Ermira Junita Abdullah

Performance Analysis of Smart Composite Structure Using Shape Memory Alloy Actuators

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.

Subsonic Wind Tunnels in Malaysia: A Review

In Malaysia, there exist wind tunnels operated by several universities and organizations. Most of them are actively used for a variety of experimental works that are needed by uncounted educational curricula and aerodynamics related researches. Lately, wind tunnels have even become increasingly accepted as one of common engineering tools in solving of unexpected and abundant wind engineering problems that are continually facing automotive industries, oil and gas companies, as well as governmental agencies and ministries. This paper is meant to present an overview of the existing wind tunnels, accompanied with information on some important technical data, and added, to a lesser extent, with complementary information about backgrounds and design philosophies. The emphasis is, however, given only to those with test section size of 1.0 square meter or larger. From the general point of view, some information about testing capabilities and trends in wind tunnel technology is also presented.

Shape memory alloy actuation effect on subsonic static aeroelastic deformation of composite cantilever plate

Shape memory alloy (SMA) is one of the smart materials that have unique properties and used recently in several aerospace applications. SMAs are metallic alloys that can recover permanent strains when they are heated above a certain temperature. In this study, the effects of SMA actuation on the composite plate under subsonic aeroelastic conditions are examined. The wind tunnel test is carried out for two configurations of a cantilever shape memory alloy composite plate with a single SMA wire fixed eccentrically. Strain gage data for both bending and torsional strain are recorded and demonstrated during the aeroelastic test for active and non-active SMA wire in two locations. The cyclic actuation of the SMA wire embedded inside the composite plate is also investigated during the aeroelastic test. The results show reduction in both bending and torsional strain of the composite plate after activation of the SMA wire during the wind tunnel test.

Experimental Study on Variable Deflection Control of SMA Actuated Composite Plate

This paper presents a variable deflection control of a fiber glass composite plate system using shape memory alloy (SMA) actuators. The technique on changing the camber of plate needs to be developed as it is the most investigated approach of shape morphing. Gradual changes of the camber along the span can create controllable twisting of the composite plate. The necessary camber change is pursued either by reconfiguration of the underlying structure or the shape changing of the composite plate or smart composite. In this proposed platform, strain gauges are used to measure the strain of the plate in a single cantilever mode while nickel titanium (NiTi) Shape Memory Alloy (SMA) wires are used as actuators to actuate the composite plate, which are controlled using Proportional-Integral-Derivative (PID) controller. In this research six strain gauges were placed at different location of the plate: tip, mid and root part of the plate. From the experimental result, it was found that the mid part of the plate had the highest change in strain value and the control system using input from the strain gauge located there produced the best performance compared to those located at the tip and root of the plate.

Conceptual Design of Flapping Wing Using Shape Memory Alloy Actuator for Micro Unmanned Aerial Vehicle

Micro Air Vehicle (MAV) has the capability to fly autonomously in complex environments which enables human to conduct surveillance in areas which are deemed too dangerous or in confined spaces that does not allow human entry. Research and development of MAVs aim to reduce their size further, thus novel techniques need to be explored in order to achieve this objective while still maintaining the MAVs’ current performance. In this paper, a conceptual design of an MAV with a main drive system using shape memory alloy (SMA) actuator to provide the flapping motion is proposed. SMA is considered superior to other smart materials due to its efficiency and large energy storage capacity. By incorporating SMA in the flapping wing MAV, it will provide users the flexibility to add more payloads by reducing bulky cables or reduce operating cost by using less fuel. However, there are some drawbacks in using SMAs such as nonlinear response of the strain to input current and hysteresis characteristic as a result of which their control is inaccurate and complicated.

Identification of Modal Properties of Composite Thin Plate Using OMA in Wind Tunnel Environment

Identification of modal parameters is crucial especially in aerospace applications whereby the interactions of airflow with aircraft structures can result in undesirable structural deformations. This structural deformation can be predicted with knowledge of the modal parameters. This can be achieved through conventional modal testing that requires a known excitation force in order to extract these dynamic properties. This technique can be experimentally complex because of the need for artificial excitation and it also does not represent actual operational condition. The current work presents part of research work that address the practical implementation of operational modal analysis (OMA) applied to a cantilevered hybrid composite plate exposed to low speed airflow in a wind tunnel. A single contactless sensing system via a laser vibrometer is employed to measure the response. OMA technique applied in a wind-on condition succeeded in extracting the modal parameters of the hybrid composite plate which correlate well with modal testing using impact hammer excitation.