Split Hopkinson Pressure Bar

The Split Hopkinson Pressure Bar (SHPB), also known as a Kolsky Bar, is a dynamic system designed to test the high strain rate material properties of various materials.

This system is instrumental in capturing the material response to sudden dynamic events and allows for the tuning of strain rates for different materials in either tension or compression.

How it Works

The SHPB system imparts a known amount of energy into materials, facilitating microsecond testing. It can be configured for single- or multiple-hit events using a matched momentum trap in compression tests. The system simulates dynamic loads akin to those experienced in scenarios such as vehicle crashes or high-energy impacts.

The striker speeds are adjustable, capable of exceeding 300 ft/sec, and strain rates can surpass 10,000/sec. Testing can be performed on samples with diameters ranging from 1/8 inch to 3 inches. The onboard heating and cooling system allows for conditioning samples in any thermal profile from -60C to 225C. The current setup features a half-inch bar diameter set up for tension specimens.

In the tension and compression configuration the SHPB operates by subjecting materials to controlled impact loading. It comprises two bars, one acting as a striker and the other as a receiver, with a sample material placed in between. When the striker bar impacts the receiver bar, a stress wave propagates through the bars and the sample material. This process creates a high-strain-rate condition within the sample, enabling researchers to study its mechanical response under rapid deformation.

The SHPB system can be used as a direct impact testing system. In this configuration a tailorable projectile can be launched at a static object.

What it is Used For

The military’s interest in Hopkinson bars stems from the need to understand how materials behave under dynamic loading conditions, which are common in battlefield scenarios. By studying materials at high strain rates, researchers can better simulate real-world situations such as ballistic impacts, explosions, and high-speed collisions.

This knowledge is crucial for designing protective equipment, armored vehicles, and structural components that can withstand the stresses and forces encountered in combat environments, thereby enhancing the safety and effectiveness of military personnel and equipment.

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