Numerical Modelling of Skin-Stringer Separation in Thermoplastic Composite Stiffened Panels

This thesis project focuses on the evaluation of the Extended Finite Element Model (XFEM) for modelling skin-stringer separation in thermoplastic composite stiffened panels. The study uses test results from a reference study in the literature on a PEKK-FC carbon composite panel with three stringers joined to the skin using a short-fibre...

Post-buckling analysis of composite stiffened panels: A systematic analysis on the influence of imperfections

Pushing the envelope of aerospace structures requires the complete exploitation of their potential in terms of load-carrying capacity per unit weight for both economic and ecological reasons: the two most important being the reduction of fuel consumption and greenhouse gas emissions. A key approach involves allowing structures like stiffened...

Weight estimation for pylons supporting large aero-engines: A KBE approach

The aviation industry confronts challenges from increased air traffic and environmental concerns. Enhancing engine efficiency becomes crucial due to persistent greenhouse gas emissions from air travel, particularly in long flights with high CO2 emissions. Higher by-pass ratios (BPR) can address this by boosting engine propulsive efficiency, yet...

Effect of multipass welds and pores on residual stresses in butt-welded joints

Welding is a widely used process in various industries for joining materials, but it can introduce several complexities that affect the mechanical properties of the welded components. In particular, the presence of pores within the welded material can have significant implications for fatigue resistance, residual stresses, and overall structural...

Thermal energy storage in metal-organic framework materials for climate control of Martian buildings

To survive on the surface of a near atmosphere-less Mars, humans must be able to provide thermal energy to buildings to sustain temperature changes from -73°C to 20°C. The goal of the thesis is to create a passively-working thermal battery using materials currently available to humans; it must be the sole heat source to the Martian buildings....

Ply Drop-off Regions within Thermoset Composites: Influence of ply drop-off regions on the cure-induced residual stress development within thermoset composites manufactured by resin transfer moulding

The aim of this study is to analyse the influence of ply drop-off regions and related parameters on the VARTM cure-induced residual stress generation and related distortions within thick thermoset composites. These parameters include the resin pocket material properties and geometry, ply orientations and cure cycle parameters. By means of a...

Impact forces on bridge piers in the event of ship collisions

The aim of this thesis is to propose a simple technique to estimate the maximum impact forces acting on bridge piers in the event of ship collisions. This technique is determined for Dutch commercial inland waterway ships (CEMT classes) and set up to be applied by bridge engineers to determine the required bridge pier strength. Many collision...

Design, analysis and application of innovative connections for optimized steel trusses: Structural behavior of innovative joints based on snap-fit connections

Steel trusses are the preferred structures when large distances are required to span due to its lightweight, the reduced deflection and its load bearing capacity. Although nowadays with the help of computational tools more efficient designs can be achieved, the geometrical shape of trusses has barely changed. This is mainly due to the ease of the...

Design Optimization of Shock Mounts Subjected to an Underwater Blast Wave

Shock mounts are crucial components in reducing the transmissibility of a shock or impact, thereby protecting the objective system. Such shock mounts are application-specific and need a redesign for specific uses. This study establishes a transient nonlinear finite element optimization procedure to design a shock mount for withstanding an...

Composite Cylindrical Shell Buckling: Simulation & Experimental Correlation

Guidelines dating back 50 years, NASA SP-8007, are employed today in the design of thin-walled launch vehicle structures. Due to advances in materials, structural designs, and manufacturing techniques since the publication of SP-8007, the development of new knockdown factors for contemporary launch vehicle structures is an ongoing subject of...

Multiscale simulations for fracture prediction in composite materials: extension for anisotropic microstructures

With a fast increasing use of composite materials in aerostructures, industry demands design tools capable to reduce experimental tests while providing reliable data. Multiscale simulations enable to model and analyze fracture processes at the microscale, thus delivering higher accuracy and fundamental information about crack processes which...

A Progressive Blended Fatigue Framework for FRPs

In general, damage models for Fibre-Reinforced Polymers (FRPs) can be divided into two categories: Continuum Damage Models (CDMs) and Fracture Mechanics Damage Models (FMDMs). Damage models within each of these categories are advantageous for different type of failure mechanisms. Therefore, it is of interest to develop a unified framework in...

Development of a Reliable and Efficient 3D Calculation Model of a High-Rise Building Under Seismic Loading

This thesis research focusses on the development of a reliable and efficient 3D calculation model of an existing high-rise, reinforced concrete building in the Groningen area, in order to analyse the dynamic behaviour of the existing and subsequently retrofitted main bearing structure of this high-rise building. The assessment of the existing...

Residual stress development in a repaired welded connection

Research shows that the fatigue strength of a Very High Strength Steel (VHSS) can be significantly negatively effected by welds in a structure. The fatigue lifetime may be extended after cracking occurs by means of fatigue crack repair. A better insight by means of Finite ElementModelling (FEM) can help in understanding the effects of a repair...

UNDEX Impact Assessment, the effects of underwater explosions on pipeline integrity

Public version.

Stresses in asphaltic wearing courses on renovated steel bridge decks

Fatigue damage is a common problem in a lot of bridges with orthotropic steel decks. Frequent maintenance is required to prevent aggravation of the problems, which gives a lot of nuisance for the traffic using the bridge. This comes especially into play at large (river) crossings where not many alternatives are available. Therefore, methods are...