A schematic of the hopkinson pressure bar is illustrated in figure 1. 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. However, as the strain gage data has discrete point, there will likely be a small di erence. Pdf speckle measurements of sample deformation in the. 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. Designing a data acquisition system for a split hopkinson pressure bar senior students are always challenged to apply their engineering knowledge and research skills gained from an engineering curriculum toward design and implementation of challenging senior design projects. The new shtb design is built around a titanium loading bar of 3. 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. 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. Select one or interval split modes to use each of these split types. Then you can start reading kindle books on your smartphone, tablet, or computer. 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. The hopkinson pressure bars are hung from the bar assembly receiver so that they sit flush with the face of the target plate.
Calculate approximate maximum impulse this arrangement will generate via numerical modelling see appendix a or specific tools such as conwep 3. Pdf split hopkinson pressure bar shpb tests on rocks. The specimen is sandwiched between the transmission and incident bar. Split hopkinson pressure bar graphical analysis tool documentation, version 1. Hopkinson bars are usually custom made based on the needs of customers, who are mostly researchers in universities or research labs. Experimental investigation of gradual damage evolution on the freeedge of composite materials. 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. When the striker bar impacts the copper disk, a nondispersive ramp pulse propagates in the incident bar and produces a nearly. However, there appears to be a lack of agreement in the literature about a number of critical issues pertaining to this test method. However, the measurements were not accurate because of the limitation of the measurement technique. Split hopkinson pressure bar shpb is an apparatus that is used to study. Example 8 hopkinson bar summary precise data for high strain rate materials is necessary to enable the accurate modeling of highspeed impacts. Dynamic rock tests using split hopkinson kolsky bar.
The compressive split hopkinson pressure bar shpb technique allows the stresses on each end of the specimen to be measured individually. Xia and others published split hopkinson pressure bar. The midpoint strain is measured by use of the interferometricstraingage method. 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. Pdf split hopkinson bar techniques for characterizing soft. Impact dynamics lab split hopkinson pressure bar youtube. Hopkinson pressure bar shpb is widely used for investigating the dynamic behavio r of various materials. 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. Advancements in the split hopkinson bar test, kaiser, michael adam, pg 6162, 18465unrestrictedetd. Split hopkinson pressure bar apparatus for compression. Specimens are loaded to strain rates on the order of 10 3 s. The impact of a striker bar on the free end of the. 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.
The splithopkinson pressure bar shpb test is one of the most versatile methods for. 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 want. 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. The most widely used method to characterise materials at high strain rates is the split hopkinson pressure bar shpb. You can split the added pdf document into single pages or enter certain page intervals and separate pages to be extracted from the file. Split hopkinson pressure bar testing of 3d woven composites. Kolskysplit hopkinson pressure bar testing of ceramics. 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.
A new split hopkinson tensile bar design sciencedirect. This apparatus consists of four long pressure bars, i. This smart pdf splitter offers two modes of file splitting. 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. First a single bar experiment is used to compare the extensometers accuracy and frequency response. The splithopkinson pressure bar, named after bertram hopkinson, sometimes also called a. A shpb facility was developed at uct to measure material properties at. Splithopkinson pressure bar testing of soft materials. Written in matlab r, the code can be freely distributed.
Pdf development of a tensile split hopkinson pressure bar. Split hopkiso pressure bar impulse experimetal pawel. Using the split hopkinson pressure bar to validate. The hopkinson pressure bar was first suggested by bertram hopkinson in 1914 as a way to measure stress pulse propagation in a metal bar. Split hopkinsonson bar test appartus advance instrument inc. This paper presents a split hopkinson pressure bar technique to obtain compressive stressstrain data for rock materials. 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. Design of a split hopkinson pressure bar research activities. 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.
Lw9397 split hopkinson pressure bar tester lw9397a. The apparatus employed was a modification of the hopkinson pressure bar, and detonators were used to produce. The system can be used for experiments with test durations of up to 500. A kolsky bar compression test consists of holding a small sample of the material to be tested between two long steel bars. Split hopkinson bar shb works on the principle of one dimensional wave propagation. A split hopkinson pressure bar technique to determine. It is found that the midpoint surface strain and the average strain agree quite well. A directtension split hopkinson bar for high strainrate. Stress equilibrium in the split hopkinson pressure bar test x. Enter your mobile number or email address below and well send you a link to download the free kindle app. A directtension splithopkinsonbar apparatus is introduced.
Click download or read online button to get split hopkinson pressure bar technique book now. In this case, a precise measurement of the reflected and transmitted waves is important to determine a reliable stressstrain relation. 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. Split hopkinson pressure bar tester advance instrument inc. John hopkinson, in 1872, studiedfor the first timethe behavior of. Numerical simulation of the split hopkinson pressure bar. Split hopkinson pressure bar for soft materials 141 figure 21. In order to generate the input signal, a striker with a u shaped crosssection fig. 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. The model k9560d hopkinson bar for high g calibration is a fully automated, turnkey system for calibrating and verifying high g range shock accelerometers. Dynamic behaviour of polymers at high strainrates based on. Split hopkinson bar is an inexpensive device for performing high strainrate experiments.
Energy for specimen deformation in a split hopkinson. 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. In the present study, the shpb test is adopted to examine the deformation response of 3dwc when subjected to high strain rates. Robust models that capture the materials response at different strain rates are important. Definition of the requirements for metals and advanced material am, composite 3. 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. Pressure waves in soils using a splithopkinson pressure bar. Download construction calibration and application of a split hopkinson pressure bar or read online books in pdf, epub, tuebl, and mobi format.
