基于弹塑性增量分析法的均质矩形截面杆系结构失效模式识别研究

Identification study on the failure mode of truss structures with homogeneous rectangular section based on elasto-plastic incremental analysis

为了研究均质矩形截面杆系结构的失效模式,本文基于弹塑性增量分析法,采用二维平面单元建立有限元模型,并根据杆件横截面上各单元高斯积分点的应力是否达到屈服应力,计算截面内弹性区高度与横截面高度的比值,据此识别均质矩形截面杆系结构的失效模式。同时,给出可以判定截面进入塑性屈服状态时该比值的建议值。研究结果表明,与传统依据塑性极限状态时结构的等效应力云图观察结构中塑性区分布情况进而识别失效模式的方法相比,本文计算结果更精确,且为用弹塑性增量分析法识别均质矩形截面杆系结构的失效模式提供了定量依据。

In order to study the failure mode of skeletal structures with homogeneous rectangular section,the Elasto-Plastic Incremental Analysis is used in this paper.Based on the Elasto-Plastic Incremental Analysis,the finite element model of skeletal structures with homogeneous rectangular section is established by using the two-dimensional plane element.And the ratio of the height of the elastic zone in the cross section to the height of the cross section is calculated according to whether the stress of gaussian integral points of each element on the cross section reaches the yield stress.Then the failure mode of skeletal structures with homogeneous rectangular section is identified.At the same time,the proposed value of this ratio is given to decide whether the cross section entered the plastic yielding state.Researches show that compared with the traditional method which identifies the failure mode according to observing distribution of plastic zones in the structure by the equivalent stress nephogram of the structure in plastic limit state,the method proposed in this paper is more accurate,and provides a quantitative basis for the identification of failure modes of skeletal structures with homogeneous rectangular section based on the Elasto-Plastic Incremental Analysis.