| Gradient material refers to a material in which the material components inside the part are distributed in a gradient along the thickness direction of the layer,and its related properties also change in a gradient.This material is widely used in aerospace,new energy and biomedicine fields.The development of rapid prototyping technology provides a good solution for the preparation of functionally graded materials.Due to the limitation of manufacturing level,the design of gradient materials is usually made up of layers of discrete component materials.the interlayer toughness in the different material components is poor under load.In order to solve this problem,this paper proposes a method for the transition of volume elements between layers.Irregular voxels are used to describe the transition volume to modeling the material layer.Through ANSYS finite element analysis,the effect of the structure parameters of the volume element on the joint surface has been studied.The problem of structural hierarchical instability has been solved in a good way,and the printing path planning has been carried out according to the proposed model.The main research contents and conclusions are as follows:(1)The transition method of interlayer according to volume unit has been proposed.By designing the volume elements of the transition between layers into trapezoids,wedges and right angles to achieve smooth transition between different gradient materials.The order of transition smoothness is: trapezoid > right angle > wedge;by designing layers distribution,interlayer performance could be improved to prevent delamination instability.(2)The generation algorithm of the inter-layer transition volume unit has been designed and the inter-layer is modeled.Irregular voxels has been designed to describe the interlayer volume elements.Through the design of the offset ratio Δ and offset thickness Δ(9 of the transition volume elements,the description of the model interlayer volume elements by irregular voxels has been achieved and the model has been generated and verified.(3)The overall modeling of the gradient material has been designed.After performing interlayer modeling based on the gradient source,an adaptive size algorithm has been designed to unify the generation algorithm of multiple voxels to ensure the accuracy of model description;the voxel discretization algorithm of the irregular voxel model has been designed to solve the problem of data conflicts converted into finite element model;It has been found that through the transitional design of interlayer volume unit,the contact area between different component materials will be relatively increased,which can improve the stability of the preparation of gradient materials.(4)The interactive selection of model gradient source has been achieved.For the FGM model description software,the display of visible surface has been achieved through the backward face algorithm,and the gradient face human-computer interaction selection algorithm is designed through the MFC control,which improves the convenience of selecting the gradient source for the inter-layer modeling.(5)The gradient material model has been transformed into a finite element model,there are66 sets of gradient material models of the interlayer volume element transition with different parameters in experiment,and the finite element method is used to analyze and solve them.It is obtained through finite element analysis that,compared with non-gradient structured composite materials,both the planar gradient structure and the gradient structure gradient material of the interlayer volume unit transition can effectively alleviate the Mises stress concentration on the bonding surface of the ceramic layer and the nickel based layer;For the transition model of interlayer volume elements,the parameter offset thickness Δ(9 is between(0.50 mm,1.00 mm)and the offset ratio Δ is between(0.20,0.40),which can relatively reduce the shear stress at the edge of the model interface.the shear stress mitigation effect is not obvious in the offset ratio Δ which is less then 0,it is verified that the transition model of the gradient material interlayer volume element can achieve the smooth transition of the gradient material to solve interface delamination problem;according to the comparison of the analysis results,When the offset thickness is 0.50 mm and the offset ratio is 0.25,the transition design of the interlayer body element has the most obvious effect of reducing the shear stress.Compared with the plane transition gradient material,the maximum shear stress can be reduced from 12.38 MPa to 5.20 MPa,a 54% decrease,which verifies the adoption Reasonable parameters for the transition of interlayer volume elements can effectively alleviate the shear stress at the boundary of the model gradient material to avoid interlayer cracking.(6)The path planning algorithm for the transition model of the inter-layer volume unit has been designed.Through comparison,the method of layering the interlayer model in the horizontal direction can increase the contact area between different component materials through laminated manufacturing.Therefore,a horizontal layering algorithm is designed for the interlayer transition body unit.Through the material properties in the voxel model,the layered contour ring is merged with the same component materials to reduce the pause of the printing nozzle.The contour ring is printed by one-way scanning method,and the path planning algorithm is designed. |
