point of inflection

The prime results include: 1) discriminant equation which clarifies the mode of instability, snap_back or snap_through, was established; 2) analytical solution was given out for the double shear beam and the load_displacement diagram for monotonic loading was presented for a full process; and 3) the problem of the energy release induced by instability was discussed.

在研究 (Ⅰ )的基础上 ,研究了剪切梁模型在裂纹萌生和失稳扩展阶段的行为特性 ,1)给出了软化失稳 (snap_through)和回折失稳 (snap_back)两种失稳行为发生的条件· 2 )对剪切梁在反平面剪切载荷及侧压力共同作用下的力学行为作了解析分析计算 ,给出了结构的位移—载荷全过程曲线· 3)讨论了失稳过程中的能量释放问题 ,并给出了回折失稳过程中结构对外界的能量释放的计算式