bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Study of the Influence of Valve Timing on Hydraulic Motor Efficiency
Authors: Tian Hao , Van de Ven James D.
Published: January 2016

The timing of the valves of a hydraulic motor plays an important role in determining the throttling energy. To reduce this dominating energy loss, the timing of the valves must allow the fluid in the chamber to be precompressed and decompressed such that there is minimal pressure differential across the transitioning valve. The optimal valve timing to achieve precompression and decompression is a function of the motor displacement, angular velocity, pressure, and air content of the fluid, thus to achieve high efficiency at all conditions, active valve timing is required. The valves in most hydraulic motor architectures are mechanically timed to the piston displacement, rendering it impossible to change the valve timing as a function of operating conditions. This paper presents one novel valve architecture that allows for such processes: a rotary valve that is controlled independently of the piston displacement, enabling active timing control. To validate the concept and test the motor valve at fixed timing and fixed displacement conditions, a prototype valve was installed on a single cylinder 3.5 cc/rev slider-crank piston motor. The nominal timing of the valve was optimized for operation for a pressure of 7 MPa, 2% entrained air by volume, and an angular velocity between 10 and 30 Hz. A model, including the pressure dynamics, leakage, compressibility, check valve dynamics, and geometry dependent parameters is developed, simulated, and compared to the experiment. The experimental system includes instrumentation for measuring the inlet and outlet flow rates, piston position, and pressure in the inlet, outlet, and cylinder. A comparison between the model and experimental data shows good agreement and demonstrate the large impact of valve timing on efficiency.
A CFD-Radial Motion Coupled Model for the Evaluation of the Features of Journal Bearings in External Gear Machines
Authors: Pellegri Matteo , Vacca Andrea
Published: January 2016

This paper presents an approach for the evaluation of the effects related to the behavior of the journal bearings on the operation of external gear machines (EGMs). In EGMs journal bearings usually support shafts of both gears. The prediction of their instantaneous axis of rotation is a key feature of EGMs, affecting the displacing action of the inter-teeth volumes and the leakages at the tip of each tooth. Past approaches presented in the literature for the evaluation of the radial micro-motions of the gears are based on classic simplified models for the hydrodynamic journal bearings based on steady-state solutions of the fluid film neglecting important hydrodynamic effects due to film squeeze — which can be relevant in case of significant radial loads variations — or they concentrate the focus of the study on the journal bearing itself regardless of the impact on the global machine operation. This work presents a CFD model coupled with a rigid model for the evaluation of the radial motions of the journal that permits to overcome the above-mentioned limitations of the existing approaches of study. The paper details the proposed model, in particular as concerns the CFD approach to solve the film flow and its coupling with a previously developed model (HYGESim) developed by the authors’ team for the evaluation of the overall operation of the EGM, used also to find the instantaneous loads on the gears. The potentials of the proposed approach are shown for the case of a pump for high pressure applications. For this case the results show how it is necessary to have a detailed approach for the evaluation of the journal bearings for a correct evaluation of the overall EGM behavior. In particular, the importance of hydrodynamic squeeze effects are shown, by comparing the model prediction with those given by the commonly used simplified steady-state approach. The comparison of simulation results with experimental data is also shown as pertain to pump case wear associated to the break in process.
Design Aspects of a Cardiac Action Hydraulic Pump
Authors: Elgamil Mohamed , Mostafa Khaled , El-Husseiny Marwan , Kassem Saad
Published: January 2016

This paper presents some design aspects of a high pressure cardiac action hydraulic pump consisting of several pumping heads. Each head has a set of followers that completely encircle a cam. The followers separate a pumping chamber, formed between the cam and the followers, from a control chamber existing outside the followers. With the cam rotation the followers move outwards and inwards with respect to the cam, causing the pumping chamber volume to increase and decrease to suck and pump oil. The pump geometric volume can be controlled by controlling the stroke of the followers through the control of the oil volume in the control chamber. Three different methods are proposed to transmit the motion from the cam to the followers. In the first method the followers are in direct contact with the cam, while in the second intermediate cylindrical rollers are inserted between the followers and the cam. In the third method, specially shaped pads are inserted between the cam and the followers. Finite element analysis (FEA) using ANSYS Mechanical software is carried out to compare between these methods regarding the generated contact stresses between the cam and the followers. FEA is also utilized to design a self-integrated priming spring in the external lips of the followers in order to allow smooth pump start up at all operating conditions. The suction and delivery valves of this pump are crucial for its reliability and high performance. They should allow high flow rates at small pressure drop and should be compact, of low inertia to operate at high frequency, and of minimum deformation under high pressures. A CFD analysis for a proposed design for these valves is performed using ANSYS/FLUENT program on three-dimensional models, where the flow rates, the pressure and velocity distributions, and the deformations of these elements are calculated.
Mathematical Model of a Hydraulic Excavator for Fuel Consumption Predictions
Authors: Casoli Paolo , Riccò Luca , Campanini Federico , Lettini Antonio , Dolcin Cesare
Published: January 2016

