Quantification of angularity of general-shape particles by using Fourier series and a gradient-based approach. (10th February 2018) - Su, D.
Graphical abstract: Highlights: A new approach for the angularity quantification of general-shape particles is proposed. Morphology of general-shape particles is reconstructed using Fourier series analysis. The gradient-based angularity index is evaluated from the reconstructed morphology. Images in commonly used standard charts are evaluated for their angularity indices. A simple-to-use criterion is suggested for the classification of particle angularity. Abstract: Particle angularity significantly affects the macroscopic mechanical behavior of aggregate assemblages. However, most of the current approaches used for quantifying particle angularity are only applicable to star-like particles. This study presents a new approach allowing the quantification of angularity of general-shape particles. The method first reconstructs the particle morphology by applying Fourier series analysis to the two-dimensional image of the particle. The gradient-based angularity index (AIg ) is then evaluated from the reconstructed morphology through numerical integration. AIg is zero for images of any circularly shaped particles, including circles and ellipses, and it increases with increasing particle angularity. Images included in commonly used standard charts are evaluated for their AIg s. The results show a consistent pattern in regard to the qualitative angularity ranking of the particles. Based on the findings, a simple-to-use criterion is suggested for the quantitative classification of particle angularity.