Study of Initiator’s Shock-Resistibility Through Impact Using Hopkinson Pressure Bar

2008 ◽  
Vol 33-37 ◽  
pp. 401-406 ◽  
Author(s):  
Qiong Deng ◽  
Yu Long Li ◽  
Tao Suo ◽  
Chun Lin Chen ◽  
Xing Min Chang
Keyword(s):  
Pulse Width ◽  
Wave Theory ◽  
Hopkinson Pressure Bar ◽  
Pulse Shaper ◽  
Finite Element Program ◽  
Analog Simulation ◽  
Critical Acceleration ◽  
Acceleration Pulse ◽  
Element Program ◽  
Pressure Bar

This paper attempted to study the properties of Slapper detonator non-energetic elements through exerting impact on them by Hopkinson Pressure Bar and evaluating the acceleration that samples received in accordance with one-dimensional stress wave theory. The results showed that the velocity pulse width could be controlled and acceleration pulse width be improved by varying the pulse shaper material and strike bar length. And the critical acceleration causing the failure of the initiator was closely connected with acceleration pulse width as well as acceleration amplitude. When the strike bar length were 126 mm, 190 mm, 270 mm and 460 mm, the acceleration pulse width were 58 μs, 93 μs, 130 μs and 160 μs, respectively, and the critical acceleration causing the failure of the initiator were about 240 000 g, 130 000 g, 74 000 g and 72 000 g, respectively. The accurateness and reliability of acceleration value was accredited to the methods of changing sampling frequency, smoothing velocity and acceleration curve, and fitting curve. The FEM analog simulation was also conducted by using the LS-DYNA finite element program. Good agreements were achieved between the acceleration curve and the simulation results.

Effect of Acceleration Pulse Shape on Damage of the Specimen under Hopkinson High-g Loading

2013 ◽  
Vol 455 ◽  
pp. 236-241
Author(s):  
Wei Liu ◽  
Rui Qi Shen ◽  
Xiao Xia Sun ◽  
Ying Hua Ye
Keyword(s):  
Axial Strain ◽  
Experimental Tests ◽  
Critical Duration ◽  
Hopkinson Pressure Bar ◽  
Pulse Shaper ◽  
Stress Increment ◽  
Time Step ◽  
Acceleration Pulse ◽  
Pressure Bar ◽  
Cylindrical Lead

Based on the free Hopkinson pressure bar high-g loading technique, the pure cylindrical lead was mounted on the end section of the incident bar as a specimen to obtain the change law of the axial strain with the shape of acceleration pulses. Both the experimental tests without using pulse shaper and numerical simulations under sine-shaped acceleration pulses were performed and axial strain of the specimen was measured. Results revealed that the shape of acceleration pulse shows highly effect on the damage of the specimen. The axial strain of the specimen arises linearly with the increasing of the acceleration peaks whose durations are all 17μs; while, due to the complexity of plastic wave propagation, 135μs is a critical duration at which axial strain reaches to the maximum under the condition of different durations. The final axial strain of the specimen is determined by both the stress level and stress increment in every time step.

scholarly journals NUMERICAL MODELLING OF WAVE SHAPES DURING SHPB MEASUREMENT

2019 ◽  
Vol 25 ◽  
pp. 25-31
Author(s):  
Radim Dvořák ◽  
Petr Koudelka ◽  
Tomáš Fíla
Keyword(s):  
Parametric Analysis ◽  
Pulse Shaping ◽  
Split Hopkinson Pressure Bar ◽  
Sensitivity Study ◽  
Hopkinson Pressure Bar ◽  
Pulse Shaper ◽  
Geometric Properties ◽  
Element Size ◽  
Split Hopkinson ◽  
Pressure Bar

The paper aims at the numerical simulation of the wave propagation in compressive Split Hopkinson Pressure Bar (SHPB) experiment. The paper deals with principles of SHPB measurement, optimisation of a numerical model and techniques of pulse shaping. The parametric model of the typical SHPB configuration developed for LS-DYNA environment is introduced and optimised (in terms of element size and distribution) using the sensitivity study. Then, a parametric analysis of a geometric properties of the pulse shaper is carried out to reveal their influence on a shape of the incident pulse. The analysis is algorithmized including the pre- and post-processing routines to enable automated processing of numerical results and comparison with the experimental data. Results of the parametric analysis and the influence of geometric properties of the pulse shaper (diameter, length) on the incident wave are demonstrated.

scholarly journals Influence of Imperfect Position of a Striker and Input Bar on Wave Propagation in a Split Hopkinson Pressure Bar (SHPB) Setup with a Pulse-Shape Technique

2020 ◽  
Vol 10 (7) ◽  
pp. 2423 ◽  
Author(s):  
Robert Panowicz ◽  
Marcin Konarzewski
Keyword(s):  
Wave Propagation ◽  
Inclination Angle ◽  
High Frequency ◽  
Pulse Shape ◽  
Split Hopkinson Pressure Bar ◽  
Hopkinson Pressure Bar ◽  
Pulse Shaper ◽  
Split Hopkinson ◽  
Pressure Bar

The effect of using a pulse shaper technique, such as rounding a striker or applying a pulse shaper on the signals recorded with the split Hopkinson pressure bar (SHPB) technique, when the striker and the input bar are in an imperfect position, was investigated. Two of the most common cases have been analyzed: an offset of the symmetry axes of the striker and the input bar; and an inclination angle between the striker and the input bar. LS-Dyna software was used to examine this problem numerically. The inclination angle imperfection has a significant impact on signal disturbances, whereas the use of a rounded striker significantly affects the limitation of the vibration flexural modes. In all considered cases, a slight imperfection causes a reduction in the high-frequency Pochhammer–Chree oscillations.

