Hello all. For some time now I've been looking for a good source of
rate-dependent stress/strain data for 7075-T651 Aluminum. Any useful
input would be very much appreciated.
Thanks.
How long have you been looking? Where have you been looking?
A few minutes in one of the right places (Engineering Index) turned up
the following three magazine articles with data for other tempers:
TENSILE TESTING OF MATERIALS AT HIGH RATES OF STRAIN.
Nicholas, Theodore (US Air Force Wright Aeronaut Lab, Wright-Patterson
AFB, Ohio) Source: Experimental Mechanics, v 21, n 5, May, 1981, p
177-185
Abstract: A tension version of the split Hopkinson bar or Kolsky
apparatus is developed for conducting tests in tension at high rates of
strain up to 10**3 s** minus **1. A number of aluminum, titanium, and
steel alloys tested in tension show increasing degrees of rate
sensitivity above 10 to 10**2 s** minus **1. Tests on 6061-T651 and
7075-T6 aluminum show measurable strain-rate sensitivity in tension at
the highest strain rates, although similar tests in compression in the
literature show essentially no strain-rate sensitivity. Details of the
apparatus and instrumentation and guidelines for its use are presented.
(20 refs.)
Revised form for the Johnson-Cook strength model
Rule, William K. (Univ of Alabama); Jones, S.E. Source: International
Journal of Impact Engineering, v 21, n 8, Sep, 1998, p 609-624
Abstract: Strength models play a key role in the numerical simulation
of impact events. A revised form of the Johnson-Cook strength model is
proposed in this paper. The revised model treats the sudden
strengthening that many ductile metals exhibit at strain rates greater
than 104/s. Strain rates of this magnitude are generally
considered to be beyond the capability of the split-Hopkinson pressure
bar and so such abrupt strengthening behavior is often not observed and
reported. A method to economically estimate all eight coefficients of
the revised strength model using quasi-static tension data and Taylor
impact test data reduced with a modified version of the EPIC finite
element code is also described. Revised strength model coefficients
were determined for: 7075-T6 aluminum, OFHC copper, wrought iron, and a
high-strength steel (Astralloy-V), A good fit to the quasi-static
tension data and Taylor impact test results was obtained for these four
different metals. The behavior of the revised strength model at high
strain rates also compared favorably with independent predictions from
an analytical model
calibrated with the Taylor impact data. (16 refs.)
Strain rate effects on tensile deformation of 2024-O and 7075-O
aluminum alloy sheet
Dorward, R.C. (Kaiser Aluminum & Chemical Corp); Hasse, K.R. Source:
Journal of Materials Engineering and Performance, v 4, n 2, Apr, 1995,
p 216-220
Abstract: Coarse- and fine-grained 2024 and 7075 alloy sheets were
tensile tested at strain rates ranging from 10-3 to
102/s. Ultimate tensile strengths decreased up to
10-1/s and increased at higher strain rates. Total
elongations at failure showed the same behavior with uniform and
localized components showing similar dependencies on strain rate. The
initial ductility decrease at low strain rates is attributed to thermal
gradients associated with a transition from isothermal to adiabatic
conditions. At strain rates above 10-1/s, ductility
increases as strain rate hardening effects become dominant. Although
the fine-grained materials had higher elongations than their
coarse-grained counterparts, both variants responded similarly to
changes in strain rate. The only difference was a tendency for
off-center failures in coarse-grained specimens tested at the slower
strain rates. (14 refs.) (Author abstract)
You might also try the Metadex data base at an engineering library. It
has search by alloy designation.
Pittsburgh Pete
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