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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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