Stress equilibrium in the split hopkinson pressure bar test. Unlike quasistatic testing machines a splithopkinson bar enables material properties to be determined in dynamic conditions. Split hopkinson pressure bar technique has been widely used to measure the dynamic tensile strength of concrete materials. The compressive split hopkinson pressure bar shpb technique allows the stresses on each end of the specimen to be measured individually. Significant progress has been made on the quantification of various rock dynamic properties, owing to the advances in the experimental techniques of shpb. The split hopkinson pressure bar shpb is also called the davies bar or the kolsky bar after those who developed the modern shpb system on the basis of the original hopkinson bar. Velocitypressure calibration of the developed setup shows higher velocities can be achieved at any particular pressure, when it is compared with the existing public domain velocity calibration of shpb setup. Figure 2 shows compression wave generation apparatus 101 to the left of split hopkinson pressure bar 102 including input bar 103 connected via test specimen 104 to output bar 105. 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.
Written in matlab, the code can be freely distributed either as an executable binary or editable matlab files. A brief description of the theory behind the shpb technique is given in the evaluation section. Split hopkinson pressure bar an overview sciencedirect topics. There are typical studies on split hopkinson pressure bar testing technique. An opensource split hopkinson pressure bar graphical data analysis tool has. The free end of the loading bar is subjected to axial impact by a projectile fired from a gas gun. A new split hopkinson tensile bar design request pdf. In the 1960s, he and coworkers developed a technique that allowed direct generation of the complete dynamic high. The splithopkinsonpressurebar 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.
One, a method of indirect tension, developed previously for metals, where a compressive pulse is converted to a tensile pulse by reflection from the bar free end. Using the split hopkinson pressure bar to validate. Building on the experience of hopkinson and davies 1948 and kolsky 1949 had independently devised the split hopkinson pressure bar shpb technique that is now commonly used for characterizing the dynamic. Split hopkinson pressure bar operations manual 592014 49 the compression pulse that was reflected by the momentum trap the hits the free face of the striker end of the transmission bar, reflecting back as tension.
Pdf design and characteristics of a split hopkinson. Using split hopkinson pressure bars to perform large strain compression tests on polyurea at low, intermediate and high strain rates jongmin shima, dirk mohra,b, aimpact and crashworthiness laboratory, department of mechanical engineering, massachusetts institute of technology, cambridge, ma 029, usa b solid mechanics laboratory cnrsumr 7649, department of mechanics, e. Stress equilibrium in the split hopkinson pressure bar test x. Due to the transient nature of the loading, dynamic tests of rock materials are very different from and much more challenging than their static counterparts. A split hopkinson pressure bar is in essence a series of waveguides for elastic waves 5. Dynamic compressive and splitting tensile tests on mortar. Beginning with raw voltages from two strain gages along with the incidenttransmitted bars mechanical and geometrical properties, the user can visually analyze forces and displacements at. Extending the use of this device to more versatile applications faces several challenges such as controlling the stress state within the specimen and mastering the measurement of forces and. A different method of applying an impact load on a concrete specimen is the splithopkinson bar, which can be used in different configurations to induce pressure, tension or torque loads gerlach.
I recently visited a lab to investigate customer complaints regarding the performance of mbond ae10 strain gage bonding adhesive. This thesis is brought to you for free and open access by. Oct 09, 2015 a split hopkinson pressure bar shpb is used to test the high strain rate material properties of materials. Dynamic rock tests using split hopkinson kolsky bar. Split hopkinson pressure bar an overview sciencedirect. 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 system comprises halfinch diameter by approximately eightfootlong incident and transmitter bars machined from 4340 steel, mounted to a free standing 25footlong, 4inch steel i. The user had come to the conclusion that the adhesive was. Hopkinson bar, shpb, shpb design, gasgun, impact testing 1. Split hopkinson pressure bar shpb testing is the most common technique for dynamic compressive testing of materials at high strain rates 2. Dynamic stress equilibration in split hopkinson pressure bar. Semantic scholar extracted view of development of a tensile split hopkinson pressure bar testing facility by kevin young. A note on data processing in the split hopkinson pressure bar tests netic energy in shpb test. Jul 20, 2016 an opensource split hopkinson pressure bar graphical data analysis tool has been developed.
Specific experiment design guidelines are provided to subject the specimen to desired testing conditions. Design of a split hopkinson bar apparatus for use with fiber. This paper presents the design of a modified split hopkinson pressure bar shpb where partial lateral con finement of the specimen is provided by the inertia of a fluid annulus contained in a long steel reservoir. Pressure waves in soils using a split hopkinson final report pressure bar j1 april 184feb 19p 6 8 o m 01. Using the split hopkinson pressure bar to validate material. 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. This paper presents the design of a modified split hopkinson pressure bar shpb where partial lateral con finement of the specimen is provided by the inertia.
