scholarly journals Using the split Hopkinson pressure bar to validate material models

2014 ◽  
Vol 372 (2023) ◽  
pp. 20130294 ◽  
Author(s):  
Philip Church ◽  
Rory Cornish ◽  
Ian Cullis ◽  
Peter Gould ◽  
Ian Lewtas
Keyword(s):  
Split Hopkinson Pressure Bar ◽  
Strain Curve ◽  
Material Model ◽  
High Rate ◽  
Hopkinson Pressure Bar ◽  
Validation Data ◽  
Material Models ◽  
Wide Range ◽  
Split Hopkinson ◽  
Pressure Bar

This paper gives a discussion of the use of the split-Hopkinson bar with particular reference to the requirements of materials modelling at QinetiQ. This is to deploy validated material models for numerical simulations that are physically based and have as little characterization overhead as possible. In order to have confidence that the models have a wide range of applicability, this means, at most, characterizing the models at low rate and then validating them at high rate. The split Hopkinson pressure bar (SHPB) is ideal for this purpose. It is also a very useful tool for analysing material behaviour under non-shock wave loading. This means understanding the output of the test and developing techniques for reliable comparison of simulations with SHPB data. For materials other than metals comparison with an output stress v strain curve is not sufficient as the assumptions built into the classical analysis are generally violated. The method described in this paper compares the simulations with as much validation data as can be derived from deployed instrumentation including the raw strain gauge data on the input and output bars, which avoids any assumptions about stress equilibrium. One has to take into account Pochhammer–Chree oscillations and their effect on the specimen and recognize that this is itself also a valuable validation test of the material model.

A Study on Reduction of Friction in Impact Compressive Test Based on the Split Hopkinson Pressure Bar Method by Using a Hollow Specimen

2014 ◽  
Vol 566 ◽  
pp. 548-553 ◽  
Author(s):  
Nobuhiko Kii ◽  
Takeshi Iwamoto ◽  
Alexis Rusinek ◽  
Tomasz Jankowiak
Keyword(s):  
Impact Test ◽  
Split Hopkinson Pressure Bar ◽  
Strain Curve ◽  
Hopkinson Pressure Bar ◽  
Compressive Test ◽  
Friction Effect ◽  
Wide Range ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
The Impact

The split Hopkinson pressure bar (SHPB) technique is widely-used to describe the impact compressive behavior of different materials including metals. During the impact test, the specimen deforms in a wide range of impact strain rate from 102 to 104 s-1. It is a reason why the method is studied for many years even though the structure of the apparatus based on the SHPB is simple. Actually, the cylindrical specimens are widely used for a compressive test and it is clearly seen that stress measured by the test includes the increment of stress (an error) derived by friction effect between a specimen and pressure bars. Therefore, it is important that the measured stress should indicate similar value as the proper stress of the material by reducing friction effect during not only quasi-static but also the impact test. Various attempts to reduce a friction effect in past have been conducted. A method to reduce friction effect is in general a use of lubricants. However, it is ineffective because it can be considered that this method contributes to an attenuation of the stress wave for obtaining the stress-strain curve under impact loading. Thus, rise time of waves obtained by the experiment becomes longer compared with a case not to use lubricants. Recently, a study can be found using a ring specimen, however, the determined thickness of the specimen is quite thin and it can be considered that a buckling effect cannot be vanished. In this study, a use of hollow specimen is suggested to solve the problem related to reduce the friction effect by decreasing a contact area between a specimen and pressure bars instead of a cylindrical specimen. The compressive experiments at various strain rates are conducted by using a hollow specimen.

Simultaneous effects of strain rate and temperature on mechanical response of fabricated Mg–SiC nanocomposite

2019 ◽  
Vol 54 (5) ◽  
pp. 659-668 ◽  
Author(s):  
K Rahmani ◽  
GH Majzoobi ◽  
A Atrian
Keyword(s):  
Strain Rate ◽  
Mechanical Response ◽  
Split Hopkinson Pressure Bar ◽  
High Rate ◽  
Dynamic Tests ◽  
Hopkinson Pressure Bar ◽  
Compaction Temperature ◽  
Static Tests ◽  
Split Hopkinson ◽  
Pressure Bar

Mg–SiC nanocomposite samples were fabricated using split Hopkinson pressure bar for different SiC volume fractions and under different temperature conditions. The microstructures and mechanical properties of the samples including microhardness and stress–strain curves were captured from quasi-static and dynamic tests carried out using Instron and split Hopkinson pressure bar, respectively. Nanocomposites were produced by hot and high-rate compaction method using split Hopkinson pressure bar. Temperature also significantly affects relative density and can lead to 2.5% increase in density. Adding SiC-reinforcing particles to samples increased their Vickers microhardness from 46 VH to 68 VH (45% increase) depending on the compaction temperature. X-ray diffraction analysis showed that by increasing temperature from 25℃ to 450℃, the Mg crystallite size increases from 37 nm to 72 nm and decreases the lattice strain from 45% to 30%. In quasi-static tests, the ultimate compressive strength for the compaction temperature of 450℃ was improved from 123% for Mg–0 vol.% SiC to 200% for the Mg–10 vol.% SiC samples compared with those of the compaction at room temperature. In dynamic tests, the ultimate strength for Mg–10 vol.% SiC sample compacted at high strain rate increased remarkably by 110% compared with that for Mg–0 vol.% SiC sample compacted at low strain rate.

