Research On Progressive Damage Simulation And Experiment Of Composite Lamina Based On Peridynamics

Peridynamics(PD)Theory has received widespread attention in structural damage simulation these years due to its abilities of describing discontinuities naturally and performing multi-scale computations.Composite materials,which possess characteristics of anisotropic and complex failure modes,have been widely used in national key areas such as aerospace,ship and automobile industry,and become a hotspot of PD research.The basic assumption of the general composite PD model is that: the in-plane bonds consist of the fiber bond and the matrix bond.,only the bond in the fiber direction is defined as the fiber bond,and all otherdirections are matrix bonds.The general model assumption while ensuring the overall accuracy of the calculation reduces the computational consumption to a certain extent.However,it is hard to fully reflect the anisotropy of the composite material when it is generalized to the general situation,which may cause significant error for different angles of the fiber orientation.In this paper,the error of the general model is numerically simulated and analyzed,and three correction methods are proposed: the horizon correction method,the approximate point correction method and the spherical function model correction method.Comparison of all correction method results show that the horizon correction and the approximate point correction can not solve the error problem thoroughly,and only the newly proposed spherical function correction can reduce the error effectively by utilizing the micromodulus function continuously changing with the angle.Based on the energy equivalence principle,micro-modulus parametercan be obtained by equating the strain energy density in the classic laminated theory with PD strain energy density from the micromodulus in the spherical function form.The Fortran programs are developed,which adopt the classic PMB material model and introduce the bond failure criterion of severing strain.In order to verify the feasibility and effectiveness of the PD method in modeling fracture,the displacement comparison and convergence analysis in elastic deformation phase as well as crack propagation simulation in failure phase are conducted in an isotropic plate model.For the purpose of the validity and accuracy verification of the PD method in the application of composite materials,the quasi-static tensile test was carried out on the composite unidirectional plate with defects.The specimen can be divided into A-type tensile sample and B-type sample with mixed crack.Through the test,failure modes of composite unidirectional plate with different fiber orientation and different defects are obtained,which provide reference data to the subsequent PD simulation.Numerical discretization are carried on the specimen of the experiment,two forms of defects in structures are considered,including the line crack and cutout.From the PD program results,the progressive propagation process of the unidirectional plates with the fiber angle of 0 °,45 ° and 90 ° are successfully simulated,and the crack propagation path and ultimate failure morphology are obtained.This indicates that the PD model results is in good agreement with those of experiment,which reflects the effectiveness of the Peridynamics theory in the crack propagation analysis and failure prediction of the composites.