This paper presents the multibody mathematical model of a hydraulic excavator, developed in the AMESim® environment, which is able to predict the machinery fuel consumption during the working cycles. The mathematical modelling approach is presented as well as the subsystems models. The experimental activity on the excavator is presented in detail. The excavator fuel consumption was measured according to the JCMAS standard. The working cycles were executed an appropriate number of times in order to minimize the stochastic influence of the operator on the fuel consumption. The results show the mathematical model capability in the machine fuel consumption prediction. The excavator model could be useful either to perform accurate analyses on the energy dissipation in the system, giving the possibility to introduce new system configurations and compare their performance with the standard one, or for the definition of novel system control strategies in order to achieve the fuel consumption reduction target.
The Design of a Powered Ankle Prosthesis With Electrohydrostatic Actuation
Authors: Yu Tian , Plummer Andrew , Iravani Pejman , Bhatti Jawaad
Published: January 2016

This paper presents the design and modelling of a new powered ankle prosthesis which combines electrohydrostatic actuation with a controllable passive damper. The new powered ankle prosthesis can switch quickly between passive mode and powered assistance mode, and is intended to just give assistance at certain points within the gait cycles, such as during toe push-off. The design concept and a prototype built to demonstrate the concept are presented. A simulation model was developed to help analyse the performance characteristics. The structure and parameterisation of the simulation model are described. A comparison between simulation results and experiment results is undertaken in order to validate the model and assist in the optimisation of the design. Some results from an initial trial with amputees are included in the paper. According to subjective feedback from the amputees, the new powered ankle prosthesis provides sufficient force at push-off to assist with walking. Future investigations will be focusing on the compactness, weight reduction and control of the powered ankle prosthesis.
Design and Modelling of a Novel Servovalve Actuated by a Piezoelectric Ring Bender
Authors: Persson L. Johan , Plummer Andrew R. , Bowen Christopher R. , Brooks Ian
Published: January 2016

This paper describes the design, simulation and testing of a piezoelectric spool valve. An actuator has been connected to the valve and tested under closed loop control. A mathematical model of the valve was produced and a prototype of the valve was tested. The mathematical model is validated against the experimental data. Step and frequency responses for both the valve and actuator are presented. It was found that displacement of the hydraulic fluid by the ring bender had an impact on the valve performance. To reduce the effect of the piezoelectric hysteresis, closed loop spool position control was evaluated. A noticeable difference can be observed between open loop and closed loop performance.
Mode Shifting in Hybrid Hydromechanical Transmissions
Authors: Larsson L. Viktor , Pettersson Karl , Krus Petter
Published: January 2016

Demands for low cost sustainable solutions have increased the use of and interest in complex hydromechanical transmissions for heavy off-road vehicles. In transmissions with multiple modes, an important condition is to maintain the tractive force during the mode shifting event. For hybrid hydromechanical transmissions, with a direct connection to a hydraulic accumulator, the impressed system pressure caused by the hydraulic accumulator has not yet been observed to interfere with this condition. In this paper, a black box model approach is used to modify the hydraulic system after obtaining knowledge regarding how it is affected by a mode shift. A comparative study is carried out where a full vehicle model of a mobile working machine is simulated with two different hydraulic systems. The results show that different system solutions imply different demands on the included components, and that the mode shifting event is not a negligible factor in heavy hydraulic hybrid vehicles.
High Performance Pressure Control for the Hydraulic Press Based on the Soft Relief Fuzzy PID Controller
Authors: Zhang Qiang , Wei Jianhua , Fang Jinhui , Wang Xiaoyi
Published: January 2016

