On the finite width correction factor in prediction models for fatigue crack growth in built-up bonded structures

Wandong Wang

doi:10.1016/j.engfracmech.2020.107156

Abstract

It is widely acknowledged that a finite width correction factor is required for the stress intensity factor in the fatigue prediction of built-up structures. This paper examines how a correction factor can be incorporated in the established model for the fatigue crack analysis of fibre metal laminates. It is revealed that the bonded fibres ahead of the crack tip mitigate the finite width effects, resulting in a smaller correction than that for monolithic metal panels. The bridging mechanism is affected by the finite width condition through the enlarged crack opening. The gained understanding is applicable for other built-up bonded structures.

Highlights

Fibre metal laminates (FMLs), a member of a big family of built-up bonded structures, consist of thin metal sheets bonded with fiber reinforced polymer layers [1]
This paper discusses the effects of finite width of built-up structures on the fatigue crack growth and delamination propagation behavior in such structures
The built-up structure concerned in this paper is the fiber metal laminate; the revealed finite width effects are applicable for metallic panels with bonded stiffeners

Summary

Introduction

Fibre metal laminates (FMLs), a member of a big family of built-up bonded structures, consist of thin metal sheets bonded with fiber reinforced polymer layers [1]. The fatigue resistant fibres remain intact and restrain the opening of the crack in the metal layers, which renders a load transfer from the cracked metal layers to the bridging fibres. This bridging mechanism significantly enhances the resistance of the metal layers to the fatigue crack growth as it reduces the stress severity seen by the crack tip. An accompanying failure mechanism in FMLs, at the composite/metal interface due to the cyclic load transfer between the cracked metal layers and the bridging fibres in the form of shear [2]

Objectives

Methods

Discussion

Conclusion