaxial Compression ◽  
Constitutive Relationship ◽  
Compression Tests ◽  
Relationship Of

scholarly journals Stress-Strain Relationship of Ca(OH)2-Activated Hwangtoh Concrete

2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
Keun-Hyeok Yang ◽  
Ju-Hyun Mun ◽  
Hey-Zoo Hwang
Keyword(s):  
Compressive Strength ◽  
Strain Curve ◽  
Peak Stress ◽  
Actual Behavior ◽  
Test Results ◽  
Stress Strain ◽  
Strain Behavior ◽  
Strain Relationship ◽  
Relationship Of ◽  
Strain Model

This study examined the stress-strain behavior of 10 calcium hydroxide (Ca(OH)2)-activated Hwangtoh concrete mixes. The volumetric ratio of the coarse aggregate (Vagg) and the water-to-binder (W/B) ratio were selected as the main test variables. TwoW/Bratios (25% and 40%) were used and the value ofVaggvaried between 0% and 40.0%, and 0% and 46.5% forW/Bratios of 25% and 40%, respectively. The test results demonstrated that the slope of the ascending branch of the stress-strain curve of Ca(OH)2-activated Hwangtoh concrete was smaller, and it displayed a steeper drop in stress in the descending branch, compared with those of ordinary Portland cement (OPC) concrete with the same compressive strength. This trend was more pronounced with the increase in theW/Bratio and decrease inVagg. Based on the experimental observations, a simple and rational stress-strain model was established mathematically. Furthermore, the modulus of elasticity and strain at peak stress of the Ca(OH)2-activated Hwangtoh concrete were formulated as a function of its compressive strength andVagg. The proposed stress-strain model predicted the actual behavior accurately, whereas the previous models formulated using OPC concrete data were limited in their applicability to Ca(OH)2-activated Hwangtoh concrete.

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