bluuebunny/crossref_metadata_2025 huggingface dataset:
In Cylinder NOx Emissions Control via Water Injection
Authors: Atkinson William , Barros Sam , Piduru Naag
Published: January 2016

Increasingly stringent emissions standards have accounted for continuing increases in the end-user cost of a modern diesel engine, most of which due to complex and expensive emissions after treatment devices such as selective catalytic reduction (SCR), which relies on urea to be injected into a catalyst bed to remove nitrogen oxide emissions from the engine exhaust.

Prior to the current emissions standards the diesel industry had been able to meet NOx levels by reducing the combustion temperature in the engine via charge gas dilution, through cooled EGR. Although successful in reducing emissions, large levels of EGR have undesirable effects on oil quality, engine longevity, overall efficiency and warranty returns. There is also a limit to the efficacy of EGR in lowering NOx emissions such that at the current EPA mandated 0.2g/kWh, it is no longer sufficient.

Another well-known NOx mitigating solution has been the introduction of water into the diesel engine combustion chamber. This has been known to decrease peak combustion temperatures and decrease NOx emissions but usage so far has been limited to stationary and marine applications due to the requirement of a separate water tank and thereby a two-tank system. Combustion of hydrocarbon fuels produces between 1.35 and 2.55 times their mass in water. As an enabler to water injection, this paper will also demonstrate a technique where the exhaust is first cooled via a heat exchanger, and then passed through a cyclonic separator to separate heavier liquid particles from the exhaust gas flow. Through vortex separation over 100% of the burned fuel mass can be recovered as liquid water from the exhaust. A prototype system was developed and installed on a VW TDI diesel engine. Tests were conducted with and without after-treatment and results have been discussed in subsequent sections. The water was then utilized in conjunction with EGR to control NOx emissions, allowing a reduction of over 97%, thus achieving the 0.2g/kWh standard with no after treatment.
Self-Regulating System for Natural Gas Cooling in a Bimodal Internal Combustion Engine
Authors: Menon S. , Weyer K. , Pedersen D. , Hagen C.
Published: January 2016

Natural gas is an attractive option for transportation applications in the United States due to its abundant availability and potential for reduced emissions. The scarcity of refueling resources imposes a barrier to widespread use of natural gas in internal combustion engines. The development of a novel bi-modal engine capable of operating in a compressor mode provides refueling capabilities without any supplemental devices and attempts to overcome this infrastructure limited barrier. Heat generated in the compression process however results in undesirable effects such as increased work input for compression, pre-heating of natural gas stored in the fuel tank, and thermal loads in the components used in the modified cylinder head. In order to make the system self-contained, heat exchangers that utilize engine coolant as a heat sink are included in the system design to maintain natural gas temperatures at an acceptable level in between compression stages. This is planned to be done in a novel fashion so as to make the system self-regulating permitting the cooling of natural gas while maintaining the coolant temperature in the cylinder head at acceptable levels to maintain combustion efficiency. To this end, an EES model of the system that incorporates elements of the original vehicle coolant system and modifications made to incorporate the heat exchangers is developed and analyzed to ensure satisfactory performance. Parametric studies of system performance as a function of varying heat loads are used to determine the best strategy to maintain acceptable natural gas temperatures without causing a drop in engine performance.
Identifying Uncertainties in Diesel Spray Rate-of-Momentum Transients Under Elevated Back Pressure
Authors: Falcone John A. , Knox Benjamin W. , Genzale Caroline L.
Published: January 2016

Rate-of-momentum measurements of transient fuel sprays are valuable for improving current combustion and emission strategies. This data provides boundary conditions for engine computational fluid dynamic (CFD) simulations and provides insight into the transient mixing characteristics of the spray prior to and during combustion. Previous researchers have quantified the rate-of-momentum of transient sprays using the impingement technique, but uncertainties remain in relating the impingement force to the injected fuel momentum at the nozzle exit. Rate-of-momentum measurements are typically performed by directing a spray onto the face of a calibrated transducer in close proximity to the nozzle. The measured impingement force is then used to quantify the rate-of-momentum at the nozzle orifice exit with the aid of a simplified control volume analysis. However, under elevated back pressures, additional terms in the control volume analysis are no longer negligible. Other non-idealities, such as non-orthogonal droplet impingement outcomes and transient mass accumulation in the control volume, can also contribute to errors in the simplified analysis.

