scholarly journals Mechanical Characteristics and Energy Evolution Laws for Red Bed Rock of Badong Formation under Different Stress Paths

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Tao Wen ◽  
Huiming Tang ◽  
Yankun Wang ◽  
Junwei Ma ◽  
Zhiqiang Fan
Keyword(s):  
Mechanical Properties ◽  
Cyclic Loading ◽  
Failure Mechanism ◽  
Energy Evolution ◽  
Dissipation Energy ◽  
Cycle Times ◽  
Loading Tests ◽  
Evolution Laws ◽  
Formation Section ◽  
Red Bed

Exploring mechanical properties of red bed rock of Badong Formation Section two (b2) from the Three Gorges Reservoir is crucial to determine the instability mode of reservoir slopes. In order to reveal the energy evolution laws for b2 rocks under different stress paths, loading tests, unloading tests, and cyclic loading-unloading tests were conducted, respectively. The results show that stress paths have significant influences on the mechanical properties and energy evolution characteristics of b2 rocks and the failure mechanism under three stress paths is revealed. Relative to the loading tests, the mechanical parameters of b2 rocks are deteriorated under the unloading conditions. In addition, the increasing trend of cumulative dissipation energy (CDE) is similar with that of total absorption energy (TAE) and the ESE-strain curves are characterized by multistep rise. For cyclic loading-unloading tests, the areas of hysteretic loop gradually increase as the cycle times increase, and the TAEs and the coefficient of the cumulative dissipation energy (CCDE) also increase gradually with approximately linear characteristics, while the CDEs gradually increase in an abrupt rate. This work can contribute to provide the failure mechanism of b2 rocks for evaluating the stability of reservoir slopes from the energy perspective.

The High Cyclic Failure Analysis of Welded Joints of CT Specimens

2010 ◽  
Vol 165 ◽  
pp. 183-188
Author(s):  
Rimantas Stonkus ◽  
Mindaugas Kazimieras Leonavičius
Keyword(s):  
Mechanical Properties ◽  
Cyclic Loading ◽  
Failure Analysis ◽  
Failure Mechanism ◽  
Welded Joints ◽  
Failure Process ◽  
Static Fracture ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

The results of failure process of welded joints subjected to high-cyclic loading are presented. Analysis of the microstructure of welded joints, indexes of mechanical properties are provided and failure mechanism in the area of fatigue and static fracture is analyzed. The fractographic analysis of CT specimens was performed by means of optical and scanning electron microscopes.

scholarly journals Influence of Loading Rate on the Energy Evolution Characteristics of Rocks under Cyclic Loading and Unloading

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 4003
Author(s):  
Jielin Li ◽  
Liu Hong ◽  
Keping Zhou ◽  
Caichu Xia ◽  
Longyin Zhu
Keyword(s):  
Cyclic Loading ◽  
Loading Rate ◽  
Energy Evolution ◽  
Dissipation Energy ◽  
Loading Rates ◽  
Cyclic Loading And Unloading ◽  
Evolution Characteristics ◽  
Increasing Trend ◽  
Loading And Unloading ◽  
Fast Increase

To analyse the effect of loading rate on the energy evolution of rocks under cyclic loading and unloading, tests on saturated limestone were conducted at loading rates of 0.15, 0.2, and 0.3 mm/min, and the evolution characteristics of plastic, elastic, dissipation, and input energies were examined under different loading rates. The results indicated that the plastic strain in the entire test was directly proportional to the loading rate. In addition, strength, residual stress, plastic energy, and dissipation energy under residual resistance were inversely proportional to the loading rate. The plastic strain exhibited a decreasing–stabilising–increasing trend, and the smaller loading rate delayed the “increasing” trend. The increasing extent of each energy exhibited the following trend: input > elastic > plastic > dissipation energy. Furthermore, the first three types of energy exhibited a slow–fast–slow–fast increase trend. The dissipation energy exhibited a fast–steady–fast–slow–fast increase trend. Additionally, the elastic energy index exhibited a large increase–steady increase–decrease trend, which was proportional to the loading rate. The damping ratio exhibited a decrease–increase–decrease–increase–decrease trend which was proportional to the loading rate in the compaction stage and inversely proportional to the plastic stage.

Deformation and Acoustics Parameters Feature of Recycled Concrete under Cyclic Loading

2011 ◽  
Vol 80-81 ◽  
pp. 213-216 ◽  
Author(s):  
Xing Wen Luo ◽  
Hai Lin Yao
Keyword(s):  
Cyclic Loading ◽  
Linear Equations ◽  
Recycled Concrete ◽  
Demolition Waste ◽  
Cycle Times ◽  
Concrete Production ◽  
Loading Tests ◽  
Three Stages ◽  
Cyclic Loading Tests ◽  
Excellent Source

Concrete demolition waste has been proved to be an excellent source of aggregates for new concrete production. Four types of recycled concrete specimens were made for cyclic loading tests in laboratory, in order to research the acoustics parameters and deformation feature of recycled concrete under cyclic loading. Acoustics parameters such as ultrasonic wave time, ultrasonic velocity and ultrasonic amplitude of recycled concrete were tested synchronously while recycled concrete were loaded. Test results show the evolution of fatigue total strain of recycled concrete undergoes three stages. The cycle times in the three stages accounted for 10%, 80% and 10% of the fatigue life respectively. These stages can be simulated by power function equations, first-order linear equations and exponential functions accordingly. Tests results show that wave time increased with the rise of cyclic times, while wave amplitude decreased in the same time.

Sign in / Sign up

Export Citation Format

Share Document