PSI - Issue 41

A.M. Ignatova et al. / Procedia Structural Integrity 41 (2022) 589–597 591 Ignatova A.M., Yudin M.V., Voronov V.L, Ignatov M.N., Gladky I.L., Inozemtsev A.A., Naimark O.B./ Structural Integrity Procedia 00 (2019) 000–000 3

M is total mass of the two particles; φ is collision angle of the particles.

α , equation (3) is suggested, having a partial solution (4) for the case where all fragments have the

To calculate v j

same velocity.

�1-k�E � � �∑ � � � �� � � � � � N � � � � ��� ,

(3)

v � � ����1-k�� � ,

(4)

k is fraction of elastic energy spent on fracture, e is elastic energy of the particle. Still, this model cannot help evaluate the dynamic change of fracture fragments velocity, except that the authors note that further motion of fragments will be described using classic mechanics equations. The most detailed account of the behaviour of non-metallic hard-melting materials exposed to wave-impact loads, exemplified by ceramics, is given in [6], suggesting a scenario for the development of damage localization in the course of nucleation of fracture regions, associated with formation of multiscale self-similar collective modes of defect ensembles. According to the authors, the prediction significance of the behaviour of fragments constituting the fragmentation field can be expanded through detailed analysis of in-situ experiments. The purpose of the study is experimental determination of the velocity of fracture fragments following an impact against a hard-melting non-metallic silicate material. Materials and methods. In this study, the affected object is potassium fluorphlogopite, a mica-crystalline material (Ignatova et al. 2021) from the group of hard-melting non-metallic silicate materials. It has a density of 2.8-2.9 g/cm 3 , the following crystal chemical formula: КMg 3 [Si 3 AlO 10 ]F 2 and composition, weight %: SiO 2 – 39-43, Al 2 O 3 – 9-12, MgO – 27-30, K 2 О –7-9, F –9-12. Compressive strength of potassium fluorphlogopite depends on the length of layers: at 50-300 µm, this parameter varies within 50 to 10 MPa, respectively. The material structure consists of criss-crossing microlayers (Fig. 1).

Fig. 1. Potassium fluorphlogopite microstructure, х100, polarized light.

Samples of potassium fluorphlogopite were fabricated in the shape of flat plates sized 280х160х15 mm (taking into account 70 mm for fixture in a clamping device of the test unit). For better visibility of the experiment results, the samples were coated with white water emulsion paint and lined with 10×10 mm cell size measurement grid (Fig. 2).