GEOMETRICALLY NONLINEAR ANALYSIS OF THIN-WALLED LAMINATED COMPOSITE BEAMS

Abstract

THE USE OF THIN-WALLED COMPOSITE BEAMS IN ENGINEERING HAS ATTRACTED GREAT INTEREST IN RECENT YEARS. COMPOSITE BEAMS AND OTHER STRUCTURAL ELEMENTS TEND TO HAVE THIN WALLS DUE TO THE HIGH STRENGTH OF THE MATERIAL. OTHER IMPORTANT ASPECT IS THAT, EVEN WITHOUT REACHING LARGE STRAINS AND WITHOUT OVERCOMING THE ELASTIC LIMIT OF THE MATERIAL, SUCH BEAMS PRESENT GEOMETRIC NONLINEAR BEHAVIOR DUE TO THEIR HIGH SLENDERNESS, LEADING TO LARGE DISPLACEMENTS AND ROTATIONS. IN THIS PAPER, A THREE-DIMENSIONAL FRAME FINITE ELEMENT FOR GEOMETRIC NONLINEAR ANALYSIS OF THIN-WALLED LAMINATED COMPOSITE BEAMS IS PRESENTED. THE FINITE ELEMENT USES THE TOTAL LAGRANGIAN FORMULATION IN ORDER TO ALLOW THE TREATMENT OF LARGE DISPLACEMENTS, BUT WITH MODERATED ROTATIONS. THE CONSTITUTIVE MATRIX OF THE LAMINATED BEAMS IS EVALUATED THROUGH A SUITABLE THIN-WALLED BEAM THEORY. IN THIS THEORY, THE EFFECTS OF THE COUPLINGS FOR SEVERAL LAYUPS ARE CONSIDERED, BUT THE EFFECTS OF THE WARPING AND TRANSVERSE SHEAR ARE NEGLECTED. COMPARISONS WITH NUMERICAL EXPERIMENTS DEMONSTRATE THE VERY GOOD ACCURACY OF THE PROPOSED FINITE ELEMENT.