Pre-straining as an effective strategy to mitigate ratcheting during fatigue in flax FRP composites for structural applications

Biobased fibre-reinforced polymer (FRP) composites, consisting of natural lignocellulosic fibres such as flax or hemp, are great alternatives to synthetic fibres to mitigate the environmental impact of high-performance composites in engineering structures. Natural fibres such as flax have damping and specific mechanical properties suitable to...

Multi-level damage diagnosis on stiffened composite panels based on a damage-uninformative digital twin

In this study, a multi-level Structural Health Monitoring methodology for stiffened composite panels is introduced. A digital twin (DT), that is, a three-dimensional finite element (FE) model, representing the pristine state baseline of the test article, is developed and verified for compressive loading in the post-buckling regime. The...

Fusion-based damage diagnostics for stiffened composite panels

Conducting damage diagnostics on stiffened panels is commonly performed using a single SHM technique. However, each SHM technique has both its strengths and limitations. Rather than straining the expansion of single SHM techniques going beyond their intrinsic capacities, these strengths and limitations should instead be considered in their...

Fatigue in fibre metal laminates: The interplay between fatigue in metals and fatigue in composites

With the introduction of fibre metal laminates (FMLs) as a (fatigue) damage tolerant material concept in aeronautics, an interesting field emerged where fatigue damage interaction plays a dominant role. The hybrid concept effectively demands evaluating fatigue damage growth based on fracture phenomena typical for both metals and fibre...

Fatigue life and damage tolerance of postbuckled composite stiffened structures with indentation damage

The fatigue life and damage tolerance of composite stiffened panels with indentation damage are investigated experimentally using single-stringer compression specimens. The indentation damage was induced to one of the two flanges of the stringer of every panel. The advantages of indentation compared to impact are the simplicity of application...

Experimental investigation of reinforced bonded joints for composite laminates

An experimental study has been carried out to investigate the behaviour of co-bonded carbon fibre reinforced plastics joints with a novel design incorporating a through the thickness local reinforcement. Different specimens were manufactured to investigate static and fatigue behaviour, as well as delamination size after impact and damage...

When Conservation Meets Engineering: Predicting the Damaging Effects of Vibrations on Pastel Paintings

Pastel paintings are one of the most fragile types of objects of art. When handling loan requests, conservators lack scientific data to assess the risk for damage in transport, and thus for making decisions whether they can be transported. A research project was initiated in 2014 to investigate the effect of vibrations on the condition of pastel...

Fatigue life of postbuckled structures with indentation damage

The fatigue life of composite stiffened panels with indentation damage was investigated experimentally using single stringer compression specimens. Indentation damage was induced on one of the two flanges of the stringer. The experiments were conducted using advanced instrumentation, including digital image correlation, passive thermography, and...

In-situ fatigue damage assessment of carbon-fibre reinforced polymer structures using advanced experimental techniques

This study focused on the in-situ fatigue damage assessment of open-hole carbon/epoxy coupons using Acoustic Emission (AE) and Digital Image Correlation (DIC) techniques. Constant amplitude fatigue tests were performed and the main objective was to investigate the damage process, the degradation process of the fatigue modules and to identify...

Mixed-Mode Fatigue Disbond on Metallic Bonded Joints

Aerospace structures have been long dealing with the safety versus weight issue. Lighter airplanes are cheaper to operate, however, they may face a safety issue because of the reduced fatigue life. Consequently, a heavier/safer structure is designed. Adhesive bonding is a joining technique that offers potential for improvement in the fatigue...