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PhD thesis in the field of knowledge 11 Mathematics and Statistics in specialty

113 Applied mathematics. Karpenko Physico-Mechanical Institute of NAS of

Ukraine, Lviv, 2022.

Despite the fact that a large volume of information is devoted to the

problem of the influence of hydrogen on the mechanical properties and resistance

to destruction of structural steels and alloys in the world and domestic literature,

this issue still remains incompletely studied. This is due to the fact that the

influence of hydrogen on the mechanical behavior of structural materials is

multifaceted, and several mechanisms can be implemented simultaneously or

independently. On the basis of the critical analysis and synthesis of experimental

and theoretical studies, the multifaceted influence of hydrogen on the mechanical

behavior and strength of structural materials with the implementation of its several

mechanisms simultaneously or independently is shown. In particular, for steels,

depending on the hydrogen concentration, two hydrogen mechanisms can

simultaneously operate in the metal: hydrogen-induced increased decohesion

(embrittlement) and hydrogen-induced increased local plasticity. The coexistence

of different mechanisms of hydrogen influence on deformation and their

simultaneous action in steels is still not sufficiently investigated. Establishing a
dominant mechanism is an extremely difficult and urgent problem. Existing

models and hypotheses about the mechanisms of hydrogen's influence on the
mechanical behavior of metals explain, as a rule, its embrittlement effect.

Therefore, the actual task and goal of my dissertation work is the mathematical
modeling of the duality of hydrogen's influence on the mechanical properties of

metal structural elements and their residual durability. The object of research is

hydrogen degradation of materials and subcritical growth of cracks in structural

elements under the action of a hydrogen-containing environment. The subject of

the research is mathematical models and methods for predicting the strength and

durability of structural elements under the dual action of hydrogen.

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