This paper describes a research program investigating the development of “moving spars” to enable active aeroelastic control of aerospace structures. A number of different concepts have been considered as part of the EU funded Active Aeroelastic Aircraft Structures (3AS) project that enable the control of the bending and torsional stiffness of aircraft wings through changes in the internal aircraft structure. The aeroelastic behaviour, in particular static deflections, can be controlled as desired through changes in the position, orientation and stiffness of the spars. The concept described in this paper is based upon translational movement of the spars. This will result in changes in the torsional stiffness and shear centre position whilst leaving the bending stiffness unaffected. An analytical study of the aeroelastic behaviour demonstrates the benefits of using such an approach. An experimental investigation involving construction and bench testing of the concepts was undertaken to demonstrate its feasibility. Finally, a wind tunnel test of simple wing models constructed using these concepts was performed. The simulated and experimental results show that it is possible to control the wind twist in practice.

Morphing aircraft structures can significantly enhance air vehicle performance. This paper highlights ongoing work to design novel compliant mechanisms that efficiently morph aircraft structures in order to exploit aerodynamic benefits. Computational tools are being developed to design structures that deform into specified shapes given simple actuator inputs. In addition, these synthesis methods seek to optimize the stiffness of the structure to minimize actuator effort and maximize the stiffness with respect to the environment (external loading). These tools have been used to study two different types of morphing systems: (i) variable geometry wings and (ii) high-frequency vortex generators for active flow control. Several case studies are presented which highlight the design approach and computational and experimental results of these morphing aircraft systems.

Rules governing airport noise levels are becoming more restrictive and will soon affect the operation of commercial air traffic. Sound produced by jet engine exhaust, particularly during takeoff, is a major contributor to the community noise problem. The noise spectrum is broadband in character and is produced by turbulent mixing of primary, secondary, and ambient streams of the jet engine exhaust. As a potential approach to controlling the noise levels, piezoelectric bimorph actuators have been tailored to enhance the mixing of a single jet with its quiescent environment. The actuators are located at the edge of the nozzle and protrude into the exhaust stream. Several actuator configurations were considered to target two excitation frequencies, 250 Hz and 900 Hz, closely coupled to the naturally unstable frequencies of the mixing process. The piezoelectric actuators were constructed of 10 mil thick d₃₁ poled wafer PZT-5A material bonded to either 10 or 20 mil thick spring steel substrates. Linear analytical beam models and NASTRAN finite element models were used to predict and assess the dynamic performance of the actuators. Experimental mechanical and electrical performance measurements were used to validate the models. A 3 inch diameter nozzle was fitted with actuators and tested in the Boeing Quiet Air Facility with the jet velocity varied from 50 to 1000 ft/s. Performance was evaluated using near-field and far-field acoustic data, flow visualization, and actuator health data. The overall sound pressure level produced from the 3 inch diameter jet illustrates the effect of both static and active actuators.

A new diaphragm actuator based on the ferromagnetic shape memory alloy (FSMA) composite is designed where the FSMA composite is composed of ferromagnetic soft iron and superelastic grade of NiTi shape memory alloy (SMA). The actuation mechanism for the FSMA composite plate of the actuator is the hybrid mechanism that we proposed previously. This diaphragm actuator is the first design toward designing a new synthetic jet actuator that will be used for active flow control technology on airplane wings. The design of the FSMA composite diaphragm actuator was established first by using both mechanical and ferromagnetic finite element analyses with an aim of optimization of the actuator components. Based on the FEM results, the first generation diaphragm actuator system was assembled and its static and dynamic performance was experimentally evaluated.

The mission space requirements imposed on the design of micro air vehicles (MAVs) typically consist of several distinct flight segments that generally conflict: the transit phases of flight require high speeds, while the loiter/surveillance phase requires lower flight velocities. Maximum efficiency must be sought in order to prolong battery life and aircraft endurance. The adaptive wing MAV developed at the University of Arizona features a thin, deformable flying wing with an efficient rudder-elevator control system. The wing camber is varied to accommodate different flight speeds while maintaining a constant total lift at a relatively low angle of attack. A new airfoil was developed from the Selig 5010 that features a small negative pitching moment for pitch stability. Wind tunnel tests were performed and stall angles and best lift-to-drag ratios were analyzed from the data. The wind tunnel data was used in a performance analysis in order to determine the flight speeds and throttle settings for maximum endurance at each camber, as well as the MAV's theoretical minimum and maximum flight speeds. The effectiveness of camber change on flight speed and endurance was examined with promising results; flight speed could be reduced by 25% by increasing the camber from 3 to 9% without any increase in power consumption.

