EXPERIMENTAL ANALYSIS OF DOUBLE BOX WING UAV.

ABSTRACT In an attempt to reduce the induced drag on a wing, Prandtl found that induced drag reduced significantly by highly increasing the number of vertically offset wings. The same result could be obtained by joining the wingtips of two vertically offset wings. This helped increase payload capacity and also reduced fuel consumption and emissions. Such a wing configuration came to be known as Prandtl’s box wing. In this work, the design and analysis of a box wing aircraft model has been carried out. The preliminary analysis is performed using XFLR5, and the computational analysis is done with the help of ANSYS 18.2. The values of experiments are computed with the help of MATLab R2017. The box wing model has shown a nearly 53.74% reduction in drag as compared with conventional wing models. The computational results of drag have been compared and validated with the results of analytical and the experimental results from the wind tunnel and found to be within 10% of the computational result. Since the drag of the box wing is significantly lesser than the conventional wings the box wing is a feasible configuration which can be used to design various aircrafts including Unmanned Aerial Vehicles and Commercial Planes

Finite Element Study on the Effect of Geometrical Parameters on the Mechanical Behavior of 3D Reentrant Auxetic Honeycombs.

Abstract Auxetic materials are a special case of cellular materials, which exhibit a negative Poisson’s ratio. This in fact is the reason behind their peculiar behavior i.e. lateral shrinkage under longitudinal compression and vice versa. Since these materials do not obey the laws of “normal” materials and go beyond common sense, they are still an emerging class which can be put to use for various purposes like self-locking reinforcing fibers in composites, controlled release media, self-healing films, piezoelectric sensors, and also be used in biomedical engineering. Their stress-strain behavior, Poisson’s ratio and impact energy absorption are controlled by bulk material as well as the unit cell geometry. Among many forms of auxetic structures available, we have chosen a three-dimensional reentrant auxetic honeycomb unit cell. The unit cell geometrical parameters were taken from literature. In this study, we try to understand the effects of strut angle through finite element simulations while keeping the bulk material, unit cell size, strut thickness and number of repetitions constant. A total of three different angles were tested, based on which we conclude that as angle increases, the Poisson’s ratio increases and Energy absorption is maximum at 30 deg