New Techniques in Measuring Plastic Strain in a Memory Material
WATERVLIET ARSENAL NY
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A Nickel-Titanium memory material was studied for the purpose of characterizing its stress-strain behavior, energy absorption capacity, and cyclic response. Instrumentation problems encountered in the testing of this unique material are discussed from the standpoint of thermal recovery effects on strain readings from strain gages and LVDT-type extensometers. Nickel foil type temperature sensors were used to measure surface temperatures from heat generated in the course of plastically straining the material. In addition, the sensors also monitored the heat applied to the specimen to effect thermal recovery from the plastic strain. Temperature-time curves using a strip chart recorder exhibited possible phase changes occurring in the material during thermal recovery after the half cycle of straining.
- Metallurgy and Metallography