scholarly journals Study on Strain Rate Effect and Size Effect of Dynamic Response Characteristics of Granite

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Zhihang Hu ◽  
Yuying Ning ◽  
Jiuyang Zhang ◽  
Jianyu Zhao
Keyword(s):  
Aspect Ratio ◽  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Impact Load ◽  
Hopkinson Pressure Bar ◽  
Aspect Ratios ◽  
Rate Of Increase ◽  
Density Index ◽  
The Impact ◽  
Time Density

Under impact load, the dynamic mechanical properties of rock are complex and changeable. The Split Hopkinson Pressure Bar (SHPB) system was used to change the impact load to carry out different strain rate loading tests on granite with different aspect ratios, and to analyze the influence of strain rate and aspect ratio on the dynamic energy consumption of granite crushing. The results show that at an impact velocity of 14 m/s, the granite with an aspect ratio of 1.4 appears to be strip-shaped fragments after being broken; the granite with an aspect ratio of 1.0 uniform square fragments after being broken; the granite with an aspect ratio of 0.6 appears to be a large number of flat fragments after being broken. When the load strain rate of the granite with an aspect ratio of 0.6 increases from 50 s-1 to 150 s-1, the energy-time density index increases significantly; when the load strain rate exceeds 150 s-1, the energy-time density index decreases. When the strain rate of granite with an aspect ratio of 1.0 exceeds 80 s-1, the energy-time density increases significantly. When the strain rate of the granite with an aspect ratio of 1.4 exceeds 60 s-1, the rate of increase of the energy-time density of the rock increases significantly.

scholarly journals Dynamic Characteristics of Deep Dolomite Under One-Dimensional Static and Dynamic Loads

2019 ◽  
Vol 101 (1) ◽  
pp. 49-56 ◽  
Author(s):  
Jianguo Wang ◽  
Yang Liu ◽  
Kegang Li
Keyword(s):  
Strain Rate ◽  
Axial Compression ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Strength ◽  
Strong Positive Correlation ◽  
Hopkinson Pressure Bar ◽  
Irreversible Damage ◽  
One Dimensional ◽  
Rock Structure ◽  
The Impact

AbstractThe failure characteristics of rock subjected to impact disturbance under one-dimensional static axial compression are helpful for studying the problems of pillar instability and rock burst in deep, high geostress surrounding rock under blasting disturbances. Improved split Hopkinson pressure bar equipment was used for one-dimensional dynamic–static combined impact tests of deep-seated dolomite specimens under axial compression levels of 0, 12, 24, and 36 MPa. The experimental results demonstrate that the dolomite specimens exhibit strong brittleness. The dynamic strength always maintains a strong positive correlation with the strain rate when the axial compression is fixed; when the strain rate is close, the dynamic elasticity modulus and peak strength of the specimens first increase and then decrease with the increase in axial compression, and the peak value appears at 24 MPa. The impact resistance of specimens can be enhanced when the axial compression is 12 or 24 MPa, but when it increases to 36 MPa, the damage inside the specimen begins to cause damage to the dynamic rock strength. Prior to the rock macroscopic failure, the axial static load changes the rock structure state, and it can store strain energy or cause irreversible damage.

scholarly journals Blasting Impact Simulation Test and Fragmentation Distribution Characteristics in an Open-Pit Mine

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Xiaohua Ding ◽  
Xiang Lu ◽  
Wei Zhou ◽  
Xuyang Shi ◽  
Boyu Luan ◽  
...  
Keyword(s):  
Coal Mine ◽  
Wave Attenuation ◽  
Split Hopkinson Pressure Bar ◽  
Impact Load ◽  
Large Diameter ◽  
Test System ◽  
Open Pit ◽  
Hopkinson Pressure Bar ◽  
The Impact ◽  
The Relationship

Based on the split Hopkinson pressure bar (SHPB) test system, dynamic impact tests of coal specimens under different impact pressures were carried out to study the relationship between the impact load and the size of crushed lump coal. Based on the theory of stress wave attenuation, the relationship between the blasting impact load in a single-hole blasting area of a coal seam and the load applied in an impact failure test of a coal specimen in the laboratory was established. According to the characteristics of the fragmentation distribution of the coal specimens destroyed under a laboratory impact load and the requirement of the minimum cost control of coal blasting in an open-pit coal mine, the fragmentation size range was divided into three groups: large-diameter, medium-diameter, and powder particles. Based on this range, the variation rule of the mass percentage of coal fragments with impact pressure was obtained. Established on the evaluation principle of the blasting effect in an open-pit coal mine, a good impact fragmentation effect was obtained. The good pressure range is 0.30 MPa≤P<0.90 MPa.

