Dynamic Analysis of Finite-Length Circular Cylindrical Shells with a Circumferential Surface Crack: Fid-Bau Portal

Dynamic Analysis of Finite-Length Circular Cylindrical Shells with a Circumferential Surface Crack

Yin, Tao / Lam, Heung-Fai

Abstract

In this paper, a new solution method is proposed for investigation of the vibration characteristics of finite-length circular cylindrical shells with a circumferential part-through crack. Four representative sets of boundary conditions are considered: simply supported, clamped-clamped, clamped-simply supported, and clamped-free. The governing equation of the cracked cylindrical shell is derived by integrating the line-spring model with the classical thin shell theory. A computationally efficient numerical solution method for determining the natural frequency of the system of a given mode is proposed. The algorithm calculates the natural frequency from an initial trial through a one-dimensional optimization process. Two initial trial estimation methods are considered: the beam-function method and Soedel’s expression method. On the basis of the case study results, a recommendation is made on the selection of a suitable initial trial calculation method. The verification of the proposed method is divided into two parts. In the first part, the intact cylindrical shell analysis results obtained from the proposed method are compared with those from the literature and from finite-element (FE) analysis using Ansys. Because relevant cracked cylindrical shell analysis results are not available from the literature, the proposed method’s performance in this case is verified using the FE method alone in the second part. The verification results demonstrate that the proposed method provides a fast and efficient way to calculate the time-domain responses of a cracked cylindrical shell. Furthermore, the case study results indicate that the dynamic characteristics of short shells are more sensitive to circumferential surface cracks than those of long shells. This observation makes it possible to extend the proposed cracked shell modeling method to crack detection following the model-based approach, especially for short shell members.