Fujun Peng

This study systematically addresses the design and aerodynamic optimization of tail configurations for bio-inspired flapping-wing robot. Based on a flapping-wing robot prototype, a theoretical model linking tail-size parameters to the pitch static stability margin was established. Six types of tail configurations — arc-shaped tail, triangular-shaped tail, swallow-shaped tail, webbed tail, T-shaped tail, and V-shaped tail — comprising 17 parametrically varied specimens were designed and fabricated. Through a high-precision decoupled wind-tunnel test platform (free stream velocity: 10 m/s, flapping frequency: 2.5 Hz), the three-axis aerodynamic moments (pitch, yaw, roll) under various actuation states were quantitatively measured. The influence of key geometric parameters such as characteristic width, opening angle, and control-surface area on handling and stability was thoroughly investigated. Experimental results show that the T-shaped tail (#53) performs best in pitch control moment and lateral-directional stability margin, with a peak pitch moment of 0.185 N·m — approximately 42 % higher than the baseline configuration — demonstrating the most outstanding overall performance. The V-shaped tail (#62) exhibits excellent lateral-directional control capability under differential actuation, achieving a roll moment of up to 0.106 N·m, albeit with pronounced control coupling effects. This research provides reliable experimental evidence and a theoretical reference for the configuration selection and parameter optimization of tails in flapping-wing robot, offering significant engineering guidance for enhancing flight quality and control effectiveness. In addition, this paper establishes a theoretical framework for preliminary tail size design based on pitch static stability and proposes a parametric design method for multi-configuration tails for flapping-wing robot. The research results not only provide a theoretical basis for tail parameter selection but also offer experimental references for tail configuration optimization and subsequent control-oriented system design.

Poor consolidations and the strength–conductivity trade-off limit the performance of copper alloys fabricated by laser powder bed fusion (LPBF). To address this, this study developed a strategy combining the response surface methodology (RSM) with direct ageing treatment (DAT) to achieve a favorable strength–conductivity synergy. The results showed that under the optimal process parameters, a high relative density of 99.25% (8.95 g/cm³ for theoretical density) was obtained. After direct ageing treatment at 490 °C for 60 min, the CuCrZr exhibited an ultimate tensile strength of 399.31 MPa and a thermal conductivity of 326.53 W/(m·K). To reveal the underlying mechanisms, this study employed a combination of systematic characterization via high-resolution transmission electron microscopy (HRTEM) and quantitative modeling. HRTEM characterized the uniformly dispersed nanoscale body-centered cubic (BCC) Cr precipitates that form semi-coherent interfaces with the face-centered cubic (FCC) Cu matrix, showing a crystallographic misorientation of approximately 10.5° intermediate between the classic Nishiyama–Wassermann and Kurdjumov–Sachs orientation relationships. Quantitative modeling indicates that the high strength arises from a synergistic effect: coherent strain fields exerted by the precipitates effectively pin retained dislocations, coupling Orowan and dislocation strengthening. Meanwhile, solute precipitation reduces lattice distortion, restoring notable thermal conductivity.

Shape memory alloy (SMA) actuators have found a wide range of applications due to their unique properties such as high force, long stroke, small size, light weight, and silent operation, etc. However, their strong nonlinear properties make them a challenge to achieve accurate actuations. A simple control strategy is presented based on the idea of adjusting the SMA wire temperature as rapidly as possible. This strategy is simple, stable, and requires no hysteresis model or thermal model. The strategy is tested first on tracking displacement outputs, and effects of updating rate and input current on control accuracy are also discussed. It is then used for active shape control of a membrane structure model by adjusting its boundary tensions. Results indicate that under the developed control strategy, SMA wire actuators can offer very good accuracy in tracking displacement outputs and tension outputs. For the membrane structure shape control, the structure shape precision is improved greatly.