This paper investigates the impact of non-idealities in impingement-based rate-of-momentum measurements on the quantified fuel injection rate. In specific, we compare the measured rate-of-momentum under back pressure and atmospheric pressure using two different transducers to quantify uncertainties that can arise under back pressure conditions. Uncertainties associated with transient mass accumulation and non-orthogonal spray deflection are also investigated. We found that back pressure affected both the start and end of injection when compared to atmospheric pressure. Under back pressure, there was a lengthened apparent start-of-injection transient, which likely results from a low pressure toroidal vortex occurring at the head of the spray. In addition, there was a longer apparent closing transient, which is likely a result of residual pressure distribution after the end-of-injection. No evidence of transient mass accumulation was observed for the injectors used in this study. Lastly, the transient spray was observed to deflect non-orthogonally from the impact point on the transducer instead of remaining parallel to the transducer face after initial impact. This deflection of the spray leads to uncertainties when quantifying the rate-of-momentum, where the apparent rate-of-momentum could be larger than the actual value.
Experimental Investigation of a Diesel Engine Fuelled With Acetone-Butanol-Ethanol/Diesel Blends
Authors: Lee Timothy H. , Lin Yilu , Nithyanandan Karthik , Zhang Jiaxiang , Li Yuqiang , Yang Jikai , Hansen Alan C. , Lee Chia-fon F.
Published: January 2016

The performance and emissions of Acetone-Butanol-Ethanol (ABE)/diesel mixtures in an AVL 5402 single cylinder diesel research engine under various engine operating conditions were investigated in this study. The experiments were conducted at three different speeds (1200, 1500, and 2000 RPM) and different injection quantities (loads) (15, 20, and 25 mg/cycle).

The fuels tested in these experiments were pure diesel, ABE10, and ABE20. The acetone-butanol-ethanol (ABE) was blended in a 3:6:1 ratio. ABE10 and ABE20 consist of 10% acetone-butanol-ethanol mixture and 90% diesel by volume and 20% ABE and 80% diesel by volume respectively.

The results showed a promising future for ABE-diesel mixture as an alternative transportation fuel. There was improved thermal efficiency even with relatively small ABE blending ratios and a slight reduction in power output due to the lower energy density. There was an overall retarded combustion phasing, including longer ignition delay time, retarded CA50 timing, peak pressure timing and end of combustion timing. Accelerated heat release during CA10∼CA50 indicates a higher degree of premixed combustion. Overall soot emissions were lower and NOx emissions were higher for ABE-containing fuels at same load and timing conditions. Tuning injection timing would be helpful for the reduction of NOx to a degree that is even lower than that of diesel.

With proper tuning of injection quantity and injection timing, adopting ABE-diesel mixtures has the potential of improving efficiency and reducing emissions at the same time. Considering the low cost of ABE production compared to other kinds of bio-fuels, ABE could become a possible alternative to the current fuel additives.
Fast Computation of Combustion Phasing and its Influence on Classifying Random or Deterministic Patterns
Authors: Lian Huan , Martz Jason , Prakash Niket , Stefanopoulou Anna
Published: January 2016

The classification between a sequence of highly variable combustion events that have an underlying deterministic pattern and a sequence of combustion events with similar level of variability but random characteristics is important for control of combustion phasing. In the case of high cyclic variation (CV) with underlying deterministic patterns, it is possible to apply closed loop combustion control on a cyclic-basis with a fixed mean value, such as injection timing in homogeneous charge compression ignition (HCCI) or spark timing in spark ignition (SI) applications, to contract the CV. In the case of a random distribution, the high CV can be avoided by shifting operating conditions away from the unstable region via advancing or retarding the injection timing or the spark timing in the mean-sense.

Therefore, the focus of this paper is on the various methods of computing CA50 for analysing and classifying cycle-to-cycle variability. The assumptions made to establish fast and possibly on-line methods can alter the distribution of the calculated parameters from cycle-to-cycle, possibly leading to incorrect pattern interpretation and improper control action.

Finally, we apply a statistical technique named “permutation entropy” for the first time on classifying combustion patterns in HCCI and SI engine for varying operating condition. Then the various fast methods for computing CA50 feed the two statistical methods, permutation and the Shannon entropy, and their differences and similarities are highlighted.
Resource Optimization for Geotechnical Protective Structures on Rights-of-Way
Authors: Barrera Nidia , Vásquez German , Gil José Vicente Amórtegui , Castañeda Bernardo , García Mauricio , Ramírez Yuddy
Published: January 2016

An analysis was performed of the charts that are traditionally employed in the determination of the separation of geotechnical protective structures on rights-of-way, such as cut-offs and trench barriers. An analysis was performed for the specific study area, with information from the existing weather and rainfall stations, which made it possible to characterize more accurately the rainfall figure required for curve fitting. Furthermore, knowledge of the soils in the area made it possible to classify them in terms of erodability. This classification was used to establish curves that better reflect the actual conditions of the soils of the rights-of-way. A conceptual analysis was performed of the need for the implementation of these structures in order to control erosion along the rights-of-way. This analysis made it possible to propose changes in the materials specification, in order to optimize costs during construction.

As a supplement to the study of the protective structures for the rights-of-way, the dimensions of the trench for the installation of the pipelines was analyzed. This analysis included a comparison of the actual construction dimensions of the trench against the dimensions recommended by international standards and the ones contained in the international literature. Certain Colombian projects that supplement the analysis are also cited. The foregoing findings were used in the preparation of certain recommendations regarding the reduction of the dimensions of the trench for certain specific technical, social, and environmental conditions.

