Bioinspiration & Biomimetics最新文献

Adaptive handling of thick or composition-changing fluids is difficult for conventional pumps. In animals, the intestine addresses this challenge by switching between segmental mixing and peristaltic transport according to the physical state of the contents. We translate this principle into a silicone soft pump composed of four pneumatic chambers, each driven by its own phase oscillator. Two tunable factors govern the collective behaviour: (i) the coupling strength, which attempts to maintain neighbouring oscillators in a travelling-wave relationship, and (ii) the local sensor feedback, which forces each oscillator to correct the deformation error of its own chamber. Numerical bifurcation analysis and time-domain simulations show that when the two strengths are balanced within an intermediate range, the controller first generates an antiphase pattern that homogenises a viscous mixture, and then spontaneously shifts to a quarter-cycle travelling wave that drives the now-fluid contents downstream. We built a physical prototype and experimentally confirmed autonomous mode switching between two glycerol-based fluids of contrasting viscosity. These results demonstrate that a minimal, bioinspired, distributed controller can endow soft devices with adaptive, multifunctional pumping capability, thereby opening new routes to food-processing, biomedical, and chemical-handling systems that operate under uncertain conditions.

Bionic serrated blades with three configurations for a voluteless centrifugal fan are proposed to improve the aerodynamic performance and suppress the noise, including triangular serrated blade (T-BLE), square serrated blade (S-BLE) and semi-circular serrated blade (C-BLE). The improved delayed detached eddy turbulence model and Ffowcs Williams-Hawkings acoustic model are employed to deal with the flow fields and acoustic characteristics. The models are first validated by comparing the experimental results and simulation data in terms of the aerodynamic and noise tests. Then, a comprehensive analysis of flow field characteristics and acoustic performance of a voluteless fan is conducted. Results indicate that the aerodynamic performance of serrated blades decreases due to the reduced air-exhaust area, with the T-BLE showing a 1.6% reduction. The improvement in wake flow pattern, vortex formation and separation for triangular serrations is pronounced. The serration designs significantly suppress primary tonal noise at the 13th blade passing frequency and other broadband noise. The total sound pressure levels of the T-BLE, S-BLE and C-BLE decrease by 6.27 dB, 4.06 dB and 5.14 dB, respectively. The serration structures inhibit noise generation and propagation by weakening periodic unsteady interactions between wake vortices and stationary flow. In general, the T-BLE achieves better noise reduction while maintaining the same aerodynamic performance.

Lightweight structures require materials with superior mechanical properties, prompting engineers to investigate composite materials. Inspired by nature's ingenuity, especially the nacre found in seashells, and the hierarchical structures observed in bone and teeth, which exhibit remarkable strength, stiffness, and toughness, this study investigates the role of inelasticity on the mechanical properties of bioinspired composite materials. In contrast to purely elastic materials, which exhibit reversible stress-strain behaviour and fail suddenly upon reaching their yield point, our study integrates plasticity and damage models to allow for a more progressive and controlled failure process. In nacre-like composites, where non-uniform stress distributions are widespread, plasticity is an important mechanism for reducing stress concentrations and avoiding catastrophic failure. This approach produces a more gradual and predictable failure mode. Here, a controlled degradation of interfaces distributes the applied stress more uniformly across the composite, increasing its overall strength and toughness. Our study utilizes representative volume element and finite element analysis to model and simulate the failure behaviour of nacre-like composites. Using the scalar degradation variable, we note that damage initiates at the interfaces perpendicular to the loading direction, followed by increased stress and eventual failure along the interfaces parallel to the loading direction. We quantify the major contribution of inelasticity in interfaces towards strength and toughness. Additionally, we highlight the previously unexplored contribution of vertical interfaces to toughness by considering influential parameters such as cohesive fracture energy (Gc). The findings of this study provide valuable insights for predicting the strength and toughness of bio-inspired composites when the matrix exhibits inelastic deformation. This work offers valuable results which could greatly help in the design and development of advanced lightweight composite materials for structural applications.

