端部受斜冲击的刚塑性悬臂梁的双铰模型

DOUBLE HINGE MODEL FOR OBLIQUE IMPACT AT THE TIP OF A RIGID PLASTIC CANTILEVER

斜冲击载荷作用在刚塑性悬臂梁的端部，引起作用在梁横截面处的弯矩以及轴力；在发生塑性变形截面处，弯矩及轴力满足交互作用屈服条件。广义应力在移行铰的邻域不违背屈服条件，屈服函数可在移行铰的背面取极大值，移行铰处的剪切力不必为零。如果悬臂梁足够长，在响应的初始阶段移行铰处非零的剪力会在梁上引起多铰变形。通过对双铰模型与单铰模型的比较发现，双铰模型计算的结果与单铰模型计算的结果很接近，单铰模型作为一个近似模型具有一定的合理性。

An oblique impulsive loading applied on a point at the tip of a rigid plastic cantilever can introduce axial stress and bending moment acting in any cross sections of the beam.The axial force and bending moment at the deformed section must satisfy the yield condition.The yield function satisfies a local extreme at the back side of the traveling hinge where yield occurs.With the coupling of the axial force and bending moment,the shear force at a traveling hinge is not necessary to be zero.This non vanishing shear stress gives multiple travelling hinges if the beam is sufficient long.Calculations of a double hinge model are compared with that of the single hinge model.It demonstrates that single hinge model is reasonable as an approximation of this model.