PSI - Issue 37

Yulia Pirogova et al. / Procedia Structural Integrity 37 (2022) 1049–1056 Yulia Pirogova / Structural Integrity Procedia 00 (2021) 000 – 000

1052

4

according to which the values of correlation functions and other statistical descriptors are found by integrating the RVE volume (Tashkinov, 2021, 2014): ( ) ( ) ( ) ( ) ( ) ( )        = − − −  ( ) 1 1 2 ( ,..., ) ... n n n V K r r r p r p r p dV . (3) For each studied RVE sample, a set of correlation functions of the second, third and fourth orders were obtained. Changes in the morphology that can be tracked with these functions were compared to the results of finite element modelling of elastic properties. 4. Samples printing The structures were manufactured using additive manufacturing based on the FDM/FFF method. Polystyrene that was used for printing of the studied structures is a thermoplastic polymer of sufficiently high strength, resistant to acids and alkalis. Samples with the inclusions taking form of octahedron, icosahedron, cube, tetrahedron with volume fraction p =0.15 as well as with the spherical inclusion and volume fraction p =0.5 were chosen as structures for 3D printing. Each structure was printed with dimensions 10x10x10mm in 3 copies. Examples of some printed structures are shown in Figure 4. The tests were carried out on a universal testing machine Instron 68SC-5. All samples were subjected to compression load with a force of F=480N.

Fig. 4 Printed samples with tetrahedron and cube inclusion shapes

5. Numerical calculation of elastic properties Three-dimensional tetrahedral finite elements were used for geometry meshing (see Figure 5). Such finite elements are widely used for the calculation of spatial bodies having a triaxial stress state. For all structures, the model properties of the polystyrene were taken: the Young's modulus of the material E=2080MPa, the Poisson's ratio ν =0.35, the density of the material 9 1.03 10  − =  t/ 3 mm . Inclusions form a porous phase. A compressive load was applied to the models through the displacements increment value 0.5 l  = .