The DARPA currently supports several programs with a focus on smart materials and structures. Two of these programs, the Smart Materials and Structures Demonstration Program and the Compact Hybrid Actuators Program (CHAP), will be described and reviewed. The Smart Materials and Structures Demonstration projects aim to show the value of smart materials-based actuation systems in realistic applications. The CHAP efforts focus on the development of new types of useful electro-mechanical and chemo-mechanical actuators that exceed the specific power and power density of traditional electromagnetic and hydraulic-based actuation systems by a factor of ten for a range of applications. Outlined are the expected capabilities, significant technical challenges, and performance advantages foreseen in successful development and transition of the technologies targeted for exploration.

The Smart Aircraft and Marine System Projects Demonstration (SAMPSON) program was a DARPA funded effort conducted by the Boeing Company, General Dynamics - Electric Boat Division, and the Pennsylvania State University. NASA Langley Research Center (NASA LaRC) was technical monitor for the aircraft demonstration, while the Navy's Office of Naval Research (ONR) was technical monitor for the marine demonstration. Dr. Ephrahim Garcia, DARPA/DSO, acted as the DARPA program manager for SAMPSON. The SAMPSON program objectives were to demonstrate smart structures based systems on large/full scale structures in realistic environments. The SAMPSON aircraft demonstration was the wind tunnel testing of a full scale F-15 aircraft inlet that was capable of in-flight structural variations accomplished using smart materials, called the 'SAMPSON Smart Inlet'. The SAMPSON Smart Inlet was removed from an F-15E airframe and structurally modified to interface with the NASA LaRC 16-Foot Transonic Tunnel model support system. This is Part I of two works documenting the SAMPSON Smart Inlet design and testing. A discussion of the design aspects and constraints will be presented here in Part I. The ground and wind tunnel testing of the Smart Inlet is presented in a separate work, Part II.

The Smart Aircraft and Marine System Projects Demonstration (SAMPSON) program was a DARPA funded effort conducted by the Boeing Company, General Dynamics - Electric Boat Division, and the Pennsylvania State University. NASA Langley Research Center (NASA LaRC) was technical monitor for the aircraft demonstration, while the Navy's Office of Naval Research (ONR) was technical monitor for the marine demonstration. Dr. Ephrahim Garcia, DARPA/DSO, acted as the DARPA program manager for SAMPSON. The SAMPSON program objectives were to demonstrate smart structures based systems on large/full scale structures in realistic environments. The SAMPSON aircraft demonstration was the wind tunnel testing of a full scale F-15 aircraft inlet that was capable of in-flight structural variations accomplished using smart materials, called the 'SAMPSON Smart Inlet'. The SAMPSON Smart Inlet was removed from an F-15E airframe and structurally modified to interface with the NASA LaRC 16-Foot Transonic Tunnel model support system. This is Part II of two works documenting the SAMPSON Smart Inlet design and testing. A discussion of the two wind tunnel tests will be presented here in Part II. The design of the shape changing components of the Smart Inlet is presented in a separate work, Part I.

The recently completed DARPA/AFRL/NASA Smart Wing Program, performed by Northrop Grumman Corporation, addressed the development and demonstration of smart materials based concepts to improve the aerodynamic and aeroelastic performance of military aircraft. This paper present a final overview of the program.

Building on the research performed during the DARPA/AFRL Smart Wing Phase 1 program to improve vehicle aerodynamic efficiency using control surfaces actuated by smart materials, the goal of the Phase 2 effort was to increase the size of the model and its control surfaces while also increasing the test dynamic pressure, Mach number and control surface deflection rate. To test the high rate, hingeless smart actuators a 30 percent scale wind tunnel model of a proposed Northrop Grumman Corporation uninhabited combat air vehicle was designed and tested. This paper describes the design, fabrication, system integration, and ground test results of the Smart Wing Phase 2 model. Among the topics that will be covered are (1) wind tunnel model selection; (2) analysis and design procedure; (3) smart control surface integration; and (4) static load and ground vibration test results and correlation.

The main goal of the Smart Wing Phase 2 Test 2 was to demonstrate high-rate actuation of hingeless, spanwise deflection variable control surfaces using smart material- based actuators. Requirement goals of 25-degree flap deflection in 0.33 sec, producing a sweep rate of 75 deg/sec, were desired. This sweep rate is similar to those specified for many of the existing military platforms with hinged control surfaces. Numerous studies were performed on many different smart material and flexible structure configurations before arriving at the final design which used an a flexcore-elastomeric skin trailing edge structure with eccentuation using high power ultrasonic motors. The final trailing edge control surface was made up of 10 eccentuator-driven segments connected together by a continuous outer skin and a flexible hinge pin at the trailing edge tip. This pin allowed the segments partial freedom to rotate about each other, but constrained any lateral motion thus giving a smooth trailing edge shape for non-uniform spanwise deflections. To control the ten segments of trailing edge, a VME-based control system with high speed, simultaneously sampled A/D and D/A boards and a dedicated DSP board was developed. This paper describes the analysis and design of the flex structure, ultrasonic motor selection and performance, element and coupon test to verify analysis, instrumentation to measure deflection, and control system development and integration that led to a highly successful test.

Northrop Grumman Corporation built and twice tested a 30 percent scale wind tunnel model of a proposed uninhabited combat air vehicle under the DARPA/AFRL Smart Materials and Structures Development - Smart Wing Phase 2 program to demonstrate the applicability of smart control surfaces on advanced aircraft configurations. The model constructed was a full span, sting mounted model with smart leading and trailing edge control surfaces on the right wing and conventional, hinged trailing edge control surfaces on the left wing. Among the performance benefits that were quantified were increased pitching moment, increased rolling moment and improved pressure distribution of the smart wing over the conventional wing. This paper present an overview of the result from the wind tunnel test performed at NASA Langley Research Center's Transonic Dynamic Tunnel in March 2000 and May 2001. Successful results included: (1) improved aileron effectiveness at high dynamic pressures, (2) demonstrated improvements in lateral and longitudinal effectiveness with smooth contoured smart trailing edge over conventional hinged control surfaces, (3) chordwise and spanwise shape control of the smart trailing edge control surface, and (4) smart trailing edge control surface deflection rates over 80 deg/sec.