Dynamic Behavior of Acrylonitrile Butadiene Styrene Under Impact Loads

2015 ◽  
Author(s):  
Alex Peterson ◽  
Denzell Bolling ◽  
Adewale Olasumboye ◽  
Ed Habtour ◽  
Jaret C. Riddick ◽  
...  
Keyword(s):  
Strain Rate ◽  
Computer Aided Design ◽  
Fused Deposition Modeling ◽  
Split Hopkinson Pressure Bar ◽  
Impact Load ◽  
Acrylonitrile Butadiene Styrene ◽  
Fused Deposition ◽  
Computer Aided ◽  
The Impact ◽  
Butadiene Styrene

This paper is aimed at providing a better understanding of the potential energy absorption benefits of components fabricated using fused deposition modeling (FDM) additive manufacturing. Using FDM, it is possible to print three-dimensional (3-D) objects created through the use of computer-aided design and computer-aided manufacturing software coupled with computer codes that enable the layer-by-layer deposition of material to form the 3-D component. Also known as direct digital manufacturing or 3-D printing, AM offers the benefit of being able to rotate printing orientation during processing to manipulate the design build and ultimately control mechanical and structural properties when subjected to dynamic loads. In this work, tensile test specimens were first fabricated to characterize the general mechanical behavior of the of 3D-printed Acrylonitrile Butadiene Styrene (ABS) material to assess its potential strain rate dependency. The mechanical evaluation under the quasi-static load was also necessary to determine the properties necessary to characterize the dynamic evolution of ABS in compression at various strain rates. ABS specimens were subsequently subjected to high strain rate deformation through the use of the Split Hopkinson Pressure Bar. During compression a new phenomenon described as a multistage collapse in which the samples undergo multiple stages of contraction and expansion was observed as the impact load was applied.

Effect of Foam Structure on Impact Compressive Properties in Foamed Polyethylene Film

2016 ◽  
Vol 715 ◽  
pp. 159-164 ◽  
Author(s):  
Kohei Tateyama ◽  
Hiroyuki Yamada ◽  
Nagahisa Ogasawara
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Testing Machine ◽  
Polyethylene Film ◽  
Elastic Response ◽  
Hopkinson Pressure Bar ◽  
Compressive Properties ◽  
Foam Structure ◽  
The Impact

The purpose of this study is to elucidate the effect of foam structure on the impact compressive properties of foamed polyethylene film. Three types of foamed PE film were prepared, which have different foam structure: base type, spheral type and dense type. A quasi-static test was performed using a universal testing machine at the strain rate of 10-3~10-1s-1. Impact tests were carried out using a drop-weight testing machine at the strain rate of 101~102s-1 and using a split Hopkinson pressure bar method at the strain rate of approximately 103s-1. It was confirmed that the foamed PE film shows an increase of the flow stress with increasing of the strain rate, regardless of the specimen type. In the spheral type specimen, the elastic response is observed immediately after compression because the cell shape of this specimen has high bending resistance in comparison with the other two specimens. In addition, it is confirmed that the relative density and cell size affects the flow stress in the foamed PE film.

