TY JOUR TI THE CALCULATION OF THE THREE-DIMENSIONAL IRREGULAR - SHAPED COMPOSITE BEAMS USING THE DOUBLE-GRID FINITE ELEMENTS KW composites KW elasticity KW beams KW finite element method KW two-grid finite elements JO Bulletin of KSAU AU Matveev, A.D. PY 2015 IS PB Krasnoyarsk State Agrarian University