Analyzing the Effect of Energy Dissipation on Thermo-Mechanical Responses of Viscoelastic Fiber Reinforced Composites Using Finite Element Method

摘要

Carbon fiber reinforced composites (CFRCs) are preferred materials used in theaerospace industry for high performance load carrying applications. The polymermatrix in CFRCs is a viscoelastic material and its mechanical properties vary withtime, temperature and applied external loads. Experimental work suggests thatpolymers and polymeric composites, subjected to high-frequency cyclic loading, cangenerate enormous amount of heat from the energy dissipation which softens thepolymer and accelerates failure. Current research efforts on the cyclic response inCFRC focus on understanding the macroscopic (overall) performance of composites,i.e., number of cycles to failure for a given frequency and loading amplitude. Asystematic understanding on the formation of heat generation and its effect on themechanical properties of the constituents in composites, and microscopic responses ofcomposite is currently lacking. Changes in the micromechanical field variables (strain,stress, temperature) of CFRCs during cyclic loading can be crucial in understandingfailure in composites. This study attempts to provide a detailed understanding on theeffect of energy dissipation due to the viscoelastic nature of polymer on the overallmechanical responses of CFRP composites subjected to cyclic loading. Finite element(FE) analyses on the deformations of CFRP composites under various boundaryconditions and loading histories are presented. A thermo-mechanical viscoelasticconstitutive model is used for the polymer which is defined using a material subroutine, inABAQUS FE code. In addition, voids are added to the CFRC models to account formanufacturing imperfections and their influence on the field variables and macroscopicbehaviors are investigated.