The Boeing Active Flow Control (AFC) System is a DARPA sponsored program to develop AFC technology to achieve a significant increase in payload and/or range for rotorcraft applications such as the V-22 tiltrotor vehicle. The program includes Computational Fluid Dynamics analysis, 0.1 scale wind tunnel and 3D testing and development of smart material based AFC actuators. This paper will provide an overview of the program, concentrating on the development and testing of the AFC actuators, and is an update of references to 1 to 3.

Current research has shown that aircraft can gain significant aerodynamic performance benefits from active flow control (AFC). AFC seeks to control large scale flows by exploiting natural response triggered by small energy inputs. The principal target application is download alleviation of the V-22 Osprey under the DARPA sponsored Boeing Active Flow Control System program. One method of injecting energy into the flow over the V22 wings is to use an active vibrating surface on the passive seal between the wing and flapperon. The active surface is an oscillating cantilevered beam which injects fluid into the flow, similar to a synthetic jet, and interacts with the flow field. Two types of actuators, or flipperons, are explored. The first is a multilayer piezoelectric polyvinylidene fluoride cantilevered bender. The second is a single crystal piezoelectric (SCP)d₃₁ poled wafer mounted on a cantilevered spring steel substrate. This paper details the development effort including fabrication, mechanical and electrical testing, and modeling for both types of actuators. Both flipperons were mounted on the passive seal between a 1/10th scale V22 wing and flapperon and the aerodynamic performance evaluated in low speed wind tunnel. The SCP flipperon demonstrated significant cruise benefits, with increase of 10 percent lift and 20 percent angle of attack capability. The PVDF flipperon provided a 16 percent drag reduction in the hover mode.

The NASA Morphing Project seeks to develop and assess advanced technologies and integrated component concepts to enable efficient, multi-point adaptability in air and space vehicles. In the context of the project, the world 'morphing' is defined as 'efficient, multi-point adaptability' and may include macro, micro, structural and/or fluidic approaches. The project includes research on smart materials, adaptive structures, micro flow control, biomimetic concepts, optimization and controls. This paper presents an updated overview of the content of the Morphing Project including highlights of recent research results.

Evolution of the design of micro air vehicles (MAVs) towards miniaturization has been severely constrained by the size and mass of the electronic components needed to control the vehicles. Recent research, experimentation, and development in the area of smart materials have led to the possibility of embedding control actuators, fabricated from smart materials, in the wing of the vehicle, reducing both the size and mass of these components. Further advantages can be realized by developing adaptive wing structures. Small size and mass, and low airspeeds, can lead to considerable buffeting during flight, and may result in a loss of flight control. In order to counter these effects, we are developing a thin, variable-cambered airfoil design with actuators embedded within the wing. In addition to reducing the mass and size of the vehicle or, conversely, increasing its available payload, an important benefit from the adaptive wing concept is the possibility of in-flight modification of the flight envelope. Reduced airspeeds, which are crucial during loiter, can be realized by an in-flight increase in wing camber. Conversely, decreases in camber provide for an airframe best suited for rapid ingress/egress and extension of the mission range.

Active noise control has been a mature field of research activity for a number of years now. However, not so many commercial applications are available. In the aerospace industry for example, there seems still to be a gap between the promising results of academic research and practical systems in service. Two main problems need to be solved : the first one is relative to system integration. Too often lab type electronic components are used, which make the systems impossible to integrate for an onboard application (bulky power amplifiers, large real time computing platforms). The second one is more fundamental in nature : it relates to the current limitation of control algorithms to fighting against only 'simple', coherent perturbations. Bluntly put, most commercial systems can deal with one or two sinusoidal perturbations. However, broadband noise reduction is really a need and should be the goal of research today. EADS CRC is working on this problem with a global system perspective. Research topics include the whole array covering compact power amplifiers, integrated actuators in aerospace structures, miniaturized controllers. In the full length paper, results will be shown regarding a compact integrated system (including control and power electronics) and a demonstrator of an active trim panel for interior noise control.

Performance test for transmitted noise reduction of smart panels is experimentally studied. Smart panel is a panel that is utilized a passive material at high frequencies and piezoelectric shunt damping at low frequencies. A multi-mode shunt damping is investigated by using the tuning method based on measured electrical impedance. Three configurations of smart panels are tested: single panel, single panel with sound absorbing material and double panel. The single panel consists of a host plate structure on which four piezoelectric patches are bonded and electrical shunt circuits are connected independently. The parameters for resonant shunt are determined by maximizing the dissipated energy through the circuit. The transmitted noise reduction performance of smart panels is tested in an acoustic tunnel. Sound absorbing material and air gap reduces the sound transmitted at the mid-frequency region effectively while the use of piezoelectric shunt damping can work at resonance frequencies of the panel structure. As a result, a remarkable noise reduction of 15dB was achieved in a wide band frequency region. The double panel exhibits better noise reduction than other panels. This approach was also applied to the structural acoustic problem of turbulent boundary layer (TBL) induced sound radiated from a panel, and results are discussed.

