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Abstract: Accurate upper-bound solutions for several typical plastic
forming problems are found, such as an obtuse wedge under the action of
a one-sided uniform pressure, the extension of a strip with ideal cuts,
and steady plastic flow, for example, drawing of a strip through a
tapered die with smooth walls, forward extrusion of a sheet from a
container with smooth walls through a slit, etc. The slip-line fields
consist of uniform fields and central fan fields in these problems. By
using of upper-bound technique, a general formula of the upper-bound
solution with n being suitable for the plastic problems is deduced. Then
, when n®¥
the accurate upper bound solutions to be identically equal to the
slip-line solutions are obtained.
Key words: Uniform fields Central fan fields Reduction ratio Accurate
upper-bound solutions
CLC No: O344
TG31
国家自然科学基金(50075025)、教育部骨干教师基金(2000K53149)和留学回国人员科研启动基金(教外司留2001.498)资助项目.
Received 20020403, received in revised form 20020820
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