Nano-mechanical properties and structural of a 3D-printed biodegradable biomimetic micro air vehicle wing

The biomimetic micro air vehicles (BMAV) are unmanned, micro-scaled aircraft that are bio-inspired from flying organisms to achieve the lift and thrust by flapping their wings. The main objectives of this study are to design a BMAV wing (inspired from the dragonfly) and analyse its nano-mechanical properties. In order to gain insights into the flight mechanics of dragonfly, reverse engineering methods were used to establish three-dimensional geometrical models of the dragonfly wings, so we can make a comparative analysis. Then mechanical test of the real dragonfly wings was performed to provide experimental parameter values for mechanical models in terms of nano-hardness and elastic modulus. The mechanical properties of wings were measured by nanoindentre. Finally, a simplified model was designed and the dragonfly-like wing frame structure was bio-mimicked and fabricated using a 3D printer. Then mechanical test of the BMAV wings was performed to analyse and compare the wings under a variety of simplified load regimes that are concentrated force, uniform line-load and a torque. This work opened up the possibility towards developing an engineering basis for the biomimetic design of BMAV wings

An experimental study of the elastic properties of dragonfly-like flapping wings for use in Biomimetic Micro Air Vehicles (BMAV)

This article studies the elastic properties of several biomimetic micro air vehicle (BMAV) wings that are based on a dragonfly wing. BMAVs are a new class of unmanned micro-sized air vehicles that mimic the flapping wing motion of flying biological organisms (e.g., insects, birds, and bats). Three structurally identical wings were fabricated using different materials: acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), and acrylic. Simplified wing frame structures were fabricated from these materials and then a nanocomposite film was adhered to them which mimics the membrane of an actual dragonfly. These wings were then attached to an electromagnetic actuator and passively flapped at frequencies of 10–250 Hz. A three-dimensional high frame rate imaging system was used to capture the flapping motions of these wings at a resolution of 320 pixels × 240 pixels and 35000 frames per second. The maximum bending angle, maximum wing tip deflection, maximum wing tip twist angle, and wing tip twist speed of each wing were measured and compared to each other and the actual dragonfly wing. The results show that the ABS wing has considerable flexibility in the chordwise direction, whereas the PLA and acrylic wings show better conformity to an actual dragonfly wing in the spanwise direction. Past studies have shown that the aerodynamic performance of a BMAV flapping wing is enhanced if its chordwise flexibility is increased and its spanwise flexibility is reduced. Therefore, the ABS wing (fabricated using a 3D printer) shows the most promising results for future applications

A bibliometric review of progress in micro air vehicle research

Micro air vehicle research has exponentially expanded since the first articles began to be published in the late 1990s. This article presents a comprehensive bibliometric review of journal articles published on micro air vehicle research from 1998 until 2015. The articles are classified into three types of micro air vehicle: fixed-wing, rotary-wing, and flapping-wing (biomimetic). These types are based upon their primary means of generating lift and propulsive thrust. The specific type of research in these articles is also examined, divided into subcategories of: aerodynamics; guidance, navigation, and control; propulsion; structures and materials; and system design. Numerous bibliometric indicators are presented and analyzed to understand how micro air vehicle research is expanding, which authoring organizations are leading the research, which external sponsoring organizations are providing funding, and the challenges that remain for future researchers. The analysis shows that the majority of the research articles are being written by organizations from the US, China, UK, France, and South Korea. Although biomimetic micro air vehicles are currently the most popular type of micro air vehicle, in recent years the growing popularity of rotary-wing micro air vehicles (especially as a guidance, navigation, and control test platform) has caused it to rival biomimetic micro air vehicles in popularity

Key parameters of air breathing two-stroke combustion engines for integration into small scale UAVs