Median fins, including the dorsal and anal fins, influence fish propulsion by lowering body drag and increasing caudal fin thrust through active movement. While their role in solitary swimming is established, their impact on hydrodynamics within schooling environments remains unclear. Using high-fidelity computational fluid dynamics simulations of in-line fish pairs, we systematically varied median fin presence on leaders and followers to isolate neighbor-induced performance changes. When comparing the full-finned configuration to the finless configuration at a leader-follower streamwise spacing (S) of 1.1 body lengths (l), the follower's drag was reduced by 9.5%. A significant contribution of the total drag reduction, about 70%, was neighbor-induced, arising from wake-body interactions with the wake of a leader that had median fins, while the rest was attributed to adding the follower's own median fins. This neighbor-induced benefit arises from stronger leader-generated vortex structures that interact with the follower's body, lowering both shear and pressure drag. The neighbor-induced benefits persist across a range of spacings, diminishing only beyondS= 1.4 l. At higher Reynolds numbers, the neighbor-induced drag reduction also dominates the total drag reduction of the follower. These findings reveal that median fins can serve as hydrodynamic tools for enhancing group swimming performance through neighbor-induced effects, extending their recognized functional role beyond self-induced improvements in solitary swimming.

With the growing demand for underground resources, traditional drilling equipment faces significant limitations in soil environments. In recent years, bionic burrowing robots have attracted increasing research attention for their potential advantages in miniaturization, adaptability, and low energy consumption, although their development is still in the early exploratory stage. This study presents a mole-inspired robot designed based on the remarkable burrowing capability of the naked mole-rat (Heterocephalus glaber), which uses its incisors to break soil and limbs to propel itself forward. The incisor mechanism of the robot achieves a single-degree-of-freedom (DOF) occlusion via a gear drive and linkage transmission system. To analyze the relationship between the incisor tip force and the servo output torque, a mechanical model based on the principle of virtual work and virtual displacement is established, and its accuracy is validated through physical experiments. The leg mechanism employs a Chebyshev-parallelogram composite linkage configuration to achieve single-DOF forward-backward leg motion. To ensure optimal kinematic performance, the leg kinematics are analyzed, and the leg link lengths are optimized through foot-end trajectory planning. Finally, a prototype was developed and tested in soils with varying moisture contents. The experimental results verify the proposed design methodology and mechanical model, confirming the feasibility and effectiveness of the mole-inspired incisor-limb coordination strategy for autonomous burrowing.

Sample Exploring the ocean environment holds profound significance in areas such as resource exploration and ecological protection. Underwater robots struggle with extreme water pressure and often cause noise and damage to the underwater ecosystem, whilebio-inspired soft robots draw inspiration from aquatic creatures to address these challenges. These bio-inspired approaches enable robots to withstand high water pressure, minimize drag, operate with efficient manipulation and sensing systems, and interact with the environment in an eco-friendly manner. Consequently, bio-inspired soft robots have emerged as a promising field for ocean exploration. This paper reviews recent advancements in underwater bio-inspired soft robots, analyses their design considerations when facing different desired functions, bio-inspirations, ambient pressure, temperature, light, and biodiversity , and finally explores the progression from bio-inspired principles to practical applications in the field and suggests potential directions for developing the next generation of underwater soft robots.

