Metallurgical and Materials Transactions A

, Volume 38, Issue 11, pp 2655–2665 | Cite as

Improved Pulse Shaping to Achieve Constant Strain Rate and Stress Equilibrium in Split-Hopkinson Pressure Bar Testing

  • Kenneth S. VecchioEmail author
  • Fengchun Jiang
Symposium: Dynamic Behavior of Materials


Assuring a constant strain rate during dynamic testing is highly desirable to support the development of physically based predictive, constitutive material models. Many dynamic tests conducted on high-work-hardening materials, or materials that do not display a classic power-law-type hardening behavior, such as materials exhibiting complex sigmoidal concave-upward hardening (shape-memory alloys or a number of textured hexagonal metals due to deformation twinning), often result in continuously decreasing strain rates as a function of strain throughout the test. Incident pulse shaping has not been fully developed or successfully demonstrated over a large range of strain in high work hardening or complex-hardening materials. To shape an incident pulse for a constant strain rate in a split-Hopkinson pressure bar (SHPB) test, a high-strength, high-work-hardening rate (HSHWHR) material was selected to fabricate the pulse shaper. Several test sample materials, namely, 50-50 NiTi superelastic alloy, higher strength 60NiTi alloy, tungsten single crystals, interstitial-free (IF) steel, and MACOR (a glassy ceramic), which display a range of strength levels, work-hardening rates, and superelastic hardening behavior in the case of 50-50 NiTi, were tested in the SHPB with and without a pulse shaper at different temperatures and strain rates. The current experiments demonstrate that HSHWHR pulse-shaper materials are ideally suited to shape the incident pulse to achieve constant strain rates and achieve stress state equilibrium, while inherently dampening high frequency oscillations in the incident pulse.


Pulse Shaper Constant Strain Rate Incident Pulse Stress Equilibrium Stress Pulse 
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Authors and Affiliations

  1. 1.NanoEngineering DepartmentUniversity of California, San DiegoLa JollaUSA

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