受内压厚壁圆筒的塑性变形条件与脆断分析  

Investigation of plastic deformation and brittle fracture in a thick-walled cylinder subjected to internal pressure

作　　者：李智慧 李玉龙[1] 汤安民[3] Li Zhihui;Li Yulong;Tang Anmin(School of Aeronautics,Northwestern Polytechnical University,710072,Xi’an,China;School of Mechanical Engineering,Baoji University of Arts and Sciences,721016,Baoji,China;School of Civil Engineering and Architecture,Xi’an University of Technology,710048,Xi’an,China)

机构地区：[1]西北工业大学航空学院,西安710072 [2]宝鸡文理学院机械工程学院,宝鸡721016 [3]西安理工大学土木建筑工程学院,西安710048

出　　处：《应用力学学报》2020年第4期1515-1520,I0009,共7页Chinese Journal of Applied Mechanics

基　　金：国家自然科学基金(11832015,11302167)。

摘　　要：基于弹性约束的概念,分析了受内压厚壁圆筒产生塑性变形的条件。发现厚壁圆筒发生脆性断裂的根本原因是,圆筒内壁高应力区因受到外壁低应力区的弹性约束,在应力达到材料的屈服条件时不能产生塑性变形。通过计算给出了受内压管道避免脆性断裂的壁厚设计和选材方法。研究结果表明,对外直径2b=300mm的不同管线钢,随屈强比从0.51增大到0.91,其临界壁厚由62.2mm降低至12.9mm,极限内压由225.2MPa降低至69.0MPa,即选用材料的屈强比越低,设计管道不发生脆断的壁厚尺寸范围越大,在临界壁厚尺寸范围内管道的极限承载能力也越高。因此使用较低屈强比的材料并控制合理的管道壁厚,能使管道在承受意外的冲击内压时,出现全面塑性变形,以吸收冲击能量,避免管道脆性断裂的发生。The plastic deformation condition of a thick-walled cylinder subjected to internal pressure is analyzed based on the idea of elastic constraint, and it is found that the fundamental reason for brittle fracture of a thick-walled cylinder is that the high stress zone on the inner wall of a cylinder is restrained by the low stress zone on the outer wall, and the plastic deformation cannot be generated freely when the stress state reaches the yield condition of the material. Through theoretical calculation, the wall thickness design and material selection of internal pressure pipeline are given to avoid the occurrence of brittle fracture. Results show that, for different types of pipeline steels with external diameter 2 b=300 mm, the critical wall thickness decreases from 62.2 mm to 12.9 mm, and the limiting internal pressure decreases from 225.2 MPa to 69.0 MPa as the ratio of yield strength and tensile strength increases from 0.51 to 0.91. That is, the lower the ratio of yield strength and tensile strength of the selected material, the larger the range of the wall thickness size without brittle fracture, and the higher the ultimate bearing capacity of the pipeline within the range of the critical wall thickness. Therefore, the use of materials with lower ratio of yield strength and tensile strength and the control of reasonable pipe wall thickness can make the pipe absorb the impact energy with overall plastic deformation, when it is subjected to unexpected impact internal pressure, so as to avoid the brittle fracture of the pipe.

关 键 词：厚壁圆筒 弹性约束 脆性断裂 塑性变形 

分 类 号：O346.1[理学—固体力学]