There are numerous bionic gripping ends adapted to different environments, but stable gripping for curved objects in wet environments is still an urgent engineering challenge. In this study, inspired by the biological properties of tree frogs, a bionic friction pad with an inner concave micropillar surface (CMF-Pad) is proposed. Through the analysis of Hertzian contact theory, the optimization mechanism of the concave surface on the contact area is revealed, and the critical curvature range of the micropillar array to guarantee the drainage performance is deduced. Experiments have confirmed that CMF-Pad exhibit significant advantages in wet environments (≥10 mg/cm² liquid film environment), its micro-channels can actively drain interfacial fluids to enhance friction, and its transverse friction is increased by about 40% compared with flat/smooth friction pads; Simultaneously, it possesses excellent curved surface adaptation and torsion resistance. In the smooth surface contact life test, the CMF-Pad maintained more than 90% of its initial friction after 10,000 cycles of contact testing. Concurrently, practical applications have verified the stability of the friction pads when gripping, handling and twisting curved objects such as medical reagent bottles by robotic arms, enables reliable manipulation in liquid-mediated interfaces through dual mechanisms: active drainage and curvature-conformal contact, providing a different solution for humid environment operation in semiconductor processing, medical equipment handling and other fields.

Space truss structures are essential components for space-based remote sensing loads with high spatial and temporal resolutions. To achieve high-precision vibration control, an accurate and efficient dynamics model is essential. In addition to the current equivalent beam model (EBM) based on the classical continuum theory, an improved equivalent beam model (IEBM) is proposed that considers the impact of the distinction between trusses and beams on torsional and shear deformations, as well as the impact of shear deformation on flexural rigidity. According to the displacement expressions of spatial beams, torsional, shear, and bending correction coefficients are introduced to derive expressions of strain energy and kinetic energy. The energy equivalence principle is then utilized to calculate the elasticity and inertia matrices, and dynamics equations are established using the finite element method. Subsequently, an IEBM is constructed by employing the particle swarm optimization approach to determine the correction coefficients with the truss natural frequency as the optimization target. The natural vibration characteristics of the structure are estimated for various material properties. Compared with the full-scale finite element model, the EBM reaches a maximum error of 80% for a low modulus of elasticity, while the maximum error of the IEBM is less than 2% for any given parameters, indicating its superior accuracy to the EBM.