Last, based on the analyses that were performed, the study proposes certain changes in the operator’s current standards, primarily regarding items such as cut-offs, trench barriers, and the dimensions of the trench. These changes will lead to a reduction in the construction costs of the geotechnical protective structures for hydrocarbon-pipeline rights-of-way. These items are typical, because the pipelines in question are located predominantly on foothill plains.
Material and Process Development of Thin Film Shape Memory Alloy for MEMS Actuator
Authors: Knick Cory R. , Morris Christopher J.
Published: January 2016

In this work we discuss the design and fabrication of a cantilever that may be actuated by utilizing the martensite to austenite phase transformation of a sputtered thin film of equiatomic NiTi shape memory alloy (SMA). The cantilever devices were fabricated on a silicon wafer using standard micro fabrication techniques, and may therefore be applicable to microelectromechanical systems (MEMS) switch or actuator applications. This paper details the development of a co-sputtering process to yield a SMA film with controllable composition of Ni50Ti50 and transformation temperature around 60° C. Shape memory effects were characterized using Differential Scanning Calorimetry (DSC), for which we demonstrated martensite-austenite phase change at 57° C for 1–3 um films, annealed at 600° C. We used wafer stress versus temperature measurements as additional confirmation for the repeatable measurement of reversible phase transformation peaking at 73° C upon heating. Up to 62 MPa was available for actuation during the thermally induced phase change. After exploring multiple approaches to a frontside wafer release process, we were successful in patterning and fabricating 10 um wide freestanding Ni50Ti50 cantilevers.
Design and Analysis of a Magnetorheological Fluid Mount Featuring Uni-Directional Squeeze Mode
Authors: Bai Xian-Xu , Chen Peng , Qian Li-Jun , Kan Ping
Published: January 2016

A magnetorheological fluid (MRF) mount featuring unidirectional squeeze mode for vehicle engine mounting system is proposed and designed to attenuate the engine vibration with characteristics of broadband and small amplitude. The MRF mount is comprised of upper and lower bases for installation, a main rubber for static load, a bobbin for electromagnetic coil winding and a squeeze plate. The bottom surface of the bobbin and the top surface of the squeeze plate form the polar plates, between which the MRF is squeezed during the rebound of the MRF mount. Combining dynamic stiffness property of passive hydraulic mounts without fluid and adjustable damping force of MRF at squeeze mode, the MRF mount could provide a unique variable dynamic stiffness and damping properties, by adjusting the exciting current. To evaluate the performance of the MRF mount, a mathematical model considering the behavior of MRF at squeeze mode is derived to theoretically analyze and numerically simulate the dynamic stiffness and equivalent damping properties of the MRF mount. Further, the MRF mount based quarter vehicle mounting system model considering suspension system is constructed to analyze the force transmissibility of engine mounting system in frequency domain and simulate the relative displacement response in time domain.
Laser Induced Lamb Wave Generation for Structural Health Monitoring of Carbon Fiber Reinforced Polymers
Authors: Sebastian Ron , Kelkel Benjamin , Gurka Martin , Traub Tobias , L’huillier Johannes
Published: January 2016

In this paper we present an innovative concept for the excitation of guided acoustic waves (lamb waves) in carbon fiber reinforced polymers (CFRP). The idea is to add this external signal generation to a passive structural health monitoring system (SHM), using the now active system for nondestructive testing (NDT). The whole system consists of piezoelectric sensors, embedded in the polymer matrix of the monitored component, the external laser in combination with a scanning device for spatial resolved generation of acoustic waves and a signal processing unit for data analysis. Using laser excitation for lamb wave generation helps to overcome several dis-advantages compared to the use of piezoelectric transducers only: The flexibility in repositioning of the excitation area allows for easy compensation of the strong signal attenuation of CFRP with a minimum number of piezoelectric transducers. The variation of laser wavelength in the range of 1024 to 3500 nm in combination with variation in intensity allows for a selective coupling of the acoustic waves either into the matrix or in the C fibers. Using piezoelectric transducers for detection only, omits the need for a large number of high-voltage amplifiers for signal generation. In this contribution we present first results of a systematic investigation of the effective generation of lamb waves in CFRP. In addition to the variation of the wavelength of the laser, the intensity was varied too. A potentially damaging influence of the laser radiation on the CFRP material was investigated.
Improved Understanding of Damage Precursors Through Local Mechanical Characterization
Authors: Cole Daniel P. , Habtour Ed M.
Published: January 2016

