Smart material

About: Smart material is a research topic. Over the lifetime, 3704 publications have been published within this topic receiving 74280 citations. The topic is also known as: intelligent material & responsive material.

Using Embedded Fiber Bragg Grating (FBG) Sensors in Smart Aircraft Structure Materials

Abstract: This paper describes the process of developing a smart material with monitoring application to the aircraft structures. A part of vertical stabilizer was selected and reproduced using carbon fiber honeycomb core sandwich panels. The sandwich panels reproduced were fabricated in accordance to the generic sandwich structure and aviation industry standards, including the materials and also the method of construction. Using a carbon fiber from Hexcel as the face-sheet, Nomex honeycomb as the core, the sandwich panel was cured using Hysol EA9330 resin according to aviation industry standard curing process. In order to make the sandwich panel as smart materials, optical sensor which has fiber bragg grating arrays, FBG, were embedded between the carbon fiber plies during the lay-out process. Using an FBG data logger, the FBG sensor signals were read before and after the FBG arrays were installed in the sandwich panels. From the initial measurement, the experiment was a success since the FBG sensors were readable and the difference in the signals was less than 1 nm. In the future, the specimen will be used for further experiment for measuring strains and establishing the existence of damage in the panel.

Stabilization of laminated beams with interfacial slip

Abstract: We study a laminated beam consisting of two identical beams of uniform thickness, which is modeled as Timoshenko beams. An adhesive of small thickness is bonding the two layers and creating a restoring force producing a damping. It has been shown that the interfacial slip between the layers alone is not enough to stabilize the system exponentially to its equilibrium state. Some boundary control has been used in the literature for that purpose. In this paper, we show that for viscoelastic material there is no need for any kind of internal or boundary control. Many structures in mechanical engineering, electrical engineering, civil engineer- ing and aerospace engineering are formed by a single beam or a number of beams. We can cite for instance, robot arms, rotor turbine and helicopter blades, turbo- machineries, electronic equipment, antennas, missiles, panels, pipelines, buildings, bridges, etc. There are mainly three important theories. The rst one is named after Euler and Bernoulli and the second one after Rayleigh. To alleviate the shortcom- ings in these two theories, Timoshenko came up with a new theory which is better suited for engineering practice and is nowadays widely used for moderately thick beams. Both, rotatory inertia and the eect of shear forces are taken into account. In his theory, Timoshenko also assumed that the plane cross-sections perpendicular to the beam centerline remain plane but could become oblique after deformation. An additional kinematics variable is added in the displacement assumptions. Inter- nal and external forces like the weight of the beam, heavy loads, wind, earthquakes and interaction with other bodies or materials are examples of some sources causing high stresses accompanying unwanted vibration. These stresses not only bring some discomfort, reduce the fatigue-life of the material and produce annoying noise but also are harmful to the structure as they may cause signicant damage or complete destruction of the machine or equipment. Therefore, some ways and devices capa- ble of enhancing dynamic stability must accompany these structures. To this end various devices and energy dissipation mechanisms have been designed either in the material itself such as smart materials (piezoelectric, pietzoceramic, viscoelastic),

Self-Healing Material with Reversible Luminescence Switch Behavior.

Abstract: Luminescent materials with dynamic responsiveness to external stimuli have attracted extensive attention for the development of advanced sensors and smart materials; however, self-healing capability is also of great importance for functional soft materials. An acid/base vapor reversibly triggered luminescence switch with self-healing ability is achieved by incorporating dynamic lanthanide metal-ligand (Ln-L) coordination into the soft polydimethylsiloxane polymer network. The emission color of the resultant luminescent material could be modulated by altering either the Eu3+/Tb3+ molar ratio or the excitation wavelength. The luminescence "On-Off" reversible switch is realized via direct alternating exposure to acid and base vapor, realizing reversible information encryption and decryption. The dynamic Ln-L cross-link as well as the hydrogen bond in the luminescent material endow it with excellent self-healing capability, high toughness, and stretchability. We believe this acid/base vapor-triggered self-healing switching strategy provides new insights for expanding the application range of luminescent materials.