Hydrogen induced cracks. Photo by CEphoto, Uwe Aranas / CC-BY-SA-3.0, source Wikimedia Commons
The Polihydra Project is a collection of resources for the Finite Element simulation of hydrogen embrittlment in mechanical parts and structures.
Hydrogen induced cracks. Photo by CEphoto, Uwe Aranas / CC-BY-SA-3.0, source Wikimedia Commons
Hydrogen embrittlement is a form of metal degradation, well recognized since several years, caused by mechanisms acting and interacting at the microscopic and atomic scales which are currently under investigation. Hydrogen embrittlement occurs in many industrial applications, as oil&gas infrastructures, pipelines for hydrogen transportations, vessels for hydrogen storage.
The deleterious macroscopic effect of the environmental adsorption of atomic hydrogen into a steel lattice is the loss of ductility, thus a decrease in mechanical properties. Recently scientists, guided by extensive experimental observations, made some efforts in the development of numerical models able to simulate the effect of hydrogen on different steels. Such tools are especially useful for the design of components working in extreme conditions. Nevertheless, the simulation of this complex phenomenon, which includes different physical parameters and the coupling of diffusion and mechanical fields, is a challenging issue.
The total hydrogen concentration is composed by two contributions in mutual equilibrium: the hydrogen concentration in the normal interstitial lattice sites (NILS), which is driven by the hydrostatic stress gradient, and the hydrogen concentration in the reversible trapping sites. At present, no commercial Finite Element software has builtin the ability of simulate hydrogen diffusion and predict the total hydrogen concetration, hence the need to implement ad hoc procedures.
The aim of the Polihydra Project is to study hydrogen embrittlement in steels through Finite Element simulations. All code produced will be released open source and will be available for download. The aim of this site is to share code, to provide a guideline to the methodology, but also to the practical use of the finite element simulations.