Impact Compressive Properties of Foamed Film with Closed Cell

2014 ◽  
Vol 566 ◽  
pp. 134-139 ◽  
Author(s):  
Hiroyuki Yamada ◽  
Ryo Okui ◽  
Nagahisa Ogasawara ◽  
Hidetoshi Kobayashi ◽  
Kinya Ogawa
Keyword(s):  
Strain Rate ◽  
Impact Test ◽  
Split Hopkinson Pressure Bar ◽  
Rate Dependency ◽  
Hopkinson Pressure Bar ◽  
Compressive Properties ◽  
Static Test ◽  
Closed Cell ◽  
Pressure Bar ◽  
The Impact

The compressive properties of foamed polyethylene (PE) film with a closed cell for electronic devices have been investigated. A commercial closed cell foamed PE film with a density of 330 kg/m3 was used. Quasi-static testing was carried out at strain rates of 10−3 to 10−1 s−1. The strain rate of the impact test was approximately 105 s−1 by means of split Hopkinson pressure bar method. Within the set of experiments, the compressive stress increased with the strain rate in both the quasi-static and impact test. In particular, the flow stress increased substantially with the increasing strain rate in the impact deformation. At strains of less than 0.4, the trapped air was locally compressed within the cells, which led to the strain rate dependency of strength in the quasi-static test and the impact test.

scholarly journals Impact Compressive Failure of a Unidirectional Carbon/Epoxy Composite: Effect of Loading Directions

2008 ◽  
Vol 13-14 ◽  
pp. 195-201 ◽  
Author(s):  
Takashi Yokoyama ◽  
Kenji Nakai
Keyword(s):  
Strain Rate ◽  
Cross Sections ◽  
Split Hopkinson Pressure Bar ◽  
Epoxy Composite ◽  
Compressive Strain ◽  
Testing Machine ◽  
Compressive Failure ◽  
Hopkinson Pressure Bar ◽  
Composite Effect ◽  
The Impact

The impact compressive failure behaviour of a unidirectional T700/2521 carbon/epoxy composite in three principal material directions is investigated in the conventional split Hopkinson pressure bar. Two different types of specimens with square cross sections are machined from the composite in the plane of the laminate. The uniaxial compressive stress-strain curves up to failure at quasi-static and intermediate strain rates are measured on an Instron testing machine. It is demonstrated that the ultimate compressive strength (or maximum stress) increases slightly, while the ultimate compressive strain (or failure strain) decreases marginally with strain rate in the range of 10-3 to 103/s in all three directions. Dominant failure mechanisms are found to significantly vary with strain rate and loading directions along three principal material axes.

Static and Dynamic Behaviors of Fibre Reinforced Recycled Aggregate Mortar

2021 ◽  
Vol 882 ◽  
pp. 237-246
Author(s):  
Sallehan Ismail ◽  
Mohamad Asri Abd Hamid ◽  
Zaiton Yaacob
Keyword(s):  
Split Hopkinson Pressure Bar ◽  
Impact Load ◽  
Dynamic Compression ◽  
Recycled Aggregate ◽  
Fibre Reinforcement ◽  
Hopkinson Pressure Bar ◽  
Loading Test ◽  
Dynamic Increase Factor ◽  
Hybrid Fibre ◽  
The Impact

This study aims to explore the inclusion of microfibre in fine recycled aggregate (FRA) mortars under dynamic impact load. A 12-mm-diameter Split Hopkinson Pressure Bar (SHPB) was employed to test the impact of a recycled mortar with a single and hybrid fibre system and to determine potential improvements in its dynamic mechanical properties. In recycled mortar production, two microfibres with different sizes and types, namely, polypropylene and nylon, were added whilst keeping the amount of microfibres at a volumetrical fraction of 0.6%. An impact loading test was conducted by using the striking bar of SHPB at impact speeds of 2, 4 and 6 m/s. The effects of fibre on failure mode, tensile curve, compressive strength and dynamic increase factor (DIF) were then analysed. Experimental findings show that the improved mortar fibre mix has superior quasi-static and dynamic compression power compared with the reference mortar mix. Meanwhile, compared with the single fibre mix, the hybrid fibre mix is more effective in enhancing the dynamic compressive ability of the recycled mortar. The recycled-hybrid-fibre-enhanced mortar showed lower DIF values compared with the reference mortar, and the inclusion of fibre reinforcement can reduce the fragmentation of the recycled mortar mix after being subjected to impact.

