Related Experiment Video
Updated: May 15, 2025
10:27
A Uniaxial Compression Experiment with CO2-Bearing Coal Using a Visualized and Constant-Volume Gas-Solid Coupling Test System
Published on: June 12, 2019
8.6K
Uniaxial Compressive Failure Characteristics and Constitutive Modeling of Fractured Coal Mass Under Different Strain
Zihao Feng1, Haitao Li1, Xiaoshan Shi1
1Deep Mining and Rock Burst Research Institute, Chinese Institute of Coal Science, Beijing 100013, China.
Materials (Basel, Switzerland)
|May 14, 2025
Summary
This study reveals how strain rate and fracture density impact coal's mechanical properties. Higher strain rates increase compressive strength, while more fractures decrease it, affecting coal's structural integrity.
Area of Science:
- Geotechnical Engineering
- Materials Science
- Rock Mechanics
Background:
- Understanding coal's mechanical behavior under varying conditions is crucial for safe mining and resource extraction.
- Fracture density and strain rate significantly influence the strength and deformation of rock materials.
- Existing models may not fully capture the complex interplay between these factors in fractured coal.
Purpose of the Study:
- To investigate the effects of different strain rates and fracture densities on the mechanical behavior of coal.
- To establish and refine a statistical damage constitutive model for fractured coal.
- To analyze the fractal characteristics of coal fragments under dynamic loading.
Main Methods:
- Computed Tomography (CT) scanning for quantifying fracture content in coal specimens.
- Uniaxial compression tests to analyze mechanical characteristics at various strain rates.
- Development and modification of a statistical damage constitutive model incorporating Weibull distribution parameters.
Main Results:
- Compressive strength positively correlates with strain rate and negatively with fracture density.
- Elastic modulus is sensitive to fracture density, especially at lower strain rates.
- Fractal dimension and fragment mass increase with strain rate, indicating greater particle size non-uniformity.
- Weibull parameters (F0, m) show distinct trends around critical strain rate (0.01 s⁻¹) and fracture density (0.3%-0.45%) thresholds.
Conclusions:
- Strain rate and fracture density are critical parameters governing coal's mechanical response.
- The modified statistical damage constitutive model provides a more accurate representation of fractured coal behavior.
- Thresholds in strain rate and fracture density significantly alter the material's damage evolution and fragmentation patterns.
Related Concept Videos
01:23Behavior of Concrete Under Compressive Load
127
Concrete exhibits specific behaviors under different compressive loads. Understanding this is crucial for understanding its structural integrity. When concrete undergoes uniaxial compression, it tends to develop cracks that run parallel to the direction of the force. These parallel cracks stem from localized tensile stresses that occur perpendicular to the compression direction. Additionally, angled cracks may appear due to the formation of shear planes.
As the concrete specimen fractures under...
As the concrete specimen fractures under...
127
01:24Stress-Strain Diagram - Brittle Materials
1.0K
Brittle materials, including glass, cast iron, and stone, exhibit unique characteristics. They fracture without considerable change in their elongation rate, indicating that their breaking and ultimate strength are equivalent. Such materials also show lower strain levels at the point of rupture. The failure in brittle materials predominantly results from normal stresses, as evidenced by the rupture created along a surface perpendicular to the applied load. These materials do not display...
1.0K
01:20Elastic Strain Energy for Shearing Stresses
137
As discussed in previous lessons, strain energy in a material is the energy stored when it is elastically deformed, a concept crucial in materials science and mechanical engineering. This energy results from the internal work done against the cohesive forces within the material. When a material undergoes shearing stress and corresponding shearing strain, the strain energy density, which is the energy stored per unit volume, is calculated. Within the elastic limit, where the stress is...
137
01:15Relation between Poisson's ratio, Modulus of Elasticity and Modulus of Rigidity
228
Deformation occurs in axial and transverse directions when an axial load is applied to a slender bar. This deformation impacts the cubic element within the bar, transforming it into either a rectangular parallelepiped or a rhombus, contingent on its orientation. This transformation process induces shearing strain. Axial loading elicits both shearing and normal strains. Applying an axial load instigates equal normal and shearing stresses on elements oriented at a 45° angle to the load axis.
228
01:20Normal Strain under Axial Loading
409
Normal strain under axial loading is an important concept in the field of mechanics of materials. Axial loading implies the application of a force along the axis of a material, like a column or bar. This force can either compress or stretch the material. In the context of axial loading, normal strain is the deformation experienced by the material in the direction of the loading force. It's calculated as the change in length divided by the original length of the material. This unitless ratio...
409
01:21Fatigue
167
Fatigue occurs when materials rupture under repeated or fluctuating loads, even at stress levels far below their static breaking strength. It typically results in brittle failure, even for ductile materials. It is a critical consideration in designing machines and structural components subjected to repetitive or varying loads. The nature of these loadings can range from fluctuating loads like unbalanced pump impellers causing vibrations to repeatedly bending a thin steel rod wire back and forth...
167