scholarly journals Mechanical Properties of Roof Rocks under Superimposed Static and Dynamic Loads with Medium Strain Rates in Coal Mines

2021 ◽  
Vol 11 (19) ◽  
pp. 8973
Author(s):  
Kun Zhong ◽  
Wusheng Zhao ◽  
Changkun Qin ◽  
Hou Gao ◽  
Weizhong Chen
Keyword(s):  
Mechanical Properties ◽  
Energy Density ◽  
Failure Mode ◽  
Dynamic Loading ◽  
Loading Rate ◽  
Dynamic Loads ◽  
Strain Rates ◽  
Static And Dynamic Loads ◽  
Roof Rocks ◽  
Rock Specimens

Roof rocks in coal mines are subjected to the combination of in situ stresses and dynamic stresses induced by mining activities. Understanding the mechanical properties of roof rocks under static and dynamic loads at medium strain rates is of great significance to revealing the mechanism of rock bursts. In this study, we employ the digital image correlation (DIC) technique to investigate the energy concentration and dissipation behaviors, failure mode, and deformation characteristics of roof rocks under combined static and dynamic loads. Our results show that both the static pre-stress and dynamic loading rate have significant effects on the uniaxial compressive strength of rock specimens. From the energy principle, when the static pre-stress is the same, both elastic strain energy density and dissipated energy density increase with increasing dynamic loading rate. The hazard of rock bursts increases with decreasing static pre-stress and increasing dynamic loading rate. At higher dynamic loading rates, more cracks are generated, and the failure becomes more violent. The crack initiation, propagation and coalescence processes are identified, and the failure mode is closely related to the evolution of the global principal strain field of the rock specimens.

The Mechanical Properties Comparative Analysis for Socked and Non-Socketed Composite Pile

2014 ◽  
Vol 1061-1062 ◽  
pp. 748-750
Author(s):  
Heng Chen ◽  
Ke Sheng Ma
Keyword(s):  
Mechanical Properties ◽  
Comparative Analysis ◽  
Seismic Performance ◽  
Dynamic Loads ◽  
Vertical Load ◽  
Interlayer Thickness ◽  
Static Loads ◽  
Soil Stress ◽  
Composite Pile ◽  
Static And Dynamic Loads

For socked and non-socketed piles in the different mechanical behavior under static and dynamic loads, the paper use ABAQUS to model, simulate the pile , the soil interlayer thickness between the bottom of the pile and bedrock are 2m, 4m under vertical load and Earthquake, cushion cap, pile and pile soil stress situation found non-socketed piles when the soil interlayer thickness within a certain range, the composite pile small subside under dynamic, static loads, the non-socketed piles can better take advantage of the pile soil has a good seismic performance in the earthquake.

Mechanical properties and failure behavior of rock with different flaw inclinations under coupled static and dynamic loads

2020 ◽  
Vol 27 (10) ◽  
pp. 2945-2958
Author(s):  
Peng Xiao ◽  
Di-yuan Li ◽  
Guo-yan Zhao ◽  
Quan-qi Zhu ◽  
Huan-xin Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Dynamic Loads ◽  
Failure Behavior ◽  
Static And Dynamic Loads

scholarly journals Dynamic Mechanical Characteristics of Impact Rock under the Combined Action of Different Constant Temperatures and Static and Dynamic Loads

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Enlai Zhao ◽  
Enyuan Wang ◽  
Zesheng Zang ◽  
Xiaojun Feng ◽  
Rongxi Shen
Keyword(s):  
Mechanical Properties ◽  
Dynamic Load ◽  
Incident Energy ◽  
Dynamic Mechanical Properties ◽  
Image Correlation ◽  
Dynamic Loads ◽  
Dissipated Energy ◽  
Dynamic Mechanical ◽  
Combined Action ◽  
Static And Dynamic Loads

The complex mechanical environment of deep coal and rock masses leads to obvious changes on their dynamic mechanical properties. However, there are few reports on the dynamic mechanical properties of rocks under the combined action of medium temperature (normal temperature ∼100°C) and static and dynamic loads. In this paper, a dynamic load and temperature combined action Hopkinson pressure bar experimental system is used to experimentally study the impact type of a fine sandstone under temperature conditions of 18°C, 40°C, 60°C, 80°C, and 100°C, an axial static load of 3 MPa, a gas chamber pressure of 0.06 MPa, and a constant temperature time of 4 h. The dynamic characteristics of the change law of the fine sandstone and the energy dissipation characteristics of the load process are analyzed, and the characteristic law of the fine sandstone surface response is analyzed using digital image correlation technology. Our results indicate the following. (1) Under conditions in which the other experimental conditions remain unchanged, the dynamic stress-strain of the fine sandstone presents a bimodal shape with a “rebound” phenomenon. Increasing temperature causes the peak strength of the fine sandstone to increase; however, the relative strength can increase or decrease. The relative increase in the strength is 1.14 MPa (°C) when the temperature increases from 40°C to 60°C, 0.15 MPa (°C) when the temperature increases from 60°C to 80°C, and 0.62 MPa (°C) when the temperature increases from 80°C to 100°C. (2) The digital image correlation results show that, under the action of a dynamic load stress wave, the fine sandstone experiences a displacement vector change on the sample surface; furthermore, under the combined action of the temperature and dynamic and static loads, the fine sandstone experiences macroscopic shear failure. The surface strain in the propagation direction of the stress wave is obviously higher and can even reach values of more than 10 times that of the strain in other directions. (3) From the perspective of energy dissipation, the incident energy, reflected energy, and dissipated energy of the fine sandstone under an impact load have the same change law. After being affected by a dynamic load, the energy rapidly increases to a certain value and then remains relatively stable. The transmitted energy is relatively small and can be approximated as a horizontal line. As the temperature increases, the incident energy, reflected energy, and dissipated energy tend to first decrease and then increase, and most of the incident energy in the fine sandstone is dissipated in the form of reflected waves.