Strain Rate Effects in Porous Materials

1998 ◽  
Vol 521 ◽  
Author(s):  
J. Lankford ◽  
K. A. Dannemann
Keyword(s):  
Strain Rate ◽  
Gas Flow ◽  
Split Hopkinson Pressure Bar ◽  
Impact Resistance ◽  
Hopkinson Pressure Bar ◽  
Porous Metals ◽  
Strain Rate Effects ◽  
Open Cell ◽  
Rate Dependent ◽  
The Impact

ABSTRACTThe behavior of metal foams under rapid loading conditions is assessed. Dynamic loading experiments were conducted in our laboratory using a split Hopkinson pressure bar apparatus and a drop weight tester; strain rates ranged from 45 s−1 to 1200 s−1. The implications of these experiments on open-cell, porous metals, and closed- and open-cell polymer foams are described. It is shown that there are two possible strain-rate dependent contributors to the impact resistance of cellular metals: (i) elastic-plastic resistance of the cellular metal “skeleton,” and (ii) the gas pressure generated by gas flow within distorted open cells. A theoretical basis for these implications is presented.

scholarly journals Dynamic Compressive Characteristics of Sandstone under Confining Pressure and Radial Gradient Stress with the SHPB Test

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Shiming Wang ◽  
Yunsi Liu ◽  
Jian Zhou ◽  
Qiuhong Wu ◽  
Shuyi Ma ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Large Diameter ◽  
Dynamic Strength ◽  
Confining Pressure ◽  
Peak Strain ◽  
Hopkinson Pressure Bar ◽  
Radial Gradient ◽  
The Impact

Research on the dynamic compressive characteristics of sandstone under radial gradient stress and confining pressure is conducive to understanding the characteristics of the surrounding rock, especially in an excavation operation for an underground mine roadway and tunnel. The present work aimed at studying the effects of radial gradient stress and confining pressure on the impact of compression of sandstone using a large-diameter split Hopkinson pressure bar. The results showed that the dynamic strength of sandstone under radial gradient stress increased with strain rate following a power function, and the dynamic strength of the sandstone under radial gradient stress was lower and more sensitive to strain rate. The increase in strain at peak stress (peak strain) was linearly correlated with the strain rate under different confining pressures. The sensitivity of the peak strain to confining pressure was lower for the sandstone with a hole, while the values of the elastic modulus were decreased. However, further increasing the stain rate would lead to an increase in the elastic modulus. Also, the ductility of the sandstone with a hole tested in this study was found to improve more significantly. Finally, with an increase in the incident energy, the absorbed energy per unit volume would increase, but would not be affected obviously by the radial gradient stress.

Study on Dynamic Behavior of AFRP-Wrapped Circular Concrete Specimens under Repeated Impacts

2017 ◽  
Vol 25 (1) ◽  
pp. 103-112
Author(s):  
Hengwen Song ◽  
Hui Yang ◽  
Shi Zhang
Keyword(s):  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Impact Damage ◽  
Peak Stress ◽  
Hopkinson Pressure Bar ◽  
Split Hopkinson ◽  
Repeated Impacts ◽  
Damage Condition ◽  
Pressure Bar ◽  
The Impact

A series of damage tests and axially repeated compressive tests with high strain rates were conducted to investigate the behavior of aramid fiber reinforced polymer (AFRP) wrapped concrete under repeated impacts. The relation between damage condition and variables such as impact number and polymer thickness were examined. The tests were performed using a 100 mm diameter Split Hopkinson Pressure Bar (SHPB) apparatus and a nonmetal supersonic test meter. Various AFRP layers were applied to produce varied confinement ratios. The experimental results indicated that the AFRP-wrapped concrete exhibited excellent performance in resisting repeated impacts. Also, the specimens maintained their shapes and bearing capacity after multiple impacts with a mean strain rate of 50 s−1. No distinct decline was observed from the history of peak stress and impact toughness in AFRP-wrapped concrete. Moreover, additional AFRP layers significantly decreased the impact damage on the core concrete, as reflected by the different strain rate histories in damage progression.

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