A soft relief controller is proposed to solve the pressure overshoot problem of the hydraulic press. Whose basic idea is to make the proportional relief valve open in advance to limit the pressure rise rate to reduce the pressure overshoot. What’s more, the fuzzy PID controller is introduced to improve the control performance. Based on the mechanism modeling method, the complete mathematical model of the hydraulic press is established to conduct the simulation research. The correctness of the mathematical model is proved through experiments. Simulation and experiment results demonstrate that the soft relief fuzzy PID controller which combines the soft relief controller and the fuzzy PID controller can guarantee the hydraulic press has no overshoot during the pressure building-up process. Furthermore, a high steady precision is achieved and the adjust time can meet the demands of most hydraulic presses.
Passivity Based Backstepping Control for Trajectory Tracking Using a Hydraulic Transformer
Authors: Lee Sangyoon , Li Perry Y.
Published: January 2016

Throttling loss is a major contributor to the low system efficiency in hydraulic systems. Hydraulic transformers can potentially be an energy efficient, throttle-less control approach for multi-actuators systems powered by a common pressure rail (CPR). The transformer transforms the input CPR pressure to the desired pressure of the actuator instead of throttling it. Regenerative energy can also be captured. For transformers to be useful, they must also have good control performance. This paper presents a a passivity based trajectory tracking controller for a hydraulic actuator driven by a transformer consisting of two mechanically coupled variable displacement pump/motors. In addition to controlling the motion of the actuator, the transformer speed can also be regulated at the most efficient operating speed. The nonlinear controller is designed using a Lyapunov function that is based upon a recently discovered natural energy storage function for hydraulic actuators. Experimental results validate the efficacy of this controller.
State Estimation Techniques for Axial Piston Pump Health Monitoring
Authors: Shinn Tyler , Carpenter Richard , Fales Roger C.
Published: January 2016

Catastrophic failures of hydraulic pumps can lead to significant machine downtime. In the mining and quarry sector this can lead to losses in the tens of thousands of dollars per hour. Predicting pump failures before they occur could lead to substantial savings for equipment owners. This work focuses on developing a pump health strategy using physics-based models of a load sense steering system typically found on off-highway machines. State observers are developed that estimate pump swashplate position in order to determine a theoretical pump flow. Pump efficiency is predicted using actual flow estimates based on measured cylinder velocities and compared to the estimated theoretical pump flow. The typical Kalman filter (KF) is implemented and compared to that of a Sequential Monte Carlo method, the Particle Filter. Observability is examined to determine the feasibility of the KF. The Particle Filter algorithm is considered for its ability to deal nicely with non-linear models with non-Gaussian noise terms. Results show that the system is observable using a limited number of measurements, for example, only pressure measurements. The two methods of estimating states give comparable results when applied to the simulated model. A leakage fault is introduced to the system. An extended Kalman filter (EKF) is used to estimate volumetric efficiency with the unknown change in leakage coefficient using state and parameter estimation. The KF was found to be unable to accurately estimate the changes in volumetric efficiency with the leakage.
Advanced Fuel Injection System Using a Supercavitating Fuel Injector
Authors: Gattoni John M. , Sykes David M. , Yelvington Paul E.
Published: January 2016

Using the latest manufacturing technology and patented nozzle geometry, an innovative high-speed (two or more injections at an engine operating speed of 6,000 RPM), lightweight fuel injection system was developed that controls supercavitation within the fuel injector nozzle. The patented supercavitating fuel injector nozzle reduces the penetration length of the fuel spray by 25–30%, average droplet size by 15.5% when operating at the same fuel pressure, and improves droplet size uniformity over conventional nozzles. The combination of these properties represents a tremendous opportunity to improve fuel delivery in engines. In addition to the performance benefits, this technology could be easily implemented into any direct-injected engine system, both compression ignition and spark ignition engines, reciprocating and rotary, because only the nozzle assembly needs to be developed for that particular fuel injector platform.
Large Eddy Simulation of an N-Dodecane Spray Flame Under Different Ambient Oxygen Conditions
Authors: Pei Yuanjiang , Hu Bing , Som Sibendu
Published: January 2016

