Phase‐field simulation of microscale crack propagation/deflection in SiC_f/SiC composites with weak interphase

Abstract

To understand the microscale toughening mechanism, the crack propagation, and stress–strain response of unidirectional SiCf/SiC composites with h‐BN interphase under transverse and longitudinal tension are investigated by a promising micromechanical phase field (PF) method along with representative volume element. Of much interest, the calculation results are well consistent with the available experimental results. With a strong dependence on the interphase strength, the toughening mechanisms during crack propagation are well presented, for example, fiber pull‐out, crack deflection, and interphase debonding. Furthermore, the longitudinal tensile strength of SiCf/SiC composites increases with decreasing the interphase strength, where only a weak enough interphase can result in a significant crack deflection by its cracking. In particular, the ratio of the interphase strength along fibers to the matrix strength should be less than 1.254 to ensure crack deflection in the interphase and fiber pull‐out. Moreover, the transverse tensile strength of SiCf/SiC composites reaches a maximum with increasing the interphase thickness into the range of 0.25–0.5 µm.

Study on the Relationship between Crack Initiation and Crack Bifurcation in Walnut Shells Based on Energy

“…Macroscopic crack initiation represents the initial phase of the overall expansion process, resulting from the energy-driven enlargement of pre-existing micro-defects or micro-voids within the material [39]. After a certain length of crack extension, crack bifurcation takes place when the crack's tip encounters non-uniform stress or energy distributions, particularly when a substantial amount of energy is injected [40,41]. It is evident that there is a connection between crack initiation and bifurcation, as both fundamentally rely on energy as the driving force.…”

Fine study of hierarchical interphase constructed by Ti3SiC2 and carbon nanotubes in SiCf/SiC composites

“…Therefore, a qualitative characterization of the interface between fibers and matrix can help us to find a solution to improve the strength and toughness of the composite materials. [7][8][9] Extensive research efforts have been dedicated to investigating the interphase in the SiC f /SiC composites. [10][11][12] The pursuit of enhanced performances has led to a significant focus on the interphase, which involves the utilization of innovative materials and hierarchical microstructures.…”