The most widely used method to characterise materials at high strain rates is the split hopkinson pressure bar shpb. To split between two pages, click on the scissors icon on the left page. Split hopkiso pressure bar impulse experimetal pawel. Definition of the requirements for metals and advanced material am, composite 3. Composite materials shawn lang a thesis submitted in partial. The second technique is the recently developed wedge bar apparatus. 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. Dynamic rock tests using split hopkinson kolsky bar system. Split hopkinson pressure bar for soft materials 141 figure 21.
Split hopkinson pressure bar technique has been extensively used to. Quasistatic material tests in tension or compression at elevated temperatures are usually performed in uniaxial testing machines in combination with an oven. Written in matlab r, the code can be freely distributed. Youngs modulus is a material constant that is a measure for how much a component is deformed when a force is applied to it. Failure was determined by defining a failure strain to start the process of element deletion. Split hopkinson bar shb methods are widely used to experimentally characterise the mechanical properties of materials undergoing rapid deformation,, and are generally classified into compression shcb, torsion shtob and tension shtb split hopkinson bars. This dynamic testing method of impacting a long bar and studying the stress waves produced in the bar was pioneered by bertram hopkinson early in the 20th century. Unlike quasistatic testing machines a splithopkinson bar enables material properties to be determined in dynamic conditions. Gasgunc file defines constants, the gasgunmain file initializes the. Robust models that capture the materials response at different strain rates are important. The splithopkinson pressure bar shpb technique complements the laser based high rate testing by providing a method for deformation at lower rates 102104 s.
A directtension splithopkinsonbar apparatus is introduced. The splithopkinson pressure bar, named after bertram hopkinson, sometimes also called a. A split hopkinson bar is used to dynamically determine material constants, for example youngs modulus or mechanical stress. The compressive split hopkinson pressure bar shpb technique allows the stresses on each end of the specimen to be measured individually. Split hopkinson bar is an inexpensive device for performing high strainrate experiments. This book an exact copy of authors phd dissertation published in 2004 by university of delaware.
The incident bar, transmission bar and striker bar are all made of same material and same crosssection area. A split hopkinson pressure bar technique to determine. One of the experimental techniques for characterising materials under the effect of high strain rates is the split hopkinson pressure bar shpb test. Development of a tensile split hopkinson pressure bar testing facility. Split hopkinson bar, which can test materials at strain rates as high as 2000 s1. G, the code can be freely distributed either as an executable binary or editable matlab files. The splithopkinson pressure bar experimental technique has been implemented to evaluate the high rate squeeze flow behavior of a concentrated shear thickening fluid stf. A schematic of the hopkinson pressure bar is illustrated in figure 1. Split hopkinson pressure bar technique download ebook. Pdf a split hopkinson pressure bar apparatus, also known as kolsky. The system can be used for experiments with test durations of up to 500. Pdf split hopkinson bar techniques for characterizing soft. Designing a data acquisition system for a split hopkinson. The results were obtained using two hopkinsonbarrelated techniques.
Jun 03, 2016 one of the experimental techniques for characterising materials under the effect of high strain rates is the split hopkinson pressure bar shpb test. Pdf split hopkinson bar techniques for characterizing. Using split hopkinson pressure bars to perform large strain compression tests on polyurea at low, intermediate and high strain rates. The mechanical properties of materials change depending upon the strain rate that they are subject to. The design, construction and testing of unique operated.
The hopkinson bar is used to impose a dynamic load on a material specimen akin to that. A note on data processing in the split hopkinson pressure bar tests netic energy in shpb test. Hopkinson pressure bar shpb is widely used for investigating the dynamic behavio r of various materials. Using split hopkinson pressure bars to perform large. In this case, a precise measurement of the reflected and transmitted waves is important to determine a reliable stressstrain relation. Pdf design and characteristics of a split hopkinson pressure bar. 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. 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.
Example 8 hopkinson bar summary precise data for high strain rate materials is necessary to enable the accurate modeling of highspeed impacts. Unlike the lbhrt setup, the shpb can be used for tensile and torsion testing as well as compression. 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. This apparatus consists of four long pressure bars, i.
