Analysis of crack formation in T-joint structures under dynamic loading

Abstract

T-joints play a vital role in the hulls of ships and bulkheads made of sandwich materials. Their design aspects and crack detection are important in preserving the safety of ships navigating through violent sea waves. In this work, an overview of the state-of-the-art of design aspects of T-joints used mainly in ship structures is first provided. The design aspects are focused on estimating static and quasi-static failure loads, fracture and fatigue characteristics. This study also develops a reduced order dynamic model for identification of cracks in T-joints. The reduced model constitutes three modal equations with piecewise-linear asymmetric characteristics in which the influence of the crack appears in terms of its length parameter. In particular, it is shown that the presence of a crack essentially affects both the amplitude and frequency content of the dynamic response due to nonlinear coupling between normal modes. Under external dynamic loading with a frequency close to the first mode frequency, the development of a crack is identified by the evolution of attractors on the configuration planes created by different combinations of modal coordinates.

In-situ repair of composite sandwich structures using cyanoacrylates

“…10 The effect of different load cases has also been examined, such as fatigue, compression 11 and off-axis bending. Crack initiation location under fatigue was similar to that 12 observed under quasi-static loading; however, damage initiation loads were lower and 13 crack advancement was more progressive in nature [5,6]. Failures under compression (-14 0°, Fig.…”

Finite element analysis of composite T-joints used in wind turbine blades

“…It supports mainly bending loads that the blade experiences when in operation and transfers shear stresses to the skin; the whole blade of course in addition to bending, experiences torsional loading that introduces additional direct and shear stresses in the blade's components, which form a 3D stress field. [6][7][8][9] T-joint design T-joints if badly designed and fabricated are prone to premature failure due to damage that mainly occurs in the form of delamination within the joint and skin-flange debonding, because of the relatively low interlaminar strength. To overcome this weakness, through-thickness reinforcement is widely considered to be an efficient way to increase the resistance of laminated composites and bonded joints against out-of-plane failures.…”