SHPB Test (Split Hopkinson Pressure Bar) 

Purpose

• Used to determine dynamic mechanical properties of materials at high strain rates (≈10²–10⁴ s⁻¹).
• Common for metals, polymers, ceramics, composites, rocks, and concrete.

Principle

• A short specimen is sandwiched between two long elastic bars.
• A stress wave generated by an impact travels through the bars.
• From incident, reflected, and transmitted waves, stress–strain–strain rate of the specimen are calculated using 1D wave theory.

Main Components

1. Striker bar – impacts the incident bar to generate stress waves
2. Incident bar – carries incident and reflected waves
3. Transmission bar – carries transmitted wave
4. Specimen – placed between incident and transmission bars
5. Strain gauges – mounted on bars to record waves
6. Data acquisition system – high-speed recording
7. Gas gun / launcher – accelerates striker bar

Measured Outputs

1. Dynamic stress–strain curve
2. Strain rate
3. Dynamic modulus
4. Yield strength, flow stress, failure behavior
5. Key Assumptions
6. One-dimensional elastic wave propagation in bars
7. Uniform stress and strain in specimen
8. Frictionless interfaces (often lubricated)

9. Applications

10. Measures material behaviour at high strain rates (impact/rapid loading).
11. Used for dynamic stress–strain characterization of metals, polymers, composites, ceramics, rocks, and concrete.
12. Applied in automotive crash, aerospace impact, and defence/ballistics studies.
13. Helps evaluate impact, blast, and shock resistance of materials.
14. Provides data for material modelling and simulation validation.
15. Used in civil and mining engineering for dynamic behaviour of rocks and concrete