scholarly journals An Empirical Method of Dispersion Correction in the Compressive Hopkinson Bar Test

1997 ◽  
Vol 07 (C3) ◽  
pp. C3-223-C3-228 ◽  
Author(s):  
D. A. Gorham ◽  
X. J. Wu
Keyword(s):  
Hopkinson Bar ◽  
Empirical Method ◽  
Dispersion Correction ◽  
Bar Test

An optical method for direct measurements of strain in a torsional Hopkinson-bar apparatus

1975 ◽  
Vol 10 (3) ◽  
pp. 172-179 ◽  
Author(s):  
M G Stevenson ◽  
J D Campbell
Keyword(s):  
Torsion Test ◽  
Hopkinson Bar ◽  
Gauge Length ◽  
Wave Reflections ◽  
Multiple Wave ◽  
Torsional Waves ◽  
Direct Measurements ◽  
Angular Velocities ◽  
Bar Test

A method has been developed to measure the related rotation of the flanges of a thin-walled tubular specimen during a torsion test. The method, which is based on the Moiré-fringe technique, is capable of use at the high rates of strain encountered during a Hopkinson-bar test, as well as at low rates of strain. In the application described, the specimen gauge length is very short, but the method could be used for specimens of considerably longer gauge length. Direct calibration of the system is easily carried out at low angular velocities. The method can then be used to measure directly the specimen strain during a Hopkinson-bar test, and thus to check the value derived from measuremets of torsional waves in the elastic bars. Results of such comparisons are given, and it is found that the values given by the two method agree well, the differnce being attributable largely to inaccuracies in the torque measurement. The new method permits the determination of specimen deformation during the later stages of the test when multiple wave reflections render the wave analysis iaccurate. In particular, it has been found that the specimen may be subjected to reversed plastic straining, so that the total plastic strain connot be determined from the permenent deformation at the end of the test.

A New Approach to Determine Dynamic Strength Model Parameters under Taylor Impact Test

2012 ◽  
Vol 525-526 ◽  
pp. 377-380
Author(s):  
F. Xu ◽  
Wei Guo Guo ◽  
Q.J. Wang ◽  
Zhi Yin Zeng
Keyword(s):  
Impact Test ◽  
Dynamic Strength ◽  
Hopkinson Bar ◽  
Optimization Techniques ◽  
Model Parameters ◽  
Strength Model ◽  
New Approach ◽  
Taylor Impact ◽  
Bar Test ◽  
Taylor Impact Test

In this paper, to determine the dynamic strength model for steels, a new approach which does not rely on the Hopkinson bar test has been proposed. As the DH36 steel for example, using the results of Taylor impact test and the quasi-static compression test, the initial parameters of Johnson-Cook plastic strength model have been fitted out, then the initial strength parameters have been optimized using the optimization techniques of the sparse Taylor impact cylinder. It has been shown that the optimized results in numerical simulation are consistent with results of Taylor impact test, and the optimized Johnson-Cook model can also well describe flow stress curve fitted from the Hopkinson bar test.

scholarly journals Dynamic Response of Deccan Trap Basalt under Hopkinson Bar Test

2017 ◽  
Vol 173 ◽  
pp. 647-654 ◽  
Author(s):  
Akx Malik ◽  
Tanusree Chakraborty ◽  
K.S. Rao ◽  
D. Kumar ◽  
P. Chandel ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Deccan Trap ◽  
Hopkinson Bar ◽  
Bar Test

Hopkinson bar experimental technique: A critical review

2004 ◽  
Vol 57 (4) ◽  
pp. 223-250 ◽  
Author(s):  
Bazle A Gama ◽  
Sergey L Lopatnikov ◽  
John W Gillespie
Keyword(s):  
Critical Review ◽  
Pulse Shaping ◽  
Hopkinson Bar ◽  
Dispersion Correction ◽  
Experimental Procedure ◽  
Hard Materials ◽  
Wide Range ◽  
Calibration Specimen ◽  
Data Tables ◽  
Made In

A critical review of three classic papers by B Hopkinson, RM Davies, and H Kolsky, and the state-of-the-art in Hopkinson bar experimental techniques is presented. The validity and applicability of the assumption made in the 1D Hopkinson bar theory are discussed. Fundamentals of the Hopkinson bar experimental procedure are outlined including bar calibration, specimen design, pulse shaping, and data analysis following the essential dispersion correction methodology. Additional data tables necessary for dispersion correction are provided to cover a wide range of Poisson’s ratio. In addition to the elastic-plastic metals, methodologies for soft and hard materials are also discussed. This paper provides the necessary information for conducting a Hopkinson bar experiment and analyzing the experimental data. This review article cites 61 references.

scholarly journals Pochhammer–Chree equation solver for dispersion correction of elastic waves in a (split) Hopkinson bar

2021 ◽  
pp. 095440622098050
Author(s):  
Hyunho Shin
Keyword(s):  
Elastic Waves ◽  
Sound Speed ◽  
Hopkinson Bar ◽  
Decimal Place ◽  
Dispersion Correction ◽  
Series Solutions ◽  
Iterative Root ◽  
Robust Algorithm ◽  
Root Finding ◽  
Split Hopkinson

A robust algorithm for solving the Bancroft version of the Pochhammer–Chree (PC) equation is developed based on the iterative root-finding process. The formulated solver not only obtains the conventional n-series solutions but also derives a new series of solutions, named m-series solutions. The n-series solutions are located on the PC function surface that relatively gradually varies in the vicinity of the roots, whereas the m-series solutions are located between two PC function surfaces with (nearly) positive and negative infinity values. The proposed solver obtains a series of sound speeds at exactly the frequencies necessary for dispersion correction, and the derived solutions are accurate to the ninth decimal place. The solver is capable of solving the PC equation up to n = 20 and m = 20 in the ranges of Poisson’s ratio ( ν) of 0.02 [Formula: see text]  ν [Formula: see text] 0.48, normalised frequency ( F) of F [Formula: see text] 30, and normalised sound speed ( C) of C [Formula: see text] 300. The developed algorithm was implemented in MATLAB®, which is available in the Supplemental Material (accessible online).

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