Fatigue Life Time Estimates of Welded Joints in Maritime Structures: a total life concept

Ships at sea encounter wave-induced cyclic loading, meaning fatigue is a governing limit state. The structural response introduces stress concentrations, hotspots, at notch geometry like welded joints locations. At the same time, the welding process typically introduces defects, meaning welded joints are typically the governing fatigue-sensitive...

Fatigue analysis and design of arc-welded and laser-welded lap joints: Toe vs. root induced failure

Fatigue might be the governing limit state in marine structures mainly induced by the waves and wind. Therefore, using a lap joint for the shell plating to replicate the appearance of a riveted joint for a retro yacht is critical due to the limited fatigue resistance. For this joint type cracks initiated at the root, which should always be...

An effective notch stress concept based total fatigue life estimate of maritime structures

Fatigue is typically a governing limit state for maritime structures, and weld joints are the most critical locations. Various fatigue damage criteria have been developed involving either an intact or cracked geometry parameter, incorporating local or global information. In this thesis, the effective notch stress based total life fatigue damage...

Shape and size optimization of a wind turbine transport structure: Structural optimization with a compliant ship foundation

Due to the growing quest for renewable energy, wind turbines grow in size. This means that higher demands are posed on the transporting structures, also called tower grillages, which brings its challenges for their design. The fact that the structures considered in this thesis are placed on a ship makes the design even more complicated....

Mean Stress Effects in Temporal and Spectral Fatigue Analysis: Loading & Response and Resistance Contributions

Fatigue lifetime has proven to be a leading design parameter for naval vessels. In the field of fatigue analysis and design of welded joints, two overall methods are distinguished: the temporal and spectral approach. Using empirical models, the spectral approach is typically preferred due to its efficiency, even though damage estimates are...

Effective Notch Stress Concept Investigations for Mode-III Loading & Response Conditions

Fatigue strength is typically a governing limit state for marine structures. Predicting an accurate fatigue lifetime is important for structures (e.g. wind turbines) that are supposed to be out at sea for decades. It is valuable for all type of structures that encounter stochastic sea loadings to optimise the design so that fatigue failure is...

Wrinkling analysis and design of Offshore Flexible Floating Solar Structures

Solar energy is considered to be one of the most promising energy alternatives among many renewable energy sources. On the pathway towards achieving climate goals, dramatic scale up of clean technologies is required, however the installation of solar energy has the burden of intense land requirement. Therefore, the onset of floating solar...

Fatigue damage accumulation in steel welded joints, subject to (random) variable amplitude loading conditions: An improved fatigue-life model for naval ship structural design

The current fatigue assessment methods for naval ships are intentionally conservative. This is in part due to uncertainties in the fatigue capacity (i.e. fatigue resistance) of the ship: the nominal and hot spot structural stress incorporate implicit conservatism due to the inherent data-scatter and the Linear Damage Accumulation Model (LDAM) by...

Framework to research and design wrinkle free very large flexible offshore solar platforms by adding permeability

Offshore solar power installations can be increased in size and efficiency compared to land based installations due to the availability of space and the cooling effect of water. To increase survivability in large waves, very large floating solar platforms can be made flexible. However, a flexible structure is susceptible to wrinkling due to...

Predicting the Pit-to-Crack Transition of Offshore Wind Turbine Foundations: A mechanistic determination

Offshore wind turbines are designed to persist harsh environmental conditions, including corrosion. Pitting corrosion is one of the most dangerous forms of corrosion. In combination with a fatigue loading, a corrosion pit could result into the failure of a structure, due to a minimal weight reduction. Of the corrosion fatigue process, the...

Multi-axial fatigue strength assessment of a turret in a FPSO

Turret structures within FPSO's are subjected to a variety of repeated loads, due to the harsh environment they operate in during their service live, meaning that fatigue is a governing limit state in turret structural design. Turret structural components are connected by arc-welded joints which are considered particularly susceptible to fatigue...

Modelling Wrinkling Behaviour of Large Floating Thin Offshore Structures: An application of Isogeometric Structural Analysis for Post-Buckling Analyses

With increasing attention to climate change,renewable energy generation has become a major topic for research anddevelopment. Wind and solar energy are generated on land, whereas wave, windand tidal energy generators are getting attention in the offshore domain. Anovel extension of onshore solar energy is the concept of...

Research on the Applicability of Metal Foam Based Sandwich Materials for Friction Stir Welded Ship Structures with Sufficient Fatigue Life Time

Research to analyse and/or develop novel materials and techniques is necessary to address competition and safeguard craftmanship in shipbuilding. In this master thesis, two new approaches to reduce the production and maintenance costs are studied: {metal foam core, metal face sheet} sandwich materials and corner adstir fillet stationary shoulder...

Wire & Arc Additive Manufacturing for Offshore Appliances: A study on ultimate strength and fatigue life

On the Assessment of Additive Manufacturing Potential in the Maritime Construction Sector: The effect on mechanical properties

Confidential thesis, only summary available.

Design and Calibration of a Multi-Axial Load Cell for Quasi-Static and Dynamic Testing

In structural analysis, multi-axial loads are often treated as a superposition of individual load com- ponents. Although this proves to be sufficient for static analyses, for dynamic and especially fatigue assessments, this sometimes leads to extreme overestimation of loads. In turn this results in highly over-dimensioning of structures to...

Transverse Strength of a Twin Hull FPSO

The size and production capacity of Floating Production, Storage and Offloading units, or FPSOs, is ever growing. SBM Offshore specialized in converting existing oil tankers into FPSOs. One of the limitations they found was the available deck space for the topsides modules. A new concept was proposed to solve this problem: a twin hull FPSO, made...