We report on the use of local mechanical characterization techniques for the understanding of structural damage precursors in various material systems. Instrumented indentation and atomic force microscopy (AFM) were used to characterize local damage in: (1) fatigued metallic beams subject to non-linear vibration, (2) individual polymer and glass microfibers, and (3) additive manufactured thermoplastics. Indentation studies of the fatigued metallic beams showed a compliance effect of up to 40% in relatively highly stressed regions. An approved fiber mounting technique allowed for indentation of unmodified surfaces of single microfibers, while AFM modulus maps of the fibers reveal local regions of relative compliance. Local mechanical tests of 3-D printed acrylonitrile butadiene styrene specimens revealed a variation in properties between printed beads and bead-bead interfaces. The nano-/micro-scale techniques developed in the present study provide a framework for understanding how damage precursors may affect processing-structure-property relationships in present and future structural aerospace materials.
Negative Pressure Waves Analysis for Crack Localization and Crack Size Estimation for 3D Printed SHM System
Authors: Hinderdael Michaël F. , De Baere Dieter , Devesse Wim , Strantza Maria , Guillaume Patrick
Published: January 2016

A new Structural Health Monitoring system was developed to allow a faster introduction of 3D printed components into safety critical applications. Additive manufacturing techniques are used to embed capillaries in a 3D printed structure that are then pressurized. Continuous monitoring of the capillary pressure allows the system to indicate the existence of a crack when the pressure deviates from the initial pressure level. A specifically developed experimental set-up enables the study of the impact of different parameters on the leak flow behavior and the occurring Negative Pressure Waves. Negative Pressure Waves are analyzed to demonstrate the crack localization and crack size estimation feasibility. It will first be theoretically proven that the size and location of the crack can be derived from the Negative Pressure Waves. Secondly, measurements will validate the crack localization and size estimation feasibility of the new Structural Health Monitoring system.
Upscaling Sensing Materials With Challenges of Sensors Embedding in Powder Based Materials and Polymers
Authors: Mekid Samir , Saheb Nouari , Daraghma Hammam , Butt Asad , Qureshi Khurram
Published: January 2016

This paper has explored and analyzed new routes to design new concepts of materials capable of feeling external effects and feed information back to a monitor and/or react through embedded actuators to resist any deformation. The material with its new artificial sensing property can be easily scaled-up to govern a whole structure at macro scale. The research has investigated a variety of manufacturing routes to build prototypes to be tested for the sake of characterization and performance assessment as well as cost analysis to assess effectiveness. This has included ultrasonic fiber optics embedding in thin Metals e.g. Aluminum which has shown some challenges to be discussed. The host materials included mainly layered manufacturing based materials e.g. powder based materials (Alloy Al6061) and additive process e.g. 3D printing with ABS material. This work has considered samples with concepts having embedded fiber optics in 1D, 2D and 3D. The integrity of the fiber optics and the host materials as well as the sensors performance has been investigated under several conditions of pressure, temperature and geometric placement of the fiber optics. A parametric compromise between materials standard performance and integrity of the sensors is to be found.
Characterization of Fiber Optics Integrity Under Several Embedding Parameters in Smart Materials
Authors: Mekid Samir , Butt Asad Muhammad , Qureshi Khurram
Published: January 2016

Single or array FBGs in fiber optics are embedded inside materials through various processes where sometimes integrity of the fibers may not be guaranteed. This paper reports on investigations of various aspects securing integrity of the measurements received from these sensors under various conditions of strains, temperature and geometry of sensors placement while embedding at materials subsurface. FBGs are very sensitive and delicate in the manipulation but offer great comprehensive measurement depending on the applications. These are required for the manual and automated embedding process of the fibers inside metals and hence the tensile, bending and temperature tests. The results have shown that if no adequate conditions of embedding are used, the sensors can be damaged and hence measurement readings can be severely affected. These conditions will constitute the parameters in the process control to be defined and monitored while embedding the sensors.
A Model for Iron-Based Shape Memory Alloys Considering Variable Elastic Stiffness and Coupling Between Plasticity and Phase Transformation
Authors: Cisse Cheikh , Zaki Wael , Ben Zineb Tarak
Published: January 2016

The paper presents a new constitutive model for iron-based shape memory alloys (Fe-SMAs) adapted from the ZM model initially proposed for Nitinol by Zaki and Moumni [JMPS2007]. The model introduces nonlinear hardening terms to account for interactions between the grains, martensite variants and slip systems that may exist within a volume element of the material. The expressions used for the hardening terms are similar to those in (Khalil et al. [JIMSS2012]). The equations of the model are derived from the expression of a Helmholtz free energy potential, with complementary loading conditions obtained within the framework of generalized standard materials with internal constraints. A detailed derivation of the implicit algorithm used for the integration of the model is provided and used for numerical simulations that are shown to agree with experimental data.
The Application of Piezo Based Subsystems for Improved Machining Processes
Authors: Drossel Welf-Guntram , Bucht André , Kunze Holger , Pagel Kenny
Published: January 2016

Due to their very high applicable forces, frequencies and their stiffness, piezoceramics are feasible to serve as integrated actuators in machines. The application of piezo based components in production engineering was subject of plenty of investigations in the past. That focuses primarily on systems for condition monitoring, structural vibration reduction or chatter prevention. However there are currently also few approaches that aim to use piezo actuators for directly induced vibrations for improved machining processes.

