A Bioinspired Self-Burrowing Probe in Shallow Granular Materials

Bioinspired strategies have been used in recent years to solve engineering problems in geotechnics. Inspired by the dual-anchor locomotion mechanism of razor clams, researchers are developing a new generation of self-burrowing probes for a wide range of applications such as site exploration and sensor deployment. Due to inherent complexities of the bioinspired self-burrowing mechanism, the interaction between the probe and the soil is not fully understood, hindering the development of physical prototypes. In this study, a model based on the discrete element method (DEM) is used to prove feasibility and study and optimize the self-burrowing process of a probe. The probe burrows in a gravity-settled chamber filled with a scaled discrete analogue of a silica sand. A stepwise methodology, including essential anchor expansion, tip penetration, and anchor retraction, is proposed to model the self-burrowing process. Tip oscillation is introduced to reduce penetration resistance, which enables efficient burrowing through continuous cycles. However, the reduction strategy of soil resistance consumes more than 50% of the total work done by the entire self-burrowing cycle. Micromechanical observations, such as the contact force network and the particle displacement field, are provided to clearly visualize the interaction between the soil and the probe. While the total energy necessary to penetrate is greater than that for an equivalent constant-rate penetration, the feasibility of such a probe is numerically proven.