Brodovy V. Determination of cyclic durability of welded elements in conditions of fatigue cracks inhibition.

The dissertation is dedicated to scientific problem of operability assurance of welded constructions with prematurely raised fatigue crack. It is shown, that the inhibition of the crack by inducing of contracted residual stresses on its front is one of possible ways to increase cyclic durability of materials and supporting elements of constructions. Experimentally shown, that the residual stresses, which are formed in the regions of fatigue crack or concentrator under the action of cyclic loading, interact with the artificially induced ones and form a new field of residual stresses. The notion of crack inhibition effectiveness coefficient was introduced. The correlation dependence of introduced coefficient on value and on order of induced residual stresses obtained. Basing on obtained correlation, the method of experimental-computational determination of cyclic durability of construction elements with fatigue crack growing under the conditions of field of induced contracting residual stresses proposed. This method was approved on the basis of experimental investigations of cyclic durability of a large-scale samples made of low-carbon steel and aircraft aluminum alloy after the inhibition of the crack by residual contraction stresses induced by local strengthening treatments.