Experiments demonstrating several vibro-acoustic mitigation technologies will be tested on the Vibro-Acoustic Launch Protection Experiment 2 (VALPE-2) aboard a Terrier-Improved Orion sounding rocket slated for launch from Wallops Island Flight Facility in May 2003. Flight data collected in November 2002 from a nearly identical launch (VALPE-1) is being used to characterize the fairing environment and design the prototype hardware for the second flight. This paper discusses the various experiments that will be tested on the VALPE-2 flight, and presents some of the measured results and lessons learned from the first flight.

The application of a new class of actuators is considered. The actuators under development combine a high energy density smart material, specifically a piezoelectric material, with internal servohydraulic components. Large displacement outputs are produced, while the high force capacity of the stiff smart material is retained, for a net high-energy output. The actuator is considered “power-by-wire” because only electrical power is provided from the vehicle or system controller. A primary motivating application is in unmanned combat air vehicles (UCAVs). The particular actuation needs of these vehicles, in flight control and other utility functions, are described and distilled to a set of relevant device requirements. Other potential applications, such as flight motion simulation, are also highlighted. The new actuation architecture offers specific advantages over centralized hydraulic systems and has capabilities not present in electromechanical actuators (EMAs). The main advantage over centralized hydraulic systems is the elimination of the need for hydraulic lines. Compared to motor-driven ball screw type EMAs, the new actuators offer higher frequency response, and a larger peak-to-average output. A laboratory test facility designed to represent the loading experienced by a UCAV control surface is described. Key steps necessary to flight qualify the actuator are introduced.

The objective of our Compact Hybrid Actuator Device (CHAD) program is to produce a novel, ultra-compact, high force actuator to meet the aggressive requirements for navigation, guidance and control of a compact missile as well as other military and commercial applications confronted with tight volume constraints. Our approach to this challenge uses the high power density of thin film shape memory alloys coupled with fluid rectification and commercial power electronics. Phase One of our program demonstrated the performance of critical technical elements in a non-compact form factor. NiTi films were reproducibly deposited and then fabricated into bubble actuators that demonstrated ≥ 100 Hz performance when forced convection heat transfer to a liquid was optimized. Increased efficiency in thermal activation was achieved through high Joule heating rates for short duty cycles; this allowed simplification of the power electronics. These technical elements were combined to produce a thin film SMA pump which ultimately demonstrated force outputs on the order of 250 N and average power densities on the order of 50 W/kg when operated at 100 Hz. The demonstrated performance shows great promise for applications requiring ultracompact form factors with high output force.

This paper describes design methodologies for construction of an actuator that uses smart materials to provide hydraulic fluid power. In the class of actuators described, hydraulic fluid decouples the operating frequency of the output cylinder from the drive frequency of the piezoelectric or other smart material. This decoupling allows the piezoelectric to be driven at high frequency, to extract the maximum amount of energy from the material, and the hydraulic cylinder to be driven at low frequencies to provide long stroke. However, due to fluid compressibility and structural compliance, the fundamental impedance match between the fluid and the piezoelectric make it difficult to convert energy from the piezoelectric into pressurized hydraulic fluid flow. The basic design tradeoffs and major technical issues are discussed in the areas of materials, mechanical design, and fluid-mechanical interface. Prototype devices and component measurements are presented. Test methods are described, and test results quantifying pump pressure and flow, and actuator force and velocity are summarized. The series of tests show the potential of these devices for high force long stroke devices powered by smart materials.