The authors are developing a cost- and weight-effective means for achieving an improved low- and mid-frequency acoustic environment in payload fairings for rockets at lift-off. The solution will be an active noise control system with an optimum selection of distributed active vibration absorbers (DAVAs) and acoustic actuators. High sound pressure inside a launch vehicle fairing during lift-off can damage delicate equipment in the payload. Space launch vehicle payload noise is a very important problem in the successful launch and deployment of space instruments and equipment. Measurements taken during the first few seconds of launch show very high sound pressure level (SPL) in the low frequency range of 60 to 250 Hz. High SPL is a severe problem because interior noise impinges on the instruments and equipment in the payload and can lead to their vibrational failure. Engineers have made moderate progress in addressing this problem by strengthening the instruments and by applying passive noise control treatment to the fairing. Both strategies incur significant penalties of added weight and financial cost and reduced allowable payload size. For further progress in suppressing low-mid frequency noise, another way is needed. The authors are developing a hybrid passive/active noise control system based on emerging technology of distributed active vibration absorbers (DAVAs). DAVAs are constructed from acoustic foam and area-distributed actuators. Passively it behaves as a tuned mass damper at low frequencies and a viscous damper at high frequencies. Actively a DAVA produces mechanical forces that are directed to reduce fairing vibrations.

This paper presents multifunctional structure-plus-power developments being pursued under DARPA sponsorship with the focus on structure-battery components for unmanned air vehicles (UAV). New design strategies, analysis methods, performance indices, and prototypes for multifunctional structure-battery materials are described along with the development of two UAV prototypes with structure-battery implementation.

We are developing structural polymer composite materials that can be converted into fuels and combusted with oxidizers for orbital propulsion of spacecraft. We have identified candidate materials and demonstrated sustained combustion with nitrogen tetroxide (NTO) as an oxidizer. To improve reaction chemistry we have evaluated several energetic additives. Detailed material compatibility tests were conducted to identify stable combinations of structural polymer and energetic additives. We have also demonstrated sustained combustion of structural polymeric materials with embedded additives and NTO. In the next phase of research, we plan to investigate hydrogen peroxide as the oxidizer. Samples of composites comprising thin metallic facesheets, structural polymer propellant matrix, and metallic mesh reinforcements (that also serve as electrical heaters/igniters for pyrolysis) were fabricated and their mechanical properties were measured. Concept of a spacecraft structural stringer, which also functions as a thruster, was developed using the composite material formulation. Both all solid and hybrid stringer-thruster designs have been developed. Prototype stringer-thrusters will be fabricated and tested in Phase II.

In multifunctional material design, two or more functions performed by distinct system components or materials are incorporated into a single component or material system to improve system performance. The aim of this paper is to present a framework for the design of structure-battery (power) multifunctional composite materials for unmanned air vehicle (UAV) applications. The design methodology is based on optimization of composite material performance indices and the use of material design selection charts introduced by Ashby and coworkers in a series of papers for homogeneous and two-phase composite materials. Performance indices are derived for prismatic structure-battery composites under various loading conditions. The development of simple design tools in the form of spreadsheet templates is also discussed. Finally, results based on the above-mentioned framework and actual material properties will be presented for structure-battery circular and square struts.

A multifunctional panel concept is presented in which a lightweight, structural sandwich panel is able to undergo a reversible change in shape upon application of a localized thermal stimulus. The shape change is effected by metallic shape memory face sheet elements, which employ a 'one-way' SM effect only. Unlike other designs, no external or bias forces are required to completed the full cycle of shape change. This is accomplished by a core design which, when one of the two face sheets is activated and thus undergoes a length change, forces the opposite face sheet to martensitically deform in tension. By alternately heating one face sheet and then the other, to transform the martensitic structure to austenite, the sandwich beam or panel is able to perform fully reversible cyclic shape changes. Heating can be accomplished electrically or by other means. The performance of the sandwich panel, in terms of required thermal power, actuation frequency, peak load bearing capacity, stiffness, and weight, can be optimized by proper selection of face sheet material and this thickness, the overall core thickness, core member thickness and length, and the design of the joint connecting cor membranes and face sheet.

Multifunctional structures are those, which combine load- bearing support in addition to additional functions such as mechanical actuation, distributed power supply or thermal management. Electron beam - directed vapor deposition technology has been used to investigate deposition methodologies for two multifunctional battery concepts: a linear/truss base nickel - metal hydride and a fiber based solid-state Li⁺ ion multifunctional battery. Porous nickel coatings for the cathodes and porous rare earth metal coatings based on La and Ni or Ti and Zr for the anodes are being investigated for the nickel - metal hydride system; where LiV₂O₅, LiPON, and Sn₃N₄ are being investigated for the Li⁺ ion based system. Electron beam - directed vapor deposition is being used for deposition of all cathode/anode structures to provide an economical method for the development of these novel multifunctional structures.

The extracellular layers of the sea urchin egg are used as a model system for understanding the role of stochastically-placed fibers in providing reinforcement. We present preliminary results of deformation of the egg, and, at a smaller scale, some results on percolation modeling of fibrous materials to determine percolation points in closed-form. We suggest some general methodologies for analysis of extracellular matrices based on this work, with implications for design in engineered structures.

One of the main properties of tensegrity structures, that sets them apart from most of structures, is that they are vary suitable for shape control. This can be accomplished by controlling lengths of string members. Tensegrity deployment is considered herein as a tracking control problem. Therefore, the required trajectories should be feasible for a given structure. For tensegrity structures, this means that in every desired configuration, the structure has to satisfy tensegrity conditions, which require strings to be in tension, and the structure to be stable. To define an open-loop deployment control law, geometry parameterization of those configurations and corresponding rest lengths of string elements guaranteeing equilibrium are defined first. By slowly varying desired geometry, an open-loop string rest length control is defined. This makes the structure track trajectories defined by the time dependent geometry parameters. Two examples are illustrated: 1. Deployment of planar tensegrity beams made of symmetric stable tensegrity units, $2)$ Deployment of plates made of stable symmetric shell class tensegrity units.

We have recently demonstrated that composites with unique properties can be manufactured by embedding many small simple machines in a matrix instead of fibers. We have been referring to these as Machine Augmented Composites (MAC). The simple machines modify the forces inside the material in a manner chosen by the material designer. When these machines are densely packed, the MAC takes on the properties of the machines as a fiber-reinforced composite takes on the properties of the fibers. In this paper we describe the Machine Augmented Composite concept and give the results of both theoretical and experimental studies. Applications for the material in clamping mechanisms, fasteners, gaskets and seals are presented. In addition, manufacturing issues are discussed showing how the material can be produced inexpensively.

