跳回失稳研究

本文以单元形函数作为单位分解函数，位移间断用富集节点的附加自由度表示，建立了允许单元内部位移非连续的统一位移场函数。结合粘结裂纹模型，研究了结构从延性到脆性失稳的特性以及引起脆性破坏的影响因素。数值计算表明：增加脆性指数可以提高结构的承载稳定性；初始预制缝可以增加结构延性但会降低极限承载力。

Study on snap-back instability of structure

In this paper, the non-discontinuous displacement field in structure allowing incorporation of discontinuous mode intra-element is established by using finite element shape function as partitions of unity, and the displacement jump across a crack is presented by extra degrees of freedom at enriched node. Combining with the cohesive crack model, the behavior of structure in the range from ductile to brittle instability and the factors influencing the brittle failure are studied. Numerical examples show that high brittleness index can improve the bearing capacity stability of the structure and the existence of crack set up in advance will increase the ductility of the structure, but it may result in the reduction of ultimate bearing capacity.