Hopkinson bar technique v 0 striker split hopkinson pressure bar shpb experiment input bar specimen output bar two force measurements ain time h r 0,t ain hh0h,ttime ll inin,t2,t ain time h r t h l t l st l in 2l st c. Split hopkiso pressure bar impulse experimetal pawel. Splithopkinson bar testing is a tried and tested method in materials testing. Download construction calibration and application of a split hopkinson pressure bar or read online books in pdf, epub, tuebl, and mobi format. A split hopkinson pressure bar shpb, also known as a kolsky bar, is a test apparatus used to characterize the mechanical response of materials deforming at high strain rates 102 104 s1. Using a fast fourier transform fft algorithm a wave dispersion correction program was developed. This allows the fully reflected pressure acting on the target plate to be recorded. Advancements in the split hopkinson bar test, kaiser, michael adam, pg 6162, 18465unrestrictedetd. Click download or read online button to get construction calibration and application of a split hopkinson pressure bar book now. Impact dynamics lab split hopkinson pressure bar youtube. Aug 28, 2014 the split hopkinson pressure bar shpb has been in use for many years to measure the compression response, principally of metals, but also more recently for much softer materials such as polymers. Split hopkinson pressure bar shpb is an apparatus that is used to study. Dynamic testing by split hopkinson pressure bars shpb.
This paper examines a laser extensometer to calculate the strain in a sample during split hopkinson pressure bar shpb experiments. This apparatus consists of four long pressure bars, i. Stress equilibrium in the split hopkinson pressure bar test. Splithopkinson pressure bar testing of soft materials. In this apparatus the specimen is loaded by a tensile wave that is generated by the release of a stored load in a section of the input bar. The mechanical properties of materials change depending upon the strain rate that they are subject to. Construction calibration and application of a split. However, there appears to be a lack of agreement in the literature about a number of critical issues pertaining to this test method. Pdf compressive split hopkinson pressure bar apparatus. You can split the added pdf document into single pages or enter certain page intervals and separate pages to be extracted from the file. High amplitude, splithopkinson pressure bar shpb laboratory tests were conducted on compacted specimens of 5080 silica sand to evaluate the influence of saturation on compressionalstress wave velocity, stress transmission, and attenuation. Split hopkinson pressure bar shpb experiment input bar specimen output bar two force measurements ain time h r 0,t ain hh0h,ttime ll inin,t2,t ain time h r t h l t l st l in 2l st c. Using the split hopkinson pressure bar to validate material. Split hopkinson bar is an inexpensive device for performing high strainrate experiments.
The free end of the loading bar is subjected to axial impact by a projectile fired from a gas gun. The effect of specimen geometry length to diameter ratio is investigated. This site is like a library, use search box in the widget to get ebook that you. Kolskysplit hopkinson pressure bar testing of ceramics. Historically, the split hopkinson pressure bar method, has been used in conjunction with homogeneous and isotropic materials to obtain information on the effect of strain rate on yield strength, for example in metals. When the striker bar impacts the copper disk, a nondispersive ramp pulse propagates in the incident bar and produces a. A directtension splithopkinsonbar apparatus is introduced. Schematic of split hopkinson pressure bar the bars used in a split hopkinson pressure bar setup are traditionally constructed of a high strength metal such as 4340 steel or a nickel alloy such as inconel. It is found that the midpoint surface strain and the average strain agree quite well.
Low pressure free pdf, djvu, doc, fb2 free download e. During experimental investigation the pulse in the incident bar was shaped by the copper disk inserted between the striker and incident bar. This article addresses the specialized aspects required to accurately quantify the behavior of soft materials, including polymers and polymeric composites, using the split hopkinson pressure bar shpb. A directtension split hopkinson bar for high strainrate. The hopkinson pressure bar was first suggested by bertram hopkinson in 1914 as a way to measure stress pulse propagation in a metal bar.
