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Aiming at the removal of native oxide film on 2024-T3 Al alloy before plasma electrolytic oxidation, the methods to reduce the fatigue damage caused by grit blasting are explored. Effects of the grit size and pressure on surface roughness, residual compressive stress (RCS), and fatigue life of the Al alloy are studied. Increasing grit size and pressure leads to the increase in the surface roughness and RCS. Based on the theorem of momentum and tool cutting principle, mechanism of the grits on the craters and RCS is revealed. It is found that the angularness of the small-sized grit results in the formation of long scratches. The grit with high kinetic energy induces the large craters and high RCS. The craters are the primary fatigue crack initiation source. Moreover, the craters with long scratch and large height lead to the premature fatigue failure of the grit blasted specimens. However, Fatigue behavior is insignificantly affected by the RCS. The results provide new insights into the fatigue deterioration mechanism and life optimization of the grit blasted samples. Consequently, a parameter optimization scheme for the fatigue life of the grit blasted Al alloy is proposed.

The stress analysis of micro-arc oxidation (MAO) coated aero Al alloys is the basis to reveal the mechanism of fatigue deterioration. To clarify effects of the coating defects on fatigue life, a stress calculation model with micropores and residual stress is established based on shear lag model in this study. The effects of porosity, substrate elastic modulus, coating thickness and residual stress on the stress are explored. The results indicate that the coating porosity and thickness are the critical factor affecting coating normal stress and interfacial shear stress, respectively. In addition, the residual stress significantly affects the interfacial normal stress. The increasing stress caused by low porosity and residual tensile stress and stress concentration at the large-sized defects are the key factors for fatigue degradation.

In this study an innovative parameterized water-bomb wheel modeling method based on recursive solving are introduced, significantly reducing the modeling workload compared to traditional methods. A multi-link supporting structure is designed upon the foundation of the water-bomb wheel model. The effectiveness of the supporting structure is verified through simulations and experiments. For robots equipped with this water-bomb wheel featuring the multi-link support, base on the kinematic model of multi-link structure, a mapping algorithm that incorporates parameterized kinematic solutions and IMU-fused parameterized odometry is proposed. Based on this algorithm, SLAM and autonomous navigation experiments are carried out in simulation environment and real environment respectively. Compared with the traditional algorithm, this algorithm the precision of SLAM is enhanced, achieving high-precision SLAM and autonomous navigation with a robot error rate below 5%.

Waterbomb structures are origami-inspired deformable structural components used in new types of robots. They have a unique radially deployable ability that enables robots to better adapt to their environment. In this paper, we propose a series of new waterbomb structures with square, rectangle, and parallelogram base units. Through quasi-static axial and radial compression experiments and numerical simulations, we prove that the parallelogram waterbomb structure has a twist displacement mode along the axial direction. Compared with the square waterbomb structure, the proposed optimal design of the parallelogram waterbomb structure reduces the critical axial buckling load-to-weight ratio by 55.4% and increases the radial stiffness-to-weight ratio by 67.6%. The significant increase in the radial stiffness-to-weight ratio of the waterbomb structure and decrease in the critical axial buckling load-to-weight ratio make the proposed origami pattern attractive for practical robotics applications.