A note on data processing in the split hopkinson pressure bar tests netic energy in shpb test, davies and hunter recom mended an optimal length. It details some of the specialized shpb techniques that facilitate testing soft materials. In this work, in a form of a senior design project, the. Splithopkinson bar shb works on the principle of one dimensional wave propagation. During experimental investigation the pulse in the incident bar was shaped by the copper disk inserted between the striker and incident bar.
However, the measurements were not accurate because of the limitation of the measurement technique. Design of a split hopkinson pressure bar research activities. 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 ring was modeled both axisymmetrically and in 3d to help ensure accuracy in results. 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 pressure time curve with the dynamic load exerted by detonation hopkinson, 1914. The presented paper is focused on the shpb impulse measurement process using experiment al and numerical methods. A series of fem simulations of shpb test were used in designing of split hopkinson pressure bar equipment and its dedicated software, developed in impact laboratory, a facility of military technical academy. 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 dynamic compressive behavior of concrete is investigated using a. This technique modifies the conventional split hopkinson bar apparatus by placing a thin copper disk on the impact surface of the incident bar. Splithopkinson pressure bar testing of soft materials.
The hopkinson pressure bar was first suggested by bertram hopkinson in 1914 as a way to measure stress pulse propagation in a metal bar. Is there a place i can get raw data for the split hopkinson pressure bar to. Each product is the most popular one at that price level. The specimen is sandwiched between the transmission and incident bar.
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. Fe modelling of a confined split hopkinson pressure bar shpb test on dry quartz sand was carried out using lsdyna in order to assess whether material model 5 could replicate experimental results, which would enable a more detailed investigation of the stress state in shpb specimen. A brief description of each of the apparatus members is given below according to their assigned numbers. Once the upload is complete, the pages of your document will be shown as thumbnails. In these systems, a stress pulse is generated through various means, e. Dynamic rock tests using split hopkinson kolsky bar. Splithopkinson pressurebar tests on concrete and mortar. The hopkinson bar is used to impose a dynamic load on a material specimen akin to that which the material will experience in dynamic situations like vehicle crashes or other highenergy events. Design of inserts for splithopkinson pressure bar testing. 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. Finite elements method in split hopkinson pressure bar. When the striker bar impacts the copper disk, a nondispersive ramp pulse propagates in the incident bar and produces a nearly. Stress equilibrium in the split hopkinson pressure bar test. 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.
Stress equilibrium in the split hopkinson pressure bar test x. The split hopkinson pressure bar experimental technique has been implemented to evaluate the high rate squeeze flow behavior of a concentrated shear thickening fluid stf. Quasistatic tests on the same kinds of specimens were performed using a standard materials testing machine. 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 pressure bar graphical analysis tool documentation, version 1. Afterward, click on the save button on the right and confirm. 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. Characterization of three himalayan rocks using a split. Oct 09, 2015 a split hopkinson pressure bar shpb is used to test the high strain rate material properties of materials. 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. What links here related changes upload file special pages permanent link page. A split hopkinson pressure bar shpb is used to test the high strain rate material properties of materials.
A directtension split hopkinson bar for high strainrate. Using the split hopkinson pressure bar to validate. John hopkinson, in 1872, studiedfor the first timethe behavior of iron wires by performing stress wave experiments. The first technique is the conventional split hopkinson pressure bar arrangement incorporating a novel coneintube striker design, which extends the practical testing range down to 100 s. The preliminary ideas behind hopkinson pressure bar were first originated in 1872 by john hopkinson 1. Limiting conditions for compression testing of flat specimens in the. Using the split hopkinson pressure bar to validate material. In this study, the strains of artificial rock were analyzed in order to estimate the deformation behavior of rocklike materials in the shpb test. Construction of data acquisitionprocessing system for. 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. The wave information along with the experimental setup properties are embedded in these les. One of the main problems occurring during tests are oscillations recorded by the strain gauges which. Naik and others published compressive split hopkinson pressure bar apparatus. Its main components are a gas gun, a striker bar, an incident bar and a transmission bar.
