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INEGI leads pioneering study of long-term fatigue to improve the prediction of structural materials' life cycle

17 February 2021
Understanding the behavior of materials is often pushing them to the limit. And the study of fatigue is exactly that: determining how many repeated cycles of load and tension the material can handle, until it fails. However, there are variables yet to be explored, and one of them is the application of load in long cycles, which extend over long periods of time.

This is the subject of a new project, which is now starting with the help of a team of researchers from INEGI, and which promises to make the prediction of the lifetime of these materials more accurate.

"Components subject to load application over long cycles are increasingly common, particularly in the transport and energy sector. This scenario leads to fatigue damage that, until now, was unpredictable", explains Abílio de Jesus, responsible for the project at INEGI.

In this context, the project will focus on metal alloys, a material used in numerous structures, from bridges to wind towers, among many others. As the project manager points out, "the study of long-term effects is usually subject to temporal and economic limitations, which can lead to unsafe projects. The tests we are going to carry out, to analyze fatigue in the extreme supercyclical regime, will fill this gap of knowledge".

Project will impact the design of future structural components

It is already known, for example, that long load cycles tend to result in cracks starting inside the material, instead of the typical surface cracks. Data like this, collected during the tests, will later inform the creation of a forecast model and contribute to the creation of more reliable components.

The project also has the participation of IDMEC - Institute of Mechanical Engineering, which recently created and patented an ultrasonic testing machine for multiaxial fatigue, which will complement INEGI's resources.

The team also has two PhD students hosted at INEGI, whose activity will complement the project. Rita Dantas, holder of a PhD scholarship from the MIT Portugal program, entitled "An integrated multiscale fatigue methodology applied to ocean structural systems", will study fatigue in steel components for offshore structural applications. On the other hand, Vítor Gomes, associated with doctoral program iRAIL, aims to evaluate the fatigue strength of the suspension of springs of parabolic laminae of rail freight wagons. This investigation is carried out in collaboration with the rail freight company, MEDWAY.

The project "Comportamento à Fadiga de Longa Duração de Ligas Metálicas de Engenharia" is co-financed by FCT - Foundation for Science and Technology.