Mater.Phys.Mech.(MPM)
No 1, Vol. 44, 2020, pages 48-60

#### STRAIN-HARDENING EFFECT ON CRITICAL STRAIN ASSESSMENT OF PIPE PLASTIC BENDING AT BUCKLING

M. Zheng, Z.M. Li

#### Abstract

 In the current paper, the characteristic factor β=[1 +0.904(σb / σs) · (1-σs / σb)] is extracted from the analytical solution of the bending moment for a rectangular strainhardening beam first. Thereafter, the characteristic factor β is transplanted into the previously proposed assessment of the critical buckling strain for rigid-perfectly plastic bending pipe by analogy method, thus an extended expression of the critical buckling strain for a pipe plastic bending including strain-hardening effect is developed, $\varepsilon_c=0.19 \frac{t}{r}\cdot \Big(1+\frac{1}{1.78r}\Big) \cdot [0.096+ 0.904/ (1-n)^2 ].$ Moreover, available test data is employed to check the suitability of the extended expression. The results show that the extended expression is reasonable to reveal the effect of Hollomon type strain-hardening behavior on the critical buckling strain of pipe plastic bending. Keywords: plastic bending, buckling, critical strain, strain-hardening, pipe

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