Abstract
This paper proposes a method to detect diffuse-mode bifurcations, which engender localization of deformation with characteristic geometrical patterns in plane-strain sand specimens. The scalar fields of a strain invariant in a two-dimensional domain observed in the specimens are expanded into a double Fourier series, and the Fourier spectra are examined. The methodology proposed is twofold: (1) examination of the spectral intensity to identify the wave number, which corresponds to a possible diffuse bifurcation mode, and (2) investigation of symmetry-breaking process of the deformation via diffuse-mode bifurcations. The proposed method is validated through an application to experimental and numerical results of plane-strain compression test, in which localized deformation and formation of shear bands were observed.