Photonic assembly packaging, adaptive optics, large optical beam control, and semiconductor test and measurement are application areas that have needs for nanometer-level precision. Utility is increased with features such as greater than 10-millimeter travel, power-off hold, high acceleration and high stiffness. Alignment applications can benefit from a high mechanical power density. This translates into smaller package size for required force, speed, travel and resolution performance. In manufacturing of photonic packages, the space around the work piece often is limited and ergonomic design considerations for workspace are helped with a small profile. Smaller system size implies less total mass and power required for a given performance level, which is highly desirable for airborne or space applications. Smaller mechanical systems benefit from higher stiffness, lower Abbe error, and are less susceptible to environmental transients. A second-generation actuator system that provides about one nanometer open loop step size with 25 millimeters of travel will be characterized. The first-generation model provided more than 100 N force at 25 mm/s speed. The device is compatible to using proprietary thin film and MEMS technology for a high-friction clamping design that simulates an “infinite gear”.

In this paper, a thin film nickel-titanium (NiTi) shape memory alloy (SMA) was used to develop a prototype compact hybrid actuator. SMA was selected as an actuating mechanism because it had the highest work density among active materials. Combining this attribute with high frequency response of thin films resulted in large power output. High drive frequency was also possible in part from manipulating the liquid flow to directly cool the SMA membranes. The actuator reached a drive frequency of 100Hz while producing 2.6Watts. The results indicated that power output is linearly related to the drive frequency since the volume flow rate increased proportional to frequency.

Design of ferromagnetic shape memory alloy (FSMA) based spring actuators is discussed where a variety of design parameters are included, design of FSMA and FSMA composite, that of compact electromagnet, and the mode of deformation of a helical spring. Advantages of FSMA and FSMA composite are simple design, faster actuation speed large axial stroke and magnetic force.

This paper discusses the design and experimental results of the improved fuel-powered compact SMA actuator system and its comparison with the first-generation design. The K-alloy SMA strip (12 mm × 0.9 mm), actuated by a forced convection heat transfer mechanism, is embedded in a rectangular channel. In this channel, a rectangular piston, with a slot to accommodate the SMA strip, runs along the strip and prevents mixing between the hot and cold fluid in order to increase the efficiency of the system. The main energy source is fuel, such as propane, in order to achieve high energy and power densities of the system. Numerical analysis was performed to determine optimal channel geometry and to estimate maximum available force, strain and actuation frequency of the SMA actuator. The combustor/heat exchanger was designed to achieve higher heat transfer rates to the hot fluid from the energy source. The SMA actuator system is composed of pumps, valves, bellows, radiator, combustor/heat exchanger and control unit. The experimental testing of the SMA actuator system resulted in 735 N force with 2.5% strain and 0.25 Hz actuation frequency in closed-loop operation.

In this work, preliminary analysis and testing of a thermoelectric compact shape memory alloy (TEC-SMA) actuator prototype will be presented. The prototype testing process will result in detailed feasibility assessment and quantification of the operational specification ranges for the TEC-SMA actuator. The actuators' potential for compactness and miniaturization will be assessed and quantified, however for the initial work presented in this paper, the prototype will not be optimally compact. The presented actuator prototype is a solid-state, thermoelectric SMA actuator that utilizes directly the thermoelectric effect for cooling an SMA element. The preliminary experimental setup consists of an SMA strip in close contact with Thermoelectric Modules (TEM)s for cooling, coupled with an LVDT, a load cell, and thermocouples to characterize and optimize the actuator bandwidth, stroke, length, output power and energy density based on SMA actuation cycles. Preliminary experimental results are presented based on the described setup for 0.5 Hz and 1.0 Hz actuation frequencies. A significant conclusion form this study is the need for power modulation for TEMs and SMA actuators for optimal performance of the TEC-SMA actuator.

A new first generation torque actuator based on ferromagnetic shape memory alloy composite is designed. The first generation actuator made of Fe bars and TiNi wires is successfully demonstrated. A simple model is proposed for prediction of angle of twist for a given constant load. The optimization of FSMA composite plate is made by a composite modeling under the constraints that the super-elastic SMA plate attains higher stress beyond the onset of the stress-induced martensite transformation while the ferromagnetic plate remains elastic.

