The design is validated by extensive finite element simulation using abaqus. Hello i am a student of the university of manchester. Numerical simulation for bar straightness effect in split. Example 8 hopkinson bar summary precise data for high strain rate materials is necessary to enable the accurate modeling of highspeed impacts. About the dynamic strength enhancement of concretelike. Correction procedure of wave signals for a viscoelastic split. Abaqus modelling of stress waves in a split hopkinson presure. However, lack of material data on different strain rates hinders the use of more ac. For this purpose, the dynamic stressstrain responses of various samples of different materials at high strain rates should be found out. The method is based on threepoint bending tests at high loading rates, performed in an experimental device which is a modification of the classical split hopkinson pressure bar. The original hopkinson device with only one cylindrical bar was modified by kolsky two bars for indirect measurements on both sides of the specimen. Limiting conditions for compression testing of flat specimens in the.
There has recently been a rising interest in the nonlinear wave transmission behavior of phononic crystals. The users manual contains a short users guide and a detailed description that covers all the aspects and running of a computer program that performs analyses of data obtained from a split hopkinson pressure bar experiment. Split hopkinson pressure bar graphical analysis tool file. The triangle velocity wave, which has less diffusion, is used as loader in the simulation. B calibration of split hopkinson pressure bar setup. Stress wave propagation in split hopkinson pressure bar submitted by smaranika nath 710ce20 in partial fulfilment of the requirements for the award of the degree of masters of technology in civil engineering structural engineering under the guidance of prof. The compressive split hopkinson pressure bar shpb technique allows the stresses on each end of the specimen to be measured individually. Is there anyone who have experience on doing splithopkinson. Eight elements were used across the specimen radius, whereas 10 elements were. For a small diameter hard specimen, the bar specimen interfaces are nonplanar, which predicts higher specimen strain and, thus, lower initial modulus in the linear elastic phase of deformation. This paper reports the research results on aluminium syntactic foams as possible core materials for protection of military vehicles.
Chief among the techniques to measure the dynamic stressstrain response of materials is the splithopkinson pressure bar. Providing learning opportunities by designing a split. Brief introduction the hopkinson pressure bar is a specialized equipment to study the dynamic mechanical properties of materials under onedimensional stress state. Simulation of the temperature rise in hopkinson bar experiments accounting for heat transfer to the bars. Pdf split hopkinson pressure bar impulse experimental. This paper presents a split hopkinson pressure bar technique to obtain compressive stressstrain data for rock materials. Singh d, salem j and widjaja s eds mechanical properties and performance of engineering ceramics and composites vi. Abaqus modelling of stress waves in a split hopkinson. Numerical split hopkinson pressure bar nshpb tests. It is a challenging task to develop a lightweight but also strong material with energy absorption capability to be used in vehicles to withstand impact and blast. A finite element model of the hopkinson bar experiment is developed in threedimensions and is used in detailed numerical analyses. This paper presents an improved specimen recovery method for the tensile split hopkinson bar tshb technique. Stress wave propagation in split hopkinson pressure bar.
Dynamic compressive and splitting tensile tests on mortar. The torsional split hopkinson bar tshb is an effective experimental technique for measuring the pure shear mechanical properties of materials at high strain rates. Finally, we found an unclassified army materials and mechanic research booklet titled design and operating characteristics of a split hopkinson pressure bar apparatus. Its main components are a gas gun, a striker bar, an incident bar and a transmission bar. An opensource split hopkinson pressure bar graphical data analysis tool has. Numerical simulations are performed using commercial explicit dynamic package abaqus explicit. Finite elements method in split hopkinson pressure bar developing process rotariu adrian, bugaru mihai, chereches tudor department of mechanics, department of mechanics military.
Using the hjc dynamic constitutive model, the split hopkinson pressure bar shpb impact test with confining pressure for concrete was simulated in the software ansyslsdyna. The split hopkinson pressure bar shpb technique is analyzed during the. A series of fem simulations of shpb test were used in designing of split hopkinson pressure bar. Feasibility of rock dynamic properties by split hopkinson pressure bar shpb was experimentally and numerically evaluated with ansyslsdyna. Can anyone give me details idea, about what kind of contact i have to define between striker bar and incident. The kolsky bar is an ideal choice to characterize the stress strain response of. Hi emeka, i performed the shpb simulation for one of my materials last year. Stress equilibrium in the split hopkinson pressure bar test x. The specimen is placed between the ends of two straight bars, called the incident bar and the transmitted bar.