We are studying the incorporation of electromagnetic effective media in the form of arrays of metal scattering elements, such as wires, into polymer-based or ceramic-based composites. In addition to desired structural properties, these electromagnetic effective media can provide controlled response to electromagnetic radiation such as RF communication signals, radar, and/or infrared radiation. With the addition of dynamic components, these materials may be leveraged for active tasks such as filtering. The advantages of such hybrid composites include simplicity and weight savings by the combination of electromagnetic functionality with necessary structural functionality. This integration of both electromagnetic and structural functionality throughout the volume of the composite is the distinguishing feature of our approach. As an example, we present a class of composites based on the integration of artificial plasmon media into polymer matrixes. Such composites can exhibit a broadband index of refraction substantially equal to unity at microwave frequencies and below.

Electroelastomers (also called dielectric elastomer artificial muscles) have been shown to exhibit excellent performance in a variety of actuator configurations, but making a compact, free-standing, muscle-like actuator capable of obtaining good performance has been a challenge. By rolling highly prestrained electroelastomer films around a compression spring, we have demonstrated Multifunctional Electroelastomer Rolls (MERs) that combine load bearing, actuation, and sensing functions. The MER spring rolls are compact, have a potentially high electroelastomer-to-structure weight ratio, and can be configured to actuate in several ways, including axial extension, bending, and as multiple degree-of-freedom actuators that combine both extension and bending. One degree-of-freedom (1-DOF), 2-DOF, and 3-DOF MERs have all been demonstrated through suitable electrode patterning on a single monolithic substrate. A 1-DOF MER with 9.6 g weight, 12 mm diameter, and 65 mm total length can deliver up to 15 N force and 12 mm stroke. Its capacitance is around 13 nF and changes linearly with strain during axial tension or compression. The MERs are useful in a number of applications where compact and high-stroke actuation is required. The applications as artificial muscles are particularly appealing, as multifunctionality prevails in natural muscles.

Electroactive polymers (EAPs) can overcome many limitations of traditional smart material and transducer technologies. A particularly promising class of EAP is dielectric elastomer, also known as electroelastomer. Dielectric elastomer transducers are rubbery polymer materials with compliant electrodes that have a large electromechanical response to an applied electric field. The technology has been developed to the point where exceptional performance has already been demonstrated: for example, actuated strains of over 300 percent. These strains and the corresponding energy densities are beyond those of other field-activated materials including piezoelectrics. Because of their unique characteristics and expected low cost, dielectric elastomer transducers are under development in a wide range of applications including multifunctional (combined actuation, structure, and sensing) muscle-like actuators for biomimetic robots; microelectromechanical systems (MEMS); smart skins; conformal loudspeakers; haptic displays; and replacements for electromagnetic and pneumatic actuators for industrial and commercial applications. Dielectric elastomers have shown unique performance in each of these applications; however, some further development is required before they can be integrated into products and smart-materials systems. Among the many issues that may ultimately determine the success or failure of the technology for specific applications are durability, operating voltage and power requirements, and the size, cost, and complexity of the required electronic driving circuitry.

Recently, there have been significant advances in using magnetostrictive particles in a polymer matrix; finding uses in many applications, both as an active transducer and a passive damper. Termed magnetostrictive particulate composites (MPC), the material provides capabilities identical or superior to the monolithic material. Fortis Technologies has been pursuing improvements in the application and fabrication of this innovative material. The MPC technology provides a passive, broadband, large temperature range, high stiffness, dampling material to be used where current technologies fall short. Damping applications of this technology include sporting goods, power/hand tools, space launch and satellite design, noise abatement and vibration isolation. Energy absorption of the composites has been measured and is approaching that of the monolithic material. The material can also be actively controlled by a magnetic field, producing a transducer that can be used for sonar applications. The advantage of this technology over those currently in use is the large power density at relatively low frequencies and the ease of fabrication, allowing less expensive and more effective conformal arrays. Effective strain output and piezomagnetic coefficients have been measured, as have its dynamic properties. The results show significant improvement of the strain output and piezomagnetic coefficients, approaching the monolithic material.

The Inertially Stabilized Rifle is a new stabilized rifle system that can eliminate the disturbances induced by the shooter. Recurve actuator is used in this system to provide the precise movement of the rifle barrel. In such a portable device, only low voltage electrical sources are available yet the piezoelectric actuator needs high voltage to drive the actuator. The actuators consume little real power but a large amount of reactive power. Furthermore, the piezoelectric actuators are present an almost purely capacitive load. In this paper, we describe the development of a low input voltage amplifier for a high voltage piezoelectric actuator. This amplifier is based on switching technology so it efficiently handles the regenerative energy from the piezoelectric actuator. This amplifier consists of two stages. The first stage is a flyback converter which boosts the (low) input voltage to the maximum voltage required by the piezoelectric actuator. The second stage is a half-bridge amplifier which delivers the output voltage to the actuator as commanded by the reference signal. The basic structure of the amplifier is described, and its performance is characterized in terms of bandwidth, distortion, and efficiency.

