scholarly journals Innovative testing technique of rock stress wave propagation

2021 ◽  
pp. 123
Author(s):  
Keyword(s):  
Wave Propagation ◽  
Stress Wave ◽  
Split Hopkinson Pressure Bar ◽  
Static Stress ◽  
Stress Wave Propagation ◽  
Testing Technique ◽  
Linear Gradient ◽  
Red Sandstone ◽  
Stress Gradients ◽  
Adjacent Structures

Inadequacy of rock mechanics chamber test devices and test systems that cannot accurately simulate gradient static stresses on specimens, this paper presented an innovative testing technique, which relates to the stress wave propagation of rock subjected gradient static stress. The method involves modification of a split Hopkinson pressure bar, such that the test specimen is subjected to gradient static stress and axial impact loading. The device has the features of simple loading and multiple static stress gradients, which verifies the feasibility of stress wave propagation test of red sandstone specimens under linear gradient static stress and conducts stress wave propagation test of red sandstone specimens under linear gradient static stress. Tests on red sandstone specimens with different static stress gradients show that the stress wave propagation of the specimens under gradient static stress is different with their corresponding homogeneous static stress state. The attenuation coefficients of stress waves are different under different conditions, and loading gradient static stress can accelerate the attenuation process. The results of this study will be useful for the analysis of stress wave propagation in deep engineering blasting and the stability analysis of adjacent structures.

Experimental and Modeling Studies of the Interlayer Effect on Stress Wave Propagation of Ceramic/Ti6Al4V Armors

2013 ◽  
Vol 753-755 ◽  
pp. 981-987
Author(s):  
Cheng Miao ◽  
Guo Fei Li ◽  
Tao Zhong ◽  
Wei Ling Yang ◽  
Lin Yang ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Energy Absorption ◽  
Stress Wave ◽  
Split Hopkinson Pressure Bar ◽  
Reflected Shock Wave ◽  
Stress Wave Propagation ◽  
Ceramic Plate ◽  
Modeling Studies ◽  
Copper Interlayer ◽  
Aluminum Interlayer

The effect of steel, copper and aluminum interlayer on the stress wave propagation of ceramic/ Ti6Al4V armors were studied by traditional Split Hopkinson Pressure Bar system in this paper. Based on the SHPB experimental results, the stress wave propagation mechanism and energy absorption in tri-layered structure were discussed. Compared to ceramic/Ti6Al4V structure without interlayer, the steel, copper and aluminum interlayer could attenuate the transmission stress level and greatly increase the energy absorption of the structure. Due to the high acoustic reluctance of steel and copper interlayer, the reflected shock wave was in compressed situation and extended a tri-axial compressive stress within the ceramic which could improve the anti-penetration properties of ceramic plate. The numerical modeling studies of ballistic testing were carried on, and then the energy densities were compared. The results showed the steel and copper interlayer could increase the energy absorption of ceramic and improve the anti-penetration of ceramic plate. The three kinds of interlayer structures all could attenuate transmitted energy and decrease the residual penetration.

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.

Stress wave propagation effects in split Hopkinson pressure bar tests

1995 ◽  
Vol 449 (1936) ◽  
pp. 187-204 ◽  
Keyword(s):  
Wave Propagation ◽  
Strain Rate ◽  
Stress Wave ◽  
Split Hopkinson Pressure Bar ◽  
Rate Sensitivity ◽  
Stress Wave Propagation ◽  
Hopkinson Pressure Bar ◽  
Propagation Effects ◽  
Split Hopkinson ◽  
Pressure Bar

Studies of the properties of materials at high strain rates by the split Hopkinson pressure bar suggest that most materials show a sharp increase in strain rate sensitivity at high rates. In this paper, analytical and numerical evidence is presented which shows that his apparent increase in the strain rate sensitivity reported in the literature may result from stress wave propagation effects present in the test. A one-dimensional analytical solution has been developed for a rate independent bi-linear material tested in a split Hopkinson pressure bar apparatus. The solution, which is based on a stress wave reverberation model, shows that there is an apparent increase in the strain rate sensitivity of the material which can only be explained in terms of large propagating plastic wave fronts in the specimen. Numerical modelling of the same test geometry for the same input material model is in excellent agreement showing conclusively that stress wave propagation effects are inevitable at high impact velocities. The assumption of uniform stress and strain distribution within a split Hopkinson pressure bar specimen is therefore incorrect at high impact velocities. The formulation of the novel numerical code used in the present work, which is based on the finite volume technique, is also presented.

The Effect of Stress Wave on Dynamic Response of Square Thin-Walled Tube

2014 ◽  
Vol 590 ◽  
pp. 63-68 ◽  
Author(s):  
Zhu Hua Tan ◽  
Bo Zhang ◽  
Peng Cheng Zhai
Keyword(s):  
Wave Propagation ◽  
Dynamic Response ◽  
Stress Wave ◽  
High Speed ◽  
Split Hopkinson Pressure Bar ◽  
Stress Wave Propagation ◽  
Hopkinson Pressure Bar ◽  
Thin Walled Tube ◽  
Split Hopkinson ◽  
Pressure Bar

The effect of stress wave propagation on dynamic response of square tube was investigated by the experimental and numerical simulation methods in the present paper. The square tubes were subjected to the axial impact by split Hopkinson pressure bar. And the deformation process of each square tube was recorded by a high speed camera. Typical dynamic plastic buckling phenomena were observed in the experiments. And the numerical calculation of the experimental load case was conducted to analyze the effect of the stress wave propagation on the initial buckling of the square tube. The results show that there is obvious stress wave propagation in the square tube before the buckling of the square tube. And the initial buckling starts from the rear end of the tube due to the propagation of the stress wave. The relation between the stress wave propagation and initial buckling of the square tube was also discussed.

Effect of interlayer on stress wave propagation in CMC/RHA multi-layered structure

2010 ◽  
Vol 70 (12) ◽  
pp. 1669-1673 ◽  
Author(s):  
Yangwei Wang ◽  
Fuchi Wang ◽  
Xiaodong Yu ◽  
Zhuang Ma ◽  
Jubin Gao ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Stress Wave ◽  
Layered Structure ◽  
Stress Wave Propagation
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