This PDF file contains the front matter associated with SPIE Proceedings Volume 7645, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

A novel class of piezoelectric-based energy-harvesting power sources has been developed for gun-fired munitions and similar high-G applications. The power sources are designed to harvest energy primarily from the firing acceleration, but from in-flight vibratory motions as well. During the firing, a spring-mass element reacts to the axial acceleration, deforming and storing mechanical potential energy. After the projectile has exited the muzzle, the spring-mass element is free to vibrate, and the energy of the vibration is harvested using piezoelectric materials. These piezoelectric-based devices have been shown to produce enough electrical energy for many applications such as fuzing, and are able to eliminate the need for chemical batteries in many applications. When employed in fuzing applications, the developed power sources have the added advantage of providing augmented safety, since the fuzing electronics are powered only after the projectile has exited the muzzle and traveled a safe distance from the weapon platform. An overview of the development of these novel power sources is provided, especially designing and packaging for the high-G environment. Extensive laboratory and field testing has been performed on various prototypes; the methods and results of these experiments are presented. In addition to presenting the development and validation of this technology, methods for integrating the generators into different classes of projectiles are discussed along with strategies for manufacturing. This technology is currently validated to the extent that prototype devices have been successfully fired on-board actual gun-fired projectiles, demonstrating survivability and indicating performance. Strategies for designing the devices for a particular round and transitioning to commercialization are also discussed.

The U.S. Department of Energy (DOE) proposes to meet 20% of the nation's energy needs through wind power by the year 2030. To accomplish this goal, the industry will need to produce larger (>100m diameter) turbines to increase efficiency and maximize energy production. It will be imperative to instrument the large composite structures with onboard sensing to provide structural health monitoring capabilities to understand the global response and integrity of these systems as they age. A critical component in the deployment of such a system will be a robust power source that can operate for the lifespan of the wind turbine. In this paper we consider the use of discrete, localized power sources that derive energy from the ambient (solar, thermal) or operational (kinetic) environment. This approach will rely on a multi-source configuration that scavenges energy from photovoltaic and piezoelectric transducers. Each harvester is first characterized individually in the laboratory and then they are combined through a multi-source power conditioner that is designed to combine the output of each harvester in series to power a small wireless sensor node that has active-sensing capabilities. The advantages/disadvantages of each approach are discussed, along with the proposed design for a field ready energy harvester that will be deployed on a small-scale 19.8m diameter wind turbine.

An ability to non-intrusively monitor remote and sealed underground nuclear repositories, using wireless sensor nodes, will be beneficial to the nuclear community and would help alleviate the nuclear waste legacy. The paper will introduce an alternative energy source to a chemical battery that would supply energy to a wireless sensor node such that it can acquire and transmit data about its environment, after a long duration of time. The presented energy source is a 'mechanical battery' which stores mechanical energy and comprises a compressed magnetic suspension mechanism. When this energy is released some of it is converted to electrical energy via electromagnetic induction. The presented model will predict the amount of electrical energy that is generated and stored in an intermediate energy storage medium, a capacitor, before it is supplied to a wireless sensor node. The model is validated against measurements and the supply and operation of a commercial wireless sensor node using a complete prototype system is demonstrated. The complete system comprises the mechanical battery and associated electronics.

In this paper we present a method for coupling wireless energy transmission with traditional energy harvesting techniques in order to power sensor nodes for structural health monitoring applications. The goal of this study is to develop a system that can be permanently embedded within civil structures without the need for on-board power sources. Wireless energy transmission is included to supplement energy harvesting techniques that rely on ambient or environmental, energy sources. This approach combines several transducer types that harvest ambient energy with wireless transmission sources, providing a robust solution that does not rely on a single energy source. Experimental results from laboratory and field experiments are presented to address duty cycle limitations of conventional energy harvesting techniques, and the advantages gained by incorporating a wireless energy transmission subsystem. Methods of increasing the efficiency, energy storage medium, target applications and the integrated use of energy harvesting sources with wireless energy transmission will be discussed.

Cornerstone Research Group Inc. (CRG) has developed and demonstrated a composite structural solution called reflexive composites for aerospace applications featuring CRG's healable shape memory polymer (SMP) matrix. In reflexive composites, an integrated structural health monitoring (SHM) system autonomously monitors the structural health of composite aerospace structures, while integrated intelligent controls monitor data from the SHM system to characterize damage and initiate healing when damage is detected. Development of next generation intelligent controls for reflexive composites were initiated for the purpose of integrating prognostic health monitoring capabilities into the reflexive composite structural solution. Initial efforts involved data generation through physical inspections and mechanical testing. Compression after impact (CAI) testing was conducted on composite-reinforced shape memory polymer samples to induce damage and investigate the effectiveness of matrix healing on mechanical performance. Non-destructive evaluation (NDE) techniques were employed to observe and characterize material damage. Restoration of mechanical performance was demonstrated through healing, while NDE data showed location and size of damage and verified mitigation of damage post-healing. Data generated was used in the development of next generation reflexive controls software. Data output from the intelligent controls could serve as input to Integrated Vehicle Health Management (IVHM) systems and Integrated Resilient Aircraft Controls (IRAC). Reflexive composite technology has the ability to reduce maintenance required on composite structures through healing, offering potential to significantly extend service life of aerospace vehicles and reduce operating and lifecycle costs.

