Its main components are a gas gun, a striker bar, an incident bar and a transmission bar. We have described an experimental method based on the shpb technique which allows dynamic tensile testing of 1. On spurious reflection waves in hopkinson bar tensile. If the incident bar, the output bar and the test specimen are of similar crosssection. A tensile split hopkinson bar apparatus is developed for testing high strain rate behavior of glassfilled epoxy. Loadinversion device for the high strain rate tensile. Using split hopkinson pressure bars to perform large. The results of the experimental measurements show that after reaching some critical strain rate tensile resistance progressively increases with increase of strain rate. The unique challenge of the isr regime is that it lies above the upper limit of standard tensile test machines and below the lower limit of typical shb arrangements and is therefore also referred to as the medium strain rate regime or the sub hopkinson bar regime. In dynamic testing the split hopkinson bar shb is used to measure concrete tensile resistance. Spray paint background matt black, attach matt white measuring marks, clamp matt black specimen. Dynamic tensile testing of sheet material using the split. The samples were cylindrical in cross section, with a reduced gage.
Allen ross ho afescrdcm hq air force engineering and servi r. There are three common types of shpb testing techniques. However, the dynamic tensile strength derived from the split hopkinson pressure bar test is affected by lateral inertia confinement, which may lead to the overestimation of dynamic mechanical properties of concrete materials. Torsion test techniques include lathe torsion testing machines, a torsional hydraulic actuator, impact torsion techniques and hopkinson torsion bar systems. Split hopkinsonson bar test appartus advance instrument inc. The genesis highspeed series offered by hbm test and measurement is the perfect data acquisition system for use on a split hopkinson bar. The shpb system can be used to carry out experiments dealing with the effects of temperature, confining pressure, and other factors on solids. The systems has been developed by adavnce instrument inc. Dynamic tensile testing of structural materials using a.
The test method employs a framing camera to make strain measurements based on direct observation of the deforming test sample. Highspeed infrared imaging of a split hopkinson pressure bar experiment. A simplified design for a splithopkinson tension bar with long. A threaded specimen attached to the solid inner hopkinson bars achieved the tensile equivalent of the kolsky apparatus for compression and the test was analyzed in the same manner as for the compression split hopkinson bar. Highspeed infrared imaging of a splithopkinson pressure. Abstract a high strain rate tensile testing technique for sheet materials is presented which makes use of a split hopkinson pressure bar system in conjunction with a load inversion device. The equipment, which had been designed for uniaxial tensile loading, was adapted for pullout bond testing, for cryogenic testing, and for biaxial compresion tension. Dynamic compressive and splitting tensile tests on mortar.
The results of the experimental measurements show that after. Improved specimen recovery in tensile split hopkinson bar. The apparatus uses a specimen gripping configuration which does not require. These techniques can provide a strain rate range between 10 2 and 10 4 s. Tensile hopkinson bar testing of plastic films at high. By suitably configuring the shpb test setup, testing of tension, compression, and shear specimens to generate the respective stressstrain curves, or testing of threepoint bend and compact tension.
In an attempt to circumvent the inherent problems associated with split hopkinson tensile bar shtb systems, a new experimental technique is proposed for the high strain rate tensile testing of sheet specimens in split hopkinson pressure bar shpb systems. Testing the high strain rate tensile strength with the split hopkinson pressure bar can be utilized to understand material properties. Split hop2inson tension bar, dynamic testing, polycarbonate. The dynamic stressstrain curves obtained by hopkinson bar testing can be subjected to a variety of possible approximations including hardwarebased issues andor accuracy reductions due to the procedures for the analysis and the postprocessing of the. First use of hopkinson bars in high rate compression testing. By kevin young a thesis submitted to the faculty of graduate studies through the department of mechanical, automotive and materials engineering in partial fulfillment of the requirements for the degree of master of applied science at the university of windsor.
For more details, visit us at highstrainrate testing of materials using split hopkinson pressure tension bar. The new design uses a u shaped striker bar as projectile and addresses several shortcomings of classical shtb designs using hollow striker bars. Material properties under impact loading were studied by means of the split hopkinson bar method. The hopkinson bar consists of two bars, incident and transmission, joined axially by the. Tensile strength testing of concrete and mortar is difficult, even in ihe. The tensile testing laboratory was conducted using an instron load frame and the bluehill data acquisition software. This results in a tensile wave propagating to the lefthand side and a. The flow stress of all the materials tested is seen to increase to some extent over the range in strain rates from 0. Evolution of specimen strain rate in split hopkinson bar test. Tensile test of a hsla steel at high strain rates with two different shtb facilities. Tensile testing using the kolskyhopkinson bar machine. The specimen used can be made of solid bars or thinwalled tubes. Split hopkinson bar shb techniques are commonly used to experimentally characterise materials at high strainrates. The shtb is an indispensable method for acquiring tensile strength data in the strain.
