初始缺陷和比例加载路径对圆柱壳弹塑性稳定性的影响

EFFECTS OF INITIAL IMPERFECTION AND PROPORTIONAL LOAD PATH ON ELASTOPLASTIC STABILITY OF CYLINDRICAL SHELL

应用非线性弹塑性稳定性理论研究圆柱壳在轴向力和内压联合作用下的弹塑性稳定性问题,得到了不同比例加载路径、初始缺陷和塑性变形发展程度对弹塑性失稳的影响规律曲线。结果表明,在内压的作用下,柱壳的临界轴向压应力在初始阶段有所提高,但从某一内压值开始将会有所下降。对于同一比例加载路径,随着缺陷因子的增加,临界屈曲轴向压应力随着相应地递减。而对于同样的缺陷因子,比例加载参数小于1.0时,临界屈曲轴向压应力随着比例加载参数的增大而增大;比例加载参数大于1.0时,临界屈曲轴向压应力随着比例加载参数的增大而减小;比例加载参数等于1.0为理想加载比例参数值。该研究丰富了内高压成形工艺的理论基础。

The elastic-plastic stability problems of cylindrical shell under internal pressure and axial compression are studied on the basis of the theory of nonlinear elastoplastic stability. The principle of effects of different proportional load paths, initial imperfect and plastic deformation on elastic-plastic sta bility is obtained. Results show that critical wrinkling axial compression stresses will increase at the beginning stage, but the stresses will reduce when the internal pressure reachesa certain value. And the critical wrinkling axial compression stresses will descend with the increment of imperfect factors. The study shows the following as well, for the same imperfect factor, the critical wrinkling axial compression stresses will increase with the increment of the proportional load parameter D when D value less than 1.0, but the values will fall down when D greater than 1.0. The ideal load path is the proportional load parameter equal to 1.0. The investigations enrich the theoretical background for internal high pressure forming technology.