Electronics that support aircraft, military, and space applications, as well as the consumer portables industry are increasingly calling for lighter-weight systems. With this, flex circuits are being used in lieu of heavier weight rigid circuit boards and flex is finding its way into increased applications. Flex offers a substrate material that is significantly lighter in weight, thinner, and more compliant than traditional rigid circuit board materials. Numerous methods of fabricating multilayer flex circuits exist; most of which involve using a n adhesive material to bond the individual patterned film layers together to create the multilayer circuit. Thus adhesives are commonly used to bond conductive foils to polyimide films, cover-layers to patterned circuits, and patterned films together to form multilayer circuits. However, adhesives can be problematic if they fail, ultimately leading to wrinkling, voids or delamination of the circuit. Numerous advantages can be gained from fabricating flex circuits without adhesives. Some of these advantages include: a reduction of materials and processing costs, lighter end-weight circuits, increased circuit flexibility, circuits with less z-axis expansion, and a matched coefficient of thermal expansion between the circuit layers. NASA Langley Research Center has developed a unique polyimide material called Langley Research Center - Soluble Polyimide or 'LaRC-SI' which can be used to make lightweight, adhesiveness flex circuits. LaRC-SI films can be bonded together simply by applying heat and pressure, and require no additional adhesive material for lamination. Once the LaRC-SI films are heated and pressed together, the individual films fuse together forming a monolithic film. Additionally, LaRC-SI flex circuits can be bonded directly to structures without the use of adhesives, simply by using a thermal compression technique. This technique provides a means of fabricating a multifunctional structure with many advantages, among the most obvious being optimized use of space.

The control of u wanted structural vibration is implicit in most of NASA's programs. Currently several approaches to control vibrations in large, lightweight, deployable structures and twin tail aircraft at high angles of attack are being evaluated. The Air Force has been examining a vertical tail buffet load alleviation system that can be integrated onboard an F/A-18 and flown. Previous wind tunnel and full-scale ground tests using distributed actuators have shown that the concept works; however, there is insufficient rom available onboard an F/A-18 to store current state-of- the-art system components such as amplifiers, DC-to-DC converter and a computer for performing vibration suppression. Sensor processing, power electronics, DC-to-DC converters, and control electronics that may be collocated with distributed actuators, are particularly desirable. Such electronic system would obviate the need for complex, centralized, control processing and power distribution components that will eliminate the weight associated with lengthy wiring and cabling networks. Several small and lightweight power amplifiers ranging from 300V pp to 650V pp have been designed using off the shelf components for different applications. In this paper, the design and testing of these amplifiers will be presented under various electrical loads.

In 1997 the BMBF announced a highly paid competition for future oriented key technologies and their industrial utilization. 230 proposals from industrial enterprises and research establishments were submitted. An independent group of experts selected altogether only 5 projects which were proposed to the BMBF. One of these projects was the major project ADAPTRONICS which is funded from 1998 to 2002 with a total volume of 25,000,000 EURO. This project is under the direction of the DLR and focuses on the integration of piezoelectric fibers and patches into lightweight structures aiming at active vibration and noise reduction, shape control and micro positioning. The main project target is the implementation of this technology in different industrial branches like the automotive industry, rail technology, mechanical engineering, medical engineering, and aerospace technology. This paper will give an overview of the recent progress and the next steps in the various tasks.

The field of 'Adaptronics' combines sensor and actuator effects with electronics. The components furnished with adaptronics shall sense relevant properties and shall adapt in an intelligent way - they shall 'feel, thick and act'. For instance, one application is the active vibration compensation of dynamically stressed structures. So far, adaptronics utilizes actuators - and partly also sensors - in the mm size range which posses a substantial stiffness. If such actuators/sensors were to be integrated into light weight structures - e.g. an carbon fiber reinforced aeroplane part or a glass fiber reinforced robot arm - the light weight structures would be severely affected in their advantageous properties. If however, these specific properties are to be maintained, the actuators/sensors have to feature a small volume and stiffness. The micro manufacturing of such systems is an activity of the Fraunhofer Institute IFAM. The approach chosen includes the utilization of piezo electric fibers in the diameter range from 20 micrometers - 200 micrometers . The micro systems consist of many fibers being contacted by interdigitized electrodes made of electrically conductive adhesives. In addition, structural adhesives and casting polymers are used. These actuator/sensor modules can be both applied onto structures, or integrated into structures. The performance of the different modules will be compared. An interesting approach for the use of sensor/actuator modules especially in prepreg fiber reinforced plastics is to also make the PZT fiber modules in a prepreg state. The presentation will feature the latest result of the developments regarding both, the manufacture and the performance of cured as well as prepreg modules.

The development of a new technology for the manufacturing of adaptive structures on the basis of thin monolithic peizoceramic wafers is an important goal of the German industrial project 'Adaptronik'. Partners from automotive-, space-, medical-, engineering- and optical industry participate in this project to enable new adaptive solutions for their applications. Due to the extreme brittleness of the piezoceramic material the manufacturing of these structures is still very demanding. Very often cracks in the piezoceramic material make the structure useless. This problem becomes serious when large scale structures with many actuators and sensor are considered. To come to more reliable results the use of encapsulated piezoceramic actuators and sensor came into focus. With respect to the great variety of different requirements given by the industrial partners the use of standardized solutions was not feasible. The goal was to develop new elements with improved performance parameters that can easily be adapted to different applications. Due to a modular concept, the developed multifunctional elements can be designed to meet a great variety of different structures was developed. A first step to adapt this technology to prototype structures has been done by the development of special encapsulated patches for an adaptive lightweight satellite mirror.

The utilization of the smart structures technology gains increasing attention in engineering and industrial applications, especially in the wide field of noise and vibration reduction of thin-walled structures. The application of distributed sensors and actuators - e.g. piezoelectric wafer or fiber arrays - directly attached at the structure or laminated into a composite structure results in a highly integrated smart structural system. An optimal exploitation of such facilities of piezoelectric materials requires effective and robust numerical tools for an optimal overall design. In our opinion the finite element approximation based on multi-field thin shell elements provides an excellent method for the simulation and the design of complex smart structures. In the paper a brief introduction in our finite element simulation and design tool is given where the focus is on the recently developed multi-field finite shell elements. These elements have been created on the basis of the classical SemiLoof element family by introducing additional degrees of freedom to approximate the electromechanical coupling. One central point in the design process is the distribution of the active material at the passive base structure to fulfill the design criteria. In the paper a design concept based on controllability and observability indices is presented, which results in an acceptable first design even in complex industrial applications. In connection with a flexible automatic meshing, which generates the overall model for structures with any amount and distribution of active wafers, the overall behavior of a smart structure can be simulated quite accurate. To underline the capability of the design and simulation tool two examples with references to mechanical and automotive applications are discussed.