The Japanese Smart Material and Structure System Project started in 1998 as five years' program that funded by METI (Ministry of Economy, Trade and Industry) and supported by NEDO (New Energy and Industrial Technology Development Organization). Total budget of five years was finally about 3.8 billion Japanese yen. This project has been conducted as the Academic Institutions Centered Program, namely, one of collaborated research and development among seven universities (include one foreign university), seventeen Industries (include two foreign companies), and three national laboratories. At first, this project consisted of four research groups that were structural health monitoring, smart manufacturing, active/adaptive structures, and actuator material/devices. Two years later, we decided that two demonstrator programs should be added in order to integrate the developed sensor and actuator element into the smart structure system and verify the research and development results of above four research groups. The application target of these demonstrators was focused to the airplane, and two demonstrators that these shapes simulate to the fuselage of small commercial airplane (for example, Boeing B737) had been established. Both demonstrators are cylindrical structures with 1.5 m in diameter and 3 m in length that the first demonstrator has CFRP skin-stringer and the second one has CFRP skin. The first demonstrator integrates the following six innovative techniques: (1) impact monitoring using embedded small diameter optical fiber sensors newly developed in this program, (2) impact monitoring using the integrated acoustic emission (AE) systems, (3) whole-field strain mapping using the BOTDR/FBG integrated system, (4) damage suppression using embedded shape memory alloy (SMA) films, (5) maximum and cyclic strain sensing using smart composite patches, and (6) smart manufacturing using the integrated sensing system. The second one is for demonstrating the suppression of vibration and acoustic noise generated in the composite cylindrical structure. In this program, High-performance PZT actuators/sensors developed in this program are also installed. The whole tests and evaluations have now been finished. This paper presents the outline of demonstrator programs, followed by six presentations that show the detail verification results of industrial demonstration themes.

Structural health monitoring using optical fiber sensor is very attractive for aerospace structures, because of lightweight, durability and capability to be embedded in composites. Especially, distributed optical fiber sensing system, such as Brillouin Optical Time Domain Reflectometer (BOTDR), is hopeful method for large-scale composite structures. However, it is necessary to solve some problems for applying to aerospace structures. Low spatial resolution, strain/temperature effect, and long measuring period are the capital problems to be solved. For solutions of these problems, we have already reported these solutions. In this paper, we present practical application of the proposed techniques through the demonstrator test. Firstly, we measured mechanical strain and temperature simultaneously during CFRP panel curing process using a combined system of BOTDR and fiber Bragg grating (FBG) sensors with wavelength division multiplexing (WDM). Secondly, we measured the distributed strain in the whole structure and applied differential spectra method for improvement of a spatial resolution.

It is well known that barely visible damage is often induced in composite structures subjected to out-of plane impact, and the mechanical properties of the composites decrease markedly. In this study, some element technologies for the detection of the damage are explained. Those are (1) the technologies for the arrangement of embedded small-diameter optical fibers which have no serious effect on the mechanical properties of composites, (2) the technologies for the egress of the optical fibers using “the embedded connector for smart structures” which can be trimmed without care about the optical fibers, (3) the technologies for the damage detection system that has the functions for data acquisition and analysis, the evaluation of the initiation and the position of damage, and the visualization of damage information. The impact test using the composite airframe demonstrator is conducted. The sensors embedded in the upper panel of the stiffened cylindrical composite structure with 1.5 m in diameter and 3 m in length, are FBG sensors for strain measurement and the optical fibers for optical loss measurement. The detection of damage in the composite structures using a developed damage detection system is demonstrated.

This paper presents an overview of the demonstrator program with respect to the damage growth suppression effects using embedded SMA foils in CFRP laminates. The damage growth suppression effects were demonstrated for the technical verification in order to apply to aircraft structure. In our previous studies, the authors already confirmed the damage growth suppression effects of CFRP laminates with embedded pre-strained SMA foils through both coupon and structural element tests. It was founded that these effects were obtained by the suppression of the strain energy release rate based on the suppression of the crack opening displacement due to the recovery stress of SMA foils through the detail observation of the damage behavior. In this study, these results were verified using the demonstrator test article, which was 1/3-scaled model of commercial airliner fuselage structure. For the demonstration of damage growth suppression effects, the evaluation area was located in the lower panel, which was dominated in tension load during demonstration. The evaluation area is the integrated stiffened panel including both “smart area” (CFRP laminate with embedded pre-strained SMA foils) and “conventional area” (standard CFRP laminate) for the direct comparison. The demonstration was conducted at 80 degree Celsius in smart area and room temperature (RT) in conventional area during quasi-static load-unload test method. As the test results, the demonstrator test article presented that the damage onset strain in the smart area was improved by 30% for compared with the conventional area. Therefore, the successful technical verification of the damage onset/growth suppression effect using the demonstrator presented the feasibility of the application of smart material and structural system to aircraft structures.