SHPB Test on Dynamical Mechanical Behavior of Concrete with High Temperature

2011 ◽  
Vol 71-78 ◽  
pp. 760-763 ◽  
Author(s):  
Bin Jia ◽  
Zheng Liang Li ◽  
Hua Chuan Yao ◽  
Jun Lin Tao
Keyword(s):  
High Temperature ◽  
Strain Rate ◽  
Mechanical Behavior ◽  
Split Hopkinson Pressure Bar ◽  
Experimental System ◽  
Wave Theory ◽  
Hopkinson Pressure Bar ◽  
Temperature Changes ◽  
Split Hopkinson ◽  
Pressure Bar

An experimental system is designed by combining the split Hopkinson pressure bar (SHPB) with microwave heating device, based on stress wave theory, availability of the experiment technique is analyzed. Tests of concrete whose temperature changes from room temperature to 650°C and impact velocity from 5m/s to 12m/s are completed and for the first time high-temperature dynamical damaging phenomena of concrete are obtained. Based on data analysis, the dynamical mechanical behavior of concrete with high temperature is affected by not only the strain rate effect whose influence keeps on decreasing with temperature increasing, but also the high temperature weakening effect. And the strain rate hardening effect is coupled with high temperature weakening effect, but the latter has greater influence.

Evaluation of High Strain Rate Characteristics of Metallic Sandwich Specimens

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Danish Iqbal ◽  
Vikrant Tiwari
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Volume Fraction ◽  
Split Hopkinson Pressure Bar ◽  
Three Dimensional ◽  
Wave Theory ◽  
Hopkinson Pressure Bar ◽  
Material Interfaces ◽  
Element Analysis ◽  
Pressure Bar

An attempt is made to investigate the dynamic compressive response of multilayered specimens in bilayered and trilayered configurations, using a split Hopkinson pressure bar (SHPB) and finite element analysis. Two constituent metals comprising the multilayered configurations were Al 6063-T6 and IS 1570. Multiple stack sequences of trilayered and bilayered configurations were evaluated at three different sets of strain rates, namely, 500, 800, and 1000 s−1. The experiments revealed that even with the same constituent volume fraction, a change in the stacking sequence alters the overall dynamic constitutive response. This change becomes more evident, especially in the plastic zone. The finite element analysis was performed using abaqus/explicit. A three-dimensional (3D) model of the SHPB apparatus used in the experiments was generated and meshed using the hexahedral brick elements. Dissimilar material interfaces were assigned different dynamic coefficients of friction. The fundamental elastic one-dimensional (1D) wave theory was then utilized to evaluate the stress–strain response from the nodal strain histories of the bars. Predictions from the finite element simulations along with the experimental results are also presented in this study. For most cases, finite element predictions match well with the experiments.

Thickness Effect of Pulse Shaper on Dynamic Stress Equilibrium in the NBR Rubber Specimen

2006 ◽  
Vol 306-308 ◽  
pp. 1007-1012 ◽  
Author(s):  
Ouk Sub Lee ◽  
Sung Hyun Kim ◽  
Jong Won Lee
Keyword(s):  
Compressive Stress ◽  
Split Hopkinson Pressure Bar ◽  
Thickness Effect ◽  
Impedance Match ◽  
Hopkinson Pressure Bar ◽  
Pulse Shaper ◽  
Modified Technique ◽  
Stress Strain ◽  
Stress Equilibrium ◽  
Pressure Bar

This paper presents an experimental finding in the Split Hopkinson Pressure Bar (SHPB) technique to obtain a better compressive stress strain data for rubber materials. An experimental technique which modifies the conventional SHPB has been developed for measuring the compressive stress strain responses of materials with low mechanical impedance and low compressive strengths such as rubber. This paper uses an all-polymeric pressure bar to achieves a closer impedance match between the pressure bar and the specimen materials. In addition, a pulse shaper is utilized to lengthen the rising time of the incident pulse to ensure stress equilibrium and homogeneous deformation of rubber materials. It is found that the modified technique can determine the dynamic deformation behavior of a rubber more accurately.

DYNAMIC DEFORMATION BEHAVIOR OF SOFT MATERIAL USING SHPB TECHNIQUE AND PULSE SHAPER

2006 ◽  
Vol 20 (25n27) ◽  
pp. 3751-3756 ◽  
Author(s):  
OUK SUB LEE ◽  
KYU SANG CHO ◽  
SUNG HYUN KIM ◽  
YONG HWAN HAN
Keyword(s):  
Compressive Stress ◽  
Deformation Behavior ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Deformation ◽  
Impedance Match ◽  
Hopkinson Pressure Bar ◽  
Pulse Shaper ◽  
Stress Strain ◽  
Dynamic Deformation Behavior ◽  
Pressure Bar

This paper presents a modified Split Hopkinson Pressure Bar (SHPB) technique to obtain compressive stress strain data for NBR rubber materials. An experimental technique with a modified the conventional SHPB has been developed for measuring the compressive stress strain responses of materials with low mechanical impedance and low compressive strengths, such as the rubber and the polymeric material. This paper uses an aluminum pressure bar to achieve a closer impedance match between the pressure bar and the specimen materials. In addition, a pulse shaper is utilized to lengthen the rising time of the incident pulse to ensure dynamic stress equilibrium and homogeneous deformation of NBR rubber materials. It is found that the modified technique can determine the dynamic deformation behavior of rubbers more accurately.

Dynamic Compressive Behavior of Granite under Active Confinement

2011 ◽  
Vol 291-294 ◽  
pp. 1227-1232 ◽  
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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