In this paper we present an overview of such systems, their parameters and the technological background. Known approaches will be classified and divided into groups considering their working principles, actuator performance and application technology. Ultra sonic machining (USM) for example is a comparatively old approach which applies ultrasonic vibrations of a sonotrode to an abrasive slurry for machining hard, brittle and nonconductive material. Vibration assisted machining (VAM) systems are rather different. They are characterized by low stroke, uncontrolled but highly frequent resonant vibrations of the tool to achieve enhanced chipping behavior or generally enable to machine certain hard materials. Fast Tool servo (FTS) systems are even more complex. They apply an overlaid controlled movement of the cutting edge to manufacture microstructures or possess to manufacture complex geometries like non circular bores or turned parts.

Selected systems will be presented in detail showing their design approach, actuator parameters, control considerations and measurement data of manufactured parts. These will be for instance an ultrasonic deep hole drilling tool, a form honing system, an active spindle mounting for micro contouring and a piezo based machine table for manufacturing non circular bores in small workpieces. Summarized the existing systems will be compared considering their advantages and eventual hindrances. Beyond that the outlook will show problems, which need to be solved in the future to enable piezo assisted machining systems a more comprehensive application in manufacturing.
Aerodynamic Characteristics Prediction via Artificial Hair Sensor and Feedforward Neural Network
Authors: Thapa Magar Kaman , Reich Gregory W. , Rickey Matthew R. , Smyers Brian M. , Beblo Richard V.
Published: January 2016

Fly by feel is a concept in which distributed sensors and actuators are integrated on an aerial system for state awareness or sensation of the environment, and make use of distributed control to increase the system maneuverability, stability and safety. Artificial hair sensors are good candidates as sensors for the fly by feel concept because they are lightweight, have low manufacturing costs and can easily be integrated on the surface of air-vehicle without affecting the flow. We investigate an application of artificial hair sensors considering its capability of measuring the local flow velocity combined with a Feedforward Artificial Neural Network to predict the aerodynamic quantities such as lift coefficient, moment coefficient, angle of attack and free-stream velocity in real-time. These quantities, when combined with the physical and unsteady aerodynamics parameters, will make a framework for designing and implementing an active controller for gust alleviation in a pitch and plunge airfoil system.
Understanding the Locomotion and Dynamic Controls for Millipedes: Part 1 — Kinematic Analysis of Millipede Movements
Authors: Garcia Anthony , Priya Shashank , Marek Paul
Published: January 2016

An investigation of the biological locomotion and control mechanisms observed in Diplopoda (millipedes) is performed in order to provide design rules for the development of a crawling millipede-inspired robot (millibot). Millipedes have long bodies with numerous pairs of legs, which allows them to perform higher ranges of motion compared to other arthropods traveling in the same environment. The relevant features of millipedes with respect to robotics include: (i) metachronal locomotion, (ii) ability to burrow through different substrates, and (iii) capability to traverse uneven terrains and align themselves swiftly when fallen over. A mathematical model is proposed describing these locomotion features that will provide guidance towards emulating these actions in a millibot.
Fused Filament Additive Manufacturing of Ionic Polymer-Metal Composite Soft Active 3D Structures
Authors: Carrico James D. , Traeden Nicklaus W. , Aureli Matteo , Leang Kam K.
Published: January 2016

This paper describes a new three-dimensional (3D) additive manufacturing (AM) technique in which electroactive polymer filament material is used to build soft active 3D structures, layer by layer. The proposed manufacturing process is well-suited for creating electroactive soft complex structures and devices, whereby the entire system can be manufactured from an electroactive polymer material. For the first time, the unique actuation and sensing properties of ionic polymer-metal composite (IPMC) is exploited and directly incorporated into the structural design to create sub-millimeter scale cilia-like actuators and sensors to macro-scale soft robotic systems. Because ionic polymers such as Nafion are not melt-processable, in the first step a precursor material (non-acid Nafion precursor resin) is extruded into a thermoplastic filament for 3D printing. The filament is then used by a custom-designed 3D printer to manufacture the desired soft polymer structures, layer by layer. Since, at this stage the 3D-printed samples are not yet electroactive, a chemical functionalization process follows, consisting in hydrolyzing the precursor resin in an aqueous solution of sodium hydroxide (NaOH) and dimethyl sulfoxide (DMSO, C2H6OS). Upon functionalization, metal electrodes are applied on the samples through an electroless plating process, which enables selected areas of the 3D-printed electroactive structures to be controlled by voltage signals for actuation, while other parts can function as sensors. This innovative AM process is described in detail and experimental results are presented to demonstrate the potential and feasibility of creating 3D-printed IPMC actuator samples.
SMA-Based Hydraulic Switching Valve
Authors: Nalbach Sophie , Motzki Paul , Seelecke Stefan
Published: January 2016

Hydraulic switching valves are vital components commonly used in hydraulic applications. In a simple configuration, the valve has two states, open and closed. A spring pushes a spool into its first position and typically an electro-magnetic actuator working against the spring force is used to pull the spool into its second position.

