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New models can predict when offshore constructions will fail

Thursday 29 Jun 17

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Emilio Martínez Pañeda
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DTU Mechanical Engineering
Emilio Martínez Paneda from DTU Mechanical Engineering has developed a new model that can predict when and how cracks will initiate and propagate in structural components exposed to aggressive environments.

He has received the prestigious Springer PhD Prize for his scientific work on this subject in his PhD, “Strain gradient plasticity-based modeling of damage and fracture” from Universidad de Oviedo, 2016. His work has been made in close collaboration with the scientists at the section of solid mechanics at DTU Mechanical Engineering.

In the energy industry, corrosion is a major problem often causing constructions to be replaced at great expenses. Hydrogen embrittlement is the main mechanism behind this process of material degradation and failure; experiments have consistently shown that hydrogen atoms can significantly reduce the fracture resistance of metallic materials. The problem is particularly severe in the Oil&Gas industry and off-shore applications, hindering the use of high performance materials.

“High strength steels have been excluded from hydrogen-sensitive applications due to their susceptibility to this form of damage and the lack of understanding of this complex chemical and micromechanical problem. This has a huge economic cost; we are giving away decades of progress in metallurgical research!” Emilio Martínez Paneda explains. “We realized that we could obtain, for the first time, accurate predictions of crack initiation and failure in a wide range of environments if we incorporated advanced material models that implicitly account for the mechanisms taking place at the small scales involved in crack tip deformation.”

New plasticity theories have been developed to incorporate the different behavior of metals across the scales, what the scientists at DTU Mechanical Engineering refer to as the “smaller is stronger” effect.

“We have used these advances plasticity theories to capture the local hardening that takes place in the vicinity of cracks,” tells Emilio Martínez Paneda.  “These dislocation-hardening mechanisms play a fundamental role in the modeling hydrogen assisted cracking. We are now able to predict when cracking will initiate for a given environment, material properties and loading conditions.”

Emilio Martínez Paneda is currently a H.C. Ørsted Postdoctoral Fellow at DTU Mechanical Engineering and working on the project “Micro scale metal plasticity: fundamentals and applications” (MICROMETAL).

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http://www.mek.dtu.dk/english/nyheder/nyhed?id=81A01354-262A-45B3-8F70-508B90DE6182
21 NOVEMBER 2017