Bionic Model Research Articles

Microstructure characteristics and mechanical properties of Meretrix lusoria shell.

The microstructure and mechanical properties of Meretrix lusoria shell were investigated. M. lusoria shell was comprised of three layers (outer layer, middle layer and inner layer). Outer layer with serried mastoid structure enhanced the connection strength with middle layer. The middle layer consisted of blocky pattern structure with porosity and crossed-lamellar structure. The inner layer exhibited the typical crossed-lamellar structure. Combined with structure characteristic, phase of aragonite confirmed the crossed-lamellar structure further, building material base for mechanical properties including flexure strength (296.26 MPa), compression strength (6.71 MPa) and crack arrest ability. Microstructure of the shell was the function base of crack deflection phenomenon, which dispersed and defused the applied load via the change of crack extension direction. The investigation of M. lusoria shell provided bionic models for the design and fabrication of bioinspired composites in engineering fields. RESEARCH HIGHLIGHTS: Microstructure and mechanical properties of Meretrix lusoria shell were investigated. Crossed-lamellar structure was the microstructure characterization. M. lusoria shell owned high flexure strength and crack arrest property.

A bio-inspired model for bidirectional polarisation detection

This study investigated a novel polarisation detection model based on the microstructure of rhabdom in mantis shrimp eyes, in which a single unit can detect two directions of orthogonal polarisation. The bionic model incorporated multi-layered orthogonal Si wire grids, and the finite-difference time-domain method was used to simulate light absorption. A single-layer Si wire grid was simulated to study the effects of thickness and duty cycle on extinction ratios. A multi-layer orthogonal wire grid was simulated to study the effects of distance between adjacent layers. The simulations revealed that the bionic model can achieve orthogonal polarisation detection. Additionally, for 600 coupled layers, the extinction ratios in both directions were greater than 60, and light absorption in the absorptive directions exceeded 96%.

Non-single bionic coupling model for thermal fatigue and wear resistance of gray cast iron drum brake

Laser bionic coupling treatment technology can improve the thermal fatigue and wear resistance of gray cast iron. In this study, many single bionic coupling models were designed to determine the thermal fatigue and friction coefficients, and the single model yielding the best thermal fatigue resistance and optimal wear resistance was identified. Crack development and growth on the inner wall of the drum brake were investigated and, based on the results, a non-single bionic coupling model was proposed. The wall thickness of the drum brake was significantly higher than that of the thermal fatigue specimen. According to the Bessel function, to obtain the same unit bodies, the laser energy required for the brake should be greater than that required for the thermal fatigue test specimen. Therefore, an orthogonal test was used to obtain the bionic coupling unit body suitable for the drum brake and, based on the results, a bionic coupling drum brake was manufactured. This brake and an unprocessed drum brake (as a control) were subjected to a bench test. The results revealed that, under the same conditions, specimens with the non-single mesh model exhibited better thermal fatigue and wear resistance than the unprocessed brake. Similarly, the service life of the bionic coupling brake was at least twice that of the unprocessed brake.

Investigation on Microstructure of Beetle Elytra and Energy Absorption Properties of Bio-Inspired Honeycomb Thin-Walled Structure under Axial Dynamic Crushing.

The beetle elytra requires not only to be lightweight to make a beetle fly easily, but also to protect its body and hind-wing from outside damage. The honeycomb sandwich structure in the beetle elytra make it meet the above requirements. In the present work, the microstructures of beetle elytra, including biology layers and thin-walled honeycombs, are observed by scanning electron microscope and discussed. A new bionic honeycomb structure (BHS) with a different hierarchy order of filling cellular structure is established. inspired by elytra internal structure. Then the energy absorbed ability of different bionic models with the different filling cell size are compared by using nonlinear finite element software LS-DYNA (Livermore Software Technology Corp., Livermore, CA, USA). Numerical results show that the absorbed energy of bionic honeycomb structures is increased obviously with the increase of the filling cell size. The findings indicate that the bionic honeycomb structure with second order has an obviously improvement over conventional structures filled with honeycombs and shows great potential for novel clean energy absorption equipment.

