OPTIMIZATION OF PASSIVE CONSTRAINED LAYER DAMPING TREATMENTS APPLIED TO COMPOSITE BEAMS

Abstract

THE GEOMETRICAL OPTIMIZATION OF PASSIVE DAMPING TREATMENTS APPLIED TO LAMINATED COMPOSITE BEAMS IS PRESENTED, USING A SANDWICH/MULTILAYER BEAM FINITE ELEMENT MODEL. THE FREQUENCY DEPENDENCE OF THE VISCOELASTIC MATERIAL PROPERTIES IS MODELED USING ANELASTIC DISPLACEMENT FIELDS MODEL. A COMPLEX-BASED MODAL REDUCTION, FOLLOWED BY AN EQUIVALENT REAL REPRESENTATION, IS CONSIDERED. PASSIVE DAMPING TREATMENTS CONSISTING OF VISCOELASTIC LAYERS SANDWICHED BETWEEN TWO COMPOSITE LAYERS ARE STUDIED, WITH THE UPPER LAYER SERVING AS A CONSTRAINING LAYER (CL) AND THE LOWER ONE AS A SPACER (OR STAND-OFF) LAYER (SL). CL AND SL PLIES NUMBER, THICKNESS AND ORIENTATION ARE CONSIDERED AS DESIGN PARAMETERS AND ARE OPTIMIZED USING A GENETIC ALGORITHM WITH EIGENFREQUENCY CHANGES AND WEIGHT CONSTRAINTS. A STRATEGY FOR MULTICRITERIA OPTIMIZATION IS PRESENTED USING, AS PERFORMANCE INDICES, THE INTEGRAL OF TRANSVERSE VELOCITIES AND THE DAMPING FACTORS OF THE FIRST ¯VE EIGENMODES AND, AS PENALTY FUNCTIONS, THE TOTAL MASS AND THE VARIATION OF EIGENFREQUENCIES DUE TO THE TREATMENT. THE RESULTS SHOW THAT THE USE OF A GLOBAL COST FUNCTION ALLOWS TO IMPROVE THE DAMPING OF STRUCTURAL VIBRATIONS WHILE MINIMIZING STRUCTURE MODIFICATION DUE TO THE TREATMENT.