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