“…Currently, there are many methods for studying the deformed state of the material in the zones of constructive stress concentration: brittle-lacquer technique [5], etching of the deformed surface [6], the method of optically active coatings [7,8], the moire method [9,10], the interferometric method [11], the tensometric method [12], the method of precision dividing grids [13][14][15][16], the finite element method [17][18][19][20] and other methods.…”