PSI - Issue 31

R. Balokhonov et al. / Procedia Structural Integrity 31 (2021) 58–63 R. Balokhonov et al. / Structural Integrity Procedia 00 (2019) 000–000

61

4

concentration in the matrix increases in case 2 as compared to case 1 (cf. Figs. 2b and c, matrix). Cracks propagate perpendicular to the tension direction and parallel to the compression axis. This fracture character is observed in both cases 1 and 2.

Fig. 2. Pressure patterns in the particle and matrix after cooling (a), cooling followed by tension (b) and tension without preliminary cooling of the composite (c). Tension elongation of the composite is 0.7 %.

The stress shown in Fig. 3 was calculated as the equivalent stress averaged over the computational domain, and the deformation was the relative elongation of the domain in the tension direction. For the comparative purpose the stress-strain curve for case 2 starts from strain of -0.7 % corresponding to the cooling induced volumetric compression. The character of crack propagation is fundamentally different in cases 1 and 2. Calculations without taking into account residual stresses show in-particle cracking, while under tension being a successor of cooling the crack propagates along the matrix-particle interface. Due to preliminary plastic deformation of the matrix occurring during composite cooling the ultimate strength of the particle material C ten under further tension of the composite is reached earlier near the interface than inside the particle. The stress-strain curve for case 1 goes higher than it does for case 2, i.e. the cooling-induced residual stresses increase the strength of the composite.

Fig. 3. Homogenized stress-strain curves for tension and cooling followed by tension of the composite, with the fractures regions of the particle being shown.