Peridynamic Analysis Of The Effect Of Initial Cracks On The Crack Propagation Of Carbon Fiber Reinforced Plastic Lamina

Carbon Fiber Reinforced Plastic(CFRP)as a new lightweight material,is widely used in automobile,aerospace and other important fields.During the production and manufacturing of CFRP,microcracks and other defects often appear in local areas.These defects will become the starting point of damage in the service process of CFRP products.With the accumulation of damage,crack propagation and fracture will be caused,which will threaten the safety of the CFRP products seriously.Therefore,accurate analysis of the effect of initial defects on the crack propagation path and failure mode of CFRP is an engineering issue that must be considered.Peridynamic(PD)theory uses integral equations to describe the mechanical behavior of materials,and the singularity and complexity of traditional mechanical models in solving discontinuous problems are avoided.Moreover,PD model can simulate crack initiation and propagation spontaneously,which has significant advantages in solving discontinuous problems such as crack and damage.This thesis constructed the PD model of the CFRP unidirectional plate based on the bond-based PD theory.And the influence of the length,location and angle of the initial cracks on the crack propagation path and ultimate failure mode of the CFRP unidirectional plate was studied by using simulation method.Firstly,the PD model of the CFRP unidirectional plate was constructed,and the corresponding C++ codes were compiled to simulate the crack propagation of two groups of CFRP unidirectional plate models with central crack under axial tensile load,respectively.Secondly,considering the fiber direction of 0 °,90 ° and 45 °,the tensile simulations on the CFRP unidirectional plate models with initial cracks at different positions,lengths and angles were carried out respectively.And the influence of initial cracks on the crack propagation path and failure mode of the CFRP unidirectional plate was analyzed.Finally,the crack propagation path and failure mode of the CFRP unidirectional plate with arbitrary initial crack in the fiber direction of 60 ° and-45 ° were analyzed.Some results can be obtained from the crack propagation simulation of the CFRP unidirectional plate models as follows:(1)The length,position and angle of the initial crack have some influence on the crack propagation path of the CFRP unidirectional plate.Generally speaking,the matrix damage occurs at both ends of the crack firstly,and the crack propagation is related to matrix damage and the propagation path is along the fiber direction.(2)The ultimate failure mode of the CFRP unidirectional plate varies with fiber orientations: In addition to the failure of 0 ° CFRP unidirectional plate due to fiber fracture at both ends,the 45°,90° and other fiber oriented unidirectional plate eventually fail due to matrix fracture.(3)For the CFRP unidirectional plate with 45 ° and 90 ° fiber direction,the length,position and angle of the initial crack may change the crack propagation path under the fixed load speed,and the crack propagation path would be bifurcated or no longer strictly along the fiber direction.