scholarly journals Testing of Weakly Weathered Granites of Different Porosities Using a Split Hopkinson Pressure Bar Technique

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Lei Yan ◽  
Liansheng Liu ◽  
Shenghui Zhang ◽  
Depei Lan ◽  
Jiangchao Liu
Keyword(s):  
Split Hopkinson Pressure Bar ◽  
Peak Stress ◽  
Stress Waves ◽  
Porous Rocks ◽  
Average Strain ◽  
Hopkinson Pressure Bar ◽  
Average Strain Rate ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
Damage Impact

Nuclear magnetic resonance (NMR) and damage impact testing, using a split Hopkinson pressure bar (SHPB) technique, were conducted on weakly weathered granites of different porosities. Based on this, this study determined and analysed the pore structure and distribution, propagation characteristics of stress waves, changes in initial tangent modulus, and energy dissipation in weakly weathered granites of different porosities. The research demonstrated that the nature of the internal porosity of weakly weathered granites changed with total porosity. Pore structure significantly influenced the amplitude of reflected waves and distortion of transmitted waves. Under constant-damage impact loads, the initial tangent modulus decreased with increasing porosity, whereas the stress-strain curves, after reaching the peak stress, had similar shapes. Peak stress and average strain rate showed a strong power-law correlation with porosity, and peak stress decreased in a power-law correlation with the increase of average strain rate. In other words, the difference in average strain resulted from different porosities when the incident energy was same, and the average strain was negatively correlated with porosity. Under damaging impact, the energy absorbed per unit volume decreased with increasing porosity. The research results reveal dynamic characteristics of natural porous rocks under damage impacts, which provide a reference for studying damage effects of porous rocks under the effects of stress waves.

scholarly journals Development of a True-Biaxial Split Hopkinson Pressure Bar Device and Its Application

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7298
Author(s):  
Shumeng Pang ◽  
Weijun Tao ◽  
Yingjing Liang ◽  
Shi Huan ◽  
Yijie Liu ◽  
...  
Keyword(s):  
Stress Wave ◽  
Impact Loading ◽  
Split Hopkinson Pressure Bar ◽  
Axial Stress ◽  
Dynamic Mechanical Properties ◽  
Stress Waves ◽  
Hopkinson Pressure Bar ◽  
Dynamic Mechanical ◽  
Split Hopkinson ◽  
Pressure Bar

Although highly desirable, the experimental technology of the dynamic mechanical properties of materials under multiaxial impact loading is rarely explored. In this study, a true-biaxial split Hopkinson pressure bar device is developed to achieve the biaxial synchronous impact loading of a specimen. A symmetrical wedge-shaped, dual-wave bar is designed to decompose a single stress wave into two independent and symmetric stress waves that eventually form an orthogonal system and load the specimen synchronously. Furthermore, a combination of ground gaskets and lubricant is employed to eliminate the shear stress wave and separate the coupling of the shear and axial stress waves propagating in bars. Some confirmatory and applied tests are carried out, and the results show not only the feasibility of this modified device but also the dynamic mechanical characteristics of specimens under biaxial impact loading. This novel technique is readily implementable and also has good application potential in material mechanics testing.

scholarly journals Antiknock Performance of Interlayered High-Damping-Rubber Blast Door under Thermobaric Shock Wave

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Xiudi Li ◽  
Chaoyang Miao ◽  
Qifan Wang ◽  
Zhengang Geng
Keyword(s):  
Shock Wave ◽  
Split Hopkinson Pressure Bar ◽  
Front Surface ◽  
Underground Structures ◽  
Hopkinson Pressure Bar ◽  
Maximum Displacement ◽  
Average Strain Rate ◽  
Split Hopkinson ◽  
High Damping Rubber ◽  
Pressure Bar

The long duration and high impulse shock wave of thermobaric bomb threatens the security of underground structures. To obtain high resistance blast door against thermobaric shock wave, firstly, the dynamic mechanic property of high damping rubber was studied by split Hopkinson pressure bar (SHPB) equipment and the stress-strain relationship of high damping rubber under average strain rate of 5200/s was obtained. Secondly, the numerical model of interlayered high-damping-rubber blast door was established with ANSYS/LS-DYNA code based on test results, and the antiknock performance of interlayered high-damping-rubber blast door under thermobaric shock wave was analyzed by contrast with ordinary blast door. The results showed that the midspan displacement of the blast door decreased firstly and then increased with the increase of thickness of the high-damping-rubber interlayer, and the optimal thickness of the high-damping-rubber interlayer for energy consuming was 150 mm in the calculation condition of this paper. With the increase of the distance between the interlayer and the front surface of the door, the midspan displacement of the blast door decreased continually. The midspan maximum displacement of interlayered high-damping-rubber blast door decreased 74.5% in comparison to ordinary blast door. It showed that the high-damping-rubber structure can effectively improve the antiknock performance of blast door under thermobaric shock wave.

scholarly journals Effects of annealing and specimen geometry on dynamic compression of a Zr-based bulk metallic glass

2007 ◽  
Vol 22 (2) ◽  
pp. 389-401 ◽  
Author(s):  
George Sunny ◽  
John Lewandowski ◽  
Vikas Prakash
Keyword(s):  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Split Hopkinson Pressure Bar ◽  
Peak Stress ◽  
Specimen Geometry ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Split Hopkinson ◽  
Pressure Bar

