Applied Mechanics and Materials Vol. 225

Abstract: The objective of this paper is to design and analyze a UAV fuselage. The UAV considered in this paper is designed for short-term use and light-weight with mass carrying capacity of 2kg. Firstly, the shape is considered for aerodynamics. Then, the internal system installation, cargo positioning and fuselage structure are designed. Finite element analysis is used for the stress analysis under the landing condition of static model with 3.5g acceleration. The short-term use is specified to be 20 life cycles and the model is verified by the dynamic drop test. The result from finite element analysis shows that the maximum stress is less than the material’s strength with safety factor of 1.1. From the dynamic drop test, the fuselage can safely support the structure under the required life cycles. Therefore, it can be concluded that UAV fuselage can achieve the requirements.

Abstract: This paper presents an ongoing study and research of a 2-Axis stabilized aerial image capturing system to obtain aerial images. Aerial images are commonly used for reconnaissance, area surveying, and also for search and rescue mission. Currently, several methods of remote sensing were developed with multiple objectives either for civil or military applications to obtain high precision images. The study involves the design and fabrication of 2-Axis stabilized image system platform. Rolling and pitching motion of an air vehicle effects while airborne to acquire sharp vertical images are the main consideration in this study.

Abstract: Applications involving the use of alternate, renewable energy sources are expanding exponentially, and are in high demand. Solar power has long been harnessed for such applications and aviation is no stranger to it with its strong drive towards becoming an environment-friendly industry. This paper describes a straight forward procedure to design and test a solar powered unmanned aerial vehicle that can fly continuously for 24 hours at any day of the year. The paper introduces the modeling and preparation of hardware testing of the propulsion and power sub-system. The main components of this sub-system are solar panels, the electromechanical drive train and the propeller. A design for a thrust stand to measure the performance of the system is also introduced.

Abstract: A new methodology has been proposed to design a dynamically similar/scaled model (DSM) of aircraft. This method uses the simulated annealing (SA) optimization algorithm to get the maximum similarity between model and full-scale aircraft with help of systems movement and using minimum ballast weight. For the ½ model of an unmanned aerial vehicle (UAV), internal arrangement is designed to achieve the desired model center of gravity position and moments of inertia. A computer code is developed, and model suitable arrangement is obtained. Results show that the proposed optimization approach to design of DSM was successfully used to find adequate model systems arrangement and minimizing ballast weight to access more capacities for data-acquisition systems or fuels. In this problem, ballast weight reduced about 0.6 kgf for a 55 kgf model, in addition of simplicity of DSM design for various configuration and flight regimes.

Abstract: Ducted fan aerial vehicles have drawn many attentions in the world because of their successful involvement in non-traditional reconnaissance and surveillance missions. However, due to inherent dynamic uncertainties as well as inconsistent responses, significant control challenges are still to be addressed. In this study, a non-linear dynamic model for ducted fan is firstly proposed to be employed for control design. This model is then validated by performing a series of standard simulation scenarios. Afterwards, an adaptive control method, named as model reference is utilized to design perfect controllers in hover as well as vertical flight. The capability of the adaptive laws to update the controller gains are evaluated for different initial conditions and command inputs. The results show that the controller is well able to regulate the state variables as well as to follow the desired commands in the presence of dynamic coupling and aerodynamic uncertainties when the vehicle flies in vertical plane and near hover condition.

Abstract: The concept of pitch control has been implemented in the design of a small vertical-axis wind turbine. Benefits gained can be shown by the experimental and numerical results presented in this paper. As found, the method of variable pitch control outperforms the one of fixed pitch control. The present results show that the former can make remarkable improvement on the starting torque as well as the aerodynamic characteristics at low tip speed ratios.

Abstract: This paper presents the newly improved design of wireless sensor technology for Structural Health Monitoring (SHM) system or continuous monitoring for Non Destructive Testing (NDT). Numerous researches have indulged in designing wireless sensor networks where the reliability and the capability to do rapid assessment on the aeronautical, mechanical and civil structure are concerned. A lot of challenges associated with the design have been discussed including on power consumption by the device with regards the operation nature over period of times vs. energy sources. This research project explores the implementation of Nano Watt XLPTM technology microcontroller from Microchip and applicable smart PZT sensors or the newly refined technique in (NDT) that utilise ultrasonic guided waveform response to detect structural defects. The developed SHM system provide low power wireless nodes to perform automatic data collection and analysis with possibilities to integrate with green energy sources more effectively thus reducing the cost of maintenance and increase the reliability of the system.

Abstract: In this work, a magnetic membrane actuator that involves simple fabrication process and low cost is developed based on electroplating technique, and its dynamic performance is examined. The magnetic actuator consists of an element of soft ferromagnetic material embedded in PDMS circular membrane. It is driven by attracting the soft ferromagnetic element using external magnet that is attached on a shaft of electrical motor. When the shaft is rotated, the magnet will move back and forth towards the membrane. In this study, the nickel element as a soft ferromagnetic material is designed as a simple circular disk with four straight arms, and it is fabricated into three different thicknesses, i.e. 49±3, 70±7 and 100±6 μm, while PDMS thickness is fixed at 280±33 µm. The dynamic performances of 2-cm membrane actuators are examined using a capacitive sensor in the actuating frequency range of 40-240 Hz. The experimental results show that there are two motion patterns, i.e. small and strong oscillations, where the transition frequency is approximately at 100 Hz. In addition, with the increment of nickel element’s thickness, gain and peak frequency, where gain peaks occur, increase while peak-to-peak amplitude decreases.

Abstract: The development towards the usage of green energy sources is currently a major concern in today’s lifestyle due to the limited supply of fossil-based energy. Many have turned to alternative energy resources that are less polluting to the environment. Replacement of the vehicle’s fuel-based engine to an electric-based engine by using alternative or hybrid energy is one of the possible paths that many studies are conducted. In the aviation field, harvesting solar energy by using solar panel to charge aircraft on-board batteries could reduce the dependency on fuel. As with any other energy conversion technology, the solar panel performance needs to be monitored so that the power output can always be maintained at maximum available power. This paper presents a research and development of a system to monitor the health of photovoltaic panel installed on aircraft by measuring its voltage and current. The measurement is conducted using low power microcontroller. The system is capable to automatically measure the output of every solar panel installed in the system by connecting them with a matched load during the measurement process. The power output is then compared to the initial values prior to installation to determine how much power is currently being generated. By knowing the actual power output of each solar panel, less efficient or defective panel can be identified and replaced during maintenance. The system can be implemented not only for an aircraft but also applicable to other system that uses solar panel as their energy resources.

Abstract: Smart structures are able to adapt, alter or change in response to external stimuli. The analysis and design of smart structures involves a highly multi-disciplinary effort which includes structures, materials, dynamics, control and design. Shape memory alloy (SMA) is a suitable candidate for actuator in the smart structure design as it can be activated to alter the shape of the structure. This paper proposes a design for smart composite structure suitable for aerospace applications. Finite element method (FEM) was used to analyze a designer structure which is able to meet the requirements for smart structure as well as determining the placement of the actuators within the structure. Due to the nonlinear behavior of the SMA actuator, it is critical to incorporate a feedback control system that is able to accurately morph the structure. A prototype of the smart composite structure was fabricated and its performance was analyzed.