Shape Memory Alloys (SMA’s) are known as actuators with very high energy density. This fact allows for the construction of very light weight and compact systems. The focus of this work is to replace the traditionally used electro-magnetic actuator in a hydraulic switching valve with an SMA wire actuator. This will allow for a reduction in the construction space and weight of the switching valve.

This work begins with an evaluation of the force and stroke requirements of a commercially available magnetic valve. Based on this information a new valve design using SMA wires is constructed to meet the same performance requirements. Once designed and fabricated, the SMA based valve is evaluated with respect to force and stroke. Finally both valves are arranged with other hydraulic components in a test station for direct performance comparison. The results concerning the hydraulic parameters like pressure and flow rate are compared to the conventional valve. In conclusion, the experimental results are displayed and an outlook on future work and possible application scenarios is given.
A C-Battery Scale Energy Harvester: Part A — System Dynamics
Authors: Nico Valeria , Boco Elisabetta , Frizzell Ronan , Punch Jeff
Published: January 2016

In recent years, the development of small and low power electronics has led to the deployment of Wireless Sensor Networks (WSNs) that are largely used in military and civil applications. Vibrational energy harvesting can be used to power these sensors in order to obviate the costs of battery replacement. Vibrational energy harvesters (VEHs) are devices that convert the kinetic energy present in the ambient into electrical energy using three principal transduction mechanisms: piezoelectric, electromagnetic or electrostatic. The investigation presented in this paper specifically aims to realize a device that converts vibrations from different ambient sources to electrical energy for powering autonomous wireless sensors. A “C-battery” scale (25.5 mm diameter by 57.45 mm long, 29.340 cm3) two Degree-of-Freedom (2-DoF) nonlinear electromagnetic energy harvester, which employs velocity amplification, is presented in this paper. Velocity amplification is achieved through sequential collisions between two free-moving masses, a primary (larger) and a secondary (smaller) mass. The nonlinearities are due to the use of multiple masses and the use of magnetic springs between the primary mass and the housing, and between the primary and secondary masses. Part A of this paper presents a detailed experimental characterization of the system dynamics, while Part B describes the design and verification of the magnet/coil interaction for optimum prototype power output. The harvester is characterized experimentally under sinusoidal excitation for different geometrical configurations and also under the excitation of an air-compressor. The maximum output power generated under sinusoidal excitation of arms = 0.4 g is 1.74 mW across a resistive load of 9975 Ω, while the output rms voltage is 4.2 V. Under the excitation of the compressor, the maximum peak power across a load resistance of 8660 Ω is 1.37 mW, while the average power is 85.5 μW.
A C-Battery Scale Energy Harvester: Part B — Transducer Optimization and Modeling
Authors: Boco Elisabetta , Nico Valeria , Frizzell Ronan , Punch Jeff
Published: January 2016

A two Degree-of-Freedom (2DoF) nonlinear electromagnetic energy harvester, which employs velocity amplification, with a volume of 26.7cm 3 and 25.6 cm3 (25.5mm diameter and 52.4mm height) is investigated in this work. These dimensions are very close to those of a C-battery (26.2mm diameter and 50mm length, for a volume of 27.8cm3), making the harvester suitable to be integrated in electronic devices. The harvester consists of a Halbach array of magnets oscillating inside a set of seven coils. The use of magnetic springs and the impacts between the two masses, leads to nonlinear harvester behaviour, broadening the harvester’s spectral response. Moreover, the impacts exploit velocity amplification on the secondary (smaller) mass, improving the electromagnetic conversion. The aim of this work is to optimize the performance of the electromagnetic transducer through analytical and numerical methods and to experimentally verify the optimization methods. This paper discusses the magnetic configuration that maximizes the variation of flux density and an analytical model is presented that predicts the optimal number of turns and wire diameter for the coils. A finite element simulation takes the output from the initial optimization calculations and predicts the output voltage of the harvester. Experimental results are then presented where various coil designs are tested and comparisons are made to the numerical results to validate the models. The experimental results also show a high volumetric Figure of Merit (FoMV), which highlights the benefits of the optimisation methods used. Finally, in order to give the reader an understanding of the system performance under real-world vibrations, the system was tested under excitation generated by human motion.
Li1.4Al0.4Ti1.6(PO4)3 Used as Solid Electrolyte for Structural Supercapacitors
Authors: Liao Guangyue , Geier Sebastian , Mahrholz Thorsten , Wierach Peter , Wiedemann Martin
Published: January 2016