Studies on the Dynamic Compressive Properties of Open-Celled Aluminum Alloy Foams

2006 ◽  
Vol 306-308 ◽  
pp. 905-910 ◽  
Author(s):  
Zhi Hua Wang ◽  
Hong Wei Ma ◽  
Long Mao Zhao ◽  
Gui Tong Yang
Keyword(s):  
Yield Strength ◽  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Strain Rates ◽  
Hopkinson Pressure Bar ◽  
Aluminum Foams ◽  
Wide Range ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
Dynamic Loading Conditions

The compressive deformation behavior of open-cell aluminum foams with different densities and morphologies was assessed under quasi-static and dynamic loading conditions. High strain rate experiments were conducted using a split Hopkinson pressure bar technique at strain rates ranging from 500 to 1 2000 − s . The experimental results shown that the compressive stress-strain curves of aluminum foams also have the “ three regions” character appeared in general foam materials, namely elastic region, collapse region and densification regions. It is found that density is the primary variable characterizing the modulus and yield strength of foams and the cell appears to have a negligible effect on the strength of foams. It also is found that yield strength and energy absorption is almost insensitive to strain rate and deformation is spatially uniform for the open-celled aluminum foams, over a wide range of strain rates.

scholarly journals A Simple Rate–Temperature Dependent Hyperelastic Model Applied to Neoprene Rubber

2020 ◽  
Vol 6 (3) ◽  
pp. 336-347
Author(s):  
A. R. Trivedi ◽  
C. R. Siviour
Keyword(s):  
Split Hopkinson Pressure Bar ◽  
High Rate ◽  
Hopkinson Pressure Bar ◽  
Temperature Dependent ◽  
Temperature Superposition ◽  
High Strain Rate Deformation ◽  
Split Hopkinson ◽  
Hyperelastic Model ◽  
Pressure Bar ◽  
Two Parameter

Abstract Rubber is widely used in engineering applications in which it may be subjected to impact loading leading to high strain rate deformation. This resulting deformation may occur at a variety of temperatures, notwithstanding the self-heating of the material. For this reason, it is necessary to study the mechanical behaviour of these materials over a range of loading conditions. The strong rate and temperature dependence of their properties provides a further motivation for this understanding. In this paper, the relationships between the response of a neoprene rubber at various strain rates and temperatures are investigated, and a simple model making use of the time–temperature superposition (TTS) principle proposed to describe the material behaviour. As it is challenging to obtain high rate data on rubbery materials using conventional apparatus, such as the split-Hopkinson pressure bar (SHPB), the simple two parameter hyperelastic model proposed here provides a useful complementary tool to interrogate the response.

Wave Propagation in the Split Hopkinson Pressure Bar

1983 ◽  
Vol 105 (1) ◽  
pp. 61-66 ◽  
Author(s):  
P. S. Follansbee ◽  
C. Frantz
Keyword(s):  
Wave Propagation ◽  
Elastic Wave ◽  
Split Hopkinson Pressure Bar ◽  
Strain Curve ◽  
Leading Edge ◽  
Elastic Wave Propagation ◽  
Mathematical Treatment ◽  
Hopkinson Pressure Bar ◽  
Split Hopkinson ◽  
Pressure Bar

Elastic wave propagation in the split Hopkinson pressure bar (SHPB) is discussed with an emphasis on the origin and nature of the oscillations that often trail the leading edge of the pressure wave. We show that in the conditions of the SHPB test the pressure bars vibrate in the fundamental mode and that elastic wave propagation can be fully described mathematically. Excellent agreement is found between experimental results and predictions of the mathematical treatment. This suggests that dispersion effects in the pressure bars can be removed from the strain gage records, which reduces the magnitude of the oscillations in the resulting stress strain curve.

