Engineering Materials

Digital image correlation is one of the fields of excellence in the Engineering Materials research group. The technique is based on computer vision techniques for full-field displacement measurement in mechanical testing.

We develop mathematical inverse methods integrated with digital image correlation (DIC) algorithms and experimental procedures that push the state of the art in DIC, especially with regard to localised deformations and computational methods that have a physical interpretation. We have unique expertise in designing patterns to optimise the performance of DIC methods, providing an unparalleled combination of displacement resolution and spatial resolution of the displacement field measured by DIC. This technology is also applied outside of the mechanical testing laboratories, enabling innovative solutions for condition monitoring and wide-area strain sensors. 

In combination with inverse methods and computational modelling of measurements, full-field displacement measurement methods like DIC yield exceptionally rich data sets for characterising the mechanical behaviour of materials and determining the parameters in the material models used to describe it.

Key personnel

• Professor Sven Bossuyt
• Professor Pedro Vilaça
• Adjunct Professor Iikka Virkkunen

Friction-based processing of materials is one of the fields of excellence in the Engineering Materials research group. Research involves fundamental and applied research in conventional and advanced engineering materials.

This topic includes established techniques, such as friction stir welding, applied to similar and dissimilar materials, and friction surfacing, a solution for thick coating and additive manufacturing. The viscoplasticity processing domain of materials has been used as an innovation platform for new advanced solutions, patented by Aalto University, for high value applications, such as hybrid friction stir channeling for thermal management of optimised multi-material components; friction flash to tube, enabling the production of seamless tubes, in open die condition, extracted from the flash continuously produced during the plunging of a consumable rod against a non-consumable rigid anvil; and through-hole extruded welding, for lightweight components made of metal and polymer-based materials.

Research is supported by dedicated digital control systems with integrated condition monitoring. Analytical and numerical modelling validated by thermal monitoring assists the development of tooling, mass and heat flow, as well as joining mechanisms. Microstructural analysis, mechanical testing with DIC and residual stress measurements are engineering methods applied to the investigation of the materials processed by conventional and new friction-based solutions.

Key personnel

• Professor Sven Bossuyt
• Professor Emeritus Hannu Hänninen
• Professor Pedro Vilaça

Hydrogen effects on metals is one of the fields of excellence in the Engineering Materials research group. These are studied using thermal desorption spectroscopy, electrochemical and plasma charging and mechanical in-situ testing.

The rapidly growing market for advanced high-strength steels for automotive production significantly increases the risks and costs associated with hydrogen-related failures of vehicle components. At the same time, the development of hydrogen-based transportation and corresponding infrastructure introduce new challenges for engineering materials, especially with regard to their resistance to hydrogen embrittlement. This is also an area of interest in ensuring the safe disposal of spent nuclear fuel, where it is also important to understand the effects of hydrogen on the mechanical and creep properties of copper and cast iron as well as the effect hydrogen has on the mechanism of stress corrosion cracking in these materials.

New concepts and equipment for thermal desorption analysis of hydrogen in materials will be commercially explored for the high-sensitivity measurement of hydrogen concentration in materials and analysis of hydrogen uptake and trapping behavior with high accuracy, especially in advanced high strength steels. The steel infrastructure needed for hydrogen economy (hydrogen production, storage, distribution) is vast. In addition to the measurement equipment, the team will offer customers services for data interpretation, analysis and statistics. 

Key personnel

• Professor Sven Bossuyt
• Professor Emeritus Hannu Hänninen
• Adjunct Professor Iikka Virkkunen

Risk and safety research is focused on developing concepts, methods, tests and frameworks for creating safe technological and socio-technological systems and for managing associated risks. These advances in risk analysis and safety science are applied to specific problems in maritime and materials engineering. This serves society by increasing our understanding of how maritime and materials safety is created and maintained and how safety risks can be managed effectively.

The fatigue and fracture of materials make up an aspect of risk and safety. For safety-critical systems like nuclear power plants and airplanes, periodic inspections combined with reliable models of crack growth enable operators to detect flaws before they reach a dangerous state. Risk and safety research addresses the non-destructive testing and the characterisation and modelling of cracks, while also including effects such as hydrogen embrittlement and thermal fatigue.

Key personnel

• Professor Pedro Vilaça