The advent of low cost civilian small scale UAV has resulted in the extension of the limits of range and endurance. Among the many design parameters, the selection of powerplants and propellers for optimal range and endurance is dependent upon known dynamic thrust and fuel consumption data for propeller-IC engine combinations. To date, extensive work has been done on both large aviation and wind turbine propellers as well as smaller RC electric motor configurations. This paper shows that the above data cannot be used to accurately predict the dynamic pressure and fuel consumption of propeller-IC engine combinations. This is because, the complete single cylinder engine and propeller combination is both an aerodynamic and thermodynamic process which must be considered in totality. In support of this, detailed wind tunnel tests were carried out on a representative IC engine and propeller combination. The results were non-linear and varied significantly from anticipated output. The paper summarises the outcomes, suggests changes to design strategies in light of the outcomes and concludes by proposing key areas of future investigation

Optimization of a synthetic jet actuator for flow control around an airfoil

This paper deals with the optimization of a synthetic jet actuator parameters in the control flow around the NACA0015 airfoil at two angles of attack: 13° (i.e. the stall angle of NACA0015) and 16° (i.e. the post stall angle of NACA0015) to maximize the aerodynamic performance of the airfoil. Synthetic jet actuator is a zero mass flux-active flow control device that alternately injects and removes fluid through a small slot at the input movement frequency of a diaphragm. The movement of the diaphragm and also the external flow around the airfoil were simulated using numerical approach. The objective of the optimization process function was maximum lift-drag ratio (L/D) and the optimization variables were jet frequency, length of the jet slot and jet location along the chord. The power coefficient of the jet was considered as a constraint. The response surface optimization method was employed to achieve the optimal parameters. The results showed that the actuator is more effective for post stall angles of attack that can lead to an enhancement of 66% in L/D

Development of a new density correlation for carbon-based nanofluids using response surface methodology

Density is among the fundamental thermo-physical characteristics of fluids that are examined prior to carrying out performance analysis of the fluid. In this study, the effect of the design variables on the density of nanofluids was studied using response surface methodology (RSM). The quadratic model produced by RSM was employed to determine the performance factors, i.e., mass concentration and temperature with reasonably good accuracy. Improved experimental correlations were proposed for the density prediction of the carbon-based nanofluids based on the experimental data. Experimentally measured densities of two different nanofluids at the nanoparticle mass concentration of up to 0.1% and the temperature range of 20–40 °C were examined. The improvement in densities compared to the density of base fluid at 20 and 40 °C is approximately 0.15% for 0.1% fraction of MWCNT–COOH nanoparticles. Additionally, the densities of F-GNP nanofluids are increased by 0.056% compared to the density of distilled water. As a final point, the RSM results were compared with the results which got from the empirical data. It was detected that the optimal RSM model is accurate and the absolute maximum deviation measured values from the predicted densities of MWCNT–COOH and F-GNP nanofluids are 0.012 and 0.009%, respectively

Design optimization of ocean renewable energy converter using a combined Bi-level metaheuristic approach

In recent years, there has been an increasing interest in renewable energies in view of the fact that fossil fuels are the leading cause of catastrophic environmental consequences. Ocean wave energy is a renewable energy source that is particularly prevalent in coastal areas. Since many countries have tremendous potential to extract this type of energy, a number of researchers have sought to determine certain effective factors on wave converters’ performance, with a primary emphasis on ambient factors. In this study, we used metaheuristic optimization methods to investigate the effects of geometric factors on the performance of an Oscillating Surge Wave Energy Converter (OSWEC), in addition to the effects of hydrodynamic parameters. To do so, we used CATIA software to model different geometries which were then inserted into a numerical model developed in Flow3D software. A Ribed-surface design of the converter’s flap is also introduced in this study to maximize wave-converter interaction. Besides, a Bi-level Hill Climbing Multi-Verse Optimization (HCMVO) method was also developed for this application. The results showed that the converter performs better with greater wave heights, flap freeboard heights, and shorter wave periods. Additionally, the added ribs led to more wave-converter interaction and better performance, while the distance between the flap and flume bed negatively impacted the performance. Finally, tracking the changes in the five-dimensional objective function revealed the optimum value for each parameter in all scenarios. This is achieved by the newly developed optimization algorithm, which is much faster than other existing cutting-edge metaheuristic approaches