Development of a Material Constitutive for High-Rate Using a Combined Experiment/Computation Method

2004 ◽  
Vol 261-263 ◽  
pp. 269-276
Author(s):  
J.F. Lu ◽  
Zhuo Zhuang ◽  
K. Shimamura
Keyword(s):  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Equivalent Strain ◽  
High Rate ◽  
Computation Method ◽  
Failure Behavior ◽  
Hopkinson Pressure Bar ◽  
Material Constants ◽  
Split Hopkinson ◽  
Pressure Bar

To describe the high-rate behaviour of metals, a revised form of the classic Johnson-Cook strength model with unknown material constants has been used. The 1D stress-strain relations as well as the effects of strain, strain rate and temperature are examined by Split Hopkinson Pressure Bar (SHPB) test. The undetermined material constants are solved using a variable-dissociation method. The element failure criterion based on maximum equivalent strain is also introduced to estimate the material failure behavior under high strain rate. A corresponding user-defined material subroutine (UMAT) has been developed for revised Johnson-Cook model, which is implemented into ABAQUS. Using this implicit scheme, several groups of finite element simulations under different strain rates are completed in ABAQUS/Standard. The results agree well with the test data and other results by explicit code.

Modelling of Micro-Concrete Behaviour under Static and Dynamic Loading

2014 ◽  
Vol 584-586 ◽  
pp. 1089-1096
Author(s):  
Remdane Boutemeur ◽  
Mustapha Demidem ◽  
Abderrahim Bali ◽  
El Hadi Benyoussef
Keyword(s):  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Compression ◽  
Dynamic Tests ◽  
Hopkinson Pressure Bar ◽  
Proposed Model ◽  
Wide Range ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
Static And Dynamic Loading

The aim of this study is to present a model for assessing the dynamic compression behaviour of a micro-concrete. This model is based on the results of numerous tests providing the developments of the mechanical characteristics of the material on a wide range of strain rate from 10-4s-1to 10+3s-1.The Split Hopkinson Pressure Bar (SHPB) dispositive, based on the wave propagation theory in materials, has-been adopted to carry out the dynamic tests on the investigated material. The proposed model is composed of two terms, each characterizing the different contributions noted in the two major explored areas of strain rate.

scholarly journals Dynamic Behavior of Aluminum Alloy Aw 5005 Undergoing Interfacial Friction and Specimen Configuration in Split Hopkinson Pressure Bar System at High Strain Rates and Temperatures

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4614 ◽  
Author(s):  
Amine Bendarma ◽  
Tomasz Jankowiak ◽  
Alexis Rusinek ◽  
Tomasz Lodygowski ◽  
Bin Jia ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Split Hopkinson Pressure Bar ◽  
Strain Rates ◽  
Compression Tests ◽  
Hopkinson Pressure Bar ◽  
Element Analysis ◽  
Wide Range ◽  
Temperature Experiment ◽  
Split Hopkinson ◽  
Pressure Bar

In this paper, experimental and numerical results of an aluminum alloy’s mechanical behavior are discussed. Over a wide range of strain rates (10−4 s−1 ≤ έ ≤ 103 s−1) the influence of the loading impact, velocity and temperature on the dynamic response of the material was analyzed. The interface friction effect on the material’s dynamic response is examined using a split Hopkinson pressure bar (SHPB) in a high temperature experiment using finite element analysis (FEA). The effect of different friction conditions between the specimen and the transmitted/incident bars in the SHPB system was examined using cylinder bulk specimens and cylinder plates defined with four-layer configurations. The results of these tests alongside the presented numerical simulations allow a better understanding of the phenomenon and reduces (minimizes) errors during compression tests at high and low strain rates with temperatures ranging from 21 to 300 °C.

SPLIT HOPKINSON PRESSURE BAR IMPULSE EXPERIMENTAL MEASUREMENT WITH NUMERICAL VALIDATION

2014 ◽  
Vol 21 (1) ◽  
pp. 47-58 ◽  
Author(s):  
Pawel Baranowski ◽  
Roman Gieleta ◽  
Jerzy Malachowski ◽  
Krzysztof Damaziak ◽  
Lukasz Mazurkiewicz
Keyword(s):  
Development Process ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Experimental Testing ◽  
Strain Gauges ◽  
Hopkinson Pressure Bar ◽  
Wide Range ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
Impulse Characteristics

Abstract Materials and their development process are highly dependent on proper experimental testing under wide range of loading within which high-strain rate conditions play a very significant role. For such dynamic loading Split Hopkinson Pressure Bar (SHPB) is widely used for investigating the dynamic behavior of various materials. The presented paper is focused on the SHPB impulse measurement process using experimental and numerical methods. One of the main problems occurring during tests are oscillations recorded by the strain gauges which adversely affect results. Thus, it is desired to obtain the peak shape in the incident bar of SHPB as “smooth” as possible without any distortions. Such impulse characteristics can be achieved using several shaping techniques, e.g. by placing a special shaper between two bars, which in fact was performed by the authors experimentally and subsequently was validated using computational methods.

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