High strain-rate compression experiments were performed with a split-Hopkinson pressure bar (SHPB) at 500–4000/s on cylindrical samples of a Zr-based bulk metallic glass (LM-1) in both the fully amorphous and annealed conditions. The effects of changes to the specimen geometry (i.e., L/D ratio) and the material heat treatment [i.e., annealing versus amorphous (as-received)], on the peak stress, strain-to-failure, and failure behavior were determined with the aid of an in situ video obtained by using a high-speed digital camera in conjunction with the split-Hopkinson pressure bar (SHPB). Examination of the in situ video recordings and light optical microscopy showed that the failed samples revealed preferential failure initiating at the sample ends due to stress concentration at the sample-insert interface. A new insert design was developed using transient, elastic-plastic finite-element simulations to reduce the effects of these stress concentrations. SHPB testing, combined with in situ video, subsequently revealed that this new experimental configuration promoted failure within the gage length and away from the sample ends in the samples tested. Significant effects of specimen geometry, insert design, and annealing on the apparent values of the peak stress, strain-to-failure, and fracture behavior were exhibited.

Experiment on Mechanical Behavior of Reinforced Concrete Subjected to Impact Loading

2012 ◽  
Vol 450-451 ◽  
pp. 523-526 ◽  
Author(s):  
Hai Feng Liu ◽  
Wei Wu Yang ◽  
Jian Guo Ning
Keyword(s):  
Reinforced Concrete ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Compression ◽  
Peak Stress ◽  
Compression Tests ◽  
Hopkinson Pressure Bar ◽  
Rate Dependent ◽  
Split Hopkinson ◽  
Reinforced Steel ◽  
Pressure Bar

The dynamic compression tests of reinforced concrete with different reinforcement ratios are carried out by split Hopkinson pressure bar (SHPB). Reinforced steel bar is placed along longitudinal and transverse direction. Experimental results show that reinforced concrete is non-linear and rate-dependent. With the enhancement of strain rate, the peak stress of reinforced concrete increases correspondingly

Dynamic strain measurement using piezoelectric polymer film

1996 ◽  
Vol 31 (6) ◽  
pp. 463-465 ◽  
Author(s):  
A L Smith ◽  
D J Mee
Keyword(s):  
Split Hopkinson Pressure Bar ◽  
Axial Stress ◽  
Stress Waves ◽  
Dynamic Strain ◽  
Strain Gauges ◽  
Hopkinson Pressure Bar ◽  
Piezoelectric Polymer ◽  
Split Hopkinson ◽  
Detection Of Stress ◽  
Pressure Bar

Piezoelectric polymers have been used to form the basis of dynamic strain gauges for the detection of stress waves. The linearity of response was tested using a split Hopkinson pressure bar arrangement. The results obtained illustrate the effectiveness of piezoelectric film strain gauges in the measurement of axial stress waves.

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.

Study on Deformation Property of EPS Concrete Under Impact Loading

2011 ◽  
Vol 71-78 ◽  
pp. 809-814 ◽  
Author(s):  
Er Lei Bai ◽  
Jin Yu Xu ◽  
Zhi Gang Gao
Keyword(s):  
Strain Rate ◽  
Impact Loading ◽  
Deformation Property ◽  
Volume Fraction ◽  
Split Hopkinson Pressure Bar ◽  
Rate Dependency ◽  
Hopkinson Pressure Bar ◽  
Average Strain Rate ◽  
Split Hopkinson ◽  
Pressure Bar

The EPS concrete with 10%，20%，30%，40%，50% EPS volume fraction were prepared. Taking critical strain as the index, the deformation property of EPS concrete with different EPS volume fraction under impact loading were studied using a 100-mm-diameter split Hopkinson pressure bar(SHPB) apparatus. The results show that the deformation property of the EPS concrete increases with the average strain rate for the strain rate effect, which takes on obvious strain rate dependency. For the EPS microscopic structure effect, the deformation property of the EPS concrete increases with the EPS volume fraction in 0~40%. Its deformation property reduces somewhat when the EPS volume fraction reaches 50%. To improve the deformation property, the optimum volume fraction of EPS is 40%.

Study on Toughening Effect in EPS Concrete

2011 ◽  
Vol 105-107 ◽  
pp. 1717-1722
Author(s):  
De Hui Zhao ◽  
Jin Yu Xu ◽  
Er Lei Bai
Keyword(s):  
Strain Rate ◽  
Volume Fraction ◽  
Split Hopkinson Pressure Bar ◽  
Plain Concrete ◽  
Rate Dependency ◽  
Hopkinson Pressure Bar ◽  
Effect Mechanism ◽  
Average Strain Rate ◽  
Split Hopkinson ◽  
Pressure Bar

To study on the toughing effect of EPS in the plain concrete, the EPS concrete with 10%,20%,30%,40%,50% EPS volume fraction were prepared. Taking specific energy absorption as the index, the toughing effect of EPS concrete with different EPS volume fraction under impact loading were studied using a 100-mm-diameter split Hopkinson pressure bar(SHPB) apparatus, and the toughing effect mechanism of the concrete was discussed. The results show that the toughing effect of the EPS concrete increases with the average strain rate for the strain rate effect, which takes on obvious strain rate dependency. For the EPS microscopic structure effect, the toughing effect of the EPS concrete increases with the EPS volume fraction in 10~30%. Its toughing effect reduces somewhat when the EPS volume fraction reaches 40~50%. To improve the deformation property, the optimum volume fraction of EPS is 20%.

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