Fatigue debonding resistance of wrapped composite X-joints

Steel jacket support structures for offshore wind turbine towers made of circular hollow sections (CHS) are becoming a competitive solution compared to monopiles in deeper waters. The current limitation to improving the durability and cost-effectiveness of the CHS structures is the low fatigue endurance of their welded joints. Fatigue-driven...

Fatigue crack growth characterization of composite-to-steel bonded interface using ENF and 4ENF tests

In this paper, mode II fatigue crack growth properties of the composite-to-steel interface are characterised through different test configurations, namely ENF and 4ENF tests. Different loading types including force control and displacement control methods are compared. An innovative shear strain based method is proposed for monitoring the...

Influence of steel yielding and resin toughness on debonding of wrapped composite joints

The concept of an innovative bonded joining technology where welding is not required is presented as an alternative to traditional welded connection for steel circular hollow section (CHS). Wrapped composite joints have potential to greatly improve fatigue endurance when applied in multi-membered truss structures, e.g. offshore jackets for...

Debonding-on-demand Fe₃O₄-epoxy adhesively bonded dissimilar joints via electromagnetic induction heating

We investigated the debonding on-demand (DoD) of adhesively bonded hybrid dissimilar joints by applying electromagnetic induction heating to the joint overlap section, wherein the epoxy resin is reinforced with iron oxide (Fe₃O₄) particles. Ti-6Al-4 V adherends were bonded with CFRP or GFRP adherends using neat/modified...

Numerical modelling of rolling contact fatigue damage initiation from non-metallic inclusions in bearing steel

Bearing failure is a cause of concern in a variety of machinery such as turbines, transmissions, drills, engines, etc. It is often associated with rolling contact fatigue (RCF) triggered from damage initiation at non-metallic inclusions (NMI's). Experimental evidence shows that damage initiation lifetime is highly sensitive to the NMI...

DIC-based monitoring on debonding crack propagation in wrapped composite joints

Wrapped composite joint is an innovative technique which connects steel hollow sections through bonding such that the fatigue performance is improved compared to welded joint. In this paper, a DIC-based method of monitoring surface strains is proposed to quantify the debonding crack propagation within the composite wrap layers during high cycle...

Combined DIC and FEA method for analysing debonding crack propagation in fatigue experiments on wrapped composite joints

Wrapped composite joint is a novel joining technology which connects steel hollow sections through bonding, completely avoiding the welding in the load transferring mechanism. Fatigue performance of wrapped joints has been experimentally shown to be superior over their welded counterparts. Aiming to enable development of prediction methods...

Surface Crack Growth in Metallic Pipes Reinforced with Composite Repair System

Surface cracks are serious threats to the structural integrity of offshore metallic pipes. This dissertation proposes a protocol of composite reinforcement on surface cracked metallic pipes subjected to cyclic loads, aiming to decrease the crack growth rate and prolong the residual fatigue life. The main objective of this dissertation is to...

Damage assessment of a titanium skin adhesively bonded to carbon fiber–reinforced plastic omega stringers using acoustic emission

This study is devoted to the use of acoustic emission technique for a comprehensive damage assessment, that is, damage detection, localization, and classification, of an aeronautical metal-to-composite bonded panel. The structure comprised a titanium panel adhesively bonded to carbon fiber–reinforced plastic omega stringers. The panel contained...

Experimental investigation on FRP-reinforced surface cracked steel plates subjected to cyclic tension

Surface cracked steel plates reinforced with single-side Fiber-Reinforced Polymer (FRP) subjected to cyclic tension are experimental studied. The main purpose is to analyze the effect of FRP reinforcement on the crack growth. The failure modes and their effects are analyzed as well. Given the single-side reinforcement, reinforcing the cracked...

Microwave-induced interfacial failure to enable debonding of composite materials

Buildings or structures consist of materials that are joined to form functional composites to which a wide variety of “surface coatings” is added. Debonding of such composites is necessary to ensure high-quality, material-specific recycling processes. This paper describes tests of the debonding behavior of gypsum plaster and tiles that were...

A strengthening system for Groningen's unreinforced masonry buildings: Fibre Reinforced Cementitious Matrix: Analytical and Numerical analysis

Existing masonry buildings represent one of the most vulnerable building typology if subjected to seismic actions. In the Groningen region a greater part of the building stock is represented by URM masonry buildings, where these structures were generally designed for gravity loads only. As a consequence of the induced seismicity in the study...

Delamination and debonding failure of laminated composite T-joints

Composites are increasingly being used in aerospace, automotive and other industries. The T-joint (also named stringer stiffened skin) is a typical connection, broadly used in thin-walled structures, such as the wing and fuselage of aircraft. This thesis presents the analysis of the delamination and debonding failure of laminated composite T...

Interaction between microcapsules and cementitious matrix after cracking in a self-healing system

A new type of self-healing cementitious composites by using organic microcapsules is designed in Guangdong Key Laboratory of Durability for Coastal Civil Engineering, Shenzhen University. For the organic microcapsules, the shell material is urea formoldehyde (UF), and the core healing agent is Epoxy. The effect of organic microcapsules on...

Interaction between microcapsules and cementitious matrix after cracking in a self-healing system

A new type of self-healing cementitious composites by using organic microcapsules is designed in Guangdong Key Laboratory of Durability for Coastal Civil Engineering, Shenzhen University. For the organic microcapsules, the shell material is urea formoldehyde (UF), and the core healing agent is Epoxy. The effect of organic microcapsules on...

Micromechanical analyses of delamination, fracture and debonding in advanced composites