Fracture mechanics and fatigue group

The fatigue & fracture mechanics research group is headed by Prof. Wim De Waele and Prof. Stijn Hertelé. The activities of the group can be divided into three topics: Fatigue and lifetime analysis, joining and additive manufacturing and quasi-static fracture and damage mechanics

Fatigue and lifetime analysis

Research project Kris Hectors

The goal of this project is to develop robust numerical tools for lifetime prediction of large-scale welded steel structures, such as railway bridges, craneway girders and offshore jackets. Python scripting and finite element simulations are combined for hot spot stress evaluation of total life and multi-axial crack propagation analysis of remaining life. Using actual data from load and condition monitoring is essential towards decision support for quantification of lifetime extension and optimization of predictive maintenance.

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Fatigue and corrosion are the main damage mechanisms for offshore wind support structures. Due to the synergy between corrosion and fatigue, reliable models for qualitative and quantitative evaluation of degradation due to corrosion and fatigue are necessary to assess the structural safety. Our objective is to develop an integrated numerical framework for pitting corrosion and fatigue that allows to construct 'smart' S‐N curves that also take into account the level of corrosion and presence of cracks.

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Research project Mojtaba Khayatazad

Fatigue cracks originating from operational loads and corrosion due to a harsh environment are severe threats to steel structures. Structural health monitoring can potentially avoid catastrophes by timely detecting such inevitable damage. The feasibility of the electromechanical impedance based method for the detection of fatigue cracks in welded steel structures is evaluated in this project. Additionally, an artificial intelligence based image analysis method is developed that allows automated detection of corrosion.

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(Offshore) wind energy is an important and growing renewable energy source in Belgium. In some cases, the industry is faced with premature roller bearing failures in the turbine drivetrain due to white etching cracking (WEC), resulting in unforeseen wind turbine downtimes. This project aims to model premature bearing failure using a multi-scale approach, fed with load history data and microstructural insight from project partners. The outcome will help the wind industry to prioritize monitoring and maintenance.

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Damages to offshore power cables account for 85% of project insurance costs. Online cable monitoring can prevent submarine cable accidents and as a result reduce O&M costs of offshore wind energy. This research project studies the feasibility of Distributed Acoustic Sensing (DAS) using embedded optical fibres as a new monitoring tool. Numerical and experimental models will be developed to link the optical sensor data to the deformation of the power cable.

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Research project Pankaj Jaiswal

Present-day interest in the use of composite-steel joints in primary structures of marine vessels requires an in-depth knowledge of the performance of thick adhesive bonds under combined loading and environmental conditions. Multi-material thick adhesive joints are subjected to quasi-static and cyclic loading. Joints are also tested after accelerated exposure to conditions which mimic the harsh marine environment. The ultimate goal is to determine their fatigue resistance on a multi-scale component level.

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The objective of the project is to develop a qualitative and quantitative understanding of the mechanisms of corrosion fatigue. The project focuses on offshore monopiles and the potential consequences of flaws in their corrosion protection system. Corrosion-fatigue experiments will be performed and complemented with finite element simulations of fatigue cracks starting from corrosion pits. This fundamental understanding will be transformed into guidelines for the estimation of the remaining fatigue life of monopile structures.

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Joining and additive manufacturing

The main goal of this project is the development of both numerical tools and experimental screening capabilities for large-scale steel components made by Wire & Arc Additive Manufacturing (WAAM). Our main focus is the development of artificial intelligence based reverse models that link microstructural properties of the printed component to the welding process parameters. Additionally we perform experimental studies for assessing the structural integrity of WAAM printed components.

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This project is a prenormative study on Wire & Arc Additive Manufacturing (WAAM). The focus is on steel components for general construction and pressure vessels. Based on a wide range of experimental activities, we will generate data on quality requirements, process parameters, geometrical features, static and fatigue strength. These data will serve as input for both WAAM related and application related standards.

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Quasi-static fracture and damage mechanics

Research project Robin Depraetere

Hydrogen will play an important role in the energy transition towards a low-carbon economy. Hydrogen-based degradation may harm the structural integrity of steel pipelines. We investigate this degradation in a combined experimental and numerical study. The ultimate goal is to develop a numerical damage model, that includes hydrogen diffusion, material degradation and ultimately damage, and experimentally calibrate and evaluate this model. Microstructural influences are complementarily examined by the Sustainable Materials Science research group.

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Research project Somsubhro Chaudhuri

Advancements in non-destructive examination (NDE) technology have led to the possibility of obtaining in-the-field 3D representations of pipeline defects. Standardized defect assessment procedures do not yet take advantage of this possibility. The primary aim of this research is to explore the possibility of integrating 3D NDE into assessment of pipeline defects by coupling the NDE output with a finite element analysis (FEA) of the defected structure. The coupled 3D NDE-FEA approach will be embedded into a multi-level engineering critical assessment framework.

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Research project Vitor Adriano

Metal components and structures are often joined by arc welding. The fracture toughness of welds is of utmost importance and is based on small-scale testing. Established fracture toughness test standards do not mention validity criteria with respect to the potential presence of volumetric imperfections such as pores. This research experimentally and numerically investigates the influence of such imperfections on the interpretation and validity of toughness tests performed on weld metals.

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Research project Dhanraj Rajaraman

Abrasion wear of metals is a major failure mode in many engineering applications, leading to huge expenditures on maintenance. The aim of this project is to increase the fundamental understanding of damage mechanisms involved in scratch abrasion by means of devoted numerical damage modelling and experimental validation testing. The outcome of this project will lead to an identification and prioritization of material parameters of influence on scratch abrasion resistance.

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