5:15 PM - 7:15 PM
[PPS06-P20] Experimental study on the tensile strength of two-component dust aggregates
Keywords:dust aggregates, tensile strength
Knowledge of the tensile strength of dust aggregates or regolith piles is significant for understanding the early stage of planet formation in the solar system and the stability of planetary objects that can be destroyed by collisions with other objects or by their own spin motion. Experimental studies on tensile strength have been conducted using samples of various pure materials, but few studies have focused on mixtures.
In this study, tensile strength measurements using the Brazilian disk test were performed on a mixture of silica and graphite. For silica, spherical particles with a volume-based median diameter of 1.2 μm were used, while for graphite, irregular particles with a median diameter of 4.4 μm were used. Samples with silica weight percentages ranging between 0% and 100% were poured into a cylindrical container with a diameter of 1 cm and compressed at 0.3 kN using a compression testing machine, resulting in volume filling factors between 0.37 and 0.60. The tensile strength σ at a volume filling factor Φ was normalized to 0.5 using the empirical equation σ(Φ)=σ(Φ)(0.5/Φ)exp(2.4(0.5-Φ)) (Afrassiabian et al., 2016; Meissner et al., 1964; Rumpf, 1970), and the tensile strength values ranged from approximately 5 kPa (100% silica) to 76 kPa (100% graphite), decreasing with increasing percentage of silica, but not linearly. Note that if the surface energies of silica and graphite were 25 mJ/m2 (Kendall et al., 1987) and 96 mJ/m2 (Fowkes, 1971), respectively, and assuming Rumpf's equation for spherical particles, the tensile strength values would both be about 15 kPa, which is 3 and 0.20 times greater than the results measured in this experiment. Possible causes of this discrepancy include the effects of the surface conditions of the particles (such as adsorbed water and roughness) and particle size distribution.
The similar trend in tensile strength variation observed by changing the component proportions was confirmed in the experimental results (Haack et al., 2020) using a sample mixture of two of the following: ice, silica, and fly ash.
In this study, tensile strength measurements using the Brazilian disk test were performed on a mixture of silica and graphite. For silica, spherical particles with a volume-based median diameter of 1.2 μm were used, while for graphite, irregular particles with a median diameter of 4.4 μm were used. Samples with silica weight percentages ranging between 0% and 100% were poured into a cylindrical container with a diameter of 1 cm and compressed at 0.3 kN using a compression testing machine, resulting in volume filling factors between 0.37 and 0.60. The tensile strength σ at a volume filling factor Φ was normalized to 0.5 using the empirical equation σ(Φ)=σ(Φ)(0.5/Φ)exp(2.4(0.5-Φ)) (Afrassiabian et al., 2016; Meissner et al., 1964; Rumpf, 1970), and the tensile strength values ranged from approximately 5 kPa (100% silica) to 76 kPa (100% graphite), decreasing with increasing percentage of silica, but not linearly. Note that if the surface energies of silica and graphite were 25 mJ/m2 (Kendall et al., 1987) and 96 mJ/m2 (Fowkes, 1971), respectively, and assuming Rumpf's equation for spherical particles, the tensile strength values would both be about 15 kPa, which is 3 and 0.20 times greater than the results measured in this experiment. Possible causes of this discrepancy include the effects of the surface conditions of the particles (such as adsorbed water and roughness) and particle size distribution.
The similar trend in tensile strength variation observed by changing the component proportions was confirmed in the experimental results (Haack et al., 2020) using a sample mixture of two of the following: ice, silica, and fly ash.