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. Specimen stress equilibrium in split hopkinson pressure bar tests of ceramics at high strain rate. This approach was applied to a split hopkinson pressure bar test on an aluminum alloy at a strain rate of about 500s. Testing of soft materials using this method requires that bars made of low impedance material should be used, in order to improve signaltonoise ratio of transmitted stress. Its used to determine the stress and strain characteristics of material under dynamic impact condition. Hybrid split hopkinson pressure bar to identify impulse. Elevated rates of strain, such as those found in impact and explosive applications, have been shown to induce phenomena such as strain hardening and phase transitions that can significantly affect the strength of most materials 14.
The split hopkinson pressure bar shpb continues to be one of the most common methods of testing materials at medium rates of strain. Fe analysis of critical testing parameters in kolsky bar. Effects of insitu stresses on dynamic rock responses. However, the use of polymeric bars requires additional analysis for data reduction, temperature complications and additional restrictions compared with traditional metallic pressure bars. Stress wave propagation in a split hopkinson pressure bar. Wave dispersion and attenuation in viscoelastic split. Split hopkinson pressure bar apparatus for compression. Experimental and numerical investigations on the use of.
Improved specimen recovery in tensile split hopkinson bar. Designing a data acquisition system for a split hopkinson pressure. Abaqus, matlab to analyze and design a realistic system and its. In order to optimize their mechanical performance the characterisation of the foam behaviour at high. For splithopkinson pressure bar test simulation by ansys. We present a procedure for measuring the dynamic fractureinitiation toughness of materials. Youngs modulus is a material constant that is a measure for how much a component is deformed when a force is applied to it. Structural effects on compressive strength enhancement of. In this study, we explore split hopkinson pressure bar shpb apparatus as a tool.
From the test hopkinson could make pressure time twists that would delineate an impact event 24. Review and cite splithopkinson bar protocol, troubleshooting and other methodology information contact experts in splithopkinson bar to get answers. Gorharn faculty of technology, the open university, walton hall, milton keynes, mk7 64. Split hopkinson pressure bar test, to research by georgin et al georgin 2003, who carried. Characterisation of aluminium matrix syntactic foams. 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. Numerical split hopkinson pressure bar nshpb tests based on the reconstitution method have been used to study the structural effects. This ratio gives an indication as to the accuracy of the bar setup and efficiency of energy transfer. Split hopkinson pressure bar technique, which decouples cleverly the inertia effect in structures 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 10 4 s1 kolsky, 1949. Finite element modeling of the behavior of armor materials. A split hopkinson pressure bar technique to determine. The incident bar, transmission bar and striker bar are all made of same material and same crosssection area. The split hopkinson pressure bar shpb is most commonly used facility to obtain material properties at high strain rates. Deformation behavior of artificial rock in the split.
I am currently modelling a split hopkinson pressure bar tensile test. Finite elements method in split hopkinson pressure bar. Split hopkinson pressure bar shpb is an apparatus that is used to study. Evolution of specimen strain rate in split hopkinson bar test. Finite element modeling of strain rate experiment for soft. The strain rate is found to be controlled by the stress and strain of the. Split hopkinson pressure bar, material model, strain rate, explicit finite element method, abaqus, simulation, dma the material behavior of polymers is known to be highly dependent on the rate of loading. Development of a tensile split hopkinson pressure bar testing facility. This technique modifies the conventional split hopkinson bar apparatus by placing a thin copper disk on the impact surface of the incident bar. I have to test its dynamic imact behaviour using split hopkinson pressure bar, i have done the experiment and have the results.
Calibration is performed by comparing the wave speed of the initial pulse versus the reflected pulse and calculating the energy ratio. 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 hopkinson pressure bar shpb is one of the most important and recognized apparatus. Shpb calibration manual and sample test compression.