Structural supercapacitors are very interesting multifunctional devices combining the properties of an electrical energy storage device and a structural component simultaneously. These types of supercapacitors are mostly equipped with solid state electrolytes, instead of traditional liquid electrolytes, avoiding leakage and safety problems and supporting the mechanical performance of the composite materials. In the present study, the Lithium-ion based solid ceramic electrolyte Li1.4Al0.4Ti1.6(PO4)3 was successfully synthesized by sol-gel method. Its electrical properties were characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Results show that Li1.4Al0.4Ti1.6(PO4)3 possesses a conductivity of 2.94×10−4 S/cm at room temperature and a specific capacity of 55.57 μF/g. The as-prepared samples were embedded into fiber composite material using the aviation approved resin RTM6 with an injection process making the composite structure flexible. Subsequently, the specific capacity and conductivity were tested getting values of 53.44μF/g and 2.00×10−4 S/cm respectively. The reason for electrical properties loss was investigated by computerized tomography (CT) and EIS tests and the results provide reference for the future research.
Structural Health Monitoring of Pipelines for Environment Pollution Mitigation
Authors: Felli Ferdinando , Paolozzi Antonio , Vendittozzi Cristian , Paris Claudio , Asanuma Hiroshi , De Canio Gerardo , Mongelli Marialuisa , Colucci Alessandro
Published: January 2016

Oil and gas infrastructures may be exposed to landslides, earthquakes, corrosion and fatigue, and to damage from thefts or vandalism, leading to leakage and failure with serious economic and ecologic consequences. For this reason, an increasing interest in applied research on monitoring and protecting pipelines (for fuel, oil and natural gas transportation) arises. Aimed at the mitigation of catastrophic effects of human and natural damage, the present paper proposes a smart real-time Structural Health Monitoring (SHM) system capable to control structural integrity continuously, focusing on the issue of spillage for thefts of fuels which are not detectable, in real-time, by the existing monitoring systems.

The system consists of a smart-pipeline containing a health monitoring integrated measurement chain, i.e. an enhanced Fiber Bragg Gratings-based fiber optics neural network on the pipes, for displacement and acceleration monitoring (gathering many other different measurements such as: ground motion, permanent ground displacement, pipeline temperature, pipeline deformation, leakage, etc.).

Specifically, the ability to measure these characteristics at hundreds of points along a single fiber and the great accuracy of each point of measure, are particularly interesting for the monitoring of structures such as pipelines in order to detect hazardous and unauthorized intrusion and damage.
Systematic Experimental Investigation of Dielectric Electroactive Polymers Using a Custom-Built Uniaxial Tensile Test Rig
Authors: Hodgins Micah , York Alexander , Seelecke Stefan
Published: January 2016

This work presents the design, fabrication and testing of a comprehensive DEAP test station. The tester is designed to perform tensile tests of planar DEAPs while measuring quantities such as tensile force, stretch, film thickness and voltage/current. The work details the specimen preparation and how the specimen is placed in the clamps. While the assembly process is performed by hand features were built-in to the design of the specimen frame and clamps to enable reliable placement and specimen geometry. Test results of the pure-shear specimen demonstrated good performance of the testing device. Although the electrode surface was rough the thickness stretch was evident during the stretching/actuation of the DEAP actuator.
Modelling Approach to Describe the Actuation Behavior of Magnetoactive Elastomers
Authors: Uhlenbusch Dominik , Maas Jürgen
Published: January 2016

Magnetoactive elastomers (MAEs) are composites made of an elastomeric matrix and a magnetizable filler material. The combination of their properties enables a MAE to undergo a change of its rheological respective damping behavior. Furthermore, it is expected that such a magnetic field can lead to an actuation of a MAE. This actuation causes actuation forces perceptible on the surfaces of MAEs. For the investigation of the induced actuation forces different MAE-probes are characterized in a first step. The resulting forces of these MAE-probes are measured by generating a variable external magnetic field in a suitable test setup. Subsequently, a finite element analysis (FEA) is carried out to investigate the behavior from a theoretical point of view by introducing an appropriate continuum mechanical model approach based on the Kelvin force. Therefore, a coupling of magnetism and structural-mechanics domain is developed and implemented using the FEA-tool Comsol Multiphyisics. Finally, the experimental and numerical results of the actuation forces are compared showing a good accordance.
Multi-Functional Topology Optimization of Piezoresistive Nanocomposite Beams
Authors: Seifert Ryan , Patil Mayuresh , Seidel Gary , Reich Gregory
Published: January 2016

This paper presents an analysis of optimization for multifunctional nanocomposites. A carbon nanotubeepoxy composite is optimized for maximum resistance change and minimum strain energy. Analysis uses a finite element method and includes the coupled physics of mechanics, electrostatics, and piezoresistivity. The problem is solved first for minimum strain energy, then two resistance maximization problems are solved. For all optimization, sensitivities are obtained analytically. After solving the individual problems a weighted sum approach is used in the multi-objective optimization of both minimizing the strain energy and maximizing the resistance change. Comments are made as to the effect of the topology optimization method as a design tool, on the shape of the optimized cross sections, and on the possible extensions on using the coupled physics topology optimization algorithm.
Self-Folding Laminated Composites for Smart Origami Structures
Authors: Chillara Venkata Siva C. , Headings Leon M. , Dapino Marcelo J.
Published: January 2016

