5Chakrabarty J. Theory of plasticity[M]. New York: McGraw-Hill Book Company, 1987: 99.
6Bibel G D, Kicher T E Reduction of springback and residual stresses during winding of a helical spring[J]. Journal ofEngineering for Industry, 1991, 113(2): 214-217.
7Yu T X, Johnson W. Influence of axial force on the elastic-plastic bending and springback of a beam[J]. Journal of Mechanical Working Technology, 1982, 6(1): 5-21.
8E1-Domiaty A, Shabaik A H. Bending of work-hardening metals under the influence of axial load[J]. Journal of Mechanical Working Technology, 1984, 10(1): 57-66.