Tumanov A. V. Russia Issledovatel'skij centr problem ehnergetiki Kazanskogo nauchnogo centra RAN, Rossiya, 420111, g. Kazan', ul. Lobachevskogo, 2/31, a/ya 190 shlyannikov@mail.ru Author's articles Elastic Mode Mixity Parameters for Semi-Elliptical Crack under Biaxial Loading