A three-dimensional particle roundness evaluation method

Particle roundness is one of the major shape parameters influencing the micro-and macroscopic mechanical properties of granular materials. Most of the existing particle roundness methods are based on 2D algorithms utilizing particle projections. However, the morphology of a particle projection will be influenced by the subjectively chosen projection angle. Based on the acknowledged Wadell’s definitions of particle corner and particle roundness, an innovative method is proposed to evaluate the 3D roundness of realistic particles in a quantitative and objective manner. This method first reconstructs the particle with a triangular mesh. Then, corner portions are identified by finding the surface vertexes with both a high local curvature and large relative connected area. After corner identification, a sphere-filling method is employed to fill the corner portions with spheres. Finally, the 3D Wadell roundness is computed by comparing the average radius of the filling spheres with the radius of the maximum inscribed sphere. Validation of the proposed 3D roundness evaluation algorithm is conducted by comparing the results of the proposed method with the results from theoretical and other existing approaches. The comparison indicates that the proposed method can be used to accurately and objectively evaluate the roundness of realistic particles.