Split Hopkinson Pressure Bar Brochure LR

7/25/2019 Split Hopkinson Pressure Bar Brochure LR

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Split HopkinsonPressure Bar

High Strain RateMaterial Testing

Split HopkinsonPressure Bar

High Strain RateMaterial Testing


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SAMPLE MATERIALSSAMPLE MATERIALS

A Split Hopkinson Pressure Bar (SHPB) is used to obtain highstrain rate material properties.The bar is used to impose a dynamicload on a material specimen akin to loads the material will experience in

service. Determining how the material properties change under service loadscan yield critical performance data.

REL's precision-made Split Hopkinson Pressure Bar includes sophisticatedyet intuitive technology to simplif y the process for the operator. Use of thelatest data recording devices and strain gauges ensure accurate measure-ments of material properties at a variety of strain rates.

The Split Hopkinson Pressure Bar by REL, Ican be found throughout the world and under tdirection of research institutions, government la

private businesses and a wide varietymaterial testing agenci

REL, Inc. has provided SHPB equipmentmaterial testing to the following organizatio

Johns Hopkins Universit

Youngstown State Universit

University of Florid

Oak Ridge National Laborator

Contact REL, Inc.

(906) 337-30to discuss yo

material analyrequiremen

oIDirection

Positive x

i t

INCIDENT BAR TRANSMISSION BAR

i = initial pulse

r = reflected pulse oI = specimen length

t = transmitted pulse

SPECIMENSPECIMEN

r

REL, Inc. manufactures steel and polymer Split Hopkinson Pressure Barsystems that are configurable to test compression, tension and torsionsamples. Sample sizes can range in diameter from 0.125" up to 3.000"and consist of a variety of materials, including:

Metal Alloys Foams and Plastics Composite and Ceramics Bio-tissue

Deformed sample shown for comparative purposes.Deformation of tested samples will vary depending on the material.

*

COMPRESSIONSPLIT HOPKINSONPRESSURE BARDESIGN

TENSILE SPECIMENAPPROXIMATELY:

0.375"W x 2.50"L x 0.125"H

REL, Inc. offers a tensionSplit Hopkinson Pressure Bar designthat uses a machined tensile specimen forobtaining the most accurate test data.


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SPLIT HOPKINSONPRESSURE BAROPERATION

SPLIT HOPKINSONPRESSURE BAROPERATION

The purpose of Split Hopkinson Pressure Bartesting is to obtain high strain rate materialproperties.

(A)To initiate high strain rate testing of amaterial, a specimen is loaded between theincident and transmission bars. (B ) Next,the striker bar launcher is pressurized withhelium or nitrogen. When fired, the launcherreleases the gas and propels a striker bar

into the end of the incident bar. The collisioncreates a compression pulse, or stress wave,that propagates through the bar toward thespecimen. (C)The incident wave is recordedby the incident strain gauge. Once the wavereaches the specimen, it splits into twosmaller waves. (D)The transmitted wavetravels through the specimen and into thetransmission bar where the energy isrecorded by the transmission strain gauge.The second wave is reflected away fromthe specimen and travels back down theincident bar. (E)At the end of the Split Hop-

kinson Pressure Bar, a stop bar absorbs theimpact of the transmission bar to completethe test. (F) Both strain gauges measure thestrain duration and amplification in the bars.The reflected (tensile pulse) recorded by theincidence strain gauge is used to calculatestrain. The portion of the compression pulsethat continues through the specimen isrecorded by the transmission gauge andis used to calculate stress. Data from thestrain gauges is routed through amplifiersand an oscilloscope to a laptop computerwhere it is stored.

OSCILLOSCOPE GRAPH

Figure 1 shows how a typical oscilloscopeoutput graph is displayed on a computer.The incident wave, transmitted wave andreflected wave are simultaneously collectedand presented in a graph of Voltage (y-axis)versus Time (x-axis).

BAR SUPPORT

The incident , transmission and stop barsare precision aligned using a series of barsupports. Each bar support moves laterallyalong an alignment key and is secured to themounting rail using built-in screw clamps.To further assist with leveling, the supports

glide on top of a blanchard ground surface.Proper bar alignment is critical for obtainingaccurate test results and minimizes theamount of noise in your recorded data.


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OSCILLOSCOPE & BRIDGE AMPLIFIERS

The strain gauges are routed through bridgeamplifiers (shown in yellow) and an oscillo-scope. Data from each gauge is conditionedand amplified for multi-channel, simultaneousdynamic recording and display. The oscillo-

scope converts the measured datafrom an analog signal to digital.RELs proprietary software furtherconverts the signal into a dynamicstress versus strain curve (Fig. 2).

DYNAMICSTRAIN GAUGE

REL uses high-precisibonded resistance strgauges to capture enfrom stress waves. Tgauges are adheredthe surface of the incand transmission barSignals transmitted frthe bar to the gauge captured and convertby RELs proprietary dacquisition system.

STRIKER BARS

Striker bars can be madefrom steel or polymers andsupplied at different diameters (0.25" up to 3"custom) and lengths (3" up to 24"). Various lengstriker bars will produce different loading duratio


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LAUNCHER CONTROLS

The striker bar launcher controls inclua gas fill valve (yellow handle), gas lease valve (silver lever) and a breeload adjustment control (large black diaTurning the dial moves a positioning r

inside of the launcher, which pushes tstriker bar forward in the breech.

STRIKER BAR LAUNCHER

The velocity of the striker bar projectile is con-trolled by pressurized helium or nitrogen thatis forced into the launch chamber. The type ofmaterial being tested and the construction ofthe striker bars in use generally determineoperating pressure.

STRESS -VS- STRAIN GRAPH

Data collected from the REL Split Hopkinson Pressure Bar (See Fig. 1)processed through a series of formulas to obtain final data (shown abovREL includes an intuitive graphical user interface for the operator to quickacquire dynamic material properties.


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EQUIPMENT SPECIFICATIONSEQUIPMENT SPECIFICATIONS

MATERIAL TESTINANDANALYS

REL, Inc. offers comprehensSplit Hopkinson Pressure Bar test

with complete material analy

For more information, contan REL material specialis

(906) 337-3018 or visit company web site

www.relinc.

SYSTEM FLEXIBILITY

- System Type (Compression, Tension or Torsion)

- System Material Construction (Steel, Polymer, etc.)

- Total Length of System

- Incident, Compression and Stop Bar Diameter

- Incident, Compression and Stop Bar Length

- Striker Bar Diameter and Length

- Striker Bar Launcher Pressure Range Requirement

* REL Split Hopkinson Pressure Bar dimensions shown for example compredesign only. Complete system build requirements will determine final dimenand equipment specifications.

REL, Inc. reser ves the right, under its Continuous Improvement Policy, to chconstruction or design details and f urnish product when so altered witreference to illustrations or specifications used herein.

Copyright 2012 REL, Inc. All rights reserved.Litho in U.S.A. Form No. 1000-06-12

*EXAMPLE COMPRESSION DESIGN

- Strain Gauge Type and Construction

- Momentum Trap Inclusion

- Acquisition System Inclusion(Computer, Amplifiers & Oscilloscope)

Documents

Split Hopkinson Pressure Bar Brochure LR