The incident bar, transmission bar and striker bar are all made of same material and same crosssection area. Low pressure by sandra brown in djvu, doc, fb2 download ebook. Xia and others published split hopkinson pressure bar. Determine scaled distance at which testing will take place using equation 1, where r is the distance from the center of the explosive, and w is the charge mass expressed as an equivalent mass of tnt. Dynamic rock tests using split hopkinson kolsky bar. Speckle measurements of sample deformation in the split hopkinsons pressure bar. Dynamic behaviour of polymers at high strainrates based on. The objective of this book is to provide the readers with a working knowledge of dynamic experiments with a kolsky bar, also widely known as a split hopkinson pressure bar shpb. Pressure waves in soils using a splithopkinson pressure bar. The splithopkinson pressure bar, named after bertram hopkinson, sometimes also called a.
John hopkinson, in 1872, studiedfor the first timethe behavior of iron wires by performing stress wave experiments. Design guidelines for the striker and transfer flange of a split hopkinson tension. High amplitude, split hopkinson pressure bar shpb laboratory tests were conducted on compacted specimens of 5080 silica sand to evaluate the influence of saturation on compressionalstress wave velocity, stress transmission, and attenuation. Article information, pdf download for evolution of specimen strain rate in split. A kolsky bar compression test consists of holding a small sample of the material to be tested between two long steel bars. Pdf high strain rate response of rocks under dynamic. The original compressive version developed by kolsky in 1949 places a thin specimen disc between incident and transmission bars. Written in matlab r, the code can be freely distributed. Introduction split hopkinson pressure bar shpb has been widely used as a tool to measure mechanical properties of a material at high strain rates, ranging from 500s to s 1. This smart pdf splitter offers two modes of file splitting. With the impact of a socalled striker bar, a compressive stress pulse is generated in the. Characterization of a laser extensometer for split.
Dispersion correction for split hopkinson pressure bar. The split hopkinson pressure bar shpb has been in use for many years to measure the compression response, principally of metals, but also more recently for much softer materials such as polymers. Mar 22, 2017 the split hopkinson pressure bar system can operate in compression and tension and allows for testing of materials at the magnitude of strain rates seen when a bullet strikes a target, for example. Youngs modulus is a material constant that is a measure for how much a component is deformed when a force is applied to it. Split hopkinson pressure bar tester advance instrument inc. Split hopkinson pressure bar technique download ebook. Then you can start reading kindle books on your smartphone, tablet, or computer. There are typical studies on split hopkinson pressure bar testing technique 22232425262728 29 30. A shpb facility was developed at uct to measure material properties at. A split hopkinson pressure bar technique to determine. Split hopkinson pressure bar graphical analysis tool. Split hopkinson pressure bar apparatus for compression. In this work, in a form of a senior design project, the.
Pdf dynamic rock tests using split hopkinson kolsky. Development and proving of a split hopkinson pressure bar used for. Split hopkinson pressure bar graphical analysis tool file. John hopkinson investigated the propagation of stress waves in the iron wire in 1872, and his son, bertram hopkinson, invented a pressure bar to obtain the pressuretime curve with the dynamic load exerted by detonation hopkinson, 1914. Robust models that capture the materials response at different strain rates are important. Hopkinson bar the model k9560d hopkinson bar for high g calibration is a fully automated, turnkey system for calibrating and verifying high g range shock accelerometers. This method offers a noncontact, direct method for measuring sample strain which does not rely on onedimensional wave propagation assumptions. The validity of the splithopkinsonpressurebar technique for measuring dynamic strain and stress is examined by comparing the average strain computed by use of that technique with the strain at the midpoint of the sample.
Energy for specimen deformation in a split hopkinson. 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. Pdf split hopkinson pressure bar shpb tests on rocks. Then you can start reading kindle books on your smartphone, tablet, or computer no kindle device required. Split hopkinson kolsky bar design, testing and applications. With acceleration levels from 1,000 to 100,000 g, the model k9560d utilizes the hopkinson pressure bar for the generation and acquisition of referenced shock inputs. The split hopkinson pressure bar shpb technique has been commonly used to investigate concrete compressive response under high strain rate. Stress equilibrium in the split hopkinson pressure bar test x. The split hopkinson pressure bar shpb or kolskys apparatus is one of the most widely used experimental techniques to study the dynamic behaviour of engineering materials at high strain rates up to 104per second. Later, in 1949 herbert kolsky refined hopkinsons technique by using two hopkinson bars in series, now known as the splithopkinson bar, to measure stress and strain, incorporating advancements in the cathode ray oscilloscope in conjunction with.