Numerical prediction on abrasive wear reduction of bulk solids handling equipment using bionic design

Abrasive wear can cause surface damage of bulk solids handling equipment. Reducing the abrasive wear is beneficial to lower the maintenance cost. Previous research elaborated on the bionic design methodology to reduce surface wear of bulk solids handling equipment. To facilitate the application of the bionic design methodology in bulk solids handling, this research examines the effectiveness of a bionic model using discrete element method (DEM) simulations. A reference case of an abrasive wear scenario in bulk solids handling is simulated, and the wear volume of a smooth chute surface is predicted. By applying a bionic model to the chute surface and using the same simulation model, the wear volume of a bionic surface is predicted. By comparisons, it is identified that the bionic surfaces produce less wear than the smooth surface. In addition, the sensitivities of the geometrical parameters for the wear reduction are predicted. Therefore, the abrasive wear reduction effectiveness of the bionic model is demonstrated.

Optimization of flapping wing mechanism of bionic eagle

The present study is focused on optimization of a double-crank-rocker flapping wing mechanism to imitate the motion of eagle wing divided into inner and outer wing with flapping, folding and twist degree of freedom, and structural flexibility. Considering the multibar dimensions of the flapping mechanism as design variables, combinatorial optimization method was applied to maximize the aerodynamic efficiency. Based on the optimization results, a bionic eagle model of 1.5 m wing span was manufactured to perform flight tests. The study results show that the optimized kinematic of motion can be achieved by using the multibar flapping mechanism; the inner wing plays the key role of producing lift while the outer wing producing thrust; as a result of the optimization, the lift was increased by 2.8% from 3.85 N up to 3.96 N and the thrust increased by 12.5% from 0.16 N up to 0.18 N, which was verified by the flight tests. The flight test also demonstrated a sustainable level flight of the bionic eagle model at a flapping frequency of 2 Hz.

Application of the Bionic Concept in Reducing the Complexity Noise and Drag of the Mega High-Speed Train Based on Computer Simulation Technologies

Regarding the continuous development of high-speed trains and the increase of running speeds, the aerodynamic design of high-speed trains has become significantly important, while reduction of drag and noise comprises a significant challenge in order to optimize aerodynamic design of high-speed trains. The design form factor of a high-speed train is highly influenced by aerodynamic aspects including aerodynamic drag, lift force, and noise. With the high-speed train as the object, the paper aims to take bionic concept as the entry point, selecting the hummingbird as the bionic prototype and extracting bionic elements to establish a bionic train model. Then, the finite volume method was used for numerical simulation and analysis of the aerodynamic performance and aerodynamic noise of the bionic high-speed train. Computational results prove that drag and noise of the bionic head type were lower than those of the original train; drag of the head train of the bionic model was reduced by 2.21% in comparison with the original model, while the whole-train drag was reduced by 3.53%, indicating that drag reduction effects are available and implying that the bionic head type could reduce drag and noise. Noise sources of the bionic train are mainly located at positions with easy airflow separation and violent turbulence motion. Large turbulence energy is in bogie areas and mainly exists at the leeward side of the bogie area. Obviously, the bogie area is the major noise source of the train. Aerodynamic noise of the bionic train in far-field comprises a wide-frequency range. Noises were concentrated within 613 Hz~3150 Hz. When the bionic high-speed train ran at 350 km/h, through comparative analysis of total noise levels at observed points of the high-speed train, it is found that this position with the maximum noise level was 25 m away from the head train nose tip, with the maximum value of 88.4 dB (A). When the bionic train ran at 600 km/h, the maximum sound pressure level at the longitudinal point was 99.7 dB (A) and the average noise level was 96.6 dB (A). When the running speed increased from 350 km/h to 600 km/h, the maximum noise level increased by 11.3 dB (A) and the average noise level increased by 11.6 dB (A). Computation results of aerodynamic noise at the point which is 7.5 m away from the rail center show that the maximum aerodynamic noise level existed at the first-end bogie of the head train, while the noise level was larger at the position closer to the ground.

Experimental investigation of aerodynamic forces and flow structures of bionic cylinders based on harbor seal vibrissa

