内压圆筒斜接管在面内循环弯曲载荷作用下的棘轮效应研究

利用自行设计的圆筒斜接管面内弯曲加载装置,采用电阻应变法,在多轴疲劳实验机上对面内循环弯曲载荷作用下的20#钢内压圆筒斜接管进行了棘轮效应试验研究,发现斜接管结构的锐角区存在棘轮应变,且主要发生在第一主应变方向即指向焊缝的方向。对于所研究的结构,最大棘轮应变点出现在对称面锐角区的接管侧。采用阶梯加载的方法获得了结构的棘轮边界点。利用修正的Jiang-Sehitoglu随动强化模型(MJS)对结构进行了循环塑性分析,并按日本三维有限元应力评价委员会(C-TDF)提出的等效塑性应变增量控制法确定了结构棘轮边界线,可用于评价结构的塑性安定性。

Ratchetting Study of Pressurized Lateral Nozzle of Cylinder Subjected to Cyclic in-plane Bending

Ratchetting of pressurized lateral nozzle of cylinder made of 200 carbon steel was experimentally studied with a muhiaxial fatigue testing system and a self- designed bending apparatus for lateral nozzle structure. Ratchetting strains were acquired by a multi -channel strain processor with strain gauges. Ratehetting strains were detected around the acute angle region of the structure. And it was founded that ratchetting occured in the direction of the first principle strain, which is directed to the intersecting weld. The maximum rateetting strain occured at the nozzle side of the actute angle region in the symmetrical plane for the disccused structue. Ratehetting boundary values of gauged points were determined by step pressure loading. MJS（ Modifed Jiang- Sehitoglu） kinetic hardening model was used to analysis the cy- clic plasticity behavior of the studied structure. And Ratchetting boundary of the structure was determined with the equivalent plastic strain increment controlling method of C - TDF （The Committee of Three Di- mensional Finite Element Stress Evaluation）, which may be used to evaluate the shakedown of the structure.