Optimization Design Of Dynamic Analysis Of Composite Structures With Viscoelastic Damping Layer

Because of its designability of mechanical property and anisotropy, the compositestructure with viscoelastic layer may be better in damping potential and structuraldamping performance, compared with traditional damper structure, which can make itsdamping characteristics better than isotropic structure and general composite structures.At the same time, the addition of viscoelastic damping layer will effect the strength ofthe whole composite structure, mechanical property of which is effected by variousfactors, such as laying angle of fiber of each layer, relative thickness of viscoelasticlayer, etc. The optimization design can be helpful to improve its good mechanicalproperty. Optimization design with genetic algorithms is one of the most widely usedmethod.Genetic algorithms was proposed in the sixty’s of last century, which has thecharacteristics of global optimization and probabilistic search. It is the computersimulation of the evolution rules in the field of biology,“It is not the strongest of thespecies that survive, but the one most responsive to change”. It is not limited in thespecific conditions, the search dirction of which is guided by each specific value in thecalculation. As it has no high requirement to target function, it is very robust andadaptable. Because of its inside implicit parallelism, which ensure its global searchability and search efficiency, it has received widely attention after proposed. With thecontinuous improvement of the theory foundation and the search performance, it hasbeen widely used in many fields, including the optimization of composite laminate.This paper introduces a method using higher-order displacement mode, whichgets the normal and shear strains firstly, and gets the stress and the strain and kineticenergy by the constitutive relations. The governing equations will be derived byvariations of displacement components through the Hamiltonian principle. The naturalfrequencies are acquired for simply supported angle-ply laminated plates. According tothis, choose the nondimensionalization natural frequency normalized to beoptimization objective, with different laying angles, elastic modulus ratio, span tothickness ratio, alone or in combination as the design variable.By the strength theory of composite laminate, this paper analyzed and calculatedthe strength performance of composite laminate, and chose strength as optimizationobjective to complete the optimization design.Based on these, this paper calculated and optimized the vibration and strength performance of a three-layered composite structure with viscoelastic mid-layer. Byusing the genetic algorithm, the double-objective optimization design was completed,which chose the loss factor and failure strength to be optimization objectives.