Post-buckling development in soft particulate composites

In this paper, we investigate the post-buckling development of instability-induced patterns in soft particulate composites. Upon reaching the critical strain level, the composite experiences microstructural buckling. Interestingly, in the post-buckling regime, the initial buckling mode may evolve into different new patterns. These transformations are governed by the initial microstructure parameters. In particular, depending on the initial distance between the columns of inclusions, the initial instabilities may develop into (i) inclusion chains with a zigzag or wavy shapes, (ii) a combination of inclusion sets in different length scales, (iii) seemingly disordered inclusion sets, (iv) and structures with strictly doubled periodicity. The different post-buckling patterns are further characterized via the discrete Fourier transform (DFT) analysis. Our results also show that the initially formed post-buckling patterns can further evolve into rather complex new shapes beyond a simple amplification in deformation.