Click download or read online button to get split hopkinson pressure bar technique book now. When the striker bar impacts the copper disk, a nondispersive ramp pulse propagates in the incident bar and produces a nearly. In this case, a precise measurement of the reflected and transmitted waves is important to determine a reliable stressstrain relation. Split hopkinson pressure bar an overview sciencedirect topics. The hopkinson pressure bars are hung from the bar assembly receiver so that they sit flush with the face of the target plate. John hopkinson, in 1872, studiedfor the first timethe behavior of. The classical split hopkinson pressure bar system is then composed of two axial bars incident bar and transmitter bar and a striker bar launched by a gas gun. By striking the end of one bar, a compressive stress wave shall be generated and will immediately traverse across the stricken bar and reaching at one end of the specimen. Split hopkinson pressure bar testing of 3d woven composites. Numerical simulation of the split hopkinson pressure bar.
The split hopkinson pressure bar shpb experimental technique is the most common method to evaluate the dynamic mechanical properties in. The classical split hopkinson pressure bar system is then composed of two axial bars incident bar and transmitter bar and a. The apparatus employed was a modification of the hopkinson pressure bar, and detonators were used to produce. Gorharn faculty of technology, the open university, walton hall, milton keynes, mk7 64. The presented paper is focused on the shpb impulse measurement process using experiment al and numerical methods. Hopkinson bars are usually custom made based on the needs of customers, who are mostly researchers in universities or research labs. Enter your mobile number or email address below and well send you a link to download the free kindle app. Composite materials shawn lang a thesis submitted in. Split hopkinson pressure bar tester the split hopkinson bar apparatus consists of two long slender bars that closely sandwich a short cylindrical specimen between them. This paper presents a split hopkinson pressure bar technique to obtain compressive stressstrain data for rock materials.
Lw9397 split hopkinson pressure bar tester lw9397a. In order to generate the input signal, a striker with a u shaped crosssection fig. Pdf split hopkinson bar techniques for characterizing. Dynamic behaviour of polymers at high strainrates based on split hopkinson pressure bar tests, international journal of impact engineering 2010, doi. Construction of data acquisitionprocessing system for. Pdf split hopkinson bar techniques for characterizing soft. The model k9560d hopkinson bar for high g calibration is a fully automated, turnkey system for calibrating and verifying high g range shock accelerometers. Jul 20, 2017 im graduating in mecanical enginiering and my final project is about hopkinson lressure bar i read all you wrote but when i run the file. Example 8 hopkinson bar summary precise data for high strain rate materials is necessary to enable the accurate modeling of highspeed impacts. This site is like a library, use search box in the widget to get ebook that you want. Development of a split hopkinson tension bar for testing stressstrain response of particulate composites under high rates of loading anthony taylor owens master of science, august 4, 2007 b. The new shtb design is built around a titanium loading bar of 3.
A split hopkinson pressure bar shpb is used to test the high strain rate material properties of materials. Design of a split hopkinson pressure bar research activities. It details some of the specialized shpb techniques that facilitate testing soft materials. Splithopkinson bar shb works on the principle of one dimensional wave propagation.
Pdf development of a tensile split hopkinson pressure bar. Kolsky bar has been extensively used for the characterization of material properties at high rates, where the results are a family of stressstrain curves with strain. High strain rate studies are typically performed using the split hopkinson pressure bar shpb technique. Large diameter split hopkinson pressure bar shpb systems required a correction of the strain signals to account for wave dispersion. This technique modifies the conventional split hopkinson bar apparatus by placing a thin copper disk on the impact surface of the incident bar. First a single bar experiment is used to compare the extensometers accuracy and frequency response. Select one or interval split modes to use each of these split types.
A new split hopkinson tensile bar design sciencedirect. Development of a tensile split hopkinson pressure bar testing facility. Comparison of strain rate regimes for shpb to some other classes of testing facilities, the shpb has evolved from the original version of dynamic. The method involving the use of a splithopkinson bar enjoys increasing popularity in many applications thanks to ever more powerful test and measurement. Pdf speckle measurements of sample deformation in the. The most widely used method to characterise materials at high strain rates is the split hopkinson pressure bar shpb. However, the measurements were not accurate because of the limitation of the measurement technique. Dynamic behaviour of polymers at high strainrates based. The original hopkinson device with only one cylindrical bar was modified by kolsky two bars for indirect measurements on both sides of the specimen.