In the present study, we investigated a new type of non-uniform surface cylinder based on a harbor seal vibrissa to reduce aerodynamic forces and suppress vortex shedding. Three vibrissa-based bionic cylinder models (i.e., models #1, #2, and #3) with different undulation wavelengths were manufactured and tested in a wind tunnel. The wind tunnel experiments were conducted at a Reynolds number of Re ≈ 50,000 based on the hydrodynamic diameter (Dh) and incoming airflow speed. The control effects on the aerodynamic forces and flow structures around the bionic cylinders were studied and compared with those of a baseline circular cylinder. In addition to measuring the surface pressure distributions using an array of digital pressure transducers, a high frequency force balance was used to determine the aerodynamic forces acting on the test models. Moreover, a digital particle image velocimetry (PIV) system was utilized to quantify the stream-wise flow structure and span-wise flow field to assess the effectiveness of the bionic cylinder models. The results revealed that a bionic non-uniform surface distribution could reduce the mean drag and suppress the fluctuating lift to a certain extent. Bionic cylinder model #2, which had a wavelength of two minor axes, worked best among the three models, and it was found to achieve a drag reduction of 15% and a maximum fluctuating lift suppression of 58% when the angle of the incoming airflow was 0°. The PIV results indicated that the non-uniform surface structure would disrupt the consistency of span-wise flow and decrease the span-wise correlation in the near wake of the test models, which could decrease the turbulent kinetic energy, mean drag, and fluctuating lift of the test models.

Experimental and numerical investigations of the aerodynamic noise reduction of automotive side view mirrors

This paper studies the aeroacoustics of the side view mirrors by wind tunnel tests and numerical simulations. The mirror is placed on a table in the wind tunnel test. Based on the experiment results, a numerical analysis model is established to analyze the acoustic field in the wake of the side view mirror by the Large Eddy Simulation (LES). The flow field and the noise level of two different side view mirrors are compared in the simulation. It is shown that, with the serration structures applied onto the mirror surface, the turbulence zone and the pressure fluctuation in the wake of the bionic model are improved effectively, which helps its flow control and noise reduction. Meanwhile, as is shown in the noise spectra, when the noise frequency is over 500 Hz, for the bionic mode, the noise is reduced to a lower level than with the original one, which further shows its effectiveness in the noise reduction.

Fabrication and Characterization of Inhomogeneous Curved Artificial Compound Eye.

Compared with the conventional compound eye processing method, a new fabrication method—namely, a mold casting method—was presented. This method is simple, low-cost, easy to implement, and can be reused. A bionic compound eye array model with 61 ommatidia arranged inhomogeneously onto a curved surface was fabricated. The curved surface had a radius of 9 mm and a thickness of 0.5 mm. The margin imaging quality was improved significantly by the analysis of light beam focus and the optical imaging properties of the fabricated compound eye. The sub-image of each ommatidium had a high resolution. There was 5% error between the collecting spot brightness and simulation analysis results, which proved that the production method is feasible.

Simulation study on dynamics model of two kinds of on-orbit soft-contact mechanism

Aiming at the problem that the operating conditions of the space manipulator is harsh and the space manipulator could not bear the large collision momentum, this paper presents a new concept and technical method, namely soft contact technology. Based on ADAMS dynamics software, this paper compares and simulates the mechanism model of on-orbit soft-contact mechanism based on the bionic model and the integrated double joint model. The main purpose is to verify the path planning ability and the momentum buffering ability based on the different design concept mechanism. The simulation results show that both the two mechanism models have the path planning function before the space target contact, and also has the momentum buffer and controllability during the space target contact process.

Study on the Mechanical Properties of Bionic Coupling Layered B₄C/5083Al Composite Materials.

Based on microstructure characteristics of Meretrix lusoria shell and Rapana venosa shell, bionic coupling layered B4C/5083Al composites with different layered structures and hard/soft combination models were fabricated via hot pressed sintering. The simplified bionic coupling models with hard and soft layers were similar to layered structure and hardness tendency of shells, guiding the bionic design and fabrication. B4C/5083Al composites with various B4C contents and pure 5083Al were treated as hard and soft layers, respectively. Hot pressed sintering maintained the designed bionic structure and enhanced high bonding strength between ceramics and matrix. Compared with B4C/5083Al composites, bionic layered composites exhibited high mechanical properties including flexural strength, fracture toughness, compressive strength and impact toughness. The hard layers absorbed applied loads in the form of intergranular fracture. Besides connection role, soft layers restrained slabbing phenomenon and reset extension direction of cracks among layers. The coupling functions of bionic composites proved the feasibility and practicability of bionic fabrication, providing a new method for improvement of ceramic/Al composite with properties of being lightweight and high mechanical strength.