Future scientific space missions based on interferometric optical and infrared astronomical instruments are currently under development in the United States as well as in Europe. These instruments require optical path length accuracy in the order of a few nanometers across structural dimensions of several meters. This puts extreme demands on static and dynamic structural stability. It is expected that actively controlled, adaptive structures will increasingly have to be used for these satellite applications to overcome the limits of passive structural accuracy. Based on the evaluation of different piezo-active concepts presented two years ago analysis and design of an adaptive lightweight satellite mirror primarily made of carbon-fiber reinforced plastic with embedded piezoceramic actuators for shape control is being described. Simulation of global mirror performance takes different wavefront-sensors and controls for several cases of loading into account. In addition extensive finite-element optimization of various structural details has been performed. Local material properties of sub-assemblies or geometry effects at the edges of the structure are investigated with respect to their impact on mirror performance. One important result of the analysis was the lay-out of actuator arrays consisting of specifically designed and custom made piezoceramic actuators. Prototype manufacturing and testing of active sub-components is described in detail. The results obtained served as a basis for a final update of finite-element models. The paper concludes with an outline on manufacturing, testing, and space qualification of the prototype demonstrator of an actively controllable lightweight satellite mirror currently under way. The research work presented in this paper is part of the German industrial research project 'ADAPTRONIK'.

The following paper presents the development of an adaptive aeronautical structure at the example of a high lift device, a so-called fowler flap. It shows the passive optimization of the flap with a complex finite element model and illustrates the necessity to develop an active structure, due to the limited possibilities to increase the efficiency of the passive flap. Different kinds of active measures are discussed and it is shown, why an activation of the structure with shape memory alloy (SMA) actuators is preferred. Additionally, the results and findings of experiments with an active spar that was developed, built, and tested at the Institute of Structural Mechanics (ISM) at the German Aerospace Center in Braunschweig are presented.

This paper reports some research results for the application study of the smart materials an structural using Shape Memory Alloy (SMA) foils. First, the authors acquired the recovery strain of CFRP laminates generated by the recovery stress of the pre-strained SMA foils. Then, the quasi-static load-unload tests were conducted using several kinds of quasi-isotropic CFRP laminates with embedded SMA foils. Micro-mechanics of damage behavior due to the effects of the recovery strain and the first transverse crack strain were discussed. The improvement of maximum 40 percent for the onset strain of the transverse cracks and maximum 60 percent for the onset strain of delamination were achieved for CFRP laminates with embedded pre-strained SMA foils compared with standard CFRP laminates. Furthermore, the authors conducted the structural element test for application to actual structures. Testing technique and the manufacturing technique of the structural element specimen were established.

Thermally activated shape memory materials have been employed as actuators fora number of years. They are generally activated by electrical resistance heaters, or sometimes by direct electrical resistance. Thermoelectric modules can also provide activation energy, and they provide several unique advantages over the more conventional heating methods. Antagonistic Shape Memory Actuator systems, the utilization of thermoelectric modules as heaters, and the advantages and practical approaches for utilizing actuators employing thermoelectrics are discussed.

This work discusses the numerical analysis, the design and experimental test of the fuel-powered compact SMA actuator along with its capabilities and limitations. Convection heating and cooling using water actuate the SMA element of the actuator. The energy of fuels, having a high energy density, is used as the energy source for the SMA actuator in order to increase power and energy density of the system, and thus in order to obviate the need for electrical power supplies such as batteries. The system is composed of pump, valves, bellows, heater (burner), control unit and a displacement amplification device. The experimental test of the first designed SMA actuator system results in 150 M Pa stress (force: 1560N) with 3 percent strain and 0.5 Hz actuation frequency. The actuation frequency is compared with the prediction obtained from numerical analysis. For the first designed fuel-powered SMA actuator system, the results of numerical analysis were utilized in determining design parameters and operating conditions.

Within the European collaborative applied fundamental research project ADAPT, fundamentals of SMA-reinforced composites were evaluated and the specific manufacturing techniques for these composites developed and realised. The involved partners are listed at the end. To demonstrate applicability of these composites a realistically scaled aerodynamic profile of around 0.5m span by 0.5m root chord was designed, manufactured and assembled. The curved skins were manufactured as SMA composites with two layers of SMA-wires integrated into the layup of aramid fibre prepregs. All SMA wires were connected such that they can be operated as individual sets of wires and at low voltages, similar to the conditions for electrical energy generation in a real aircraft. The profile was then mounted on a vibration test rig and activated and excited by a shaker at its tip which allowed to test the dynamic performance of the profile under different external loading conditions with various internal actuation conditions through the SMA wires. The paper includes some background of the design and manufacturing of the aerodynamic profile and will discuss some of the results determined recently on the test rig. A view with regard to future wind tunnel testing will be given as well.

Traditionally smart material actuation has been reserved for high technology industries such as space and aerospace; however, as the field matures more and more instances are found in low-cost, high production areas. This paper describes one such instance - the application of shape memory alloys to auxiliary functions in appliances. This investigation focused on lid locks for washing machines because it is representative of several other applications found in appliances including valves, dispensers, locks, brakes, etc. Several competing concepts for SMA actuated lid locks are discussed including simple analytical design models and experimental characterization of proof-of-concept prototypes. A comparison of these designs based on performance (force, response times), energy (power requirements) and economic metrics is given. From this study, a final concept was developed based upon the best attributes of the different concepts. The resulting proof-of-concept prototype demonstrated improved performance over the current state with a potential for cost reduction.

