Stress uniformity of split Hopkinson pressure bar under half-sine wave loads

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.

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Numerical Simulation the Stress Uniformity in Split Hopkinson Pressure Bar Testing

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.634-638.2861 ◽

2013 ◽

Vol 634-638 ◽

pp. 2861-2864

Author(s):

Hong Bin Jin

Keyword(s):

Numerical Simulation ◽

Wave Propagation ◽

Split Hopkinson Pressure Bar ◽

Hopkinson Pressure Bar ◽

Large Area ◽

Test Technique ◽

Split Hopkinson ◽

Shpb Test ◽

Pressure Bar ◽

Stress Uniformity

The assumption of uniform stress in a test specimen is fundamental to SHPB test technique. In the present paper, a numerical simulation of wave propagation in SHPB is performed to validate the assumption. A one-dimensional model based on CSPM is firstly developed. Then the wave propagations in SHPB with various area ratios of bar/specimen are simulated. The results show that the condition of stress uniformity is not satisfied, especially at the beginning of wave propagation. For the large area specimen, the stress tends to be uniform. While for the small area specimen, the non-uniformity of stress is more apparent.

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Dynamic Compressive Behavior of Granite under Active Confinement

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.291-294.1227 ◽

2011 ◽

Vol 291-294 ◽

pp. 1227-1232 ◽

Cited By ~ 1

Author(s):

Gang Chen ◽

Yu Chun Kuang ◽

Xi Cheng Huang ◽

Ai Min Xu

Keyword(s):

Strain Rate ◽

Pulse Shaping ◽

Split Hopkinson Pressure Bar ◽

Hopkinson Pressure Bar ◽

Pulse Shaper ◽

Safety Requirements ◽

Split Hopkinson ◽

Active Confinement ◽

Pressure Bar ◽

Stress Uniformity

The behaviour of geologic material such as granite under impact loading is involved in the study of safety requirements of structures in extreme simulations such as earthquakes, accidental impacts or explosions. Based on incident pulse shaping design of quasi-brittle material for dynamic tests, experiments on granite under uniaxial and active confinement conditions are conducted with the split Hopkinson pressure bar(SHPB). By adding the soft material mass as the pulse shaper, the stress uniformity in the specimens before fracture is ensured and the fluctuation of test data due to incident stress pulse is avoid. The experimental results show that the compressive strength is increasing with the strain rate and the confined pressure. The fragments size decreases with the strain rate. The research method and conclusion could be used to analyze the dynamic behavior of the other brittle materials.

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Analysis of the Impact of the Frequency Range of the Tensometer Bridge and Projectile Geometry on the Results of Measurements by the Split Hopkinson Pressure Bar Method

Metrology and Measurement Systems ◽

10.2478/mms-2013-0047 ◽

2013 ◽

Vol 20 (4) ◽

pp. 555-564 ◽

Cited By ~ 12

Author(s):

Wojciech Moćko

Keyword(s):

Test Bench ◽

Split Hopkinson Pressure Bar ◽

Dynamic Deformation ◽

Spectral Width ◽

Hopkinson Pressure Bar ◽

Computing Environment ◽

Split Hopkinson ◽

Pressure Bar ◽

The Impact ◽

Bench Model

Abstract The paper presents the results of the analysis of the striker shape impact on the shape of the mechanical elastic wave generated in the Hopkinson bar. The influence of the tensometer amplifier bandwidth on the stress-strain characteristics obtained in this method was analyzed too. For the purposes of analyzing under the computing environment ABAQUS / Explicit the test bench model was created, and then the analysis of the process of dynamic deformation of the specimen with specific mechanical parameters was carried out. Based on those tests, it was found that the geometry of the end of the striker has an effect on the form of the loading wave and the spectral width of the signal of that wave. Reduction of the striker end diameter reduces unwanted oscillations, however, adversely affects the time of strain rate stabilization. It was determined for the assumed test bench configuration that a tensometric measurement system with a bandwidth equal to 50 kHz is sufficient

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