Damage Mechanics Model Of Carbon Fiber Reinforced Polymer

Carbon fiber reinforced plastic(CFRP)have been widely used in various engineering fields due to their outstanding material properties.In the process of progressive failure analysis of carbon fiber reinforced resin matrix composites,there are a variety of damage modes,such as fiber break,matrix cracking,interlayer delamination,etc.These damage modes interact with each other and are coupled for the composite structure,which brings in great difficulties to carrying capacity analysis.Therefore,this dissertation is based on the phenomenological analysis theory of continuum damage,and deeply investigate the damage mechanism of composite materials,and establishes a damage mechanics model that is suitable for CFRP.The dissertation first systematically summarizes the methods of constructing the damage constitutive model of composite materials.Based on the comprehensive literature review,according to the continuum damage mechanics theory,combined with the nonlinear constitutive relationship and experimental results,a three-dimensional damage mechanics model describing the progressive failure analysis of carbon fiber reinforced resin composite laminates is systematically developed.The damage mechanics model in the layer uses the Hashin criterion to determine the initiation of fiber damage,and the Puck criterion is used to determining the damage initiation matrix.The damage model can be divided into fiber tensile damage,fiber compression damage,matrix tensile damage,and matrix compression damage.Material damage performance model based on fracture energy toughness is used to calculate the performances of the material after damage.When the matrix damage occurs,the transverse damage variable and the shear damage variable are respectively redefined,the coupling effect between the variables is considered,and the elasto-plastic nonlinear constitutive relation is used.Through the secondary development of the large-scale commercial finite element program,a new intralayer damage mechanics model proposed in this dissertation is realized.The model of the interlaminar damage mechanics uses cohesive model,and predicts the initiation of delamination by the secondary nominal stress criterion and the degradation of material properties caused by delamination through the B-K model.This model performs numerical analysis on the off-axis compression of the unidirectional plate and the center-opening laminated plate.The prediction results of the example are of good agreement with the experimental results reported in literature,which verifies the rationality and effectiveness of the damage mechanics model.Finally,according to the test characterization,this damage mechanics model of the CFRP was used to establish the damage mechanics model of T700 CFRP.The numerical results are consistent with the tensile test results of the T700 CFRP laminates.The damage mechanics model of CFRP established in this dissertation can be effectively applied to the composite bearing performance analysis.It is of great significance and engineering application value to carry out progressive damage analysis of composite materials for the engineers.