Study of the Shielding Interactions between Double Cracks on Crack Growth Behaviors under Fatigue Loading

Zhichao Han,Huifang Li,Caifu Qian

doi:10.3390/met10020202

Abstract

In this paper, the interactions between double cracks with a co-bisector-line were investigated theoretically and experimentally. Fatigue crack growth tests of specimens with a single crack or double cracks were carried out to measure the crack growth rates, and finite element calculations were performed to obtain the stress intensity factors at crack tips. It was found that when the double cracks are in co-bisector-line, they present shielding interactions which reduce the stress intensity factors at crack tips as well as the crack growth rates. By modifying the stress intensity factors and the Paris equation considering the shielding interactions, a new simplification method was proposed to simplify the double cracks into a single crack with the same crack growth rates.

Highlights

In engineering equipment or components, such as welded joints, ships, aircrafts, pressure vessels, etc., multiple cracks may initiate and grow under the fatigue loading [1,2,3,4]
Interactions between Conclusions double cracksare with co-bisector-line are investigated through experiments numerical simulations
(1) For the considered double cracks, they present shielding interactions on the stress intensity at crack tips and crack growth rates, which can be explained from the mechanical point of view

Summary

Introduction

In engineering equipment or components, such as welded joints, ships, aircrafts, pressure vessels, etc., multiple cracks may initiate and grow under the fatigue loading [1,2,3,4]. In the initiation and propagation process, cracks may influence and be influenced by the neighboring cracks [5] or, in other words, interactions between multiple cracks exist under the fatigue loading. For the multiple cracks, the driving force, for example, the stress intensity factor (SIF), should be affected by the interactions between multiple cracks [7]. Neglect of crack interactions will lead to an inaccurate estimate of fatigue levels of engineering components [8,9,10]. It is of great importance to investigate the interactions between multiple cracks

Results

Discussion

Conclusion