Simulation Study Of The Crack Propagation In 3D Printed Disks Based On The Peridynamic Method

In recent years,with the development of 3D printing technology,3D printing materials have been widely used in industrial manufacturing,medical devices,aerospace and other fields.Compared with the traditional physical methods such as water jet and sawing,3D printing materials are often used as experimental materials for scientific researchers because of their precise geometry and homogeneity.However,in the process of sample preparation,small initial cracks are often left in the sample due to process errors and other reasons.These microcracks will accumulate and expand under the influence of external factors such as long-term load holding and temperature action of the sample,and eventually lead to failure fracture of the sample due to crack penetration and loss of bearing capacity.This will not only lead to premature failure of materials and waste,but also lead to sudden fracture failure of structures or components in the working state,and even cause serious property loss and casualties.In the process of material fracture,the crack propagation path and the type of coalescence play a decisive role in the failure mode of material.Therefore,it is of great significance to understand and predict the mechanical mechanism of crack initiation,propagation and coalescence in 3D printing materials for the safety evaluation of engineering structures,improvement of material strength and reduction of fracture accidents.With the mature development of 3D printing technology in recent years,3D printing materials have been widely used and developed rapidly in the fields of industrial manufacturing,medical equipment,jewelry and aerospace.Compared with the traditional physical methods such as water jet and sawing,the materials produced by 3D printing technology are very suitable as experimental materials for researchers due to their precise geometry and homogeneous characteristics.Based on this,the disc prepared by 3D printing technology is selected to simulate the crack propagation behavior of real materials in reality.There are still relatively few simulation studies on crack propagation paths and crack filling of 3D printing materials.Therefore,this paper uses the emerging peridynamics to simulate crack growth of brittle disks.Let's explore the crack propagation mechanism of the material.In this paper,based on the peridynamics(PD)method,the crack propagation behavior of 3D printed disks under quasi-static compression load is simulated and studied.The influences of the inclined angle,number and location of pre-existing cracks on the crack path and type are investigated.The crack growth law and crack coalescence mechanism of 3D printed disks are revealed.The results of this study provide important theoretical significance and reference value for the fracture behavior of 3D printing materials.The main contents of this paper are as follows:Firstly,based on the bond-based peridynamics(BBPD)method,a numerical model is established to consider the propagation of a pre-existing single crack in disks.In this paper,the process of initial crack initiation,crack propagation and crack penetration through the disk under the constant compression rate and seven different inclinations of equal length 8mm crack is studied.In addition,based on the fact that the crack is not filled,the process of path growth after filling is studied.Comparing the simulation results of single crack without filling with the existing experimental results,it shows that the near-field dynamics method is correct and effective in simulating single crack and crack filling path propagation behavior.Secondly,a numerical model is established based on the ordinary state-based peridynamics(OSPD)method,which considers the propagation of a pre-existing double cracks.Among them,the crack growth and coalescence process of double cracks with equal length of 8mm under constant compression rate and different obliquity are mainly studied.In addition,the change of path propagation of collinear and non collinear cracks before and after filling and the distribution of stress and strain in the process of propagation are studied.The relationship between the final crack type and stress-strain is analyzed and explained.Finally,the rule of crack propagation and coalescence in the case of multiple double cracks is summarized.Thirdly,a numerical model is established based on the ordinary state-based peridynamics method,which considers the propagation of a circular crack with pre-existing triple cracks.At first,the crack growth process of the central crack under constant compression rate is studied when the left and right cracks are kept horizontal.Then,the path growth changes under the influence of many factors such as crack filling,loading rate,crack length,loading boundary and so on are further investigated.The results show that crack filling can effectively improve the material strength and slow down the crack initiation and propagation speed.The loading boundary has a great influence on the circular boundary,and the crack branching in the loading area,which has a certain influence on the crack path in the loading area.