Numerical Simulation Analysis of the Effect on the One-Dimension Assumption in Different Diameter SHPB Pressure Bar by Two Kinds of Loading Waveform

2013 ◽  
Vol 787 ◽  
pp. 759-764
Author(s):  
Sheng Zhang ◽  
Xiang Hao Yang ◽  
Xin Wen Li
Keyword(s):  
Stress Wave ◽  
Split Hopkinson Pressure Bar ◽  
Simulation Analysis ◽  
Sine Wave ◽  
Stress Waves ◽  
One Dimension ◽  
Hopkinson Pressure Bar ◽  
Finite Element Software ◽  
The One ◽  
Pressure Bar

t is one of precondition of determining rock material dynamic parameters for one-dimension assumption of the elastic pressure bar. In order to analyze its effect by loading wave type, the dynamic stress was simulated with Ls-dynamic finite element software, when SHPB(Split Hopkinson Pressure Bar) pressure bar with diameter of 50 mm, 75 mm and 100 mm were impacted respectively by a cycle rectangular loading wave and half sine loading wave. The stress waves of cross section in different diameter pressure bar and the different distance with pressure bar end were compared and analyzed. The results indicated that the dispersion of stress waves was very serious and the matching ability of stress wave at different distances in pressure bar was poor when the rectangular wave was loaded. However, the dispersion of stress wave was not obvious with the increase of the diameter of pressure bar and the change of pressure bar when the half sine wave was loaded. The half sine loading wave which can strictly meet the one-dimension assumption is one of the ideal loading waveforms of the rocky heterogeneous materials.

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 Stress Attenuation and Energy Absorption of the Coral Sand with Different Particle Sizes under Impacts

Proceedings ◽  
2018 ◽  
Vol 2 (8) ◽  
pp. 545
Author(s):  
Xiao Yu ◽  
Li Chen ◽  
Qin fang ◽  
Wuzheng Chen
Keyword(s):  
Energy Absorption ◽  
Stress Wave ◽  
Wave Attenuation ◽  
Split Hopkinson Pressure Bar ◽  
Particle Size Effect ◽  
Particle Sizes ◽  
Hopkinson Pressure Bar ◽  
Coral Sand ◽  
Stress Zone ◽  
Pressure Bar

The stress wave attenuation and energy absorption in the coral sand were respectively investigated. A series of experiments were carried out by using a new methodology with an improved split Hopkinson pressure bar (SHPB). Four types of coral sand, i.e., particle sizes of 1.18–0.60 mm, 0.60–0.30 mm, 0.30–0.15 mm, and 0.15–0.075 mm, were carefully sieved and tested. Significant effects of coral sand on stress wave attenuation and energy absorption were observed. Correlation between stress wave attenuation and energy absorption of coral sand was validated. Conclusions on particle size effect of stress wave attenuation and energy absorption, which support each other, were drawn. There existed a common critical stress zone for coral sand with different particle sizes. When the stress below this zone, sand with small particle sizes attenuates stress wave better and absorb energy more; when the stress beyond this zone, sand with larger particle sizes behave better on stress wave attenuation and energy absorption.

Numerical Investigation of the Stress Wave Propagation in the Incident Bar and the Specimen

2014 ◽  
Vol 602-605 ◽  
pp. 98-101 ◽  
Author(s):  
Raja Ahsan Javed ◽  
Shi Fan Zhu ◽  
Chun Huan Guo ◽  
Feng Chun Jiang
Keyword(s):  
Stress Wave ◽  
Dynamic Fracture ◽  
Sine Wave ◽  
Stress Wave Propagation ◽  
Stress And Strain ◽  
Hopkinson Pressure Bar ◽  
Time Duration ◽  
Fracture Properties ◽  
Propagation Behavior ◽  
Pressure Bar

Hopkinson pressure bar apparatus is extensively used for the measurement of the dynamic fracture properties. For accurate measurement of the dynamic fracture properties we need to understand concepts and principles associated with the test setup. The understanding of stress wave in the bar and specimen is also very important. In the current work, ANSYS LS-DYNA software is used to simulate the propagation behavior of the time based loading and generation of stress wave. The stress and strain plots in the specimen and the incident bar are obtained as an output of the analysis. The analysis of the plots suggest that, for the same time duration the rising trend is observed for the plots of stress and strain of incident bar whereas a sine wave trend is observed for the plots in the specimen.

scholarly journals Experimental and Numerical Evaluation of Rock Dynamic Test with Split-Hopkinson Pressure Bar

2017 ◽  
Vol 2017 ◽  
pp. 1-12
Author(s):  
Kang Peng ◽  
Ke Gao ◽  
Jian Liu ◽  
Yujiao Liu ◽  
Zhenyu Zhang ◽  
...  
Keyword(s):  
Split Hopkinson Pressure Bar ◽  
Dynamic Properties ◽  
Dynamic Test ◽  
Propagation Distance ◽  
Sine Wave ◽  
Pulse Loading ◽  
Hopkinson Pressure Bar ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
Stress Uniformity

Feasibility of rock dynamic properties by split-Hopkinson pressure bar (SHPB) was experimentally and numerically evaluated with ANSYS/LS-DYNA. The effects of different diameters, different loading rates, and different propagation distances on wave dispersion of input bars in SHPB with rectangle and half-sine wave loadings were analyzed. The results show that the dispersion effect on the diameter of input bar, loading rate, and propagation distance under half-sine waveform loading is ignorable compared with the rectangle wave loading. Moreover, the degrees of stress uniformity under rectangle and half-sine input wave loadings are compared in SHPB tests, and the time required for stress uniformity is calculated under different above-mentioned loadings. It is confirmed that the stress uniformity can be realized more easily using the half-sine pulse loading compared to the rectangle pulse loading, and this has significant advantages in the dynamic test of rock-like materials. Finally, the Holmquist-Johnson-Concrete constitutive model is introduced to simulate the failure mechanism and failure and fragmentation characteristics of rock under different strain rates. And the numerical results agree with that obtained from the experiment, which confirms the effectiveness of the model and the method.