We present pulse shaping techniques to obtain compressive stressstrain data for brittle materials with the split hopkinson pressure bar apparatus. The high strain rate characterization of materials is usually performed using the split hopkinson pressure bar within the strain rate range 1000 s1. The impact velocity is imposed to the impactor that hits the flange of the input part. Clearly, the apparent strainrate enhancement of material strength due to structural effects cannot be considered as a genuine strainrate effect. The results show that the dispersion effect on the. There are some parameters directly related to the bars alignment such as their straightness, the impact face parallelism, and the neutral axis offset. Finite elements method in split hopkinson pressure bar developing process rotariu adrian, bugaru mihai, chereches tudor department of mechanics, department of mechanics military technical academy, politehnica university of bucharest george cosbuc avenue 8183, bucharest, splaiul independentei 3, bucharest romania. Using split hopkinson pressure bars to perform large. Full shpb tests with viscoelastic bars were simulated and the data reduced to determine the material properties of hyperelastic specimens.
Development of a split hopkinson tension bar for testing stressstrain response of particulate composites under high rates of loading except where reference is made to the work of others, the work described in this thesis is. The strain rate sensitivity of polyurea is characterized using a modified split hopkinson pressure bar shpb system. 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 most of the test duration. Dynamic behaviour of polymers at high strainrates based on.
You have to use instance and constraints options in asse. Mengfurther investigation on the dynamic compressive strength enhancement of concretelike materials based on split hopkinson pressure bar tests. Impact dynamics lab split hopkinson pressure bar youtube. A biaxial failure envelop for concrete under high strain. 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. Metal bar is loaded by impact of a projectile or by an explosive and the pressure wave propagates along the bar until it. The method is based on the trapping of residual stress waves with the use of momentum trap bars. Although shpb technique has been verified for metallic materials, the validity and accuracy of shpb results for nonmetallic materials have not been thoroughly studied. The axial strain measured directly from the strain gage and obtained from the process analysis of threewave method were compared. Although there are various setups and techniques currently in use for the splithopkinson pressure bar, the underlying principles for the test and measurement are the same. Although shpb technique has been verified for metallic materials, the validity and accuracy of shpb results for nonmetallic materials have not been. Pressure waves in soils using a splithopkinson pressure bar. Hello everyone, i am testing a bio degradable material for bone implants. Split hopkinson pressure bar is an apparatus that is used to study materials behavior under high speed deformation, where strain rate is very high.
Providing learning opportunities by designing 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 abaqus explicit dynamics simulation of wave propagation during split hopkinson pressure bar shpb test. Although there are various setups and techniques currently in use for the split hopkinson pressure bar, the underlying principles for the test and measurement are the same. Bars alignment in a split hopkinson pressure bar influences the quality of signal recorded during experiments, and thus affects the data of material properties being measured.
Split hopkinsonson bar test appartus advance instrument inc. 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. 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. I have to test its dynamic imact behaviour using split hopkinson. The confining pressure was simulated by applying constant pressure around the specimen. The solid model of the apparatus is built using cad software solidworks. Split hopkinson pressure bar tester advance instrument inc. Most of the experiment have been carried out using the split hopkinson pressure bar shpb test to generate high strain rate up to 10 3 sec1 grote et al.
Finite element simulation was conducted using abaqus to ensure that the striker cylinder sustains the. Kolskysplit hopkinson pressure bar testing of ceramics. 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. Rule of hopkinson bar the split hopkinson bar test is the most regularly used system for choosing material properties at high rates of strain. Abaqus 36, where the finitestrain viscoelastic model is builtin. Pdf materials and their development process are highly dependent on proper experimental testing under wide range of loading within which highstrain. Split hopkinson pressure bar operations manual 592014 3 operational procedure once the split hopkinson pressure bar has been setup, aligned, leveled, and commissioning is complete, the following procedure is to be. Finite element simulation for design verification of a. The most widely used experimental setup, split hopkinson pressure bar, has given significant results at high strain. The effects of different diameters, different loading rates, and different propagation distances on wave dispersion of input bars in shpb with rectangle and halfsine wave loadings were analyzed.
