1. Professor, Academician of the National Academy of Sciences of Armenia Institute of Mechanics, National Academy of Sciences, 24B Baghramyan Ave., Yerevan 0019, Armenia.
2. Assistant Professor, Russian-Armenian (Slavonic) Univ., Senior Researcher, Institute of Mechanics, National Academy of Sciences, 24B Baghramyan Ave., Yerevan 0019, Armenia (corresponding author).
3. Researcher, Institute of Mechanics, National Academy of Sciences, 24B Baghramyan Ave., Yerevan 0019, Armenia.