Numerical Simulation of the Rational Loading Waveform in Large Diameter SHPB Dynamic Test for Rock-Like Materials

2011 ◽  
Vol 243-249 ◽  
pp. 2419-2422 ◽  
Author(s):  
Feng Qiang Gong ◽  
Xi Ling Liu ◽  
Ke Gao
Keyword(s):  
Split Hopkinson Pressure Bar ◽  
Large Diameter ◽  
Dynamic Test ◽  
Pulse Waveform ◽  
Hopkinson Pressure Bar ◽  
Triangular Waveform ◽  
Finite Element Software ◽  
Transmission Distance ◽  
Loading Waveform ◽  
Rectangular Waveform

For rock-like materials, large diameter SHPB (Split Hopkinson Pressure Bar,SHPB) is necessary and essential in dynamic test. Based on the finite element software ANSYS/LS- DYNA, the transmission of different stress pulse waveform in large diameter bar was simulated and the loading waveform dispersion effect was investigated in this paper. Three typical stress pulses (rectangular waveform, triangular waveform and half-sine waveform) with the same duration time and maximum stress amplitude value were loaded on input bar of SHPB. The time-stress curves of different transmission distance on input bar were traced and recorded and four specific aspects were discussed respectively. Compared with rectangular waveform and triangular waveform, the results of numerical analysis indicated that there isn’t pulse waveform dispersion for half-sine waveform to transmit in large diameter SHPB and there is enough increased time to satify stress equilibrium before rock-like materials failure. The half-sine stress wave is able to meet the one-dimensional assumptions in the propagation process and can be used in large diameter SHPB test.

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 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.

Confinement device to assess dynamic crushability of wood material

2017 ◽  
Vol 232 (8) ◽  
pp. 1418-1432 ◽  
Author(s):  
J Wouts ◽  
G Haugou ◽  
M Oudjene ◽  
H Naceur ◽  
D Coutellier
Keyword(s):  
Finite Element ◽  
Split Hopkinson Pressure Bar ◽  
Large Diameter ◽  
Hybrid Approach ◽  
Hopkinson Pressure Bar ◽  
Wood Material ◽  
Element Analysis ◽  
Multiaxial Stress State ◽  
Split Hopkinson ◽  
Pressure Bar

Cellular materials such as wood are widely and advantageously used as shock absorbers in various transport applications. The design and manufacturing of structures made of these materials require the knowledge of their dynamic compressive properties at various strain rates and stress states. Therefore, it is challenging to conduct dynamic multiaxial stress state experiments and especially on split-Hopkinson pressure bar apparatus where stress hardening increases as a function of velocity. This paper presents the so-called verification and validation methodology for confining solutions dedicated to impact on viscoelastic split-Hopkinson pressure bar system with large diameter bars. The method is a hybrid approach combining finite element analysis and an original experimental validation. Based on finite element results, particular attention is given to the mass, the material and the geometry to minimize the confining device influence on the propagation of elastic waves and thus on the material response of the tested specimens. It is essential to avoid spurious reflected waves at the new interfaces of the system in order to ensure the validity of the experimentation. The numerically predicted solutions are experimentally validated and preliminary results in the context of dynamic loadings using wood material are presented.

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 dynamic asymmetric fracture test and determination of the dynamic fracture toughness of large-diameter cracked rock specimens

2019 ◽  
Vol 23 (Suppl. 3) ◽  
pp. 897-905
Author(s):  
Yiqiang Lu ◽  
Mingzhong Gao ◽  
Bin Yu ◽  
Cong Li
Keyword(s):  
Fracture Toughness ◽  
Dynamic Fracture ◽  
Split Hopkinson Pressure Bar ◽  
Impact Load ◽  
Failure Process ◽  
Large Diameter ◽  
Dynamic Stress Intensity Factor ◽  
Dynamic Fracture Toughness ◽  
Hopkinson Pressure Bar ◽  
Rock Specimens

We propose large-diameter (160 mm) pre-cracked chevron notched Brazilian disc (P-CCNBD) specimens were used to study the asymmetric fracture law and determine the dynamic fracture toughness of rock. Specimens were diametrically impacted by a split Hopkinson pressure bar. The dynamic fracture failure process of each specimen was monitored by crack propagation gauges and strain gauges. Each of the large-diameter P-CCNBD specimens was found to exhibit prominent asymmetric fracture under impact load. The stress equilibrium condition cannot be satisfied. The dynamic fracture toughness values of the rocks were measured using the experimental-numerical method rather than the quasi-static method. The calculation results showed that the dynamic fracture toughness of rocks increases with the dynamic loading rate. In addition, at the 3-D crack front, the dynamic stress intensity factor was found be substantially different at each point. These data suggest that the dynamic fracture toughness of P-CCNBD specimens should be calculated by removing the value affected by an edge arc crack and taking the average value of the remaining points.

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 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.

Ø100mm SHPB Equipment and its Application

2011 ◽  
Vol 99-100 ◽  
pp. 891-895
Author(s):  
Zhi Gang Zhang ◽  
Meng Shen Li ◽  
Xiao Long Wang ◽  
Xiao Lei Zhong ◽  
Qing Li
Keyword(s):  
Performance Index ◽  
Split Hopkinson Pressure Bar ◽  
Large Diameter ◽  
Hopkinson Pressure Bar ◽  
Study Material ◽  
Split Hopkinson ◽  
And Performance ◽  
Pressure Bar ◽  
Further Development ◽  
Nonhomogeneous Materials

Hopkinson Pressure Bar (HPB) is one of the main sets to study material dynamic mechanic properties. Large diameter HPB is mainly used for nonhomogeneous materials. In this paper the properties of Split Hopkinson Pressure Bar (SHPB) of Ø100mm are introduced, including its structure and performance index. The main problems of large diameter SHPB are analyzed. The further development and application of SHPB are also explored.

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