The interest in "morphing" structures that can undergo drastic shape changes has steadily grown in recent years. This paper considers a particular type of morphing structure that can exhibit significant modulus change, enabling the deformation to occur with low applied forces (and low stress in the material). Specifically, shape memory polymer is used as the enabling material, and it is transitioned from hard to soft to allow deformation, then returned to its hard state after deformation to carry structural loads. Given the large deformations of these types of structures, conventional linear mechanics models are not adequate to predict the behavior or to be used as design tools. This paper explores the use of quasi-static three-dimensional nonlinear finite element modeling to study the force deformation behavior of a morphing link. The modeling approach for the morphing process is shown to produce results that are representative of experimental observations. In addition, capabilities are explored to use the numerical methods to study the potential of partial transitioning of the link, in which only a portion of the shape memory polymer material is transitioned. By transitioning only a portion of the link, the power and transition time can be reduced without compromising the applied forces or final shape, and the functionality of the link can be increased as well. The results point to the nonlinear modeling as a promising tool for optimizing the design and operation of morphing structures.

Unimorph active rigidity joints, constructed from Shape Memory Alloy and Shape Memory Polymer and capable of bending actuation, are reported in this work. An embedded aluminum shim was added to each joint as a structural element to facilitate actuation. Joints were actuated using ohmic Tri-Phase and pulse heating processes with different results. It appeared that openloop position control could be achieved using pulse heating. Actuator improvements and future experiments are proposed.

Cornerstone Research Group Inc. (CRG) has developed environmental exposure tracking (EET) sensors using shape memory polymers (SMP) to monitor the degradation of perishable items, such as munitions, foods and beverages, or medicines, by measuring the cumulative exposure to temperature and moisture. SMPs are polymers whose qualities have been altered to give them dynamic shape "memory" properties. Under thermal or moisture stimuli, the SMP exhibits a radical change from a rigid thermoset to a highly flexible, elastomeric state. The dynamic response of the SMP can be tailored to match the degradation profile of the perishable item. SMP-based EET sensors require no digital memory or internal power supply and provide the capability of inexpensive, long-term life cycle monitoring of thermal and moisture exposure over time. This technology was developed through Phase I and Phase II SBIR efforts with the Navy. The emphasis of current research centers on transitioning SMP materials from the lab bench to a production environment. Here, CRG presents the commercialization progress of thermally-activated EET sensors, focusing on fabrication scale-up, process refinements, and quality control. In addition, progress on the development of vapor pressure-responsive SMP (VPR-SMP) will be discussed.

A fiber reinforced thermosetting styrene-based shape-memory polymer composite (SMPC) is developed, and the main objective is to investigate the deployment performances for SMPC. Firstly, the fundamental material properties, such as mechanical properties and shape recovery properties, are evaluated. It indicates that the SMPC shows nonlinear viscoelasticity at a temperature range between T_g -20°C and T_g +20°C. At/above T_g, the shape recovery ratio of SMPC upon bending is above 90%. The shape recovery properties of SMPC become relatively stable after some packaging/deployment cycles. Then, the micro-deformation mechanism is characterized by optical microscopy and SEM. The fiber microbuckling is the primary deformation mechanism in bending of SMPC, and it ensures that the SMPC can achieve high packaging strain and avoid fiber failure. With the microbuckling, SMPC materials are suitable to be used in deployable structure components because of their high strain-to-failure capability. For the analytical research, the relationship between deployment moment and angle is derived by using dynamic theory. It shows that the SMPC shell shows a linear bending stiffness when recovering, and meanwhile performs a self-locking function at the final state because of sharply increase in moment. It implies that SMPC is a good candidate material for deployable structures.

A model is developed which describes the dynamic response of a Terfenol-D actuator with a hydraulic displacement amplification mechanism for use in active engine mounts. The model includes three main components: magnetic diffusion, Terfenol-D constitutive model, and mechanical actuator model. Eddy current losses are modeled as a one-dimensional magnetic field diffusion problem in cylindrical coordinates. The Jiles-Atherton model is used to describe the magnetization state of the Terfenol-D driver as a function of applied magnetic fields. A quadratic, single-valued model for the magnetostriction dependence on magnetization is utilized which provides an input to the mechanical model describing the system vibrations. Friction at the elastomeric seals is modeled using the LuGre friction model for lubricated contacts. The actuator's dynamic response is quantified in terms of the output displacement in the unloaded condition and force output in the loaded condition. The model is shown to accurately quantify the dynamic behavior of the actuator over the frequency range considered, from near dc to 500 Hz. An order analysis shows that the model also describes the higher harmonic content present in the measured responses. A study on the variation of energy delivered by the actuator with the load stiffness reveals that the actuator delivers the highest energy output near the stiffness match region.

