Characterization of Dynamic Material Response

Contact Information

Kathryn A. Dannemann, Ph.D.
Principal Engineer
Computational Mechanics
(210) 522-2523

Sidney Chocron, Ph.D.
Senior Research Engineer
Computational Mechanics
(210) 522-3698

image: SwRI High Rate Test Facility

SwRI High Rate Test Facility


image: Dynamic mechanical test specimens

Dynamic mechanical test specimens


image: Compressive shear band and associated local microcracking in a tungsten alloy tested at a high 
					strain rate

Compressive shear band and associated local microcracking in a tungsten alloy tested at a high strain rate


image: Shear failure in glass specimen following confined compression testing

Shear failure in glass specimen following confined compression testing


image: Damage profile captured with numerical simulation

Damage profile captured with numerical simulation

The performance of materials at high strain rates is of interest for various applications, including structural, military, and sports. Southwest Research Institute (SwRI) has a long history of characterizing the high strain rate response of materials. The SwRI High Rate Test Laboratory housing the Split-Hopkinson pressure bar apparatus has been designated an ASME Historic Mechanical Engineering Landmark, based on pioneering work in the 1960s that allowed direct generation of the complete stress-strain curve for a single impact.

High Rate Evaluation Facility

The SwRI High Rate Evaluation Facility is equipped with instrumentation for measuring, recording, and analyzing test data for strain rates approaching 5,000 s-1. High-speed imaging systems are also available to record the high rate response.

Lab capabilities include high rate testing in tension, compression, torsion and three-point bend. Microstructural characterization of tested material can be accomplished to determine deformation and failure mechanisms. The facility is staffed with experienced personnel who can adapt test conditions to meet unique requirements.

Dynamic Test Capability

  • Tension (epsilon < 2 × 103 s-1)
  • Compression (epsilon < 5 × 103 s-1)
  • Torsion (epsilon < 2 × 102 s-1)
  • Fracture toughness
  • Taylor impact (epsilon~105 s-1)

Materials Testing Experience

  • Armor materials
  • Blast-resistant materials
  • Metals
  • Ceramics
  • Glass
  • Powders/granular materials
  • Biological materials (tendons, ligaments, bone)
  • Porous/foam materials
  • Polymers
  • Fiber composites
  • Fabrics
  • Concrete
  • Rocks and soils

Materials Characterization

  • Deformation response: stress-strain curves
  • Strain rate effects
  • Failure mechanism determination
  • Shear and delamination testing
  • Dynamic deformation and displacement measurements
  • Fracture
  • Constitutive model development
  • Determination of Johnson-Cook model constants

Dynamic Test Equipment

  • Split Hopkinson pressure bar systems
    • Compression
    • Tension (direct, indirect)
    • Environments: vacuum, air, Ar, N
  • High temperature ≤ 1000 °C
  • High-speed torsion actuator
  • High-speed data acquisition system
  • High-speed imaging systems (up to 106 frames/second)
  • High-speed strain gage amplifiers
  • Displacement mapping system for 3-D dynamic strain measurements
  • Confining pressure apparatus (≤ 500 MPa)

Support Capabilities and Facilities

  • Numerical simulations of experiments ((LS-DYNA, CTH, EPIC)
  • Metallurgical laboratory
    • Optical and scanning electron microscopy
    • Damage profile captured with numerical simulation
    • Energy dispersive spectroscopy
    • Auger spectroscopy
    • X-ray diffraction
  • Ballistics and Explosives Range
  • Mechanical test laboratory
    • Low strain rate material characterization
    • Tri-axial compression and extension
    • High-temperature testing
    • Testing in extreme environments
    • Customized testing
  • Full-service machine shop

Related Terminology

high strain rate  •  dynamic mechanical behavior  •  dynamic fracture toughness  •  Split-Hopkinson pressure bar  •  confining pressure  •  high-speed imaging  •  failure mechanisms  •  shear banding  •  homeland security

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Southwest Research Institute® (SwRI®), headquartered in San Antonio, Texas, is a multidisciplinary, independent, nonprofit, applied engineering and physical sciences research and development organization with 9 technical divisions.