The theory and application of plastic anisotropy have extensively developed in the main field of sheet metal forming. Round tubes and bars are generally used for tube forming and forging; they exhibit plastic anisotropy similarly to sheets. In this paper, assuming that these materials show anisotropy with three cylindrical orthogonal symmetry axes,
r, θ and
z, we used the simple anisotropic criterion proposed by Hill in 1948 as follows: 2
C2 =
F (σ
θ- σ
z)
2 +
G (σ
z- σ
r)
2 +
H (σ
r- σ
θ)
2. In the tube materials, the ratios ε
θ/ε
r =
F/
G and ε
θ/ε
z =
H/
G are not necessarily equal to unity. For a tube of A6063 in JIS as an example,
F/
G = 0.55 and
H/
G = 0.69 were determined by a tube tensile test and a tube wall compression test, respectively. In the bar materials, we theoretically showed that anisotropy affects the mean stress in the tensile/compression test. Also, by a semi-cylinder compression test, for a round bar of A2017-F in JIS as an example,
F/
G = 0.37 was determined. Moreover, in the ring compression test for determining frictional coefficient, we found using FE analysis that anisotropy and friction affect the reduction in internal diameter.
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