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High Strain Rate Testing Services

Using Controlled Impulses of Energy for High Strain Rate Material Testing

A car crash, a ballistic event, a volcano, an IED explosion, football players’ helmets colliding, and high speed machining. What do these events have in common? The materials in all of these circumstances are subject to a high rate of deformation. The performance of materials under a high strain rate can be significantly different than the performance under quasi-static loading conditions. (slower loading rate)

Government mandates for fuel-efficient vehicles lends impetus for vehicle manufacturers to study weight reduction strategies, without sacrificing safety. Engineers are developing and/or evaluating lighter materials that maintain required strength and energy adsorption during an impact event. The Split Hopkinson Pressure Bar / Kolsky Bar can be utilized to understand material properties at high strain rates because it provides a controlled impulse of energy that simulates what the material will experience in a dynamic event.

How a Split Hopkinson Pressure Bar Works
 
The most common Split Hopkinson testing is in compression as shown in the diagram to the left. Traditional uses of the Split Hopkinson Pressure Bar / Kolsky Bar include:

  • High strain rate testing
  • Material characterization
  • Material response
  • Johnson-Cook parameters
 

Applications

New methods are being developed to test in both tension and shear. Likewise, new applications for this test include:

  • Prediction of volcanic eruptions
  • Viscoelastic response
  • Earthquake waves
  • Soil (aggregates) in shear
  • Development of explosives
  • Blunt trauma

Split Hopkinson Pressure Bar / Kolsky Bar has proven to be successful in the evaluation of energy absorbing materials including metals, glasses, ceramics, polymers, and foams. See the reference material for examples in various applications.

 
REL's SURE-Bright
The Split Hopkinson Pressure Bar / Kolsky Bar runs by a gas gun being pressurized and released. This causes the striker bar to impact the incidence bar. The incident pulse wave triggers the oscilloscope which then begins to record the pulse signals. These pulse signals are produced by the change in resistance in the strain gages on the incidence and transmission bars. Raw data is collected and stored in a graph of voltage vs. time and is then converted to a stress-strain plot.
 
Split-Hopkinson Pressure Bar Lab
 
REL has a Split Hopkinson Pressure Bar / Kolsky Bar Laboratory (pictured above) complete with test material preparation, X-Ray, SEM, and for testing and evaluation of new methods. REL tailors to the needs of customers to determine the best test method for their individual material needs. REL provides machined test samples and striker bars.
Striker Bars
Striker Bars
SHPB Test Sample

Before & After Test Sample
 
REL provides custom-built Split Hopkinson Pressure Bars / Kolsky Bars specific to customer’s laboratories and built to their needs.

Dynamic Testing capabilities of REL’s SURE-TestTM Systems

SURE-Launch Automated Gas Guns

High Strain Rate Compression Testing

  • Rock
  • Metal
  • Polymers
  • Memory Foam
  • Aluminum Foam

High Strain Rate Tension Testing
(with High Speed Imaging, SURE-BrightTM Lighting Systems and Integrated DIC in SURE-PulseTM Data Analysis Software)

  • Standard and High Strength Metal Alloys
  • Glass Fiber – Epoxy Composite
  • Film tensile tests

REL SURE-Launch

SURE-Servo Dynamic Test Module

3-Point Bend Testing with Edge/Point Tracking in SURE-PulseTM Data Analysis Software

Momentum Transfer Tests

Lower Strain Rate (Range)

  • Foam
  • Tension comparison to high strain rate tests

REL SURE-Servo

SURE-Temp Specimen Heater

High and Low Temperature Tests

  • Specimen heating up to 1000˚C
  • Specimen cooling down to -100˚C

REL SURE-Temp

Other Dynamic Tests

  • Drop Tests
  • Pipe Burst Testing
  • Film Testing
  • 50 G Testing
Contact REL to learn more about our experience and how our systems can help you with your high strain rate material testing.
REL Inc.
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