Telepath: Understanding Users from a Human Vision Perspective in Large-Scale Recommender Systems

Designing an e-commerce recommender system that serves hundreds of millions of active users is a daunting challenge. To our best knowledge, the complex brain activity mechanism behind human shopping activities is never considered in existing recommender systems. From a human vision perspective, we found two key factors that affect users’ behaviors: items’ attractiveness and their matching degrees with users’ interests. This paper proposes Telepath, a vision-based bionic recommender system model, which simulates human brain activities in decision making of shopping, thus understanding users from such perspective. The core of Telepath is a complex deep neural network with multiple subnetworks. In practice, the Telepath model has been launched to JD’s recommender system and advertising system and outperformed the former state-of-the-art method. For one of the major item recommendation blocks on the JD app, click-through rate (CTR), gross merchandise value (GMV) and orders have been increased 1.59%, 8.16% and 8.71% respectively by Telepath. For several major ad publishers of JD demand-side platform, CTR, GMV and return on investment have been increased 6.58%, 61.72% and 65.57% respectively by the first launch of Telepath, and further increased 2.95%, 41.75% and 41.37% respectively by the second launch.

Numerical simulation on the impact of the bionic structure on aerodynamic noises of sidewindow regions in vehicles

The paper adopted a bionic hemispherical convex structure in the A pillar-rear view mirror regions according to actual requirements. Furthermore, impacts of the bionic structure on aerodynamic characteristics and noises in the region were studied. Friction resistance of airflows was greatly reduced, fluctuations and pulsation pressures of flow fields were also reduced, and characteristics of flow fields and sound fields were improved. The computational results were finally verified by the experimental test. Firstly, the aerodynamic lift force coefficient and drag force coefficient of the bionic model were computed, and they were obviously lower than those of the original model. The adhesive force between tires and ground during vehicle running was increased, and the danger degree of “waving” of high-speed vehicle running was weakened. In this way, stability of vehicle running could be improved. Secondly, flow fields of the bionic model were computed. Compared with the original model, an obvious vortex was behind the original model, while no vortexes were behind the bionic model. Therefore, convex structures of the bionic model had obvious impacts on flow fields behind the rear view mirror. Airflow separation situations were obvious improved at wheels, windshield and rear side windows of the bionic model. Due to blocking of convex structures of the A pillar and rear view mirror in the bionic model, airflows was hindered and obvious dragging phenomena were formed. Therefore, flow fields in the side window regions could be improved greatly. In addition, the flow field scope under the rear view mirror in the bionic model was also decreased. Ringed vortex structures appeared behind the rear view mirror in the bionic model. The ringed vortex structures were closely interlaced and then extended together backwards. Vortexes behind the rear view mirror in the original model were chaotic, where most of them were attached on the surface of side windows. In the original model, turbulent flows with certain strength were on the right upper corner of the side window region. In the bionic model, no turbulent flows were in the same regions. This result indicated that through using the bionic convex structures, airflows flowing through side windows could be combed and could move backwards towards upper and lower edges of the side windows. It could be predicted that pulsation pressures on the side window surface would surely decrease. Therefore, aerodynamic noises caused by pulsation pressures in side window regions would also be improved correspondingly. Especially in regions behind A pillar-rear view mirrors, the maximum noise reduction amplitude reached about 20 dB.

A Hybrid Bionic Image Sensor Achieving FOV Extension and Foveated Imaging.

Based on bionic compound eye and human foveated imaging mechanisms, a hybrid bionic image sensor (HBIS) is proposed in this paper to extend the field of view (FOV) with high resolution. First, the hybrid bionic imaging model was developed and the structure parameters of the HBIS were deduced. Second, the properties of the HBIS were simulated, including FOV extension, super-resolution imaging, foveal ratio and so on. Third, a prototype of the HBIS was developed to validate the theory. Imaging experiments were carried out, and the results are in accordance with the simulations, proving the potential of the HBIS for large FOV and high-resolution imaging with low cost.

Study of Response Difference Amplification and Bionic Coupled Circuit in Small Acoustic Array for Spatial Localization

Precisions of localization are a function of the size of an array. A kind of parasitoid fly, Ormia ochracea, performs an extraordinary directional hearing ability despite its tiny-scaled auditory organ. In this paper, vibration modes and transfer functions of the Ormia ochracea's ear model were calculated, and the phase difference amplification in responses are analyzed to investigate the directional hearing mechanism. A novel three-element bionic model is proposed for spatial sound source localization for small distance-wavelength ratios. The amplification of the phase difference of this model is verified. In order to realize the bionic localization model, based on electric-mechanic analogy method, a system that consists of a triangular acoustic array and a bionic coupling circuit is designed and tested. Frequency responses of the circuit output, as a means of transfer function of the system, are taken into estimation of the source directions. The result has shown that this circuit design has better performance in estimating the direction of sound sources compared to the uncoupled array with same size.