A key issue in wearable robotics is the design of an exoskeleton robot with human-like motor capabilities to match the wearer's natural locomotion in daily life. It poses a challenge for an exoskeleton to replicate the sophisticated motor intelligence that enables humans to master a variety of agile motor skills. We herein propose a new design principle for lower limb exoskeletons that can transfer human motor intelligence to the robotic mechanical system and thereby endow the designed exoskeleton with natural locomotion capabilities. We first captured the synergistic characteristics among lower limb joints in human natural locomotion, and identified basic motor primitives (i.e., kinematic synergies). Then we established the mechanical design principle for exoskeletons capable of replicating the locomotor synergistic characteristics. Finally, we proposed the implementation of the kinematic synergies to ensure the compactness and lightweight of the exoskeleton. Experimental tests were conducted on a prototype exoskeleton to validate the effectiveness of the proposed design principle. The results confirmed that the proposed exoskeleton could assist users in completing a variety of locomotor tasks while exhibiting inherent characteristics of human locomotion. These findings demonstrate the potential of the design principle to advance the development of wearable exoskeletons for applications such as daily mobility assistance, post-stroke rehabilitation, and industrial load-carrying.

Bird-like flapping-wing aerial vehicles (BFAVs) emulate avian flight mechanisms and exhibit superior maneuverability, efficiency, and adaptability. Conventional scaling law models, typically based only on body mass or wing area, fail to capture the aerodynamic influence of the wing shape. This study integrates multi-source avian morphological datasets with additional wingbeat frequency samples to analyze the scaling relationship between wing morphology and flapping kinematics. The hand-wing index (HWI) is introduced as a morphological descriptor of wing shape. The results indicate that HWI could independently characterize wing shape. Distinct HWI distributions among the four wing types-elliptical, lift, soaring, and high-speed, demonstrate a strong link to flight strategy. An improved HWI-Mass-Area (HMA) model was developed for wingbeat frequency prediction, achieving higher accuracy and stronger biological interpretability than traditional allometric models. Based on this model, a 0.3 kg flapping-wing prototype with a lift-type wing (HWI = 32.4) was designed and fabricated, demonstrating the applicability of the model in bioinspired design. This study establishes a morphology-informed scaling framework bridging avian biomechanics and engineering, offering a quantitative foundation for parameterized BFAV design.

Aquatic organisms exhibit remarkable diversity in swimming strategies, even within shared modes such as body-caudal fin (BCF) propulsion. Here, we investigate the biomechanical underpinnings of BCF swimming by mapping performance trade-offs across a 6-dimensional design space. Using a computational framework that integrates computational fluid dynamics, machine learning, multi-objective optimization, and global sensitivity analysis, we identified distinct Pareto-optimal fronts between swimming speed and cost of transport. Along these fronts, we uncovered key performance relationships, including that propulsive efficiency is maximized when speed and cost of transport are weighted nearly equally in the objective function, highlighting the benefits of balancing competing demands. We further demonstrate that multiple combinations of kinematic traits can yield comparable performance, revealing both redundancies and sensitivities that provide a mechanistic basis for the diversity of swimming patterns observed in fish. Together, these results generate new biological hypotheses and suggest how evolutionary pressures may shape locomotor design.

Birds utilize feathered wings where individual feathers serve as distinct control surfaces that deform locally under the effect of aerodynamic forces and introduce complex interaction effects. The role of these effects in improving lift generation remains unclear. To investigate this, we analyze a feather-inspired control surface of a flapping foil, composed of three pitching and heaving rigid membranes (referred to as feathers) designed to enhance lift in flapping flight. Two-dimensional numerical simulations are conducted at a Reynolds number of 5000, evaluating the performance of the proposed control surface at three Strouhal numbers (St=0.08,0.12, and 0.2), representative of small bird flight conditions. Our results show that specific combinations of feather lengths maximize the lift-to-power ratio for each Strouhal number. The best-performing cases generate up to twice the mean lift force of a single feather for the same power expenditure. AtSt = 0.12, varying the heave amplitude has minor effects on the peak feather performance. While the upstroke (downstroke) generally produces negative (positive) lift, performance gains are primarily driven by minimizing negative lift during the upstroke. We also quantify the inter-feather interaction effects, which are more pronounced at higher Strouhal numbers. The proposed control surface may be useful in developing efficient micro- and unmanned aerial vehicles.