Papers by Keyword: Smart Structure

Abstract: Hybrid composite material has been widely used in many engineering applications (e.g., for automobiles)and has several advantages over conventional fibre-reinforced composite materials, such as high strength-to-weight ratio and low cost. However, combining two kinds of reinforcement fibre within a common matrix may lead to different failure modes, such as delamination between the layers and fragmentation when the structure is subjected to high loads. To avoid this problem, real-time damage detection should be integrated into the hybrid composite structures for structural integrity. This paper outlines the working mechanisms and the initial fabrication of an integrated capacitive sensor into the intra-ply hybrid composite. The tensile test was conducted to perform the basic characterization of the proposed sensor and provide self-sensing functionality (smart structure). The results illustrate that damage between layers can be detected by in-situ monitoring. It is shown that the initial damage was detected at the turning point where the relative change in capacitance begins to decrease and when the axial tensile force increases. In addition, the developed smart material has shown a linear sensitivity toward crosshead displacement up to the turning point, and applying the monitoring is useful in self-sensing for hybrid composites.

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.

Abstract: The key problem for improving the precision of grating sensor is the subdivision technolgy. According to the instable condition of traditional monostable trigger subdivision circuit works on fast condition, this paper adopts CPLD to judge the logic signal, can identify direction, subdivide and count. In addition, we have introduction of the exterior synchronous clock .The technology not only overcome the instable situation but also improve anti-jamming of circuit system .It has been proved that the method get the better effort in practice.

Abstract: The parts of smart components consisting of structural and smart materials are conventionally produced separately and assembled in additional processes afterwards. An alternative approach to combine the forming of metallic parts and the assembly of components in one process step is proposed in this paper. Numerical and experimental investigations are carried out to investigate the influence of the axial clamping of the tube during the integration of a ring part through rotary swaging. The experiments also demonstrate the producibility of smart components by incremental forming processes without damaging the sensitive functional parts, which is proven by a functioning test.

Abstract: Suitable applications of smart structures for multifunctional spaces are going to be found by this paper. Logical argumentation research method is applied to identify a special smart structure which its features match to architectural requirements of multifunctional spaces. Hence, the smartness of architectural structures has two distinct scales: nanoscale and real scale, the application of these structures is based on two scales. Nanoscale smart structures have the capabilities which differ from real-scale smart structures. The analysis of features of multifunctional spaces shows that these kinds of spaces require structures which are smart both in nanoscale and real scale. As a result, combined-scale smart structures are recommended for multifunctional spaces.

Abstract: In this study a Finite Element Analysis for cantilever plate structure excited by proof mass is presented. To investigate the influence of different geometry parameters like thickness, length and width on the maximum deflection and resonance frequency. Configuration of piezoelectric actuators attached to the plate structure in order to identify the optimal configuration of the actuators for selective excitation of the mode shapes of the cantilever plate structure. The Finite Element Modeling based on ANSYS12.0 package using modal analysis and harmonic analysis is used in this study for cantilever plate structure excited by patch type of piezoelectric plates of PZT-5H4E of different geometrical parameters like thickness, length & width on the cantilever beam. To study the maximum deflection , the readings are taken by varying different geometry parameters . With this different geometrical parameters first modal analysis is done to know the different modes shapes and their natural frequencies and the frequency of particular mode shape at which the deflection is maximum. Then in the second stapes Harmonic Analysis is carried out near same frequency and the deflection amplitude is found out. Thus simulation of a cantilever beam is done by varying different thickness of piezoelectric plates and the substrate material. The same simulation is carried for different lengths’ & width. Finally the results are combine presented on graph , which clearly shows the effect of variation of geometry parameters on the beam deflections and accordingly change in natural frequency.

Abstract: The fiber Bragg grating sensors (FBGs) have been recently introduced: they present a photorecord grating on the fiber itself, which allows the reflection of a certain wavelength of the input light spectrum. The applied strain is estimated relying on changes of the reflected wavelength. One of the possible applications that has prompted us to study this type of sensors is the possibility to create smart dynamometric structures based on carbon fiber by embedding FBGs. Many papers are available in literature about some applications with smart structures but there is not yet an appropriate metrological characterization about these FBG sensors, their strengths and weaknesses: for these reasons it was deemed useful making several tests on FBG sensors in terms of measurement accuracy, signal to noise ratio, ability to compensate for thermal effects and their behavior for dynamic applications. All these results have been compared to electrical strain gauge ones, which represent the actual reference strain measurement systems. The various solutions to compensate for thermal effects have offered several information for further analyses and the basis for a future use of these sensors for static or semi-static tests. Being fully aware of FBGs characteristics allows to draw down guidelines about their integration in composite materials for the most different applications, understanding in a better way the sensor response.

Abstract: The fiber optic Bragg grating (FBG) sensors have been recently introduced: they presenta photo-record grating on the fiber itself, which allows the reflection of a certain wavelength of theinput light spectrum. The applied strain is estimated based on changes of the reflected wavelength.The metrological characteristics of FBGs have been tested and compared to strain gages ones, whichrepresent the actual reference measurement systems. It was decided to integrate the measurementsystem directly into a composite material, having achieved good results during the static and dynamictests [1]. We made carbon fiber specimens (two for traction and two for bending tests) with FBGsintegrated into them. The results were surprising: the integration of ``nude'' fiber optic sensor didnot cause damage or deterioration in the quality of measurement, the signal noise was maintained atbaseline levels and response to dynamic stress was definitely comparable to that offered by electricalstrain gauges

Abstract: Optical fiber sensors with light weight, small size and immunity to electromagnetic interference have been found to be a promising device for use in the development of smart structures. It is well known that the strain transfer from the host structure to the optical fiber sensor is dependent on the bonding characteristics such as adhesive layer and bonded length. In this investigation, the optical fiber sensor is surface bonded on the host structure. A theoretical model consisting of the optical fiber, adhesive layer and host material, is proposed to determine the strain in the optical fiber sensor induced by the host structure. The theoretical predictions were validated with the numerical analysis using the finite element method.

Abstract: There is increasing demand for developing smart structures in various electronic and electromechanical systems during past two decades. The modeling analyzing and manufacturing of these small-scale components remained always a challenging job. Finite element capability available in commercial software package ANSYS makes it convenient to perform modeling and analyzing of these smart structures. In this study a 3-D finite element analysis for cantilever plate structure excited by patches of piezoelectric actuator is presented. To investigate the influence of actuator location and configuration of piezoelectric actuators attached to the plate structure in order to identify the optimal configuration of the actuators for selective excitation of the mode shapes of the cantilever plate structure. The finite element modeling based on ANSYS package using modal analysis and harmonic analysis is used in this study for cantilever plate structure excited by patch type of piezoelectric actuators of PZT-5A at different locations of same geometrical parameters on the cantilever beam. The results clearly indicate optimal locations and configuration of the piezoelectric actuator patches for achieving the excitation of plate modes. Consequently, the results indicate that effective active damping of structural vibration of the cantilever plate can be achieved by proper positioning of the piezoelectric actuator patches.