Study On Peridynamics Simulation Method Of Anti-penetration Of Ceramic/metal Composite Structures

Ceramic metal composite structure with high hardness,high bending strength of ceramic materials as the front layer and materials with high tensile strength,high elongation as the backing layer,has excellent penetration resistance.The current numerical methods for studying the penetration resistance of ceramic/metal composite structures under ballistic impact still have many deficiencies.Peridynamics(PD)is a novel nonlocal theory that is well suited for simulations involving damage and fracture behavior.At present,the existing rate-dependent bond-based PD(BB-PD)constitutive model considering the rotation effect and the Johnson-Cook(JC)metal model based on non-ordinary state-based PD(SB-PD)have been proved to be able to simulate the dynamic mechanical behavior of ceramics and metals under shock loading,respectively.However,there is no research on the anti-penetration behavior of ceramic/metal composite structures under the theory of PD.This paper focuses on the anti-penetration simulation method of ceramic/metal composite structure,establishes a new contact algorithm suitable for PD,and proposes a parallel algorithm suitable for ceramic damage and damage simulation,the anti-penetration simulation system of ceramic/metal composite structure under the framework of PD theory was realized,and the exploratory research on the damage mode and dynamic fracture behavior of ceramic/metal composite structure under penetration is carried out.The main contents and achievements of the paper are as follows:(1)Aiming at the problem of low computational efficiency of the existing ratedependent ceramic PD constitutive considering the rotation effect,focusing on the bond force update algorithm and bond damage update algorithm that cost most in the calculation,by sorting out the data structure,setting the logical array to reduce the number of cycles,and setting the thread scheduling to balance the computing load,etc.,the parallel optimization of the rate-dependent ceramic PD model in CPU-based Open MP mode is carried out,and the simulation program of the front penetration of the projectile body is verified.By running simulations between 1 and 32 threads,the relationship between the program’s computation time,speedup,and parallel efficiency is analyzed.The results show that the parallel program can obtain a speedup ratio of1.7～23 times compared with the serial program under the condition of ensuring the calculation accuracy,and the running time of the program is greatly reduced.The parallel efficiency shows a downward trend with the increase of the number of threads.(2)The applicability of the anti-penetration simulation of the JC peridynamic constitutive model based on non-ordinary state-based,which describes the dynamic mechanical behavior of metals,is verified.Compared with the Taylor impact test,the ratio of the residual length to the original length obtained by simulating the frontal impact of the alloy column on the rigid plane at different impact speeds is compared with the test results.The results show that the existing JC metal constitutive model based on non-ordinary state-based can be used to describe the dynamic mechanical response of the metal plate in the ceramic/metal composite structure during the penetration process.(3)On the basis of the contact algorithm commonly used in the existing BB-PD theory,the optimization and improvement are carried out.Aiming at the problems of multi-body contact between different materials and self-contact after the particles are completely damaged in the contact process,a contact search algorithm based on the bucket sorting algorithm and a contact force algorithm based on the penalty function method are established,and combined with the existing PD contact algorithm that describes the contact between the projectile and the target plate,a new contact algorithm is constructed to describe the complex contact problem inside the ceramic/metal composite structure during the penetration process of the projectile.(4)The ceramic model based on BB-PD theory and the metal model based on SBPD are combined through the improved contact algorithm to form a ceramic/metal composite structure anti-penetration simulation system.The contact between the projectile and the ceramic/metal composite target plate adopts the contact algorithm under the BB-PD theory,and the penalty function method is used for the problems multi-body contact and self-contact problems of the particles in the target plate.The calculation format of the two models is unified,and the PD program frame and flow of the ceramic/metal composite model is constructed,and the analysis program of the antipenetration simulation system model of the ceramic/metal composite structure is written in Fortran language.(5)Experimental comparative verification and mechanism analysis of the antipenetration simulation system model of ceramic/metal composite structure.The frontal impact experiment of the ceramic/metal composite structure was simulated and analyzed,and the crack propagation mode,damage change of the ceramic faceplate and metal backplate,as well as the crack initiation and propagation law under different impact speeds are compared with the experimental and other numerical simulation results,which verifies that the system model can effectively simulate the whole process of penetration.The mechanism of damage and stress change process of the composite structure is analyzed,which lays the foundation for the peridynamic study of the ceramic/metal composite structure protective armor and the structural design of the new ceramic/metal composite armor.