Direct Measurement of Multiaxial Yield Loci as a Function of Plastic Strain
- Metallurgy Division, MSEL, National Institute of Standards and Technology, U.S. Department of Commerce, Gaithersburg, MD (United States)
A new technique has been developed to directly measure multiaxial stress-strain surfaces in sheet metal. The methodology involves using the Raghavan modification of the in-plane Marciniak biaxial stretching test to produce various multiaxial strain states, ranging from uniaxial through plane strain to balanced biaxial. An x-ray stress measuring system is used to probe the stress at a point, and the plastic strain level and state at the point is measured optically using a deforming circle. The sample undergoes pure in-plane stretching free of any frictional contacts, and the stress measurement does not depend on any assumptions beyond Bragg's law and Hooke's law. Results will be presented comparing balanced biaxial stress-strain curves parallel and normal to the rolling direction with uniaxial results. It is found that the strain hardening exponent for biaxial tension is significantly lower than the uniaxial value, and this will be discussed in terms of common assumptions used in modeling forming processes. These results form part of the data available for Benchmark 3.
- OSTI ID:
- 20726151
- Journal Information:
- AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 778; ISSN APCPCS; ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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