Using split hopkinson pressure bars to perform large. 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. Pressure and temperature induced redshift of the sodium d. The split hopkinson pressure bar conventional device is mainly limited to test homogeneous ductile nonsoft materials under uniaxial compression. It is rather a philosophical approach to solve the problem of measuring impact events. Pdf wave dispersion and attenuation in viscoelastic. Hopkinson bars are usually custom made based on the needs of customers, who are mostly researchers in universities or research labs. The hopkinson bar is used to impose a dynamic load on a material specimen akin to that. The splithopkinson pressure bar, named after bertram hopkinson, sometimes also called a kolsky bar, is an apparatus for testing the dynamic stress strain response of materials. Figure 1 shows a diagram of the basic hopkinson bar setup. Dynamic tensile strength enhancement of concrete in split. Nt final tfrom 86101 to a883 0 arck 1929 16 supplementary notation availablility of this report is specified on reverse of front cover. Hybrid split hopkinson pressure bar to identify impulse. Bulks of albc obtained by reactively spark plasma sintering.
Hybrid split hopkinson pressure bar to identify impulsedependent wave characteristics of viscoelastic phononic crystals a. Specific experiment design guidelines are provided to subject the specimen. 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. The hopkinson bar technique is named after bertram hopkinson who, in 1914, studied the shape and evolution of stress pulses as a function of time as they propagated down a long rod. Dynamic tests are usually conducted using the split hopkinson bar or kolsky bar systems, which include both split hopkinson. These high strains are used to induce the strain hardening and phase a transition phenomenon which affects the strength. The modern shpb system is widely used in the laboratory studies on stress waves in various types of solids such as metals, rocks, concrete, and so on. 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. Dynamic tests are usually conducted using the split hopkinson bar or kolsky bar systems, which include both split hopkinson pressure bar shpb and split hopkinson tension bar shtb systems. The splithopkinson pressure bar, named after bertram hopkinson, sometimes also called a. Split hopkinson pressure bar graphical analysis tool.
Dec 20, 2019 samples were tested for their impact behavior by the split hopkinson pressure bar method. A different method of applying an impact load on a concrete specimen is the split hopkinson bar, which can be used in different configurations to induce pressure, tension or torque loads gerlach. Dynamic crack propagation and fracture behavior of pre. Finite element simulation for design verification of a. During very high impacts and extreme applications higher rates of strain are obtained. Design customization and development of split hopkinson.
Splithopkinson bar shb works on the principle of one dimensional wave propagation. Development of a tensile split hopkinson pressure bar testing facility. Pdf split hopkinson pressure bar shpb tests on rocks. Compression wave 106,107 is generated by initially placing impactor bar 109 under a preload force by hydraulic actuator 108 in the direction of arrow a until fragile component 110 ruptures causing end 109a to. Velocity pressure calibration of the developed setup shows higher velocities can be achieved at any particular pressure, when it is compared with the existing public domain velocity calibration of shpb setup. Modifications are introduced for obtaining reliable data. Indeed, the kolskyhopkinson bar machine is not a simple experimental device. An evolving quantification tool and technique for constitutive model validation george t. Dynamic rock tests using split hopkinson kolsky bar system. The method involving the use of a splithopkinson bar enjoys increasing popularity in many applications thanks to ever more powerful test and measurement. Split hopkinson pressure bar shpb technique, which decouples cleverly the inertia effect in structures and strain rate effect in materials, has been widely used to characterize the dynamic performance of various engineering materials at high strain rate, such as rock 2933, concrete 3438, and ceramics 39, 40 at high strain rates.
In principle, the apparatus is similar to that first used by kolsky in 1949. Beginning with raw voltages from two strain gages along with the incidenttransmitted bars mechanical and geometrical properties, the user can visually analyze forces. In order to test wood under conditions similar to those in a refiner, an existing split hopkinson pressure bar shpb setup 7 was modified. For testing low stiffness materials such as rubbers or low strength materials such as low density cellular solids considered primarily herein, there are many advantages to replacing the metal bars with polymer bars. This tension pulse follows the compression pulse down the bar. The theory governing the specifics of hopkinson bar testing has been around for decades. Split hopkinson pressure bar apparatus capable of generating a compression wave or pulse in an input bar or member, said apparatus comprising an input bar or member, actuator means, a fragile or frangible component and an impactor bar or member held, in use, adjacent one end of the input bar or member and supported to resist movement in a direction away from said input barmember when the. The condition of dynamic stress equilibrium is not satisfied automatically when a split hopkinson pressure bar shpb is employed to determine the dynamic properties of soft materials. An analysis of the split hopkinson pressure bar by defense technical information center.
