scholarly journals Experimental Investigation of the Confined Behavior of Concrete under Shear Loading at High Strain Rates

Proceedings ◽  
2018 ◽  
Vol 2 (8) ◽  
pp. 496
Author(s):  
Reem Abdul-Rahman ◽  
Dominique Saletti ◽  
Pascal Forquin
Keyword(s):  
Experimental Investigation ◽  
Experimental Technique ◽  
Shear Test ◽  
High Strain ◽  
Compressive Load ◽  
Hopkinson Bar ◽  
Shear Loading ◽  
Strain Rates ◽  
Split Hopkinson ◽  
Metallic Cell

A new experimental technique has been developed to investigate the confined shear behavior of concrete under dynamic conditions. The technique is based on the ‘Punch through shear test’ and consists in pre-stressing a concrete sample prior to testing it under shear. The pre-confinement is applied by means of a metallic cell instrumented with gages to register the stresses during the test; it consists in deforming the cell with a compressive load and then inserting the specimen into the cell. When the load is released, the cell applies a confinement to the sample. Two notches are performed from each side of the specimen and a displacement is applied to the central part in order to produce shear inside the vertical ligament. Dynamics tests are done with the Split Hopkinson Bar setup where a striker, an incident and two output bars are used. Two sets of specimens have been tested, saturated and dry concrete.

scholarly journals A Review of the Torsional Split Hopkinson Bar

2018 ◽  
Vol 2018 ◽  
pp. 1-17 ◽  
Author(s):  
Xiao Yu ◽  
Li Chen ◽  
Qin Fang ◽  
Xiquan Jiang ◽  
Yongkang Zhou
Keyword(s):  
Experimental Technique ◽  
High Strain ◽  
Pure Shear ◽  
Single Pulse ◽  
Hopkinson Bar ◽  
Combined Loading ◽  
Strain Rates ◽  
High Strain Rates ◽  
Split Hopkinson Bar ◽  
Split Hopkinson

Mechanical behavior of materials at medium and high strain rates (101∼104 s−1) is the foundation of developing mechanical theories, building material models, and promoting engineering design and construction. The torsional split Hopkinson bar (TSHB) is an effective experimental technique for measuring the pure shear mechanical properties of materials at high strain rates. In this study, the state-of-the-art in TSHB experimental technique is presented. Five typical types of TSHB loading mechanisms, i.e., prestored energy loading, explosive loading, direct impact loading, flywheel loading, and electromagnetic loading, were systematically reviewed. The TSHB fundamentals were outlined, which include elementary components, basic assumptions, working principles, the pulse shaping technique, specimen design, and the single-pulse loading technique. In addition, the combined loading and high/low temperature experimental techniques, which were developed based on TSHB, were also discussed in detail. Nearly all necessary elements for conducting a TSHB experiment and analyzing the experimental data were provided. Some research directions should be further pursued, such as extending the range of applicable materials and developing the combined loading techniques.

scholarly journals Challenges related to testing of composite materials at high strain rates using the split Hopkinson bar technique

2018 ◽  
Vol 183 ◽  
pp. 02021 ◽  
Author(s):  
Ahmed Elmahdy ◽  
Patricia Verleysen
Keyword(s):  
Composite Materials ◽  
High Strain ◽  
Hopkinson Bar ◽  
Dynamic Strain ◽  
Strain Rates ◽  
High Strain Rates ◽  
Strain Fields ◽  
Split Hopkinson Bar ◽  
Gauge Section ◽  
Split Hopkinson

The design of sample geometries and the measurement of small strains are considered the main challenges when testing composite materials at high strain rates using the split Hopkinson bar technique. The aim of this paper is to assess two types of tensile sample geometries, namely dog-bone and straight strip, in order to study the tensile behaviour of basalt fibre reinforced composites at high strain rates using the split Hopkinson bar technique. 2D Digital image correlation technique was used to study the distribution of the strain fields within the gauge section at quasi-static and dynamic strain rates. Results showed that for the current experiments and the proposed clamping techniques, both sample geometries fulfilled the requirements of a valid split Hopkinson test, and achieved uniform strain fields within the gauge section. However, classical Hopkinson analysis tends to overestimate the actual strains in the gauge section for both geometries. It is, therefore, important to use a local deformation measurement when using these 2 geometries with the proposed clamping technique.

