Papers by Keyword: Smart Structure

Abstract: Today, the components of smart structures consisting of structural and smart materials are generally produced separately and assembled in additional processes afterwards. An alternative approach, which combines the forming of metallic parts and the assembly of the structures in one process step, is proposed in this paper. Incremental forming processes are applied for this operation. Significant joining mechanisms will be analyzed and some applications of this combined forming and assembly process are shown. As sensors, smart components allow a monitoring of appearing loads, as actuators they allow an active influencing on appearing disturbances. The research contains numerical analyses and experimental tests.

Abstract: Continuous optical fiber sensing technique has the advantages of continuous measurement, corrosion preventing, anti-electromagnetic interference and high precision. This paper integrates continuous optical fiber into smart structure system. It combines the advantages of continuous optical fibers with self-adapting function of smart structures. It may have wide uses in engineering. But it is developing. It has some key technologies to be solved, such as the manufacture and embedment technique of special optical fibers, optimized arrangements of fibers, smart identification of the signal, analysis processing for enormous data and realization of self-adapting function.

Abstract: In this paper, the advantages of smart materials and structures are introduced. Because of the influence of friction, it’s difficult to deploy the large ring truss antenna driving by cable. The SPMC hinge is added in the deployable joint, the deployable antenna is deployed by heating the material to cause recovery strain, which substitutes for the driving by cable. Describe the behavior of SPMC material, and do the simulation, from the analysis results, we can aim that the stress of SPMC satisfies the yielding stress when the node is furled. At the same time, the force to expand the antenna caused by heating SPMC is also obtained. Compared the different size of width, the variation of recovery force can be got.

Abstract: Though with its big restoring force and large deformation characteristic, shape memory alloy (SMA) is commonly used in the research of active vibration control for smart structure, the presence of its thermal hysteresis often leads to bad control performance. A vibration control method based on alternate multichannel driving SMA is proposed to improve the SMA based smart structural vibration control performance by reducing the effect of thermal hysteresis of SMA. The technical methods, the design of the experimental structure, the construction of the experimental platform is illustrated, with the principle and operating process of the experiment and experimental results described. By embedding the SMA driving elements into the epoxy substrate and mounted epoxy plate into the framework of the aircraft prototype, experimental analysis and verification is done. The experimental results show that alternate multichannel driving of SMA for vibration suppression of smart structure is feasible, and the performance is improved to a certain extent.

Abstract: A kind of adaptive searching optimization active vibration control system of smart structure with piezoelectric materials was put forward, and the smart flexible cantilever structure was analyzed, the active vibration control system was realized in the lab. The result proved the methods’ feasibility and practicability.

Abstract: Optical fiber sensor with small size, light weight and immunity to electromagnetic interference can be embedded and integrated into the host material to form an ideally smart structure system. One must recognize that optical fibers are foreign entities to the host structure, therefore will induce high stress state in the vicinity of the embedded sensor irrespective of the small size of the fiber. To address this concern, present paper focuses the attention on constituent interaction between the optical fiber, coating, matrix and host material. An analytical model to predict the stress fields in the vicinity of the embedded optical fiber is presented. The theoretical development is based on the four concentric cylinders model which represents the optical fiber, protective coating, matrix and host material, respectively. The host material is considered to be a composite with reinforced fiber parallel to the optical fiber. In this investigation, the host structure is subjected to in-plane shear loading. The effects of the coating and host material on the stress distribution in the vicinity of the embedded optical fiber are presented through a parametric study.

Abstract: The certification of retro-fitted structural health monitoring (SHM) systems for use on aircraft raises a number of challenges. One critical issue is determining the optimal means of supplying power to these systems, given that access to the existing aircraft power-system is likely to be problematic. Other conventional options such as primary cells can be difficult to certify and would need periodic replacement, which in an aircraft context would pose a serious maintenance issue. Previously, the DSTO has shown that a structural-strain based energy harvesting approach can be used to power a device for SHM of aircraft structures. Acceleration-based energy harvesting from airframes is more demanding (than a strain based approach) since the vibration spectrum of an aircraft structure varies dynamically with flight conditions, and hence a frequency agile or (relatively) broad-band device is often required to maximize the energy harvested. This paper reports on the development of a prototype vibro-impacting energy harvester with a ~59 gram flying mass and two piezoelectric bimorph-stops. Over the frequency range 29-41 Hz using a continuous-sine 450 milli-g r.m.s. excitation, the harvester delivers an average of 5.1 mW. From a random band-passed 25-45 Hz excitation with r.m.s. 450 milli-g, the average harvester output is 1.7 mW.

Abstract: Butt welding of 0.2mm thick TiNi shape memory alloy sheet was successfully realized by using micro impulse laser whose average power is 80W and the microstructure of welded joint was study in this paper. The results show that, the welded joint of micro laser welding can be divided into four zones according to grain size and microstructure. The microstructure in base metal zone is rolled structure and the grains are coarse and heterogeneous. The microstructures of welded seam center zone are fine equiaxed crystals and the microstructures of both lower surface and upper surface edge zone are columnar crystals. There is almost no obvious coarse grain heat-affected zone at the edge between welded seam and base metal. There is obvious segregation layer in local area of welded seam because the content of Ti and Ni elements is changed and different with base metal during the crystallizing course of welding pool.

Abstract: The possibility of uniting two or more different materials to obtain structures capable to feel and adapt to environmental alterations and operational conditions, has been leading to the development of active composites with functional properties that makes possible the control of shape, vibration, rigidity and/or structural integrity monitoring. These characteristics are very well accepted in modern technological applications. In this context, active composites were manufactured using pre-impregnated (Pre-Pregs) of carbon fiber reinforced polymer (CFRP) and NiTi shape memory alloy (SMA) thin wires in different conditions. The functional capacity of the obtained CFRP-NiTi smart composites was verified through detection of buckling and thermal contraction/expansion effects by electrical heating of the NiTi wires inside the CFRP matrix. Although the NiTi wires represent a minimum volumetric fraction in the CFRP-NiTi produced systems, its influence was evidenced.

Abstract: Shape memory alloys (SMA) are thermo-responsive materials where deformation can be induced and recovered through temperature changes. Therefore, SMA are considered smart materials. In this work, an epoxy beam reinforced by NiTi SMA wires was developed. This active composite contains five pre-trained NiTi SMA wire actuators, evenly distributed along the neutral plane of the epoxy beam, which can be activated by resistive heating. The results of different ways for electrical activation of the smart composite in a simply clamped mode are discussed. It was possible to demonstrate the viability of this concept for attenuation of mechanical vibrations by controlled electrical heating of the NiTi wire actuators.