(738e) 3D Printing of Tuneable Coloured Agglomerates - Strain Distribution Study of a Single Agglomerate Design

The current study presents a novel and reliable method for producing 3D printed agglomerates with different colour distributions and material properties with two-fold aims: providing feasible and accurate control on compression of multiple copies of the same 3D printed agglomerate under different compression angles, and better tracking of individual particle positions after agglomerate breakage.

Multi-coloured agglomerates in cubic tetrahedral and random sphere shapes (used in a previous study [1]) were printed with both rigid and soft bonds using a Statasys Connex 3 using standard vendor polymers and colours to indicate different regions of the agglomerate. The surface and structural properties of the agglomerate, including surface roughness and printing accuracy, were analysed. The agglomerate breakage behaviours under quasi-static compression in an Instron were analysed as a function of bond strength (by varying the polymer used to print the bonds), loading rate (0.02-1 mm/s) and loading directions. The strain distribution was then plotted for the random sphere agglomerate structure as a function of these variables. In addition, agglomerate structures with designed internal macro-voids in different positions and sizes were also created and their breakage behaviour analysed an effort to better understand parameters governing the mechanical properties of agglomerates with cavities and voids. The results showed than a single agglomerate has a distribution of strengths, depending on the orientation and strain rate. This is the first time that a wide distribution of “strength” for a single agglomerate has been demonstrated, as the 3D printing technique allows multiple identical copies of the same agglomerate to be tested under systematically controlled conditions. Similarly, the removal of particles and bonds in key positons also showed effects on the agglomerate strength. Overall the results demonstrate a new technique to understand agglomerate deformation and breakage, including due to defects and cavities, which is an inevitable process during particle handling in industry but poorly understood at present.

Reference

[1] Ge, R., et al., 3D printed agglomerates for granule breakage tests. Powder Technology, 2017. 306: p. 103-112.