This study investigates the tribological behavior of the attachment force between bio-inspired claw–spines and rough surfaces and conducts theoretical and model-based analyses of the corresponding attachment mechanism. Based on critical interfacial tribological theory, a frictional mechanics model for a single claw–spine interacting with an arbitrary rough surface was developed. Furthermore, a stiffness-matrix-based mechanical model of bio-inspired claw–spine attachment to arbitrary surfaces was established, together with a contact interaction model between the claw–spine and the contact surface. The force distribution during the contact and attachment of the claw–spine to arbitrary surfaces was analyzed in detail. Criteria for determining stable claw–spine attachment were formulated, and the safe range of frame displacement variation under the corresponding conditions was identified. Based on these analytical results, a test platform for the bio-inspired claw–spine attachment structure was designed. In the experiments, the developed attachment-force measurement system was used to measure and analyze the frictional attachment forces generated by the claw–spine foot on different rough surfaces. After the claw–spine entered the stable attachment stage, the maximum claw–spine attachment forces measured on 60-grit, 80-grit, and 120-grit sandpaper surfaces were 0.62 N, 0.54 N, and 0.61 N, respectively. The corresponding maximum attachment forces measured on horizontal and vertical brick surfaces were 0.92 and 0.99 N, respectively. The results provide a basis for the mechanical analysis and force sensing of bio-inspired claw–spine attachment states and establish theoretical and experimental foundations for subsequent research on attachment-state recognition and motion control based on attachment-force feedback.

The effect of different concentrations of oleic acid additive on the yield behavior of a magnetorheological fluid (MRF) was investigated from the perspective of tribology. Different concentrations of oleic acid (OA) influence the magnetorheological effect by altering the lubricating properties of the base carrier liquid. Good lubricity of the carrier fluids led to lower shear stresses. The friction between the particles and that between the particles and plates were a part of the shear stress. The structural evolution was promoted by both lubrication and shearing. The shearing thinning of the MRF was delayed under good lubricity, and the particles were easier to roll. The friction forces, along with Brownian forces, Stokes forces, and magnetic attraction, affect the structural evolution of MRF. This study provides a new theory for the formulation design of magnetorheological fluids, reducing design costs and improving production efficiency.

To resolve the problems of low operational efficiency and high plant injury rate in mechanized garlic scape harvesting, this study systematically investigated the interfacial mechanical and mechanical damage characteristics of garlic scapes during the pulling-out process. Basic mechanical properties of garlic scapes, including tensile, compressive, bending and shear behaviors, were first measured to clarify the inherent mechanical basis for interfacial mechanical and injury evolution. Pulling-out mechanical tests of garlic scapes were subsequently conducted utilizing three types of working tools to explore the interfacial mechanical response between tool and garlic scape during harvesting operation. Meanwhile, X-ray CT scanning technology was adopted to qualitative characterize the internal piercing damage of garlic scapes induced by tool extrusion and mechanical contact. The test results indicated that the tensile strength and fracture displacement of garlic scapes exhibited a gradual decreasing trend from the apical segment to the basal segment. Increasing tensile speed further improved the tensile strength and fracture displacement of garlic scapes while shortening the fracture duration. Additionally, the compressive, bending and shear resistance of garlic scapes all declined progressively from the top to the base, revealing distinct spatial heterogeneity in mechanical and mechanical adaptability. Comparative mechanical test results demonstrated that the conical tool achieved the highest pulling-out success rate in tool-scape interfacial mechanical operation, yet accompanied by relatively severe internal piercing damage to garlic scapes. Differences in pulling-out performance among the piercing tools may be attributed to the combined effects of piercing height, local tissue properties, pseudostem confinement, and tool-tip geometry. The clarified interfacial mechanical laws and damage mechanisms in this study can provide a fundamental theoretical basis for the optimal design of clamping, piercing and pulling-out mechanical matching devices for high-efficiency and low-damage garlic scape harvesters.

In order to provide a theoretical basis for the monitoring and control of the formation process of round bales, the friction test platform for the rolling formation of round bales was built to study the interaction between steel roll and material in the forming process. The results showed that the torque value of the steel roller at the lowest position (No. 2 steel roll) in the bale chamber was closely related to the forming process of the round bale. According to the change of the torque value, the forming process can be divided into an initial stage, straw core formation stage, compression stage and bale-forming stage. The change of torque value can be used for monitoring the forming process of round bales. During the forming process, materials were subject to sliding friction and rolling friction. From the initial stage to the forming stage, the friction of materials gradually changed from sliding friction to rolling friction, and the surface contacted between the material and the steel roll gradually changed to line contact. The interaction model of steel roll and material was established and verified; the model showed that the maximum error between the theoretical value and the experimental value of the forming density is 13.24% and the minimum error is 0.75%. The forming density of round bales was positively correlated with the mass of material fed per second and negatively correlated with the volume of the bale-forming chamber. The forming density of round bales can be expressed by the tangential force per unit length of No. 2 steel roll under the condition that the moisture content of material, the mass of material fed per second and the volume of the baling chamber were fixed. The model provides a theoretical basis for monitoring and controlling the forming process of round bales.

As new energy vehicle drive motors develop toward higher rotational speeds and power levels, a more comprehensive characterization of the geometric condition of high-speed ball bearings is increasingly required, while conventional single-section measurements have difficulty capturing continuous axial geometric variations. To characterize continuous axial geometric variations in high-speed ball bearings for new energy vehicle drive motors and explore whether these variations exhibit trends consistent with vibration responses, four typical bearing models were investigated using X-ray computed tomography (XCT), reconstruction, and dimensional extraction. Equivalent inner and outer diameters were obtained from consecutive sections within the selected axial profile segment. The mean values of the equivalent inner and outer diameters were used to represent the dimensional level, while the standard deviation and range were used to quantify the axial fluctuations. The results showed that the equivalent inner and outer diameters of different bearing samples exhibited different degrees of axial variation within the selected axial profile segments. Meanwhile, the mean equivalent inner and outer diameters measured by XCT differed from the corresponding nominal dimensions. Further comparison showed that, within the current sample set, no stable correspondence was observed between the axial variation descriptors of the XCT-derived equivalent inner and outer diameters and the vibration test results. XCT can nondestructively acquire geometric information from consecutive axial sections and quantitatively characterize equivalent inner and outer diameter fluctuations, complementing single-section roundness measurement and providing theoretical guidance for surface-quality evaluation and manufacturing-process improvement.

To investigate the contact mechanical performance of helicopter main gearbox rotor shaft bearings under a complex load spectrum, this study focuses on the contact stress and load-carrying characteristics of bearings operating under high-speed and heavy-load conditions. Based on the rotor shaft system of a helicopter main gearbox and Hertzian contact theory, quasi-static analyses were performed on four tapered roller bearings and one cylindrical roller bearing mounted on the shaft system conducted in Romax. The results indicate that the maximum contact stresses of the bearings do not exhibit sustained high-stress states under most operating conditions. The peak-stress conditions account for only extremely small time proportions in limited cases, namely 0.003429% and 0.025%. The contact stresses on both the inner and outer raceways exhibit a non-uniform distribution along the roller length, with local peak values appearing near the highly loaded roller-raceway contact regions. This suggests that during the design process of the helicopter main gearbox rotor shaft, special attention should be given to this region. The present results provide a theoretical basis for subsequent life-index verification and offer an effective analytical method for the design and validation of such critical components.