The Relationship Between Tensile Strength and Shear Strength in Composite Materials Subjected to High Strain Rates

1988 ◽  
Vol 110 (2) ◽  
pp. 191-194 ◽  
Author(s):  
Chi-Yuen Chiem ◽  
Zeng-Gang Liu
Keyword(s):  
Yield Stress ◽  
Stress Ratio ◽  
High Strain ◽  
Equivalent Strain ◽  
Shear Loading ◽  
Strain Rates ◽  
Orthogonal Direction ◽  
Shear Yield ◽  
Split Hopkinson ◽  
The Relationship

This paper contributes to understand the dynamic behavior of a woven carbon/epoxy composite subjected to tensile and shear impact loading in the orthogonal direction by using the tensile and torsional split-Hopkinson bars, respectively. The influences of the equivalent strain rates on the tensile and shear yield stress and strength are found. The yield stress ratio and strength ratio between tensile and shear loading on this composite are compared at a range of the equivalent strain rates from 500 s−1 to 3000 s−1. The relationship between the strain rates and these ratios are established. The failure mechanism is analyzed by microscope observation on the rupture surface of the specimens.

scholarly journals Combined shear/tension testing of fibre composites at high strain rates using an image-based inertial impact test

2018 ◽  
Vol 183 ◽  
pp. 02041 ◽  
Author(s):  
Lloyd Fletcher ◽  
Jared Van-Blitterswyk ◽  
Fabrice Pierron
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Stress Wave ◽  
Impact Test ◽  
High Strain ◽  
Hopkinson Bar ◽  
Test Method ◽  
Strain Rates ◽  
Fibre Composites ◽  
Split Hopkinson

Testing fibre composites off-axis has been used extensively to explore shear/tension coupling effects. However, off-axis testing at strain rates above 500 s-1 is challenging with a split Hopkinson bar apparatus. This is primarily due to the effects of inertia, which violate the assumption of stress equilibrium necessary to infer stress and strain from point measurements taken on the bars. Therefore, there is a need to develop new high strain rate test methods that do not rely on the assumptions of split Hopkinson bar analysis. Recently, a new image-based inertial impact test has been used to successfully identify the transverse modulus and tensile strength of a unidirectional composite at strain rates on the order of 2000 -1. The image-based inertial impact test method uses a reflected compressive stress wave to generate tensile stress and failure in an impacted specimen. Thus, the purpose of this study is to modify the image-based inertial impact test method to investigate the high strain rate properties of fibre composites using an off-axis configuration. For an off-axis specimen, a combined shear/tension or shear/compression stress state will be obtained. Throughout the propagation of the stress wave, full-field displacement measurements are taken. Strain and acceleration fields are then derived from the displacement fields. The kinematic fields are then processed with the virtual fields method (VFM) to reconstruct stress averages and identify the in-plane stiffness components G12 and E22.

Combined compression-shear loading at high strain rates: the split Hopkinson pressure shear bar

2008 ◽  
Author(s):  
Peng-duo Zhao ◽  
Fang-yun Lu ◽  
Yu-liang Lin ◽  
Rong Chen ◽  
Jun-ling Li ◽  
...  
Keyword(s):  
High Strain ◽  
Shear Loading ◽  
Strain Rates ◽  
High Strain Rates ◽  
Split Hopkinson

Mechanical Behavior of Rubber at High Strain Rates

2006 ◽  
Vol 79 (3) ◽  
pp. 429-459 ◽  
Author(s):  
C. M. Roland
Keyword(s):  
Hydrostatic Pressure ◽  
Strain Rate ◽  
Mechanical Response ◽  
High Strain ◽  
Glassy State ◽  
Hopkinson Bar ◽  
Strain Rates ◽  
Rate Data ◽  
Split Hopkinson ◽  
Low Strain Rate

Abstract Methods to obtain the mechanical response of rubber at high rates of strain are reviewed. These techniques include the extrapolation of low strain, low strain rate data, the limitations of which are discussed, extrapolations to elevated hydrostatic pressure, and direct determinations using split Hopkinson bar and drop weight testers, as well as miscellaneous methods. Some applications involving rubber at strain rates sufficient to induce a transition to the glassy state are described.

