DEVELOPING THE NEXT GENERATION OF HYDROGEN ASSISTED FRACTURE MODELS

Lead Research Organisation: Imperial College London
Department Name: Civil & Environmental Engineering

Abstract

The project aims at developing a new generation of multi-physics and multi-scale models that can predict material fracture due to hydrogen embrittlement, enabling Virtual Testing and preventing catastrophic failures.

Hydrogen is ubiquitous and has remarkable properties and applications. Its isotopes will provide the nuclear fusion fuel for humanity in the next half century and the use of hydrogen as energy carrier is one of the most promising solutions to our energy crisis. In defiance of these opportunities, hydrogen has been known for over a hundred of years to cause catastrophic failures in metallic structures. This phenomenon not only jeopardizes the role of hydrogen as a forthcoming energy carrier but also continues to restrict the use of modern steels in current energy infrastructure. The fracture resistance of metallic materials is drastically reduced in the presence of hydrogen (by up to 90%!) and the susceptibility to hydrogen damage increases with material strength. Thus, hydrogen assisted cracking is particularly severe in high-strength steels and the lack of understanding has halted their use in the energy, defence, transport and construction sectors, sacrificing decades of metallurgical progress. In modern high-performance alloys, hydrogen embrittlement is observed even in benign environments (e.g., due to humidity) and its impact is ubiquitous: from bolt cracking at the Leadenhall building to off-shore structural collapse.

With current engineering approaches being mainly empirical and highly conservative, there is a strong need to: (1) understand the mechanisms of such hydrogen-induced degradation; and to (2) develop mechanistic-based models able to reproduce the microstructure-dependent mechanical response at scales relevant to engineering practice. The successful project will lead to a new generation of hydrogen embrittlement models, able to quantitatively predict the occurrence of hydrogen assisted cracking at a scale relevant to engineering applications.

The main objectives of the project are the following:

(1) Developing a multi-physics computational framework capable of dealing with the large scales inherent to engineering practice while resolving the microstructural nature of the problem.

(2) Acquiring fundamental insight into the underlying physical mechanisms by performing critical experiments.

(3) Developing new mechanism-based constitutive models that reduce empiricism by explicitly considering the underlying physical mechanisms.

(4) Predicting cracking thresholds and subcritical crack growth rates in a mechanism-based framework, and validating predictions through advanced materials testing.

EPSRC research areas:Structural engineering, Manufacturing technologies, Materials engineering - metals and alloys, Materials for energy applications

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/R513052/1 01/10/2018 30/09/2023
2261867 Studentship EP/R513052/1 28/09/2019 27/09/2023 Mehrdad Isfandbod