Although there are various setups and techniques currently in use for the split hopkinson pressure bar, the underlying principles for the test and measurement are the same. A high strain rate tensile testing technique for sheet materials is presented which makes use of a split hopkinson pressure bar system in conjunction with a load inversion device. Pdf a new split hopkinson tensile bar design robert. The strain rate is found to be controlled by the stress and strain of the. The strain rate is found to be controlled by the stress and strain of the deforming specimen, geometry the length and diameter of specimen, impedance of bar. One important aspect of highstrain rate characterisation using shbs is the necessity to tailor the input pulse to the needs of the. Four different materials were tested, including 6061t6 aluminum alloy, a36 hot rolled steel, polymethylmethacrylate pmma, cast acrylic, and polycarbonate. Split hopkinson pressure bar an overview sciencedirect. A method of tensile testing of materials in dynamic conditions based on a slightly modified compressive split hopkinson bar system using a shoulder is described in this paper. The dynamic response of sheet metals at high strain rate is investigated with a tensile split hopkinson bar test using plate type specimens. Pdf a method of tensile testing of materials in dynamic conditions based on a slightly modified compressive split hopkinson bar system using a. Schindler swiss federal laboratories for materials testing and research empa, ueberlandstrasse 129.
Tensile test of a hsla steel at high strain rates with two. A new split hopkinson tensile bar design sciencedirect. A recent variation of this technique was adapted to tensile testing by isakov et al. Development of a tensile split hopkinson pressure bar testing facility. Pdf a new split hopkinson tensile bar design robert gerlach. Dynamic properties of concrete strength using split hopkinson s pressure bar shpb test. Tensile tests were conducted on dualphase highstrength steel in a split hopkinson tension bar at a strainrate in the range of 150600s and in a servohydraulic testing machine at a strainrate.
Tensile testing of materials at high rates of strain. Split hopkinson bar shb works on the principle of one dimensional wave propagation. In addition to the shpb, there are also other types of stress wave testing systems such as split hopkinson tensile bar and split hopkinson torsional bar. The new design uses a u shaped striker bar as projectile and addresses several shortcomings of classical shtb designs using. The spit hopkinson pressure bar shpb apparatus is located in the strength of materials laboratory at the nanyang technological university ntu. Because of the symmetry only one quarter of the crosssection was. How to convert pdf to word without software duration. Effect of specimen geometry in tensile hopkinson bars testing.
Pdf a novel method for pulse shaping of split hopkinson. With compressive loads applied to its boundaries, the load inversion device introduces tension into a sheet specimen. Split hopkinson pressure bar technique has been widely used to measure the dynamic tensile strength of concrete materials. The effect of specimen geometry length to diameter ratio is investigated. A tension split hopkinson bar for investigating the dynamic behavior. Stressstrain curves in tension obtained on a large number of structural materials at strain rates up to s are presented. At thiot ingenierie, we design compression bars that are unequalled on the market, as well as direct tensile test bars with a revolutionary. Stress in the sample is determined using traditional shpb wave analysis. Pdf a tensile split hopkinson bar for testing particulate polymer. Pdf a tensile split hopkinson bar apparatus is developed for testing high strain rate behavior of glassfilled epoxy. The hopkinson bar technique is named after bertram hopkinson who, in 1914, studied. May 1981 tensile testing of materials at high rates of strain. Dynamic tensile strength enhancement of concrete in split.
High strain rate tensile testing of sheet materials using. Most experimental results show that the tensile strength of concrete material increases with strain rates. The specimen is placed between the ends of two straight bars, called the incident bar and the transmitted bar. The system can be used for experiments with test durations of up to 500. Pdf influence of specimen geometry on split hopkinson. Pdf dynamic properties of concrete strength using split. Providing a controlled impulse of energy that simulates what.
A directtension split hopkinson bar for high strainrate. An experimental technique is developed for testing materials at strain rates up to 10 3 s. A direct tension split hopkinsonbar apparatus is introduced. Tensile tests at different test velocities were performed in an earlier work calle et al. A modified split hopkinson bar apparatus used for high strain rate tensile testing is described. In addition, hbm provides you with strain gauges developed and produced inhouse for installation on a split hopkinson bar. Hopkinson bar techniques for the intermediate strain rate. The specimen strain rate in the split hopkinson bar shb test has been formulated based on a onedimensional assumption. This work presents a new design for a split hopkinson tensile bar shtb and generated representative experimental results.
The paper describes the basic features of the equipment and gives the technical specifications of the matrials and components used. Dynamic compressive and splitting tensile tests on mortar using split hopkinson pressure bar technique 732 latin american journal of solids and structures 12 2015 730746 split hopkinson pressure bar technique, which decouples cleverly the inertia effect in struc. This chapter reflects the expertise and technical knowhow of tensile testing in split hopkinson bar systems of dr carlo albertini, who was a researcher at the joint research centre jrs of the european commision in ispra, italy. Watch a polymer sample take the heat during a split hopkinson bar experiment. Tensile hopkinson bar testing of plastic films at high strain rates. Procedure for carrying out test in shpb and subsequent analysis. This work presents a new design for a split hopkinson tensile bar shtb as well as generated representative experimental results.
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