Peridynamic Modeling Through Micro-CT Images For Failure Simulation Of Composite Microstructure

Since the fields of fiber-reinforced composites expand continuously,the effect of microstructure damage on the mechanical properties of composites has become an essential yet unclarified issue.It is particularly important in the analysis of the failure of composite materials,the calculation and simulation of discontinuous problems such as progressive damage and fracture of microstructures.Traditional continuous mechanics theories and methods are difficult to be solved because the derivative of displacement is not defined at discontinuities when calculating the initiation and propagation of the multi-crack for composite microstructures.In addition,for the modeling problem of composite microstructure,there is a great error between theoretical modeling and actual engineering practice,which makes it difficult to save the information of the real structure when solving.Therefore,it is necessary to develop a feasible and efficient method to model and simulate the microstructure failure of fiber-reinforced composites.Peridynamics is a novel nonlocal mechanics theory,adopting spatial integral equations to describe the interaction between materials points.As a nonlocal theory based on integral equations,peridynamics is more effective to simulate the whole process of materials from elastic deformation(continuous problem)to the initiation and propagation of crack(discontinuous problem).Besides,Micro-computed Tomography scanning technology can be used to obtain the internal information of the structure without destroying the structure to quickly build spatial discrete model containing real microstructural information of composites.Therefore,the following work is done in this paper by combining the peridynamics and Micro-CT scanning technology:(1)In this paper,a peridynamic discrete model based on Micro-CT images is proposed to reconstruct the microstructure of composite materials.By introducing the gray threshold segmentation technology into the Micro-CT image processing,a spatial discrete model containing microstructure information of composite materials can be quickly established.The discrete model can be directly used for the peridynamics simulation of the microstructure failure process.Thus,this method avoids the complex preprocessing process that traditional numerical simulation technology needs to establish a smooth geometric model based on pixel points and then divide it into finite element grids.Consequently,the in situ composition distribution information of the composites microstructure is greatly preserved.(2)Based on the peridynamics theory,this paper adopts the solution method under the finite element framework to construct the peridynamic model of the composite material.Based on the above method,the numerical calculation of different bond elongation at different material components is realized.Thus,the discontinuous Galerkin element is used to solve the mechanical problem of crack from initiation to propagation and complete failure of composite microstructure based on Micro-CT image reconstruction.The simulation results show that this method can better utilize the internal information of the microstructure for mechanical calculation.(3)Based on the Peri FEM discrete method,a new peridynamics-based finite element that can describe the microstructure of composite materials is established and its element stiffness matrix is constructed for general finite element platform in this paper.The Abaqus user subprogram UEL is written to realize the implicit calculation of the Peri FEM and the calculation of the microstructure damage of the composite material.Based on commercial software,the two-dimensional,three-dimensional simulation calculations of composite microstructure reconstructed by Micro-CT are realized,and according to the simulation results,the failure mechanism of the composite microstructure is analyzed.