Smart manufacturing process was developed to manufacture the demonstrator access door panel. The process integrated three basic methods, process simulation, process monitoring, and process control. For the first step, we simulated and predicted how the resin impregnated through the perform. And taking this result into consideration, we fixed the process parameters. In manufacturing, the dielectric film sensor was placed on the surface of the mold cavity to evaluate the resin flow. Dielectric property of the sensor changed as the resin impregnated. Dielectric sensor system is linked to the process control system. A personal computer of the control system acquired the process data from sensor system and controlled the pressure of the injection point. The three-dimensional door panel, 700mm width, with Fiber Bragg Grating (FBG) sensors embedded, without any dry-spot existing, was manufactured by this method. Effectiveness and advancement of smart manufacturing process was confirmed.

The study to reduce noise and vibration in aircraft cabin through PZT was implemented, using a semi-monocoque structure, 1.5m in diameter and 3.0m long with 2.3mm skin, which stimulates an aircraft body. We utilized PZT of 480 pieces bonded on inner surface of the structure as sensor and actuator. We applied random noise of low frequency range between 0~500Hz to the test model. We tried to reduce the vibration level of structure and internal air due to the external load by controlling the PZTs. Two control methods, gain control and feed-forward control, were tried. We measured internal sound pressure on 150 spots and compared overall values of sound pressure with gain control to them without control and evaluated its reduction capability. The tests showed 4.0dB O.A. reduction at maximum in gain control and 3.5dB O.A. reduction at maximum in feed forward control.

Monitoring the integrity of filament wound composite structures such as solid rocket motors and liquid fuel bottles is important in order to prevent catastrophic failures and to prolong the service life of these structures. To ensure the safety and reliability of rocket components, they require frequent inspection for structural damages that might have occurred during manufacturing, transportation, and storage. The timely and accurate detection, characterization and monitoring of structural cracking, delamination, debonding and other types of damage is a major concern in the operational environment. Utilization of a sensor network system integrated with the structure itself can greatly reduce this inspection burden through fast in-situ data collection and processing. Acellent Technologies, Inc. is currently developing integrated structural monitoring tools for continuous monitoring of composite and metal structures on aircraft and spacecraft. Acellent's integrated structural monitoring system consists of a flexible sensor/actuator network layer called the SMART Layer, supporting diagnostic hardware, and data processing/analysis software. Recently, Acellent has been working with NASA Marshall Space Flight Center to develop ways of embedding the SMART Layer inside filament wound composite bottles. SMART Layers were designed and manufactured for the filament wound bottles and embedded in them during the filament winding process. Acellent has been working on developing a complete structural health monitoring system for the filament wound bottles including data processing tools to interpret the changes in sensor signal caused by changes in the structural condition or material property. A prototype of a filament wound composite bottle with an embedded sensor network has been fabricated and preliminary data analysis tools have been developed.

This paper highlights the installation and monitoring to date, as well as key findings of a second generation of fiber Bragg grating traffic sensors installed into the I-84 freeway near Portland, Oregon for the purpose of counting and classification of traffic.

In order to extend the life time of building and civil infra-structure, nowadays, patch type fibrous composite retrofitting materials are widely used. Retrofitted concrete columns and beams gain the stiffness and strength, but they lose toughness and show brittle failure. Usually, the cracks of concrete structures are visible with naked eyes and the status of the structure in the life cycle is estimated with visible inspection. After retrofitting of the structure, crack visibility is blocked by retrofitted composite materials. Therefore, structural monitoring after retrofitting is indispensable and self diagnosis method with optical fiber sensor is very useful. In this paper, we try to detect peel out effect and find the strain difference between main structure and retrofitting patch material when they separate each other. In the experiment, two fiber optic Bragg grating sensors are applied to the main concrete structure and the patching material separately at the same position. The sensors show coincident behaviors at the initial loading, but different behaviors after a certain load.

