Study on the Interaction between Soil and the Five-Claw Combination of a Mole Using the Discrete Element Method

Abstract

A mole is a born digger spending its entire existence digging tunnels. The five claws of a mole's hand are combinative to cut soil powerfully and efficiently. However, little was known in detail about the interaction between the soil and the five-claw combination. In this study, we simulated the soil cutting process of the five-claw combination using the discrete element method (DEM) as an attempt for the potential design of soil-engaging tools to reduce soil resistance. The five-claw combination moved horizontally in the soil bin. Soil forces (draught and vertical forces) and soil failure (soil rupture distance ratio) were measured at different rake angles and speeds. Results showed that the draught and vertical forces varied nonlinearly as the rake angle increased from 10 to 90°, and both changed linearly with the speed increasing from 1 to 5 m/s. The curve of the soil rupture distance ratio with rake angles could be better described using a quadric function, but the speed had little effect on the soil rupture distance ratio. Notably, the soil rupture distance ratio of the five-claw combination in simulation was on average 19.6% lower than the predicted ratio of simple blades at different rake angles indicating that the five-claw combination could make less soil failure and thereby produce lower soil resistance. Given the draught and vertical forces, the performance of the five-claw combination was optimized at the rake angle of 30°.

Biomimetic Rotary Tillage Blade Design for Reduced Torque and Energy Requirement

“…The rotary tillage blade started to break the soil after the whole body of the blade entered the soil, and then, soil wedge was formed in front of the blade as shown in Figure 15 . Based on the previous study [ 20 ], the soil rupture distance ratio of the five-claw combination was about 19.6% smaller than the predicted values of simple blades. It indicated that the soil failure wedge of the BB-1 was significantly diminished so that a lower force was needed for soil shearing.…”

“…The lateral spacing between two adjacent claws is labelled as Δ x . All of the parameters were recorded and presented in Table 2 according to the previous literature [ 20 ]. From the studies by Godwin [ 21 , 22 ], the working depth/width ratio and the tine spacing are the important parameters to determine the categories of blades, soil failure pattern, and soil forces.…”

“…Ji et al [ 19 ] only characterized the geometry of the second claw of mole rats. However, when a mole rat cuts soil, the five fore claws always work synergistically with an opened-up but coplane configuration, which is described as multiclaw combination, for efficient cutting [ 20 ]. Moreover, the contour curves of the five claw tips also significantly affect the soil-cutting performance of mole rats.…”

Design of Structural Parameters of Cutters for Tea Harvest Based on Biomimetic Methodology

“…Shi et al [16] established the 3D models of crop stalks and cutters by using response surface methodology to determine the optimal combination of the kinematic parameters of the cutter at a cutting speed of 1.6 m/s, cutting angle of 15°, and working speed of 1 m/s. Biomimetic technology has recently been applied to optimize the design of traditional agricultural machinery and to improve its energy utilization [17][18][19][20]. It combines biological principles with engineering problems for developing solutions.…”

Bionic Nonsmooth Drag Reduction Mathematical Model Construction and Subsoiling Verification

“…In recent years, the development of bionics has injected new vitality into agricultural machinery drag reduction technology [27][28][29]. Natural organisms have evolved excellent functions and unique geometric structures over billions of years, and among them, animals that are good at digging have evolved superior digging organs.…”