Additive Manufacturing of Kirigami Metasurfaces

Kirigami- the Japanese art of paper cutting – is used extensively as a design philosophy for stretchable and morphable structures. An array of cuts on a thin planar sheet creates a structure that can morph into a 3D pattern on applying an in-plane uniaxial load. This type of structure is called a kirigami metasurface. A subset of this type of...

Correlation between the Mechanical Properties and the Structure of the Equine Osteochondral Interface During Maturation

The osteochondral interface is known to smoothly mitigate the stress concentration over the surface area of the subchondral bone, with a structural transition from the cartilage to bone. These sites in the body are exposed to high forces, which makes them prone to failure. To improve the repair strategies, a better understanding of the...

Experimental Study of Shock Wave/Boundary-Layer Interactions over Fluttering Panels

Supersonic flows cause thin panels to flutter, which is characterized by high-amplitude self-sustained oscillations, increasing the risk of fatigue failure. Flutter is known to be exacerbated when a shock wave impinges on the panel, creating a shock wave/boundary-layer interaction (SWBLI) which promotes separation of flow and leads to increased...

Global and local analysis of the mechanical and structural characteristics of carotid atherosclerotic plaques for rupture risk assessment

The rupture of atherosclerotic plaques present in vital arteries is the main trigger of fatal cardiovascular events, such as heart attacks and strokes. Plaque rupture is a mechanical failure of the fibrous plaque tissue that ensues upon large deformations of the tissue, induced by the blood pressure. Current knowledge on the rupture...

An Experimental Study on Supersonic Panel Flutter Using Simultaneous Digital Image Correlation and Schlieren

Supersonic panel flutter is a self-excited vibration, where energy is transferred into thin flexible panels, such as skin panels in supersonic vehicles, from the (supersonic) flow around them, which can lead to their rapid fatigue failure. Relevant examples of this include the failure of skin panels in the X-15 vehicle, or violent oscillations...

Learning from Nature's Failures: Mimicking Hierarchy in Natural Structures to Create Damage-Tolerant Lattice Materials

To create a more sustainable future for aviation, new, lighter-weight structures and materials will need to be engineered. It will also be critical that damage tolerance and safety are not compromised in the process. Lattice materials represents one avenue of exploration; however, two key challenges arise: limited experimental work has been...

Combined Acoustic and Optic Characterization of Damage Mechanisms in Internally Pressurized Composite Pressure Vessels

To achieve CO2 emissions reductions, the automotive industries are moving towards more sustainable solutions. One of those are fuel cell electric vehicles (FCEVs) which rely on the chemical reaction of hydrogen to produce electricity. The hydrogen is stored in a gaseous and compressed form in composite pressure vessels (CPVs) which must be...

Experimental and Numerical Investigation into the Influence of Layup Sequence on the Mechanical Performance of Composite Pressure Vessels for H₂ Storage

Fuel cell electric vehicles can provide the possibility to meet CO₂ emission reduction targets, but these vehicles require cost effective energy storage solutions. The current most mature technology uses compressed hydrogen, stored in composite pressure vessels (CPVs) manufactured by filament winding. Structural optimization of CPVs...

Steel 3D printing for structures: An explorative study on the tear-out strength of a pin or bolt in a Wire and Arc Additively Manufactured carbon steel plate

Additive manufacturing (AM), or 3D printing, is emerging as a technology for different applications made of steel. It is expected that in the coming years the construction industry will benefit from the free and lightweight forms that can be fabricated and the possible material savings. A few experimental results of 3D printed stainless steel...

Blunt Notch Behaviour of Stainless-Steel-CFRP Fiber Metal Laminates

Joining of aerospace structures has been accomplished using mechanical fasteners since the advent of flight. With the growing application of lightweight composite structures in aircrafts, joining methods involving fasteners have been under scrutiny. The lack of material plasticity and high notch sensitivity of composites in the presence of...

Investigating energy dissipation for a methodology to fatigue master curves

The effect of nodal topology on cellular solid mechanics: A preliminary diagnostic experimental investigation

Additive manufacturing allows material structuring, supporting the fabrication of multiple-level structures or metamaterials. Through the lens of classical stress reduction, nature’s cellular solid structures feature stress-homogenizing nodal topologies. Avian long bones are an example. Research into the mechanics of open cell cellular solids...

Assessment of crack kinematics in concrete beams using digital image correlation

Digital Image Correlation analysis is performed to obtain measurements of the crack kinematics of four reinforced concrete beams without shear reinforcement. The results are used to implement the critical shear displacement theory. This new theory proposes that the opening of the critical inclined crack can be considered as a lower bound for the...

Measurements and Monitoring the Behaviour of Crossbeam in Orthotropic Bridge Deck with 3D Digital Image Correlation

Digital Image Correlation is a cheap and easy to use measurement method that has been proved to characterise any solid material parameters up to plastic deformation range. The digital image correlation measurement system is based on the tracking of a collective number of pixels from the surface of the reference image to the deformed image. This...

The influence of the Transition Zone on the structural behavior of pin connected areas in local metal reinforced composites

Fibre Metal Laminates (FML) are hybrid composites, with the attempt to combine the advantages of metals and fibre reinforced plastics. Their promising properties are used locally in joining areas to reduce the structural weight. As the metal foils density, in this case a steel alloy, is much higher than the density of carbon plies, its amount...

Compression-Compression and Tension-Compression Fatigue of Textile Carbon-Epoxy Composites: Experimental Testing and Instrumentation

Efficient design of woven composite structures is limited by a knowledge gap in predictive modeling of their behaviour. Fatigue modeling in particular is difficult and limited by a lack of experimental data. For compression-compression (C-C) or tension-compression (T-C) fatigue, experimental results in literature are uncommon. In this master...

Application of digital image correlation to glass fibre-reinforced composites under transverse tensile loading

Fibre-reinforced polymer composites (FRPs) have been used in structural applications for years mainly due to their outstanding specific mechanical properties. In this thesis, the characterisation of the strain field upon transverse tensile loading of glass fibre-reinforced polymers (GFRPs) was investigated by applying digital image correlation ...

Discrete 3D Digital Image Correlation (DIC) using particle reconnaissance

This bachelor project is done for the study of strain localisation in geomaterials. The conventional material testing only describes the fabric behaviour globally. In order to create better understanding of how sand/rock particles move under compression, micro X-ray CT-scans are made of specimens from the material in question. An X-ray CT-scan...