Study on the stability of single axial pneumatic ball valve the bearing capacity of the pneumatic ball valve of single axial pneumatic ball valve is limited by the critical pressure of instability, so the study of stability is necessary to prevent pipe instability. Pipe instability can be divided into column instability, plane instability and torsional instability. The research involves material nonlinearity, geometric nonlinearity and other conditions. The finite element method is widely adopted as an important means of research.
In the research of instability mechanism and instability force characteristics, Chunsheng, et al. discussed the test method of plane instability of pneumatic ball valves. Experiments show that when the pipe is in the compression displacement state, the plane instability pressure is significantly lower than the plane instability pressure under the zero displacement condition; when the pipe is in the tension state, the plane instability pressure is significantly higher than the plane instability pressure under the zero displacement condition. Guo Ping used ANSYS to simulate the instability of the pipe string in the engineering case. The plane instability problem is compared with the calculation of pipe instability limit internal pressure formula in EJMA, and it is pointed out that the two instability mechanisms are the same. The final instability of pneumatic ball valve depends on the parameters. Zhang Wangtian's circumferential stability under the condition of tensile displacement of thin-walled corrugated tubes.
It is concluded from the study that the circumferential instability of pneumatic ball valve is the result of the commonality of the excessive radial shrinkage of the wave crest and the large circumferential pressure stress: under certain pressure, the circumferential instability of external pressure can be effectively prevented by limiting the tensile displacement of pneumatic ball valve.