Hopkinson bars are usually custom made based on the needs of customers, who are mostly researchers in universities. Li school of mechanical, aerospace and civil engineering, pariser building, the university of manchester, sackville street, manchester m 9pl, uk abstract. Using the split hopkinson pressure bar to validate material. Thus buildings in those areas which have threats from explosions should be blast resistant. By ansyslsdyna i am trying to simulate the split hopkinson pressure bar shpb test. The designed split hopkinson bar consists of two metallic bars with a specimen placing in between, a striker assembly, an air compressor, instrumentation and a data acquisition system. Pdf evolution of specimen strain rate in split hopkinson. Aug 28, 2014 c viscoelastic split hopkinson pressure bar simulation. Split hopkinson pressure bar shpb has become a frequently used technique for measuring an uniaxial compressive stressstrain relationship of various engineering materials under high strain rates, the pulse shape is sensitive to the length of striker bar. Split hopkinson pressure bar graphical analysis tool. In this study, the strains of artificial rock were analyzed in order to estimate the deformation behavior of rocklike materials in the shpb test. Experimental and numerical evaluation of rock dynamic test. Metal bar is loaded by impact of a projectile or by an explosive and the pressure wave propagates along the bar until it reaches its end.
Simulation of the temperature rise in hopkinson bar. By ansyslsdyna i am trying to simulate the splithopkinson pressure bar shpb test. In the present investigation, a modified direct impact split hopkinson pressure bar apparatus was modeled using the finite element software abaqus 6. The device is composed of a hydraulic piston along with nylon input and output bars. Vishay signal conditioning amplifier instruction manual. Im using abaqus explicit and modelling the setup as 3dsymmetric. Unconfined compression experiments at a strain rate of 10s and greater were performed on indiana limestone by frew et al. The striker bar sits in the barrel at the gas gun chamber. A split hopkinson bar is used to dynamically determine material constants, for example youngs modulus or mechanical stress. A biaxial failure envelop for concrete under high strain rate conditions hyogyoung kwak1 and hangul gang2 1, 2. In the split hopkinson bar test, a short tube moulded case is sandwiched between two long bars.
Article information, pdf download for evolution of specimen strain. Split hopkinson pressure bar operations manual 592014 9 b calibration of split hopkinson pressure bar setup. Determination of dynamic fractureinitiation toughness. Shpb calibration manual and sample test compression rel, inc. The geometry was the same as in the experimental setup figure 1b.
Is there anyone who have experience on doing split hopkinson pressure bar test simulation by ansys lsdyna. Typically, the user will test many samples on one bar setup. Pulse shaping techniques for testing brittle materials with a. The classical split hopkinson pressure bar system is then composed of two axial bars incident bar and transmitter bar and a striker bar. Split hopkinson bar shb works on the principle of one dimensional wave propagation. Numerical simulation of shpb test for concrete under. Stress equilibrium in the split hopkinson pressure bar test. Experimental and numerical investigations on split hopkinson. Hybrid split hopkinson pressure bar to identify impulsedependent.
To go even higher, we must employ projectiledriven impacts that induce stresswave propagation in the sample materials. Split hopkinson pressure bar, tension testing, numerical analysis, strainrate effects. Finite elements method in split hopkinson pressure bar developing process. 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. Split hopkinson pressure bar simulation using abaqus. However, experimental studies focusing on the nonlinear wave transmission behavior of phononic crystals have been predominantly performed on 1d granular crystals using customized impact apparatus. 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. Split hopkinson pressure bar simulation using abaqus imechanica.
Split hopkinson pressure bar shpb technique has been used widely to measure the dynamic strength enhancement of concretelike materials at high strainrate between 10 1 and 10 3 s. Split hopkinson pressure bar shpb abaqus simulation. Finite element modeling of strain rate experiment for soft biological materials. The computer program was written specifically for an ibm pcxt. Dynamic behaviour of polymers at high strainrates from 101 to 104 s1 is.
The specimen strain rate in the split hopkinson bar shb test has been formulated based on a onedimensional assumption. Feb 01, 2018 the abaqus explicit dynamics simulation of wave propagation during split hopkinson pressure bar shpb test. 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. Coupled with the loading device, a highspeed photography system was used to measure the crack mouth opening. When the striker bar impacts the copper disk, a nondispersive ramp pulse propagates in the incident bar and produces a. Bar setups are explicitly used for split hopkinson pressure bar testing. A polymeric split hopkinson pressure bar technique shpb is preferred for testing materials with low mechanical impedance. When the striker bar impacts the copper disk, a nondispersive ramp pulse propagates in the incident bar and produces a nearly. An optical method of strain measurement in the split. Dynamic behaviour of polymers at high strainrates based on split hopkinson pressure bar tests y. I am modelling a shpb assembly together with the specimen, and i am having trouble with placing the loads,creating the boundary constrain between the incident, transmitter bar and the specimen.
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