The Deformation of Lead in Torsion at High Strain Rates

1972 ◽  
Vol 39 (3) ◽  
pp. 651-656 ◽  
Author(s):  
J. Duffy ◽  
R. H. Hawley ◽  
R. A. Frantz
Keyword(s):  
Flow Stress ◽  
High Strain ◽  
Hopkinson Bar ◽  
Explosive Loading ◽  
Strain Rates ◽  
High Strain Rates ◽  
Split Hopkinson Bar ◽  
Nominal Strain ◽  
Split Hopkinson ◽  
Loading Tests

Experiments are described in which specimens of lead are strained in torsion at high rates using the split Hopkinson bar and explosive loading. Tests were conducted at nominal strain rates of 1000 sec−1 and 5000 sec−1 as well as at “static” rates. Values of the flow stress correspond closely with those obtained in axial tests by other investigators at corresponding rates.

scholarly journals Numerical Simulation on the specimen dynamic plastic deformation behaviour in the torsional split Hopkinson bar test

2018 ◽  
Vol 183 ◽  
pp. 01020
Author(s):  
Chen Gang ◽  
Huang Xicheng ◽  
Chen Junhong ◽  
Zhong Weizhou
Keyword(s):  
Numerical Simulation ◽  
High Strain ◽  
Hopkinson Bar ◽  
Experimental Results ◽  
Shear Behaviour ◽  
Strain Rates ◽  
Dynamic Shear ◽  
Split Hopkinson ◽  
Strain Stress ◽  
Strain Signal

The torsional split Hopkinson bar (SHB) is an important method to study the dynamic shear behaviour and shear localization of materials under high strain rates. Different specimen sizes were used in literatures, and the size of the specimen might have an effect on the experimental results. Numerical simulation on torsional SHB tests was carried out with LS-DYNA. The strain signal on the incident and transmitted bars were obtained from the simulation just as the experiment. Then the numerical strain-stress relationship of the material was derived from the numerical strain signal using the experiments data process of torsional SHB. The agreement between numerically derived strain-stress results and the specimen material properties specified in numerical modelling indicates that the torsional SHB is applicable to study the dynamic shear behaviour of materials under high strain rates. The specimen gauge diameter has no significant effect on the dynamic torsional test result. However, higher adhesive strength is required to fix the larger gauge diameter specimen on the bars. The specimen gauge thickness has little effect on the experimental results with a modified formula to calculate the specimen stress. Still, the increase of specimen gauge thickness will lead to the increase of non-uniformity of specimen stress and strain (strain rate). Based on the simulation analysis, suggestions on the specimen size design are given as well.

Effects of Additives on Tensile Properties of Polyhydroxyalkanoate/Polycaprolactone Polymer Blends

2016 ◽  
Vol 715 ◽  
pp. 39-42 ◽  
Author(s):  
Masahiro Nishida ◽  
Yoshiaki Ito ◽  
Hideyuki Shinzawa ◽  
Masakazu Nishida ◽  
Yoshio Hayakawa
Keyword(s):  
Tensile Strength ◽  
Polymer Blends ◽  
High Strain ◽  
Hopkinson Bar ◽  
Tensile Tests ◽  
Strain Rates ◽  
Security Issue ◽  
Elongation At Break ◽  
Split Hopkinson ◽  
Dynamic Tensile Tests

Bioplastics have attracted attention over the years from a perspective of environmental protection. Recently, attention is focused on bioplastics derived from inedible objects. Polyhydroxyalkanoates (PHAs) are known as a microbial origin plastic and expected to deal effectively with the food security issue. In this study, in order to use PHA for industrial and machinery parts and products, polycaprolactone (PCL) was blended with a PHA-based pellet to improve ductility and tensile strength. The effects of additives on tensile strength and elongation at break, dynamic tensile tests of the polymer blends were examined using split Hopkinson bar (SHPB) method at high strain rates.

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