In this paper, a high speed fiber optic sensor weigh-in-motion (WIM) system is proposed. Bragg gratings which have several advantages such as good reproducibility and good multiplicity compare to other optical fiber sensors are used for the system. Fabry-Perot filter for the signal process, which cannot be used in the high speed measurement because of the limitation in fast operation of PZT, is excluded. A new signal processing system which employs bandwidth filter is proposed and bridge type new sensor package design is also proposed. The proposed fiber optic WIM system is tested in the laboratory and experimented with actual trucks. The new concept of calibration coefficient "k" is introduced and calculated by the experiments. The calculated calibration coefficients show good approximations to real axial weights regardless tire widths.

Increasingly, scientific and military missions require the use of space-based optical systems. For example, new capabilities are required for imaging terrestrial like planets, for surveillance, and for directed energy applications. Given the difficulties in producing and launching large optics, it is doubtful that refinements of conventional technology will meet future needs, particularly in a cost-effective manner. To meet this need, recent research has been investigating the feasibility of a new class of ultra-lightweight think-skin optical elements that combine recent advances in lightweight thermally formed materials, active materials, and novel sensing and control architectures. If successful, the approach may lead to an order of magnitude reduction in space optics areal density, improved large scale manufacturing capability, and dramatic reductions in manufacturing and launch costs. In a recent effort, a one meter thin-film mirror like structure was fabricated. This paper provides an overview of tools used to model and simulate this structure as well as results from structural dynamic testing. In addition, progress in the area of non-contact global shape control using smart materials is presented.

The next generation of large ground-based optical telescopes are likely to involve a highly segmented primary mirror that must be controlled in the presence of wind and other disturbances, resulting in a new set of challenges for control. The current design concept for the California Extremely Large Telescope (CELT) includes 1080 segments in the primary mirror, with the out-of-plane degrees of freedom actively controlled. In addition to the 3240 primary mirror actuators,the secondary mirror of the telescope will also require at least 5 degree of freedom control. The bandwidth of both control systems will be limited by coupling to structural modes. I discuss three control issues for extremely large telescopes in the context of the CELT design, describing both the status and remaining challenges. First, with many actuators and sensors, the cost and reliability of the control hardware is critical; the hardware requirements and current actuator design are discussed. Second, wind buffeting due to turbulence inside the telescope enclosure is likely to drive the control bandwidth higher, and hence limitations resulting from control-structure-interaction must be understood. Finally, the impact on the control architecture is briefly discussed.

A hexapod capable of precision positioning is described. The differences between serial and parallel motion control are presented, and the potential advantages of parallel systems realized as hexapods are highlighted. Actuation options for positioning hexapods are considered in light of a requirement for a high ratio of range to resolution and a need for zero power hold. For positioning of smaller payloads, piezoelectric-based step-and-repeat actuation becomes attractive. The merits of existing and new piezoelectric step-and-repeat actuators are evaluated. A point-and-hold hexapod designated PH1, and its performance, is described, along with several areas identified for possible design improvement. This motivates the development of advanced struts using similar actuation technology. Test results are presented, and a new hexapod, the PH2, is described. This system includes encoder-based feedback control of leg lengths, and a complete software-based user interface and control system. Hexapod test results and performance measurements are presented, and planned future enhancements are described.

The structural advantages of parallel kinematic mechanisms for highly dynamic motions are undisputed. The mass values to be moved are essentially determined by the structure of the end effector platform. The accuracy of machines with parallel kinematic drive concepts is decisively defined by the joint and feed unit assemblies. Statical (except in hexapods) and dynamical bending and torsional loads limit the shape of the strut geometry. As a rule, an increase in volume to enhance stiffness at the same times results in an increase in weight and thus worse dynamic characteristics. Active compensation and damping elements provide an alternative to passively increasing stiffness by geometries fitted to load. An active compensation of torsion is aimed at achieving a high "virtual" torsional stiffness of the whole drive unit by means of a compensation drive which is based on piezoelectric actuators. The compensation drive works autonomously and measures and corrects the appearing torsional deformation in a self-controlled manner, independent of the end effector platform' s position in the working space adjusting feed units.