Current seals used for vehicle closures/swing panels are essentially flexible, frequently hollow structures whose designs are constrained by numerous requirements, many of them competing, including door closing effort (both air bind and seal compression), sound isolation, prevention of water leaks, and accommodation of variations in vehicle build. This paper documents the first portion of a collaborative research study/exploration of the feasibility of and approaches for using active materials with shape and stiffness changing attributes to produce active seal technologies, seals with improved performance. An important design advantage of an active material approach compared to previous active seal technologies is the distribution of active material regions throughout the seal length, which would enable continued active function even with localized failure. Included as a major focus of this study was the assessment of polymeric active materials because of their potential ease of integration into the current seal manufacturing process. In Part 1 of this study, which is documented in this paper, potential materials were evaluated in terms of their cost, activation mechanisms, and mechanical and actuation properties. Based on these properties, simple designs were proposed and utilized to help determine which materials are best suited for active seals. Shape memory alloys (SMA) and electroactive polymers (EAP) were judged to be the most promising.

In this paper, information on the various aspects of smart materials is compiled in an easy-to-consult format by conducting extensive survey of published articles and including the properties of the materials. The compilation of a comprehensive database on smart materials enables to expedite a material selection process in the design of smart material devices or systems. We show the compiled database in a legible format such as GUI based computer software that determines and simulates what material to use based on properties and performance. Finally, the associated system-level models for selected materials are developed and shown in the compilation.

Problems in using shape memory alloys (SMA) in industrial applications are often caused by the fragmentary knowledge of the complex activation behavior. To solve this problem, Fraunhofer IWU developed a Matlab®-based simulation tool to emulate the properties of a SMA wire based on the energy balance. The contained terms result of the characteristic material behavior combined with thermal, electrical, and mechanical conditions. Model validation is performed by laboratory tests. It is shown that there is almost no difference between the measured and the simulated actuator movement. Due to the good quality of the model it is possible to use it in a control loop. Knowing current and voltage enables the computation of the electrical resistance of the actuator and can therefore be used for feedback control. Implementation of the results into industrial applications is exemplified by integration of an actuator in a flap as used in air condition systems of cars. Furthermore, the SMA-based drive will be compared to an electromechanical drive.

Microforming requires high-precision motion due to scaling issues. A Terfenol-D transducer was considered to provide bulk motion for micro-extrusion. Because Terfenol-D cannot practically produce the necessary 2.5 mm displacement for this micro-extrusion experiment, a lever system was designed to amplify the output displacement. Compliant joints (flexures) were used to replace conventional bearings, resulting in a flexible, solid-state lever mechanism. By eliminating the backlash and static friction associated with conventional bearings, it should be possible to improve displacement precision as required to meet the geometric tolerance demands of microforming. A chief concern when designing flexure joints that see large amounts of axial loading is compliance, which leads to not only loss of motion but also loss of accuracy as the lever system responds differently under different loads. However, because Terfenol-D already has load-dependent response, this loss of accuracy is moot when coupled with a Terfenol-D prime mover, as it already requires load-dependent control. Preliminary FEM analysis has shown this design to have lever ratio losses of approximately 4% from half load to full load, with lower than predicted stress.

This paper presents the development of active aluminum-matrix composites manufactured by Ultrasonic Additive Manufacturing (UAM), an emerging rapid prototyping process based on ultrasonic metal welding. Composites created through this process experience temperatures as low as 25 °C during fabrication, in contrast to current metal-matrix fabrication processes which require temperatures of 500 °C and above. UAM thus provides unprecedented opportunities to develop adaptive structures with seamlessly embedded smart materials and electronic components without degrading the properties that make these materials and components attractive. This research focuses on developing UAM composites with aluminum matrices and embedded shape memory NiTi, magnetostrictive Galfenol, and electroactive PVDF phases. The research on these composites will focus on: (i) electrical insulation between NiTi and Al phases for strain sensors, investigation and modeling of NiTi-Al composites as tunable stiffness materials and thermally invariant structures based on the shape memory effect; (ii) process development and composite testing for Galfenol-Al composites; and (iii) development of PVDF-Al composites for embedded sensing applications. We demonstrate a method to electrically insulate embedded materials from the UAM matrix, the ability create composites containing up to 22.3% NiTi, and their resulting dimensional stability and thermal actuation characteristics. Also demonstrated is Galfenol-Al composite magnetic actuation of up to 54 μ(see manuscript), and creation of a PVDF-Al composite sensor.

