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...

The effect of temperature on fatigue strength of poly(ether-imide)/multiwalled carbon nanotube/carbon fibers composites for aeronautical application

This work concerns the fatigue behavior at three different temperature conditions (−40, 20, and 80°C) and the addition of multiwalled carbon nanotube (MWCNT) into a carbon-fiber reinforced poly(ether-imide) composite. The incorporation of MWCNT into the composite increased the tensile strength and Young's modulus by up 5 and 2%, respectively....

Online Remaining Fatigue Life Prognosis for Composite Materials Based on Strain Data and Stochastic Modeling

The present study utilizes a state-of-the-art stochastic modeling with structural health monitoring (SHM) data derived from strain measurements, in order to assess the remaining useful life (RUL) online in composite materials under fatigue loading. Non-Homogenous Hidden Semi Markov model (NHHSMM) is a suitable candidate with a rich mathematical...

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...

Structural health monitoring data fusion for in-situ life prognosis of composite structures

A novel framework to fuse structural health monitoring (SHM) data from different in-situ monitoring techniques is proposed aiming to develop a hyper-feature towards more effective prognostics. A state-of-the-art Non-Homogenous Hidden Semi Markov Model (NHHSMM) is utilized to model the damage accumulation of composite structures, subjected to...

Physics of delamination onset in unidirectional composite laminates under mixed-mode I/II loading

In order to understand the physics of the delamination onset in laminated composites, an experimental investigation of delamination growth is presented. The main objective of this paper is to demonstrate that delamination onset occurs at lower values than Gc defined by the ASTM standards, and that the strain energy release rate level at which...

Explaining the multiple energy thresholds for damage mechanisms activation in laminate composites under cyclic loadings

After half a century of developing fatigue delamination prediction models, where accuracy seems more important than physical understanding, this research aims to merge both aspects. To that aim, strain energy release (SER) within the fatigue load cycle was studied using acoustic emission. The correlation between the measured strain energy...