In past years, Amplified Piezoelectric Actuators (APA) have been applied to a variety of industrial applications that take advantage of their quick response and precise positioning capabilities. More recently, APA's have been integrated into valve designs to obtain both rapid and precise proportional flow control. This paper presents the design and measurement results of two gas valves that have recently been developed. The first gas valve uses a small APA that is driven by a switching amplifier to obtain a high frequency modulation. A frequency modulation higher than 400Hz, along with a stroke of 100μm, have been measured. These results show that such a design could be applied to fuel injection systems. The second gas valve is also based on an APA. It includes a linear amplifier and a servo controller to obtain an accurate proportional response dedicated to precise gas flow control. Such valves are interesting for instrumentation and space applications, where they can provide a linear and stable flow control. The low power consumption of the piezoelectric valve in space applications is an additional advantage. A stable flow of dry nitrogen ranging from 0.1sccm to 200sccm has been measured with an inlet pressure of 1bar. A variety of modeling tools has been used to design these valves: finite element modeling for the electro-mechanical aspects and for the contact mechanics between the poppet and the seat, as well as computational fluid dynamics for the flow simulation. These tools make it possible to modify the valve design in order to meet different requirements and serve other applications.

Ferromagnetic Shape Memory Alloys (FSMA) are a class of active materials based on nickel alloys which offer controllable, large mechanical straining based on applied mechanical stress and magnetic fields. Actuation is based on crystallographic switching between meta-stable martensite phases. The high speed, binary switching, and no power hold behavior of the FSMA material are particularly well suited for latching valve applications such as hydraulic valves, optical switches, and electromechanical relays. This paper describes the design, development, and testing of a FSMA based actuator system to drive an industrial, hydraulic, latching valve. An opposing actuator configuration is used to switch the valve spool between spool positions, as well as to reset the opposing actuator element. Specific issues addressed in the design include FSMA material strain modeling, spool movement modeling, magnetic driving coil design and circuit controller design. A prototype system, based on a commercially available latching valve platform, was constructed and tested. Size of the complete system, including two FSMA actuators, valve body, and spool is 19 × 19 × 89 mm. Maximum valve actuation frequency of the prototype system is 133Hz in a 1000 psi hydraulic test bed.

In this paper, a theoretical study is presented to examine the behavior a fail-safe magneto-rheological fluid (MRF) damper based on a temperature compensated skyhook strategy for a quarter car model of a High Mobility Multi-purpose Wheeled Vehicle (HMMWV). A fail-safe MRF damper is a controllable semi-active device that in the event of power or control system failure behaves as a passive damper with certain viscous damping capacity. The damper's viscous force changes significantly with temperature. Vehicle suspension system is required to operate in a wide range of temperature. The temperature effects on the performance of MRF damper should be considered in the control system design. Displacement and acceleration response of the vehicle sprung mass for the quarter car model are discussed at the operating temperature range of a MRF damper. Simulation results under off-road excitation demonstrated that the compensated skyhook control system improves MRF damper performance in reducing the sprung mass displacement and acceleration compared to the uncompensated skyhook control system.

This study focuses on the design and characterization of a multi-plate magneto-rheological fluid (MRF) limited slip differential (LSD) clutch. Three-dimensional electromagnetic finite element analyzes are performed to optimize the MRF LSD clutch design. The torque transfer capacity of the clutch is predicted utilizing Bingham-Plastic constitutive model of the MRF. The MRF LSD clutch is tested at different velocities and applied magnetic fields. The clutch heating is also examined under different operating conditions to determine the thermal effects on the torque transfer performance of the multi-plate clutch.