Blast quantification using hopkinson pressure bars protocol. Later, in 1949 herbert kolsky refined hopkinson s technique by using two hopkinson bars in series, now known as the split hopkinson bar, to measure stress and strain, incorporating advancements in the cathode ray oscilloscope in conjunction with. Split hopkinson pressure bar testing of unsaturated sand. Split hopkinson pressure bar a split hopkinson pressure bar shpb, also known as a kolsky bar, is a test apparatus used to characterize the mechanical response of materials deforming at high strain rates 102 104 s1. A split hopkinson bar apparatus, also known as kolsky bar that is capable of conducting compressive strain rate testing in the approximate ranges from 50 to 104 in. Split hopkinson bar shb works on the principle of one dimensional wave propagation. Split hopkinson pressure bar for soft materials 141 figure 21. Specimens are loaded to strain rates on the order of 10 3 s. The specimen strain rate in the split hopkinson bar shb test has been. Experimental investigation of gradual damage evolution on the freeedge of composite materials. Download fulltext pdf high strain rate response of rocks under dynamic loading using split hopkinson pressure bar article pdf available in geotechnical and geological engineering august 2017. A kolsky bar, also widely known as a split hopkinson pressure bar shpb, is a characterization tool for the mechanical response of materials deforming at high strain rates 102 104 s1.
The splithopkinson pressure bar shpb test is one of the most versatile methods for. Unlike quasistatic testing machines a splithopkinson bar enables material properties to be determined in dynamic conditions. Introduction split hopkinson pressure bar shpb has been widely used as a tool to measure mechanical properties of a material at high strain rates, ranging from 500s to. To overcome these limitations the split hopkinson pressure bar shpb was developed. A schematic of the hopkinson pressure bar is illustrated in figure 1. Split hopkinsonson bar test appartus advance instrument inc. The high strain rate characterization of materials is usually performed using the split hopkinson pressure bar within the strain rate range 1000 s1. Hopkinson pressure bar shpb is widely used for investigating the dynamic behavio r of various materials.
A split hopkinson bar is used to dynamically determine material constants, for example youngs modulus or mechanical stress. The impact produces a strain wave that moves down the incident bar, through the sample, and then into the second bar. Split hopkinson pressure bar shpb is an apparatus that is used to study materials behavior under high speed deformation, where strain rate is very high. Designing a data acquisition system for a split hopkinson. Split hopkinson pressure bar graphical analysis tool documentation, version 1. Definition of the requirements for metals and advanced material am, composite 3.
Split hopkinson pressure bar shpb is a widely used experimental technique to characterize the mechanical properties of materials at high strain rates. A novel technique has been developed for the direct noncontact measurement of the radial deformations of a specimen during a compression kolsky bar splithopkinson pressure bar experiment. The split hopkinson pressure bar shpb testing technique has been used to derive the constitutive equations of engineering materials at high strain rate using the reflected and transmitted waves measured from the input and output bars. The midpoint strain is measured by use of the interferometricstraingage method. Split hopkinson pressure bar apparatus for compression testing. One of the main problems occurring during tests are oscillations recorded by the strain gauges which.
The compressive split hopkinson pressure bar shpb technique allows the stresses on each end of the specimen to be measured individually. Using the split hopkinson pressure bar to validate. All content included on our site, such as text, images, digital downloads and other, is the property of its content suppliers and protected by us and international laws. The specimen is sandwiched between the transmission and incident bar. High g accelerometer calibration calibration the modal. In the present study, the shpb test is adopted to examine the deformation response of 3dwc when subjected to high strain rates. Its main components are a gas gun, a striker bar, an incident bar and a transmission bar. The first bar, called the incident bar, is impacted on the end with a striker bar fired from a small air gun. Evolution of specimen strain rate in split hopkinson bar test. The system can be used for experiments with test durations of up to 500. The impact of a striker bar on the free end of the.
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