It is well known that barely visible damage is often induced in composite structures subjected to our-of-plane impact, and the mechanical properties of the composites decrease markedly. So far, for the significance of the damage monitoring, the impact test of the CFRP laminate plates with embedded small-diameter optical fibers were conducted, and it was found possible to detect impact load and impact damage in real-time by measuring the optical loss and strain response. But the stiffened composite panels, which are the representative structural elements of airplane. Are characterized by different impact damage from that of the composite plates. In this study, single-mode and multi-mode optical fibers are used as a sensor for detecting impact load and impact damage in curved/stiffened composite panels. Those fibers have polyimide coating and about 40 micron in diameter which will have no serious effect on the mechanical properties of composites. Impact test are performed using the panels with wavy embedded optical fibers. The characteristics of impact damage are investigated. The impact load, the strain measured by FBG sensors and the optical intensity of the optical fibers embedded in the composites are monitored as a function of time. And we discuss the relationship between optical response, impact load and impact damage.

This paper describes the installation and testing of a large-scale fiber optic sensor network on the British Trimaran Research Vessel (RV) Triton. In this on-going project with the Naval Surface Warfare Center, Carderock Division (NSWCCD) and the British Defence Science and Technology Laboratory (formerly DERA), Systems Planning and Analysis, Inc. (SPA) recently completed the installation and at-sea testing of an integrated hardware/software structural monitoring system for rough sea trial testing of the RV Triton. This paper describes a fiber optic Bragg grating sensor network comprising of 51 sensors, the interrogation system, and the processing algorithms used to simultaneously record strain data at both high- and low-speed frequencies, including triggering of the high-speed channels. This paper also details the sensor layout and installation process with emphasis on lessons learned during this procedure. The test procedure and sample data results are presented. Finally, conclusions are drawn from our experience and recommendations are given for future large-scale installations of optical sensing systems.

Quantitative data on the stress-strain behavior of walls and roofs of underground mines are unavailable. It is established practice to use roof bolts to support roofs in mines. Smart materials have been developed for roof bolts that act as sensors in systems capable of monitoring the stress/strain history of mine roofs with the goal of detecting structural defects and damage. The systems can be designed for a passive mode to monitor peak strain or an active mode for real-time alarm response. The systems are low-cost and capable of long-term operation which, in the case of waste isolation facilities, can involve very long time periods. The smart materials to be used in this application are TRIP (Transformation Induced Plasticity) steels. TRIP steels are materials that change state from austenitic, nonmagnetic to a martensitic, ferromagnetic phase as the material undergoes straining. There is a direct correspondence of the peak strain level experienced in the material with the percentage of ferromagnetism, hence monitoring the relative amount of the ferromagnetic content will indicate the level of strain (and therefore, stress). The phase transition that accompanies the straining is irreversible so the monitor material indicates the peak strain until that value is subsequently exceeded. Materials research discussed will cover the selection of compositions with a suitable ferromagnetic response and the development of thermomechanical treatments to achieve high tensile strength required for this application.

Assembly and measurement of photonic subsystems or integrated optical components is transitioning from manual to semi-automated and fully automated configurations. Controlled motion, which allows movement in the 10-millimeter range with resolution of nanometers, is a critical requirement for successful assembly or functional verification of an assembly. Application specific requirements may include holding position at sub-micrometer levels for hours, repeatability of 0.1 percent over 100 micrometers to 0.005 percent over 10 millimeters, and simple controls for systems as basic as 2 degrees of freedom to multiple robots with 6 degrees of freedom each. New clamping technology, in an INCHWORM(brand motor, utilizes a combination of MEMS fabricated features and proprietary clamp interface materials to increase the clamp friction. This allows much higher push forces to be generated or the design freedom to trade force for size. Power versus Force curves are presented. Resolution, velocity, stiffness, and simple control are maintained in a much smaller package. Single mode fiber optic devices have active areas in the 5-10 micrometer range. Assembly needs are going smaller. A relatively powerful motor with dimensional resolution and time stability that can be incorporated into ever smaller robots will be needed to meet future photonic automation requirements.

A single-stage servovalve using direct piezoelectric actuator drive is described. The single-stage servovalve design offers higher bandwidth than conventional two-stage valves. It takes advantage of the high energy density in piezoelectric materials while addressing the need for internal amplification of stroke. When used alone, the valve can regulate pressure, and when used in combination with a hydraulic output device it forms part of an effective servohydraulic actuator. Development of a direct drive prototype valve is described. Discussion includes design issues related to low stroke smart material actuators such as piezoelectrics. Component and subsystem testing and results are reviewed. Electronic drive and control of the piezoelectric and overall device along with performance in the control of fluid flow is discussed. The value of the new servovalve is shown in the combination of the valve with a hydraulic output device. Data are supplied for this servohydraulic actuator. The new actuator shows promise for a motion simulator application and more generally for motion control at higher bandwidth than is possible with currently available servohydraulics.

Aerospace applications of MEMS products, originally developed for automotive mass markets, are discussed. Various sensor examples with a high dual use potential are presented: inertial sensing, flow and gas sensing, robust micro sensors including SiC- and GaN-based devices, as well as first approaches towards flexible and distributed microsystems. In Europe the automotive industry is one of the main MEMS market drivers, simply because of the sheer size of this market and Europe's strong position in this industrial field. Main MEMS activities are development and integration of vehicle dynamics sensing systems, passenger safety and navigation systems, air and fuel intake systems, as well as sensor systems for exhaust gas after treatment and climate control. Benefits on the customer side are increased safety, passenger comfort and reduced fuel consumption. Benefits on the manufacturer's side are increased sub-system integration, modularity and reduced production cost. In the future the aerospace industry is likely to benefit from the introduction of micro-systems for the same reasons as the automotive industry. Interests of the aerospace industry are increasing safety and reliability of airplane operation, health and state monitoring of fuselage and airplane subsystems as well as improving service and maintenance procedures. In comparison to automotive applications, the numbers of devices needed is likely to be much smaller, however, new challenges arise in so far as distributed sensing and actuating microsystems will be needed. The idea is to identify and to exploit synergies between automotive mass market MEMS applications and lower-volume aerospace ones. The effort necessary to meet aerospace requirements and the extent of necessary trade-offs in customizing automotive MEMS is addressed considering the above-mentioned examples.

