Early detection of impact fatigue damage in an adhesively-bonded connection using acoustic emission

Wind turbine blades carry the risk of impact damage during transportation, installation, and operation. Such impacts can cause levels of damage that can propagate throughout the structure compromising performance and safety. In this study, the effect of impact damage on fatigue damage propagation in test specimens representative of a spar cap...

Acoustic emission-based remaining useful life prognosis of aeronautical structures subjected to compressive fatigue loading

An increasing interest for Structural Health Monitoring has emerged in the last decades. Acoustic emission (AE) is one of the most popular and widely studied methodologies employed for monitoring, due to its capabilities of detecting, locating and capturing the evolution of damage. Most literature so far, has employed AE for characterizing...

Unfolding the Early Fatigue Damage Accumulation for Cross-ply Laminates

Fatigue damage of composite laminates has attracted considerable attention from research community and industry, in view that laminated structures are inevitable to suffer from fatigue loading during their service life. It is rather complicated to understand and explain, what governs the initiation, accumulation, interaction (synergy or...

The effect of mode II fatigue crack growth rate on the fractographic features of CFRP composite laminates: An acoustic emission and scanning electron microscopy analysis

The present study is focused on the characterization of the fatigue damage features in carbon/epoxy laminates under mode-II loading conditions. To this aim, a sinusoidal cyclic load was applied to the End-Notched Flexural (ENF) specimens and the fatigue behavior of specimens was investigated. Scanning Electron Microscope (SEM) was used to...

Damage Diagnostics of a Composite Single-Stiffener Panel Under Fatigue Loading Utilizing SHM Data Fusion

A case study is presented in which the first steps are made towards the development of a structural health monitoring (SHM) data fusion framework. For this purpose, a composite single-stiffener panel is subjected to compression-compression fatigue loading (R = 10). The carbon-epoxy panel contains an artificial disbond of 30 mm, which was...

Combined Impact and Fatigue Loading in CFRP: Effects of the timing of an impact event during cyclic loading of composite aircraft structures

This research experimentally investigates the effects of an impact event during fatigue loading of a CFRP structure. Open-hole specimens were impacted in-situ during a short interruption of a tension-tension cyclic loading program. The impact was aimed directly below the central hole, with the critical fatigue damage path being left and right of...

Scrutinizing interlaminar fatigue loading cycle in composites using acoustic emission technique: Stress ratio influence on damage formation

Current models for delamination propagation prediction in fiber-reinforced polymer (FRP) composites exhibit limitations to explain the physics underlying the mechanisms of damage formation in fatigue. In order to contribute in this field, this research focuses on the study of damage development within a single loading cycle of FRP double...

A cycle-by-cycle fatigue damage analysis of biaxial composite structures utilizing acoustic emission

In the present work, a fatigue damage analysis of biaxial Carbon Fibre Reinforced Polymer (CFRP) specimens loaded at two different stress levels and a fatigue ratio, R=0.1, was performed. A cycle-by-cycle approach was used, utilizing results from Acoustic Emission (AE) measurements. The aim was to investigate the influence of the applied...

Investigating energy dissipation for a methodology to fatigue master curves

Using acoustic emission to understand fatigue crack growth within a single load cycle

Current methods for prediction of fatigue crack growth are based on empirical correlations which do not take the crack growth behaviour within a single cycle into account. To improve these prediction methods, more understanding of the physical mechanisms of crack growth is required. In this research the acoustic emission technique was used to...

Acoustic Emission-Based Methodology to Evaluate Delamination Crack Growth Under Quasi-static and Fatigue Loading Conditions

The aim of this study was to investigate the applicability of acoustic emission (AE) technique to evaluate delamination crack in glass/epoxy composite laminates under quasi-static and fatigue loading. To this aim, double cantilever beam specimens were subjected to mode I quasi-static and fatigue loading conditions and the generated AE signals...