Capturing Rapid Deformations: The High-Speed Optical Extensometer

Accurate measurement of material deformation under high-strain rate conditions is pivotal in materials science. Traditional contact-based methods often fall short in capturing rapid events with the necessary precision. To address this, the Innovation, Design, and Engineering Education Laboratory (IDEELab) at Mississippi State University developed the High-Speed Optical Extensometer, a non-contact measurement system capable of recording strain at unprecedented speeds.

The Need for High-Speed, Non-Contact Measurement

In dynamic testing scenarios, especially those involving Split Hopkinson Pressure Bar (SHPB) experiments, materials are subjected to rapid loading conditions. Traditional strain gauges can be intrusive and may not provide the temporal resolution required for such fast events.

The High-Speed Optical Extensometer offers a solution by utilizing optical methods to measure strain without physical contact, enabling precise, high-speed data collection without interfering with material behavior.

Technical Specifications and Innovations

The extensometer employs high-speed line scan cameras to capture deformation events with exceptional clarity:

• Frame Rate: Capable of recording up to 300,000 frames per second, allowing for detailed analysis of rapid deformation processes.

• Resolution: Offers high spatial resolution, ensuring precise measurement of strain across the specimen.

• Non-Contact Measurement: Utilizes optical techniques to eliminate the need for physical attachment to the specimen, reducing potential interference with the material's natural response.

Collaboration with REL, Inc.

IDEELab’s extensometer technology has been integrated into commercial products by REL, Inc. REL’s C1-300k High-Speed Line Scan Optical Extensometer incorporates these advancements, providing researchers and industry professionals with a reliable, high-performance tool for high-strain rate testing.

This collaboration underscores the practical impact of university-driven research on advancing industry standards.

Applications and Benefits

• Enhanced Accuracy in SHPB Testing: Improves the precision of strain measurements in high-strain rate experiments, leading to more reliable data.

• Reduced Equipment Size: The optical system enables the use of shorter incident bars in SHPB setups, making the apparatus more compact and manageable.

• Versatility: Suitable for testing a wide range of materials, from metals to polymers, under dynamic loading conditions.

Conclusion

The High-Speed Optical Extensometer developed by IDEELab represents a significant leap forward in the field of dynamic material testing. By combining high temporal resolution with non-contact measurement capabilities, this technology addresses longstanding challenges in capturing rapid deformation events.

The successful collaboration with REL, Inc. further demonstrates the extensometer’s value in both research laboratories and industrial applications, advancing the accuracy and efficiency of materials science worldwide.