Force feedback is a new technology that has great potential in human-machine interfaces. While guiding the end effector of a robot through an environment using a hand-held actuator, force feedback is needed to make the user feel the environment conditions like stiffness along which the end effector moves. This along with the already available visual feedback will allow the user to guide the robot exactly along the path that he or she intends thereby enhancing the performance. Easily controllable actuators that give quick response at the user end are needed here. This paper demonstrates the effectiveness of MR fluid devices in such force feedback applications. The force-feedback experiment includes a simple setup that depicts a typical situation wherein a user controls the movement of an external linear hydraulic actuator using a MR sponge damper. Force and displacement sensors sense the environment conditions along which the end effector of the hydraulic actuator moves. This information is then used to control the MR damper to provide appropriate force feedback to the user. The setup is tested with different environments like springs with various stiffnesses and for extreme cases with mechanical stops thereby demonstrating the flexibility in using MR sponge dampers for various force feedback applications.

An active structural control system was developed and implemented on a hexapod milling machine to increase metal removal rate of the machine. The control system hardware consisted of dynamic actuators, sensors, processors and a telemetry system. The control law was implemented in software in the control processor. The objective of the control system was to reduce the dynamic response of the milling tool thereby improving its stability and its maximum depth-of-cut. System design including sensor and actuator development was guided using finite element modeling techniques. The components were constructed, and a successful experimental demonstration resulted.

Composites containing thin Shape Memory Alloy (SMA) wires show great potential as materials able to adapt their shape, thermal behavior or vibrational properties to external stimuli. The functional properties of SMA-composites are directly related to the constraining effect of the matrix on the reversible martensitic transformation of the embedded pre-strained SMA wires. The present work reports results of a concerted European effort towards a fundamental understanding of the manufacturing and design of SMA composites. This first part investigates the transformational behavior of constrained SMA wires and its translation into functional properties of SMA composites. Thermodynamic and thermomechanical experiments were performed on SMA wires. A model was developed to simulate the thermomechanical behavior of the wires. From the screening of potential wires it was concluded that NiTiCu, as well as R-phase NiTi appeared as best candidates. Requirements for the host composite materials were surveyed. A Kevlar-epoxy system was chosen. Finally, the quality of the SMA wire-resin interface was assessed by two different techniques. These indicated that a thin oxide layer seems to provide the best interfacial strength. A temperature window in which SMA composites can be safely used was also defined. The manufacturing and properties of the SMA composites will be discussed in Part II.

The manufacturing route and resulting properties of adaptive composites are presented in the second part of this European project report. Manufacturing was performed using a specially designed frame to pre-strain the SMA wires, embed them into Kevlar-epoxy prepregs, and maintain them during the curing process in an autoclave. Composite compounds were then tested for strain response, recovery stress response in a clamped-clamped configuration, as well as vibrational response. Through the understanding of the transformational behavior of constrained SMA wires, interesting and unique functional properties of SMA composites could be measured, explained and modeled. Large recovery stresses and as a consequence, a change in vibrational response in a clamped- clamped condition, or a reversible shape change in a free standing condition, could be generated by the SMA composites in a controllable way. These properties were dependent on composite design aspects and exhibited a reproducible and stable behavior, provided that the properties of the matrix, of the wires and the processing route were carefully optimized. In conclusion, the achievements of this effort in areas such as thermomechanics, transformational and vibrational behavior and durability of SMA based composites provide a first step towards a reliable materials design, and potentially an industrial application.

The objective of this product is to address the specific need for improvements in the efficiency and effectiveness in physical separation technologies in the screening areas. Currently, the mining industry uses approximately 33 billion kW-hr per year, costing 1.65 billion dollars at 0.05 cents per kW-hr, of electrical energy for physical separations. Even though screening and size separations are not the single most energy intensive process in the mining industry, they are often the major bottleneck in the whole process. Improvements to this area offer tremendous potential in both energy savings and production improvements. Additionally, the vibrating screens used in the mining processing plants are the most costly areas from maintenance and worker health and safety point of views. The goal of this product is to reduce energy use in the screening and total processing areas. This goal is accomplished by developing an innovative screening machine based on smart materials and smart actuators, namely smart screen that uses advanced sensory system to continuously monitor the screening process and make appropriate adjustments to improve production. The theory behind the development of Smart Screen technology is based on two key technologies, namely smart actuators and smart Energy Flow ControlT (EFCT) strategies, developed initially for military applications. Smart Screen technology controls the flow of vibration energy and confines it to the screen rather than shaking much of the mass that makes up the conventional vibratory screening machine. Consequently, Smart Screens eliminates and downsizes many of the structural components associated with conventional vibratory screening machines. As a result, the surface area of the screen increases for a given envelope. This increase in usable screening surface area extends the life of the screens, reduces required maintenance by reducing the frequency of screen change-outs and improves throughput or productivity.

Morphing as an independent variable is addressed. Potential missions to demonstrate the value of morphing are presented and discussed. The effects of morphing on vehicle kinematics is demonstrated for takeoff, landing, and turn rate. At the system level, the effects of variable lift-to-drag ratio and specific fuel consumption on vehicle weight are examined for cruising flight. An example mission is presented to demonstrate how morphing can be implemented in constraint and sizing analyses, which are at the core of the aircraft conceptual design process. A comparison of morphing and non-morphing aircraft weights is made. It is demonstrated in some cases morphing adds weight due to requiring a structure to complete two missions. The requirement for new structural concepts is briefly discussed.