COMPOSITES WITH SIMULTANEOUS VIBRATION CONTROL, ENERGY HARVESTING - PDF document

18 TH INTERNATIONAL CONFERENCE ON COMPOSITE MATERIALS COMPOSITES WITH SIMULTANEOUS VIBRATION CONTROL, ENERGY HARVESTING AND SELF-SENSING CAPABILITIES Y. Wang 1 and D. J. Inman 2* 1 Department of Mechanical Engineering, Virginia Tech, Blacksburg, VA 24061, USA 2 Department of Aerospace Engineering, University of Michigan, Ann Arbor, MI 48109, USA * Corresponding Author (DanInman @umich.edu) Keywords : Composites, Energy Harvesting, Self-sensing, Simultaneous Control 1 Introduction This work builds off of our previous research in self-charging structures [4]. A small prototype of the Multifunctional structures hold promise for new motivating device is illustrated in Fig. 2. This efficiencies in vehicles and other structural systems. multifunctional wing spar consists of collocated self- Here we examine the possibility of integrating three powering and self-sensing functionalities, as well as functions into a structural system by combining the simultaneous energy harvesting and gust alleviation functions of energy harvesting, self-sensing and abilities. reduced energy control into a composite structure. The composite considered here is a sandwiched material with the hope that future research will include a more integrated composite. Each functionality is described in detail and structural modeling results are presented. The motivating application is the wing spar of a UAV with the goal of providing self-contained vibration suppression and gust alleviation. The layered components consist Fig. 2. A sandwich composite spar with solar panel, of: the fiberglass spar, a thin film battery, piezoelectric and thin film battery materials. piezoceramic wafers, a flexible solar array and an electronics module as illustrated in Fig. 1. The basic concept is that the wing vibrates some L 3 =115mm z L 1 =30mm L 4 =600mm during normal flight under normal conditions. These L 2 =99.6mm vibrations along with any available sunlight are harvested. When the wing experiences a strong, x unexpected aerodynamic load (gust) the spar will B. QP16N (Harvester, Sensor) A. Flexible Solar Panel sense the increased vibration levels and provide C. Thinergy Thin Film Battery D. Printable Circuit Board (PCB) active control to reduce the vibration and help E. Fiberglass Substrate F. MFC(Actuator) maintain stability. G. Foam, Fiberglass Composite H. Epoxy DP 460, Kapton Fig.1. Schematic of multifunctional sandwich 2 Components composite wing showing the various functionalities. The structural functionality (Fig.1) is a UAV The key issues in researching the possible usefulness multifunctional wing spar, designed to fit in the of such an approach are 1) how much energy can be polystyrene insulating foam (G) core wrapped in harvested, and 2) is harvested energy enough to fiberglass substrate (E), for lightweight and strength effectuate active control. Certainly, passive control purposes. The PZT harvester/sensor (B) layered on can be achieved through aero-elastic harvesting as the top surface of the fiberglass substrate uses shown in [1] through passive means (shunt monolithic PZT (QuickPack QP10n). The Micro- damping). Here we focus on active reduced energy Fiber Composite MFC 8528 P1 is the PZT actuator control and look for the controller that uses the (F) layered on the bottom surface of the fiberglass minimum amount of energy [2]. Also key substrate. The MFC was recently developed in the importance is the weight added and in that context NASA Langley Research Center [5]. Due to its high does such an approach make sense [3]. actuating authority, the d33 effect P1 type MFCs are commonly used as PZT actuators. The thin film

COMPOSITES WITH SIMULTANEOUS CONTROL, HARVESTING AND SELF- SENSING CAPABILITIES   battery (C) (Thinergy MEC-1017SES batteries) (2 r 1) x    (3) 1 cos( ). allows for power storage from harvesting as well as r 2 L for energy supply for wind gust alleviation. The For the considered multifunctional electromechanical electronics module combines energy harvesting wing spar, the extended Hamilton’s principle over a conditioning, sensing circuitry, and the optimal given time period satisfies the following relation in vibration controller discussed below on a single layer terms of kinetic T , potential energy U , internal of Printable Circuit Board (PCB). These energy E ie and non-conservative energy E nc : multifunctional layers, together with the foam core, t 2 form the multi-layer wing spar. 3M ScotchWeld TM       (4) ( T U E E ) dt 0. ie nc DP460 epoxy, bracketed by Kapton, is used in the t 1 individual layer layup. Both are grouped together as The electromechanical energy follows the Euler- layer H. The wing spar geometric and material Lagrange Equations: properties are given in Table 1.      d T T U E E     ie nc   (5) Table 1. Geometric and Material Properties of , q ( ), t v t ( ).      i i dt q q q q q Multifunctional Wing Spar. Young’s Substituting the assumed mode solutions into the Layer Lengt Widt Thickness Mass h h(m (mm) (g) Module kinetic, potential and internal energy terms yields: (mm) m) (GPa) 1  N       Solar 85 28 0.2 0.69 52 o a , o a , o a , o a , (6) U [ ( ) t ( ) t k ( ) t v ( ) t ]; i l il i i Panel 2  i l , 1 QP10N 59.6 25.4 0.38 2.25 67  L 4 1 N w    Battery 25.4 25.4 0.18 0.46 55       o a , o a , b T ( ( ) t ( ) t m 2 ( ) t A x ( ) dx ) i  i l il i s 25.4 25.4 0.20 0.23 60 2 t PCB  i l , 1 0 (7) Fiberglass 735 28 10 185.2 71  L 4 1 w  Substrate   2 b A x ( )( ) dx ; MFC 85 28 0.18 2.92 63  s 2 t 0 Foam, 650 28 0.76 4.10 60 Fiberglass 1  N composite     o a , o a , o a , o a , o a , (8) E ( v C v ). 3D Epoxy 1580 28 0.008 0.35 3 i ie i p 2  i 1 Kapton 1580 28 0.0075 0.41 3.7 Here ρ , A s , v are the global density, the cross section area of the wing spar, and the voltage across the PZT electrodes. Here, the superscripts o , a , denote the 3 Electromechanical Euler-Bernoulli Modeling output (harvesting/sensing) and the actuation PZT layers. The subscripts s , p represent the wing spar The absolute transverse displacement of the wing structure and PZT layer, respectively. spar at any point x and time t is given by: The mass and stiffness components are defined   as: w x t ( , ) w x t ( , ) w ( , ), x t (1) b rel   L 4 where w b ( x,t ) and w rel ( x,t ) stand for the base and    (9) m A x ( ) dx , relative transverse displacement of the wing spar. il s i l 0 The relative vibration response can be represented as L 4 L L 2 3     finite series expansion of admissible trial functions   '' ''   '' '' o a , E o a , (10) k E I dx E I dx . il s s i l p i l 31,33   and unknown modal coordinates : r x ( ) r t ( ) 0 L 1 Here E , I denote Young ’ s modulus and the second   N   moment of inertia, respectively. Note that an over- ( , ) ( ) ( ), w x t x t (2) rel r r dot stands for ordinary differentiation with respect to  r 1 the temporal variable t , and a prime denotes ordinary where N is the truncation order of the series. The differentiation with respect to the spatial variable x .  admissible trial function has to satisfy the r x ( ) The coupling coefficient is defined as: above boundary conditions. In order to avoid   L 2, 3 L hyperbolic eigenfunction forms, a simple admissible  '' o a , o a ,  J dx . (11) i trial function is adopted here, which is typically used ie p L 1 for long, thin cantilever beams [6]: