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Structural failure analysis of fast-spinning small bodies by finite element method

Presentation #506.05D in the session Asteroids: Near-Earth Objects (Oral Presentation)

Published onOct 23, 2023
Structural failure analysis of fast-spinning small bodies by finite element method

The study of the structural stability of small bodies can help us understand their material composition and mechanical properties, and provide clues about the formation and dynamical evolution of small bodies. Some near-Earth asteroids have fast spin speeds and exhibit tensile stress in their internal states. The traditional Mohr-Coulomb yield criterion and Drucker-Prager yield criterion may not accurately describe the structural stability of small bodies dominated by tensile stress. In response to this issue, we propose a tensile stress yield criterion based on nonlinear yield trajectories, the paper conducts finite element analysis of small bodies’ structural failure, studies the minimum cohesion of small bodies while maintaining structural stability, and compares the results with iterative analysis using the D-P yield criterion. The results indicate that regardless of the tensile or compressive stress state, the core region of a small body first reaches a plastic state and its structure fails, followed by the surface region near the equator, and the surface of a small body at the pole is the most stable. This indicates that there is a material flow from the core of a spinning small body to the equator, which may be the cause of the Equatorial ridge. Furthermore, the influence of two important factors, spin angular velocity and the size of small bodies, which dominate the failure mode of small bodies, are studied. It is found that the limiting cohesive force of small bodies increases rapidly with the spin angular velocity according to the law of Power function. With the increase of spin speed, the failure mode of small bodies gradually changes from compressive stress to tensile stress. At the same time, the larger size of small bodies, the more likely it is to fail. The cohesion force and the size of small bodies also have a power exponential relationship of ~2, and as the size of small bodies increases, the failure mode gradually becomes dominated by tensile stress. Based on the above research, structural failure analysis is conducted on three possible models of 2016 HO3 under rapid spin. Research can provide important references to study the accurate internal structure of fast spinning small bodies.

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