Effect of Strain Rate on Tensile Properties of Injection Molded Multiwall Carbon Nanotube Reinforced PA 6/6 Nanocomposites

2020 ◽  
Author(s):  
Seyed Hamid Reza Sanei ◽  
Hanna Drozynski ◽  
Dakota Hetrick
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotube ◽  
Strain Rate ◽  
Tensile Properties ◽  
Loading Rate ◽  
Multiwall Carbon Nanotube ◽  
Strain Rates ◽  
Chain Mobility ◽  
Injection Molded ◽  
Multiwall Carbon

Abstract The mechanical properties of polymers highly depend on the loading rate, however, the effect of loading/strain rate with the addition of Carbon Nanotube is not well understood. In this study, the effect of Carbon Nanotube (CNT) content on the rate dependence of polymers was studied. Injection molded mini-tensile samples with CNT content ranging from 0 to 15wt% at strain rates of .0006, .0013, .0019 and .0025 s−1 were tested. It was found that as strain rate increased, the ultimate strength and Young s Modulus of the tensile specimens increased. It was also shown that addition of CNT will lower the chain mobility of polymer and lower the polymer dependence of properties to strain rates.

scholarly journals Comparative Studies on the Behaviour of Flat Panels Made of GRP Under Static and Dynamic Loads

2022 ◽  
Vol 58 (4) ◽  
pp. 222-237
Author(s):  
Costel Iulian Mocanu ◽  
Alin Pohilca ◽  
Liviu Moise ◽  
Daniela Ioana Tudose
Keyword(s):  
Mechanical Properties ◽  
Scientific Community ◽  
Research Study ◽  
Dynamic Loads ◽  
Plastic Plate ◽  
Optimal Reinforcement ◽  
Manufacture Process ◽  
Reinforced Plastic ◽  
Static And Dynamic Loads ◽  
Commercial Applications

Glass reinforced plastic, so called GRP, is a composite material made of glass strands called fibbers woven together to create a flexible fabric. GRP is a lightweight material with many and diverse applications ranging from the manufacture of reservoirs for different liquids to the manufacture of boats, yachts, chairs and even children playground furniture. The behaviour of this material under static and dynamic loads is still raising interest from the scientific community and a large number of researchers. This continued interest is due to the material versatility for different applications depending on its manufacture process that has a significant weigh-in in the material mechanical properties. These resulting mechanical properties need to be carefully analysed and benchmarked prior to using the obtained material in commercial applications. The scope of this research study is to analyse the behaviour of glass reinforced plastic plate panel with reinforcements on one and two directions under static and dynamic loads employing both experimental and numerical methods for results validation. The methods used in this research study for the dynamic loads can also be applied successfully to other composite materials. Additionally, the stress plots have been analysed in iteration in order to ensure the most optimal reinforcement pattern.

scholarly journals Impact of static and dynamic loads of vehicles on pavement

2020 ◽  
Vol 164 ◽  
pp. 03025
Author(s):  
Elena Kurakina ◽  
Sergey Evtiukov
Keyword(s):  
Elastic Modulus ◽  
Dynamic Loading ◽  
Flexible Pavement ◽  
Strength Properties ◽  
Road Surface ◽  
Dynamic Loads ◽  
Diagnostic Capacity ◽  
Loading Tests ◽  
Static And Dynamic Loads ◽  
Static And Dynamic Loading

The present paper substantiates urgency of studies on early deterioration of pavement layers and on reasons entailing it. The aim was to investigate static and dynamic loads imposed on a road surface by vehicles in order to detect signs of early deterioration of pavement and understand its reasons. Certain tasks were set: to define diagnostic capacity for performing test works on road surface with the use of static and dynamic loading equipment; to carry out an elastic modulus analysis on the basis of static and dynamic loading tests performed; to assess strength properties of flexible pavement. The paper describes methods for determining strength properties of a road surface with the use of special static and dynamic loading equipment. The authors provide data on diagnostic capacity of tests of a pavement performed with the use of special testing equipment. The paper gives a list of potentials, advantages and fundamental features of the following units of equipment: apparatus for plate bearing tests, Dina-3M, UDN-NK, Dynatest apparatus. The main parameters of equipment for dynamic loading tests are provided. The results of both dynamic and static loading tests performed in Saint Petersburg and the Leningrad region are given. Deflection bowls and elastic modulus were determined. Coefficients of the dynamic elastic modulus being reduced to the static one were calculated. Strength properties of flexible pavement were assessed.

The Effect of Small Additions of Carbon Nanotubes on the Mechanical Properties of Epoxy Polymers under Static and Dynamic Loads

2018 ◽  
Vol 63 (1) ◽  
pp. 32-40 ◽  
Author(s):  
A. E. Tarasov ◽  
E. R. Badamshina ◽  
D. V. Anokhin ◽  
S. V. Razorenov ◽  
G. S. Vakorina
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Dynamic Loads ◽  
Epoxy Polymers ◽  
Static And Dynamic Loads
Sign in / Sign up

Export Citation Format

Share Document