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The calculation model for determining of residual durability of plate with straight corrosion-mechanical crack under long-term static tension and multiple time concentrated quasi-dynamic load is proposed. The model based on the energy approach for a study of delayed crack growth, models of pulsed load applying and the main mechanisms of corrosion-mechanical crack propagation. Based on this model, the dependence of residual life of the plate of X60 pipeline steel on a number of time concentrated quasi-dynamic loadings is investigated. 

This article presents detailed description of the cast-iron short barrel bombard in late 14 early 15th century from Lviv History museum collection. Briefly analyzed some options of the wooden gunstock cannon, developed and described the wooden gunstock of the handheld bombard.