scholarly journals The effect of perforations on the stress wave propagation characteristics of multilayered materials

2016 ◽  
Vol 29 (12) ◽  
pp. 1680-1695 ◽  
Author(s):  
Alper Tasdemirci ◽  
Ali Kara
Keyword(s):  
Stress Wave ◽  
Split Hopkinson Pressure Bar ◽  
Stress Wave Propagation ◽  
Large Strains ◽  
Hopkinson Pressure Bar ◽  
Multilayered Structures ◽  
Backing Plate ◽  
Split Hopkinson ◽  
Multilayered Materials ◽  
Pressure Bar

The effect of perforated interlayers on the stress wave transmission of multilayered materials was investigated both experimentally and numerically using the Split Hopkinson pressure bar (SHPB) testing. The multilayer combinations consisted of a ceramic face plate and a glass/epoxy backing plate with a laterally constrained low modulus solid or perforated rubber and Teflon interlayer. The perforations on rubber interlayer delayed the stress rise time and reduced the magnitude of the transmitted stress wave at low strains, while the perforations allowed the passage of relatively high transmitted stresses at large strains similar to the solid rubber interlayer. It was concluded that the effect of perforations were somewhat less pronounced in Teflon interlayer configuration, arising from its relatively low Poisson’s ratio. It was finally shown that SHPB testing accompanied with the numerical simulations can be used to analyze the effect of compliant interlayer insertion in the multilayered structures.

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.

scholarly journals Numerical Simulation of Split-Hopkinson Pressure Bar Tests for the Combined Coal-Rock by Using the Holmquist–Johnson–Cook Model and Case Analysis of Outburst

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Beijing Xie ◽  
Dongxin Chen ◽  
Hao Ding ◽  
Guangyu Wang ◽  
Zheng Yan
Keyword(s):  
Numerical Simulation ◽  
Rock Burst ◽  
Split Hopkinson Pressure Bar ◽  
Tensile Failure ◽  
Hopkinson Pressure Bar ◽  
Finite Element Software ◽  
Split Hopkinson ◽  
Coal Rock ◽  
Pressure Bar ◽  
The Impact

In the coal and rock dynamic disasters, such as the rock burst, dynamic load damage often acts simultaneously on the combined coal and rock mass. Based on the split-Hopkinson pressure bar (SHPB) test of the combined coal and rock with a bullet velocity of 4.590–8.791 m/s, the numerical model of four kinds of combined coal and rock with different sandstone-coal-sandstone ratios, including 1 : 1 : 1, 2 : 1 : 1, 1 : 1 : 2, and 1 : 2 : 1, is investigated. A finite element software (LS-DYNA) and the Holmquist–Johnson–Cook (HJC) constitutive model of rock are employed in these regards. The stress waveform, the oscillation phenomenon of stress wave, and the damage process of the specimen in the impact test of the composite coal and rock are studied. The obtained results show that the compression-shear failure is the main failure mode of the coal body and the tensile failure of the sandstone along the axial direction in the composite coal-rock specimens. Moreover, it is found that combination of coal and rock samples is mainly destroyed by the coal body, which has no correlation with the impact speed and combination mode. Finally, numerical simulation about Hongling coalmine extralarge tunnel malfunction is carried out. Obtained results showed the protruding and stress change processes of the coal seam of the tunnel exposing. It is found that the simulation results are in an excellent agreement with those from the field investigation. The present study may provide a reference for further understanding the mechanism of the coal and rock dynamic disasters, such as the rock burst.

scholarly journals Experimental Study on Stress Wave Propagation Crossing the Jointed Specimen with Different JRCs

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
S.N. Hong ◽  
H.B. Li ◽  
L.F. Rong
Keyword(s):  
Wave Propagation ◽  
Stress Wave ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Compression ◽  
Three Dimensional ◽  
Stress Wave Propagation ◽  
Roughness Coefficient ◽  
Rock Masses ◽  
Hopkinson Pressure Bar ◽  
Pressure Bar

Most of the rock masses in the outer crust of the Earth are discontinuous. They are divided by joints, faults, fractures, etc. And those discontinuities, generally referred to as joints, greatly affect the property of the rock masses. The paper experimentally investigates the stress wave propagation crossing the jointed specimens. The tests were conducted on the split Hopkinson pressure bar (SHPB). The test specimens consist of two parts cast by cement mortar. Both parts have an irregular surface, and they were designed to match each other completely. The surfaces where two parts meet make an artificial joint. The surfaces of the joints were scanned by a three-dimensional scanner to obtain its actual topography and then to calculate the roughness of the surface, i.e., the joint roughness coefficient (JRC). A set of jointed specimens with JRC ranging from 0 to 20 were made and used in dynamic compression experiments. During the tests, signals were captured by strain gauges stuck on the incident and transmitted bars of the SHPB apparatus. The incident, reflected, and transmitted waves across the jointed specimens were obtained from the test records. We found out that more stress wave would transmit through the jointed specimen with larger JRC. Besides, collected data were processed to get the dynamic stress-strain relation of jointed specimens and the stress-closure curves of the joints. The results show that the joint increases the deformation of the specimen, and the stiffness of the jointed specimen would increase slightly when the joint is rougher.

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.

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