Active fiber composites (AFCs) find applications in a variety of industrial, commercial, and aerospace markets as both actuators and sensors. Among the key attributes of AFCs relative to conventional monolithic piezoceramic actuators are high strain energy density, unidirectional response, conformability, and robustness. Recently, performance enhancements in AFCs have been demonstrated through the use of a modified injection molding process to produce piezoceramic modules with multiple identical fibers of a uniform rectangular cross section. AFC actuators made from Type II PZT fiber modules exhibit free micro-strains of 1830 ± 30 ppm at a peak-peak E-field drive of 26.1 kV/cm, and show exceptional part-to-part uniformity. In addition, AFCs made from injection molded PMN-PT fiber modules show a low-field d₃₃ of 650 pm/V. The successful incorporation of PMN-PT materials into AFCs also demonstrates the viability of using highly textured ceramic PMN-PT piezofibers, for which even larger increases in strain response are expected.

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 dumper. Termed magnetostrictive particulate composites (MPC), the material provides capabilities identical or superior to the monolithic material. Fortis Technologies has been pursuing improvements in the applications and fabrication of this innovative material. Specifically, this MPC technology provides a passive, broadband, large temperature range, high stiffness, damping material to be used where current technologies fall short. A novel manufacturing technique based on magnetic fields has been developed to distribute magnetostrictive particulates in a polymer resin and apply it in thin-layer on surfaces for vibration damping in environments typical of turbomachinery fan blades. These magnetostrictive particulates provide damping through domain wall switching, a non-conservative action which provides a high loss factor, and, in turn, significant vibration mitigation. The magnetostrictive damping composites can be easily fabricated into thin films, provide stiffness and strength while also incorporating damping capabilities which exceed in performance and temperature range viscoelastic materials, the current state of the art for applied blade damping. Analytical studies, a finite element analysis and experimental study of the new material in a typical turbomachinery blade loading condition has been conducted and has demonstrated the benefits of this technology.

We have incorporated arrays of conductive electromagnetic scattering elements such as straight copper wires and copper coils into fiber-reinforced polymer composites, resulting in materials with required structural and further electromagnetic functionality. The scattering elements provide controlled electromagnetic response for tasks such as filtering and may be used to tune the overall index of refraction of the composite. Integration of these metallic elements into traditional fiber-reinforced polymer composites has introduced other opportunities for multifunctionality in terms of self-healing, thermal transport and perhaps sensing applications. Such functionalities are the result of fiber/wire integration through textile braiding and weaving, combined with a new polymer matrix that has the ability to heal internal cracking through thermo-reversible covalent bonds. Multifunctional composites of this kind enhance the role of structural materials from mere load-bearing systems to lightweight structures of good thermo-mechanical attributes that also have electromagnetic and other functionalities.

This paper reports an experimental study on active vibration reduction for automotive shafts with the use of piezoelectric material. The work focuses on an axle of an Audi A2. The demand in the automobile sector for higher comfort in the vehicle is of a great importance alongside the requirements of lighter weight and low fuel consumption. These requirements are typically in conflict with each other. One solution is the use of intelligent materials instead of viscoelastic materials and proof mass absorbers. These solutions are quite heavy especially at low frequencies. Active vibration control and piezoelectric devices are advantageous in this application due to their low mass to performance ratio. Our research study explores the use of such piezoelectric devices for an axle. In conjunction with electronics it will reduce vibrations in the first natural bending mode of the axle. Laboratory tests simulated the condition present in the road. At first a stationary set up was used, then a simulated disturbance was input at the attachment points of the shaft. Finally, a test with rotating shaft was performed. Piezoelectric devices (custom QuickPacks from ACX, a Division of Cymer) were used as sensors and as actuators to properly control the axle during the different operating conditions. The power consumption of each actuator pair was less than 20W. The work described here details the test setup, the control strategy, the hardware implementation as well as the test results obtained.

A series of new design viewpoints for piezoelectric systems are detailed which integrates a method that can introduce no-phase delay filters into finite structures as well as which extends the distributed sensor concept to the design of traditional point sensors can be shown to expand the design freedom of piezoelectric sensors and actuators. An inertia-based free-fall sensor that can measure the start of free-fall motion as well as a piezoelectric transformer with a voltage conversion efficiency higher than 99% are two of the examples used to demonstrate the wide applicability of these new concepts.