Origami-folding principles can be used with laminated composites to produce lightweight structures that are capable of drastic changes in shape. This paper presents a smart composite that can actively change its crease pattern to fold itself into different rigid shapes and provide a large range of motion. The composite uses a smart material with variable modulus sandwiched between two fiber-reinforced elastomeric skins, one of which is prestressed. Change in modulus of the sandwiched core layer allows prestress in the elastomeric skin to actuate the fold. Unfolding the structure to a flat shape can be accomplished through either embedded or external actuation. Passive composite panels were fabricated for model development and validation. An analytical model was developed based on classical laminate plate theory to study the influence of core modulus, core thickness, and elastomeric skin prestress on the equilibrium curvature of the composite structure. Selected smart materials that provide a change in modulus when stimulated are discussed as candidates for the core layer of the self-folding composite.
Interrogation of Bilayers in a Multi-Droplet Cluster for Membrane-Based Sensing
Authors: Nguyen Mary-Anne , Tamaddoni Nima , Sarles Stephen A.
Published: January 2016

The long-term vision of our work is to create a new class of smart material that utilizes networks of active, synthetic cell membranes for sensing, actuation, and energy harvesting. Having multiple membrane structures is specifically targeted because a higher density of functional membranes is expected to enable amplification and collective utility, similar to how living tissues and organisms utilize networks of highly connected cells to accomplish large tasks. While there are several known methods for assembling droplet-based networks of synthetic lipid bilayers, there has been much less effort to develop methods for electrically characterizing each interface in a multi-bilayer-droplet network. This paper specifically focuses on a strategy for using electrical measurements to independently record transmembrane currents occurring at each bilayer in multi-bilayer networks where the number of bilayers present is equal to or greater than the number of droplets in the system. Using a multichannel patch clamp amplifier, we develop a measurement technique for sequentially assigning sensing electrodes to apply a non-zero voltage or function as virtual ground (V=0). Experimental studies on a three-droplet cluster containing three bilayers confirm the validity of the proposed approach for independently interrogating each membrane, and the results allow extension of the method to networks with 4–7 droplets. Furthermore, alamethicin peptide gating is monitored using the measurement cycle in order to interrogate all interfaces. Due to high total membrane area, highly packed systems can provide an increase in the magnitude of sensing current generated by a stimulus. Such amplification could feasibly be employed in droplet-based hair cell sensing applications in which airflow or vibration acts as the perturbation source, and the proposed approach and challenges for interrogating the transduction response in a multi-membrane hair cell sensor are discussed herein.
Investigation of the Adhesion Properties of Laminated Multilayer-Actuators Based on DEAP Material
Authors: Bokermann Kai , Maas Jürgen
Published: January 2016

Transducers based on dielectric electroactive polymers (DEAP) gained a lot of attention within the last years. By applying an electric field, the elastomer material, coated with compliant electrodes on its opposing surfaces, deforms. Due to this electromechanical coupling DEAP transducers are predestined for generator and actuator applications. However, to increase the absolute energy gain or the actuation, multilayer DEAP transducers are used. To withstand tensile forces a reliable adhesion between the single layers of the transducer is mandatory. If the transducer is made from high-quality pre-fabricated polymer films it is preferable to laminate the layers without glue in order to keep the processing steps simple and fast. Therefore, within this publication the adhesion between the material surfaces is theoretically and experimentally investigated. For this purpose, different adhesion theories are studied based on the properties of polymers. In particular, the adsorption theory is theoretically considered in more detail and used to determine the surface energy experimentally for different elastomer materials. By using the obtained surface energies, models are derived to describe the adhesion between them. Finally, the adhesion is experimentally investigated by corresponding experiments.
Analysis and Optimization of a Shape Memory Alloy-Based Self-Folding Sheet Considering Material Uncertainties
Authors: Peraza Hernandez Edwin A. , Hartl Darren J. , Malak Richard J. , Lagoudas Dimitris C.
Published: January 2016

Origami-inspired active structures have important characteristics such as reconfigurability and the ability to adopt compact flat forms for storage. A self-folding shape memory alloy (SMA)-based laminated sheet is considered in this work wherein SMA wire meshes comprise the top and bottom layers and a thermally insulating compliant elastomer comprises the middle layer. Uncertainty in various parameters (e.g. material properties) may affect the performance of the sheet, which is explored here. Different modeling approaches are studied in order to compare their accuracy and computational cost. A numerical approach based on the Euler-Bernoulli beam theory is selected due to its accuracy when compared to higher fidelity finite element simulations and its low computational cost, necessary to perform a large number of design evaluations as required for uncertainty analysis. Optimization is performed considering uncertainty in the material properties. Failure probabilities under mechanical constraints and expected values of fold curvature and blocking moment are considered during optimization of the self-folding sheet. The multiobjective genetic algorithm for technology characterization P3GA is used to obtain the Pareto dominant designs. Most designs forming the Pareto frontier have the same values for certain design parameters such as the distance between the wires in the SMA meshes non-dimensionalized by SMA wire thickness, elastomer layer thickness non-dimensionalized by SMA wire thickness, and applied temperature. The design parameter deciding the trade-off between fold curvature and blocking moment is found to be the SMA wire thickness.