Active control of friction between sliding surfaces is of significant interest in automotive applications. It has been shown that the friction force between sliding surfaces can be reduced by superimposing ultrasonic vibrations on the sliding velocity. This principle can be applied to systems in which solid state lubrication is advantageous. This paper investigates ultrasonic lubrication for creating adaptive seat belts with controllable force at the interface between the D-ring and webbing. By precisely controlling the seat belt force during a crash event, superior restraint can be achieved relative to existing systems which are designed as a compromise for various occupants and loading conditions. Proof-of-concept experiments are conducted in order to experimentally determine the performance limits and mechanics of a seat belt webbing subjected to macroscopic sliding motion and superimposed out-of-plane ultrasonic vibrations. The experimental setup consists of a high-capacity ultrasonic plastic welder and an apparatus for creating controlled relative motion between the welder tip and seat belt webbing. Analytical modeling using LuGre friction is presented which characterizes the parametric dependence of friction reduction on system settings in the presence of ultrasonic vibrations.

This research investigates a supporting structure with smart struts under a vibratory load. In the case of most rotorcraft, structure-borne noise and vibration transmitted from the gearbox contains multiple spectral elements and higher frequencies, which include gear mesh frequencies and their side bands. In order to manage this issue, significant research have been devoted to active smart struts which have tunable stiffness such that a higher level of attenuation is possible. However, present techniques on active control are restricted mostly to the control of single or multiple sinusoids and thus these are not applicable to manage modulated and multi-spectral signals. Therefore, enhanced control algorithms are required in order to achieve simultaneous attenuation of gear mesh frequencies and their side bands. Proposed algorithms employing two nonlinear methods and one model-based technique are examined in this study. Their performance is verified by comparing with conventional algorithms. Moreover, these algorithms are implemented to exhibit whether they are feasible to narrowband or broadband control through experiments with a single smart strut. Novel methodologies are expected to be applied to several active vibration and noise control practices such as vehicles and other engineering structures.

Shape Memory Alloys (SMA) have proven to be a lightweight, low cost alternative to conventional actuators for a number of commercial applications. Future applications will require a more complex shape changes and a detailed understanding of the performance of more complex SMA actuators is required. The purpose of this study is to validate engineering models and design practices for SMA beams of various configurations for future applications. Until now, SMA actuators have been fabricated into relatively simple beam shapes. Boeing is now fabricating beams with more complicated geometries in order to determine their strength and shape memory characteristics. These more complicated shapes will allow for lighter and more compact SMA actuators as well as provide more complex shape control. Some of the geometries evaluated include vertical and horizontal I-beams, sine wave and linear wave beams, a truss, and a beam perforated with circular holes along the length. A total of six beams were tested; each was a complex shape made from 57% Nickel by weight with the remainder composed of Titanium (57NiTi). Each sample was put through a number of characterization tests. These include a 3-point bend tests to determine force/displacement properties, and thermal cycling under a range of isobaric loads to determine actuator properties. Experimental results were then compared to modeled results. Test results for one representative beam were used to calibrate a 3-D constitutive model implemented in an finite element framework. It is shown that the calibrated analysis tool is accurate in predicting the response of the other beams. Finally, the actuation work capabilities of the beams are compared using a second round of finite element anaylysis.

As a novel bionic actuator, pneumatic artificial muscle has high power to weight ratio. In this paper, the experimental setup to measure the static output force of pneumatic artificial muscle was designed and the relationship between the static output force and the air pressure was investigated. Experimental result shows the static output force of pneumatic artificial muscle decreases nonlinearly with increasing contraction ratio. A variable camber wing based on the pneumatic artificial muscle was developed and the variable camber wing model was manufactured to validate the variable camber concept. Wind tunnel tests were conducted in the low speed wind tunnel. Experimental result shows that the wing camber increases with increasing air pressure.

As a novel smart material, shape memory polymer possesses the special thermo-mechanical property of shape memory effect. Its shape memory effect is closely related to the glass transitions between the glass state and rubber state induced by temperature changing. It is of engineering and theoretical meaning to investigate and describe the glass transition behaviors of shape memory polymer. In this study the glass transition behaviors of an epoxy-based shape memory polymer containing linear epoxy monomer are investigated using the tests of dynamic mechanical analysis. Results show both glass transition critical temperatures and storage modulus at rubber state of the epoxy-base shape memory polymer decrease as the content of linear monomer in such material increases. However the transition temperature width increases as the linear monomer content increases. A new glass transition model is supposed to describe the glass transition behaviors of epoxy-based shape memory polymer based on the experimental results. Numerical simulations show that the new glass transition model well predicts the glass transition behaviors of the epoxy-based shape memory polymer containing linear epoxy monomer.