Laboratory and numerical investigations of the effect of geometric parameters on the buckling capacity of thin-walled composite cylindrical shells under external pressure loading.

Buckling is one of the important issues in determining the mechanical behavior of cylindrical shells, especially composite shells. What makes the buckling matter important in composite cylindrical shells is the complexity of the behavior of these structures under the influence of a variety of special loads such as buckling under external pressure load. Uniform lateral loading in tanks occurs when tanks are in the state of liquid discharge. Moreover, if special contrivances such as the drainage valves do not work or properly, then buckling phenomenon and will cause an overall failure in the tank. In this research, the air suction system is used in order to apply external pressure and study the buckling behavior of specimens. As the buckling occurs, tiny cracks are created with a mild sound in the shell wall and in the extreme stage the loading process stops when it collapses. In this paper, the effect of geometric parameters, such as the R/t and L/R of a composite tank under external pressure, on buckling behavior is investigated. Obtained results are compared with software and theoretical results. The results showed in specimen of the same length, by increasing the geometric parameter R / t, the buckling capacity of the shells decreases and the number of buckling modes increases and by increasing the geometric parameter L / R, the buckling capacity of the shells increases and the number of buckling modes decreases.