Fabrication of 3D Capillary Vessel Models with Circulatory Connection Ports.

Bionic microscopic vessel models can contribute to the development of vascular treatment skills and techniques for clinical training. Most microscopic vessel models are limited to two dimensions, but three-dimensional (3D) models are important for surgery, such as on retina microscopic vessels, for the observation of colon microvessels, for measuring the deformability of red blood cell (RBC), and so on. Therefore, bionic 3D blood vessel models are increasingly in demand. For this reason, it is necessary to establish 3D fabrication techniques for microchannels. In this study, we established two fabrication methods for 3D microfluidic devices for the development of microscopic vessel models. First, we employed an exposure method using photolithographic technology. Second, we employed a 3D method using femtosecond laser and mask hybrid exposure (FMEx). Both methods made it possible to fabricate a millimeter-scale 3D structure with a submicrometer resolution and achieve an easy injection of solution. This is because it was possible to fabricate typical microfluidic channels used for model inlet and outlet ports. Furthermore, in the FMEx method, we employed an acid-diffusion effect using a chemically amplified resist to form a circular channel cross-section. The acid-diffusion effect made it realizable to fabricate a smooth surface independent of the laser scanning line width. Thus, we succeeded in establishing two methods for the fabrication of bionic 3D microfluidic devices with microfluidic channels having diameters of 15–16 µm for mimicking capillary vessels.

BIonic system: Extraction of Lovelock gravity from a Born–Infeld-type theory

It was shown that both Lovelock gravity and Born–Infeld (BI) electrodynamics can be obtained from low effective limit of string theory. Motivated by the mentioned unique origin of the gauge-gravity theories, we are going to find a close relation between them. In this research, we start from the Lagrangian of a BI-type nonlinear electrodynamics with an exponential form to extract the action of Lovelock gravity. We investigate the origin of Lovelock gravity in a system of branes which are connected with each other by different wormholes through a BIonic system. These wormholes are produced as due to the nonlinear electrodynamics which are emerged on the interacting branes. By approaching branes, wormholes dissolve into branes and Lovelock gravity is generated. Also, throats of some wormholes become smaller than their horizons and they transit to black holes. Generalizing calculations to M-theory, it is found that by compacting Mp-branes, Lovelock gravity changes to nonlinear electrodynamics and thus both of them have the same origin. This result is consistent with the prediction of BIonic model in string theory.

Disguised Bionic Sonar Signal Waveform Design with Its Possible Camouflage Application Strategy for Underwater Sensor Platforms

The covertness of an active sonar is a very important issue and the sonar signal waveform design problem is studied to improve covertness of the system. Many marine mammals produce call pulses for communication and echolocation, and existing interception systems normally classify these biological signals as ocean noise and filter them out. Based on this, a disguised sonar signal waveform design approach with its camouflage application strategy for underwater sensor platforms is proposed by utilizing bio-inspired steganography. We first construct bionic sonar signal waveforms which are very close to the true whale whistle, and then embed these constructed bionic sonar signal waveforms into the true whale call trains to hide the real sonar signal waveforms. According to the time-frequency structure of the true whale whistle, a bionic sonar signal model is established to generate the proposed sonar signal waveforms. A single sonar signal is used to measure the range of the target and a combination of two sonar signals is utilized for measuring its speed. A high-performance range and speed measurement algorithm is deduced in detail. Based on the constructed signal waveforms and the characteristics of false killer whale call trains, a camouflage application strategy is designed to improve the camouflage ability of the sonar signal sequence. Finally, simulation results are provided to verify the performance of the proposed method.

Bionic Attitude Transformation Combined with Closed Motion for a Free Floating Space Robot

In order to realize the small error attitude transformation of a free floating space robot, a new method of three degrees of freedom(DOF) attitude transformation was proposed for the space robot using a bionic joint. A general kinematic model of the space robot was established based on the law of linear and angular momentum conservation. A combinational joint model was established combined with bionic joint and closed motion. The attitude transformation of planar, two DOF and three DOF is analyzed and simulated by the model, and it is verified that the feasibility of attitude transformation in three DOF space. Finally, the specific scheme of disturbance elimination in attitude transformation is presented and simulation results are obtained. Therefore, the range of application field of the bionic joint model has been expanded.