The hindwings of beetles are folded under the elytra when they are at rest but are extended during flight, which can provide bioinspiration for the design of deployable micro air vehicles (MAVs). Beetle hindwings must be able to be both securely locked under the elytra and freely extended for flight, depending on the required action. To investigate the locking mechanism, this study used environmental scanning electron microscopy (ESEM) to examine the microstructures of the elytra, hindwings and abdomen of the Asian ladybeetle, Harmonia axyridis (Pallas, 1773). On the ventral side (VS) of the elytra, the microtrichia show a transitional structure from the lateral edge to the medial edge. On the hindwing surface, the folded regions were observed on both the dorsal side (DS) and the VS. On the abdomen, the microtrichia between the abdominal segments show a cyclical change from sparse to dense in each segment in the middle of the abdomen. Furthermore, the different directions of microtrichia that lead to self-locking friction on the surfaces of the hindwing, elytron and abdomen appear to facilitate interlocking. A model for the interlocking of the hindwings of the H. axyridis was established, and its underlying mechanism is discussed.

The knee joint plays a key role in kinematic and kinetic performances of pedestrain locomotion. The key role of meniscus with matched ligaments in joint stability and movability has not been fully explored in current robotic knee designs. We fabricate a bioinspired robotic knee based on a kinematic model of an anatomical knee in order to reveal the relationship between the meniscus, ligaments and their stability and movability, respectively. The kinematic model was built from magnetic resonance imaging of the human knee with generated contact profiles and customized ligament fibers. Then, the bioinspired knee was designed, and its dynamic stability was maintained by ligaments and specific contact profiles, which were acquired based on the kinematic model. Finally, a monopod robot with the bioinspired knee assembled was developed for dynamic testing. The results show that (1) a smooth rolling–sliding motion can be achieved with the addition of menisci and compatible ligaments; and (2) joint stiffness can be adjusted by changing the springs and activation lengths of ligament fibers. This study gives biomimetic insights into a new design of knee joint for a robotic/prosthetic leg.

This work presents a numerical study of the water-exit characteristics of a bioinspired unmanned aerial-underwater vehicle (UAUV) equipped with a front-mounted propeller. A robust solution framework was established on the basis of a modified Shear Stress Transport (SST) turbulence model, volume of fluid (VOF) multiphase formulation, overset grid technique, and six degrees of freedom (6-DOF) motion model; the framework was verified against a canonical water-exit case of a sphere. Inspired by the morphology and water-exit behavior of flying fish, a bioinspired three-dimensional (3D) model was designed. Using this framework, the effects of the front-mounted propeller configuration, exit velocity, and exit angle were examined; the exit process under different conditions was analyzed; and the relationship between exit drag and exit state was quantified. The results demonstrate that the proposed approach can resolve the water-exit performance of the bioinspired UAUV in detail. Folding the front-mounted propeller effectively reduces exit drag and mitigates high-pressure concentrations on the blades. When the exit velocity is ≥8 m/s and the exit angle θ ≤ 30°, the peak exit drag does not surpass 90.004 N. The peak exit drag exhibits a pronounced quadratic relationship with both exit velocity and exit angle. To ensure safe water exit, the UAUV should avoid exiting with the front-mounted propeller deployed and avoid excessively low exit velocities and overly large exit angles. The numerical investigation of exit drag provides effective bioinspired design guidelines and a feasible analysis strategy for UAUV development. In conclusion, the findings provide crucial insights for designing more efficient bioinspired UAUVs, particularly in terms of minimizing water-exit drag and optimizing the configuration of the front-mounted propeller.

The cultural confidence is crucial to the development of a country. Based on China's national conditions and the learning habits of Chinese students, this paper explores the topics and designs of integrate curriculum ideology and politics into the courses of mechanical major in higher education. The topic of cultural self-confidence is raised nowadays after chronically low cultural confidence along with comprehensive development in all fields. This positive recognition of cultural self-confidence can help students setting specific plans to apply for a job and their further study under learning the examples with profound implications of strong willpower, vitality of high-quality traditional culture, differentiated aesthetic and development direction of China.