Pdf compressive split hopkinson pressure bar apparatus. Split hopkinson pressure bar test engineering breakdown. The split hopkinson pressure bar is a device used for characterizing material properties submitted to dynamic loading, producing high stress and strain waves. 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. Separate one page or a whole set for easy conversion into independent pdf files. The axial strain measured directly from the strain gage and obtained from the process analysis of threewave method were compared. This paper presents a split hopkinson pressure bar technique to obtain compressive stressstrain data for rock materials. Split hopkinson pressure bar shpb apparatus along with digital storage oscilloscope lds sigma 100 and high frequency strain amplifiers fylde feh359ta. Hopkinson bars are usually custom made based on the needs of customers, who are mostly researchers in universities or research labs. The splithopkinson pressure bar allows for dynamic deformation at high strain rates 10 310 4 s.
When the striker bar impacts the copper disk, a nondispersive ramp pulse propagates in the incident bar and produces a. Split hopkinsonson bar test appartus advance instrument inc. Composite materials shawn lang a thesis submitted in. The most widely used method for obtaining high strain rate material data is the split hopkinson pressure bar, often called a kolsky bar. Deformation behavior of artificial rock in the split. Dogbone specimens introduction the split hopkinson pressure bar schematic shown in fig. Manufacturing of the split hopkinson pressure bar the split hopkinson pressure bar is designed and built as shown in figure 2. Split hopkinson pressure bar testing of unsaturated sand. Split hopkinson pressure bar graphical analysis tool file. If you have an engineering background, it is likely that you have come across one of the most famous testing methods.
Pdf development of a tensile split hopkinson pressure bar. Later, bertram hopkinson introduced a method to characterize the pressure variations with respect to time due to an impact produced by a bullet or explosive. The method involving the use of a splithopkinson bar enjoys increasing popularity in many applications thanks to ever more powerful test and measurement. 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.
Hopkinson bar techniques for the intermediate strain rate. The split hopkinson pressure bar shpb technique is analyzed during the initial stages of loading by means of axisymmetric finite element simulations of d. Currently coding a wave separation script for the split hopkinson pressure bar. We use the technique in combination with texture measurements and insitu tem. The shpb in our lab is a compression testing rig, though plans are being made for a.
As in the method devised by hopkinson, the pressure is applied normally to one end of a cylindrical steel bar, producing a stress pulse which gives rise to radial and longitudinal displacements in the bar. A split hopkinson pressure bar shpb system with a special shape striker has been suggested as the test method by the international society for rock mechanics isrm to determine the dynamic. 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. Uploaded files are deleted within 1 hour from our servers. Gorharn faculty of technology, the open university, walton hall, milton keynes, mk7 64. The high strain rate characterization of materials is usually performed using the split hopkinson pressure bar within the strain rate range 1000 s1. 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. Experimental study on split hopkinson pressure bar pulse. Split hopkinson pressure bar graphical analysis tool. 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. Subsequently the data is recorded in comma separated file format and transferred to.
Select different page numbers in your preferred order and click on more to split 5 files or more. However, as the strain gage data has discrete point, there will likely be a small di erence. Modelling splithopkinson pressure bar tests on quartz sand. This week a brief introduction to the basics of this technique is covered. Split hopkinson pressure bar shpb tests are used to characterize the soft tissue. Split hopkinson bar shb works on the principle of one dimensional wave propagation. File retainment settings can be configured in preferences. Also for dynamic compression testing with a splithopkinson pressure bar, it is common to attach an oven to the test rig for heating of the samples 10,11. Subject matter of this book is split hopkinson pressure bar or kolskey bar, an instrument for the dynamic characterization of materials. In order to reduce and eliminate the waveform dispersion effect, two pulse shaping techniques are adopted to improve the incident wave shape. Split hopkinson pressure bar testing the split hopkinson pressure bar shpb technique complements the laser based high rate testing by providing a method for deformation at lower rates 102104 s. The effect of specimen geometry length to diameter ratio is investigated. May, 2014 the results were obtained using two hopkinsonbarrelated techniques. In this paper are analyzed and evaluated by the simulations means three major topics.
Splithopkinson bar testing is a tried and tested method in materials testing. The striker bar sits in the barrel at the gas gun chamber. Output pdfs are stored for 7 days by default, but can be stored up to 1 year premium or 1 hour. A new split hopkinson tensile bar design sciencedirect.
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