The split hopkinson pressure bar technique corresponds to a high strain rate deformation of the aluminum alloy at high stress. Split hopkinson pressure bar shpb testing has traditionally been carried out using metal bars. Introduction split hopkinson pressure bar shpb is a wellestablished experimental technique for testing of materials under high strainrates. The striker bar sits in the barrel at the gas gun chamber. Split hopkinson pressure bar technique, which decouples cleverly the inertia effect in struc tures and the strain rate effect in materials, has been used widely to characterize the dynamic compressive performance of various engineering materials at high strain rate in the region of 10 2. The splithopkinson pressure bar shpb was designed and built by swri personnel in 1962. The splithopkinson pressure bar shpb test is one of the most versatile methods for determining the dynamic mechanical properties at high strain rates in the range of 1. Split hopkinsonson bar test appartus advance instrument inc. Split hopkinson pressure bar graphical analysis tool documentation, version 1. Splithopkinson pressure bar testing of soft materials. An opensource split hopkinson pressure bar graphical data analysis tool has been developed. Split hopkinson pressure bar apparatus capable of generating a compression wave or pulse in an input bar or member, said apparatus comprising an input bar or member, actuator means, a fragile or frangible component and an impactor bar or member held, in use, adjacent one end of the input bar or member and supported to resist movement in a direction away from said input bar member when the. Most experimental results show that the tensile strength of concrete material increases with strain rates. John hopkinson, in 1872, studiedfor the first timethe behavior of iron wires by performing stress wave experiments.
Freebody diagram of the adherends and adhesive layer c variation of shear. 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. As compression waves are reflected as tension waves on free surface, the specimen is loaded in tension. Its main components are a gas gun, a striker bar, an incident bar and a transmission bar. Torsional split hopkinson bar to study rate effect in 1 alu. Split hopkinson kolsky bar design, testing and applications. Impact dynamics lab split hopkinson pressure bar youtube. Gorharn faculty of technology, the open university, walton hall, milton keynes, mk7 64. The free body diagram of the springmass part is shown in fig.
The conventional split hopkinson pressure bar apparatus is modified by shaping the incident pulse such that the samples are in dynamic stress equilibrium and have nearly constant strain rate over. Pressure waves in soils using a splithopkinson pressure bar. Most experimental results show that the tensile strength of concrete mater. Ulric lindholm with a presentday swri split hopkinson pressure bar apparatus. Wave dispersion and attenuation in viscoelastic split hopkinson pressure bar. Pressure waves in soils using a splithopkinson final report pressure bar j1 april 184feb 19p 6 8 o m 01. John hopkinson, in 1872, studiedfor the first timethe behavior of. A split hopkinson bar apparatus capable of conducting compressive strain rate tests at rates ranging from 50 to 10 to the 4th power in. The authors systematically describe the general principles of kolsky bars, or split hopkinson bars, which are widely used for obtaining dynamic material properties.
The customer complained that when attempting to bond strain gages to a split hopkinson bar using mbond ae10 that not only was the gage output unstable but the gages were popping off. A split hopkinson pressure bar shpb is used to test the high strain rate material properties of materials. 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. The incident bar, transmission bar and striker bar are all made of same material and same crosssection area.
Written in matlab r, the code can be freely distributed. Split hopkinson bar shb works on the principle of one dimensional wave propagation. Split hopkinson pressure bar is an apparatus that is used to study materials behavior under high speed deformation, where strain rate is very high. Pdf compressive split hopkinson pressure bar apparatus. The kolskyhopkinson bar machine selected topics ramzi. In contrast to unconfined testing, or a constant cell pressure applied before axial loading, lateral restraint is permitted to develop throughout the axial loading. Today, the swri split hopkinson pressure bar remains the standard test technique for high strain rate materials characterization. Dynamic stress equilibration in split hopkinson pressure. 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. Design of a split hopkinson pressure bar with partial lateral. U split hopkinson pressure bar tests 12 personal author s c. A split hopkinson pressure bar apparatus, also known as kolsky bar that is capable of conducting compressive strain rate testing in the approximate ranges from 50 to 104 inin per second was designed as a part of a senior design project. The split hopkinson pressure bar conventional device is mainly limited to test homogeneous.
Samples were tested for their impact behavior by the split hopkinson pressure bar method. Experimental and numerical investigations on the use of. 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. Abstract dynamic properties of rocks are important in a variety of rock mechanics and rock engineering problems. It consists of two cylindrical bars of the same diameter, respectively. Advancements in the split hopkinson bar test by michael adam kaiser abstract the split hopkinson bar test is the most commonly used method for determining material properties at high rates of strain. Pdf development of a tensile split hopkinson pressure bar. Allen ross a type of report 3b time covered 4 date of report year, month, day 5s p4,3e cc7. Splithopkinson bar testing is a tried and tested method in materials testing. Design of a split hopkinson pressure bar with partial. 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. For testing low stiffness materials such as rubbers or low strength materials such as low density cellular solids considered primarily herein, there are many advantages.
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