Dispersion correction for split hopkinson pressure bar. During experimental investigation the pulse in the incident bar was shaped by the copper disk inserted between the striker and incident bar. The striker bar sits in the barrel at the gas gun chamber. Split hopkinson kolsky bar design, testing and applications. Split hopkinson pressure bar apparatus for compression testing. 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. Characterization of a laser extensometer for split. Comparison of strain rate regimes for shpb to some other classes of testing facilities, the shpb has evolved from the original version of dynamic. Split hopkinson pressure bar graphical analysis tool. 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. Construction calibration and application of a split. The original hopkinson device with only one cylindrical bar was modified by kolsky two bars for indirect measurements on both sides of the specimen. The presented paper is focused on the shpb impulse measurement process using experiment al and numerical methods.
Low pressure free pdf, djvu, doc, fb2 free download e. Development and proving of a split hopkinson pressure bar used for. 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. Using a fast fourier transform fft algorithm a wave dispersion correction program was developed. Split hopkinson pressure bar technique download ebook. To overcome these limitations the split hopkinson pressure bar shpb was developed. Pdf compressive split hopkinson pressure bar apparatus. 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. With the impact of a socalled striker bar, a compressive stress pulse is generated in the. The split hopkinson pressure bar shpb technique has been commonly used to investigate concrete compressive response under high strain rate.
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. Low pressure by sandra brown in djvu, doc, fb2 download ebook. 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. Construction of data acquisitionprocessing system for. High strain rate studies are typically performed using the split hopkinson pressure bar shpb technique.
This paper examines a laser extensometer to calculate the strain in a sample during split hopkinson pressure bar shpb experiments. 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. Evolution of specimen strain rate in split hopkinson bar test. When the striker bar impacts the copper disk, a nondispersive ramp pulse propagates in the incident bar and produces a. Split hopkinson pressure bar graphical analysis tool file. Designing a data acquisition system for a split hopkinson. 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. Youngs modulus is a material constant that is a measure for how much a component is deformed when a force is applied to it. 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. This method offers a noncontact, direct method for measuring sample strain which does not rely on onedimensional wave propagation assumptions.
The free end of the loading bar is subjected to axial impact by a projectile fired from a gas gun. Pdf split hopkinson bar techniques for characterizing. High g accelerometer calibration calibration the modal. This technique modifies the conventional split hopkinson bar apparatus by placing a thin copper disk on the impact surface of the incident bar. It details some of the specialized shpb techniques that facilitate testing soft materials.
The incident bar, transmission bar and striker bar are all made of same material and same crosssection area. 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. The specimen strain rate in the split hopkinson bar shb test has been. Pdf high strain rate response of rocks under dynamic. 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. 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 original compressive version developed by kolsky in 1949 places a thin specimen disc between incident and transmission bars. Then you can start reading kindle books on your smartphone, tablet, or computer no kindle device required. 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. Composite materials shawn lang a thesis submitted in. Dynamic testing by split hopkinson pressure bars shpb. The high strain rate characterization of materials is usually performed using the split hopkinson pressure bar within the strain rate range 1000 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. Speckle measurements of sample deformation in the split hopkinsons pressure bar.
Pdf dynamic rock tests using split hopkinson kolsky. Article information, pdf download for evolution of specimen strain rate in split. The method involving the use of a splithopkinson bar enjoys increasing popularity in many applications thanks to ever more powerful test and measurement. A note on data processing in the split hopkinson pressure bar tests netic energy in shpb test.
John hopkinson, in 1872, studiedfor the first timethe behavior of iron wires by performing stress wave experiments. Split hopkinson pressure bar testing of unsaturated sand. Click download or read online button to get construction calibration and application of a split hopkinson pressure bar book now. Stress equilibrium in the split hopkinson pressure bar test. Design guidelines for the striker and transfer flange of a split hopkinson tension. The impact produces a strain wave that moves down the incident bar, through the sample, and then into the second bar. 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. Gorharn faculty of technology, the open university, walton hall, milton keynes, mk7 64. Its main components are a gas gun, a striker bar, an incident bar and a transmission bar. Using the split hopkinson pressure bar to validate material. 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 is an apparatus that is used to study materials behavior under high speed deformation, where strain rate is very high. A split hopkinson bar is used to dynamically determine material constants, for example youngs modulus or mechanical stress.
A split hopkinson pressure bar shpb is used to test the high strain rate material properties of materials. One of the main problems occurring during tests are oscillations recorded by the strain gauges which. Unlike quasistatic testing machines a splithopkinson bar enables material properties to be determined in dynamic conditions. This site is like a library, use search box in the widget to get ebook that you. The classical split hopkinson pressure bar system is then composed of two axial bars incident bar and transmitter bar and a. In this work, in a form of a senior design project, the. This allows the fully reflected pressure acting on the target plate to be recorded. Development of a tensile split hopkinson pressure bar testing facility. 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. Large diameter split hopkinson pressure bar shpb systems required a correction of the strain signals to account for wave dispersion. Dynamic behaviour of polymers at high strainrates based. 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.
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. Split hopkinson pressure bar shpb is a widely used experimental technique to characterize the mechanical properties of materials at high strain rates. There are typical studies on split hopkinson pressure bar testing technique 22232425262728 29 30. Dynamic behaviour of polymers at high strainrates based on split hopkinson pressure bar tests, international journal of impact engineering 2010, doi. Splithopkinson bar testing is a tried and tested method in materials testing. Splithopkinson bar shb works on the principle of one dimensional wave propagation. The first bar, called the incident bar, is impacted on the end with a striker bar fired from a small air gun. The split hopkinson pressure bar shpb experimental technique is the most common method to evaluate the dynamic mechanical properties in. Split hopkinson pressure bar an overview sciencedirect topics.