An n-dodecane spray flame was simulated using a dynamic structure large eddy simulation (LES) model coupled with a detailed chemistry combustion model to understand the ignition processes and the quasi-steady state flame structures. This study focuses on the effect of different ambient oxygen concentrations, 13%, 15% and 21% at an ambient temperature of 900 K and an ambient density of 22.8 kg/m3, which are typical diesel-engine relevant conditions with different levels of exhaust gas recirculation (EGR). The liquid spray was treated with a traditional Lagrangian method. A 103-species skeletal mechanism was used for the n-dodecane chemical kinetic model. It is observed that the main ignitions occur in rich mixture and the flames are thickened around 35 to 40 mm off the spray axis due to the enhanced turbulence induced by the strong recirculation upstream, just behind the head of the flames at different oxygen concentrations. At 1 ms after the start of injection, the soot production is dominated by the broader region of high temperature in rich mixture instead of the stronger oxidation of the high peak temperature. Multiple realizations were performed for the 15% O2 condition to understand the realization to realization variation and to establish best practices for ensemble-averaging diesel spray flames. Two indexes are defined. The structure-similarity index analysis suggests at least 5 realizations are needed to obtain 99% similarity for mixture fraction if the average of 16 realizations are used as the target at 0.8 ms. However, this scenario may be different for different scalars of interest. It is found that 6 realizations would be enough to reach 99% of similarity for temperature, while 8 and 14 realizations are required to achieve 99% similarity for soot and OH mass fraction, respectively. Similar findings are noticed at 1 ms. More realizations are needed for the magnitude-similarity index for the similar level of similarity as the structure-similarity index.
SI Engine Top Ring Coating Resistance to Accelerated Scuff and Spalling
Authors: Chen Yu , Sytsma Steve
Published: January 2016

Modern SI (spark ignition) engines are continuing to evolve for improved fuel economy by utilizing increased peak cylinder pressure, reduced section size piston rings, reduced cylinder bore surface finish, reduced lubricating oil viscosity, usage of alternative fuels, and with potentially increased fuel dilution. These changes all increase the potential for asperity contact between the top ring outer periphery and the cylinder wall, thereby creating a more challenging operational environment for the top ring.

To evaluate the resistance of new advanced top ring coatings, a new aggressive test cycle promoting ring face fatigue and scuffing was developed. The test cycle has been shown to be successful in failing a production GNS (gas nitride steel) coating in 10 hrs of run time.

This paper also presents relative performance data for different top ring face materials and ring features. The ring coatings evaluated include traditional coatings such as GNS and PVD (physical vapor deposition) coating as well as thermal spray coatings consisting of conventional plasma, HDAP (high density air plasma), and HVOF (high velocity oxygen fuel).
Multidimensional Modeling and Validation of Dual-Fuel Combustion in a Large Bore Medium Speed Diesel Engine
Authors: Wijeyakulasuriya Sameera , Jupudi Ravichandra S. , Givler Shawn , Primus Roy J. , Klingbeil Adam E. , Raju Mandhapati , Raman Ashwin
Published: January 2016

High fidelity, three-dimensional CFD was used to model the flow, fuel injection, combustion, and emissions in a large bore medium speed diesel engine with different levels of natural gas substitution. Detailed chemical kinetics was used to model the complex combustion behavior of the premixed natural gas, ignited via a diesel spray. The numerical predictions were compared against measured multiple cycle pressure data, to understand the possible factors affecting cyclic variation in experimental data. Under conditions with high natural gas substitution rates, diesel was injected much earlier than firing-TDC. This additional mixing time allowed the active radicals from diesel dissociation to initiate combustion from the cylinder wall and propagate inwards. 0%, 60%, and 93% natural gas substitution rates (by energy) were tested in this study to develop computational capabilities needed to accurately model and understand the underlying physics. Several innovative computational methods such as adaptive mesh refinement (which automatically refines and coarsens the mesh based on the existing solution parameters), and multi-zoning (which groups chemically similar cells together to reduce combustion calculation time) were utilized to obtain accurate predictions at a lower computational cost. Important engine emissions such as NOx, CO, unburnt HC, and soot were predicted numerically and compared against measured engine data.
Understanding In-Cylinder Flow Variability Using Large-Eddy Simulations
Authors: Van Dam Noah , Rutland Christopher
Published: January 2016

Multi-cycle Large-eddy simulations (LES) of motored flow in an optical engine housed at the University of Michigan have been performed. The simulated flow field is compared against particle image velocimetry (PIV) data in several cutting planes. Circular statistical methods have been sued to isolate the contributions to overall turbulent fluctuations from changes in flow direction or magnitude. High levels of turbulence, as indicated by high velocity root-mean square (RMS) values, exist in relatively large regions of the combustion chamber. But, the circular standard deviation, a measure of the variability in flow direction independent of velocity magnitude, is much more limited to specific regions or points, indicating much of the turbulence is from variable flow magnitude rather than variable flow direction. Using the circular standard deviation is also a promising method to identify critical points, such as vortex centers or stagnation points, within the flow, which may prove useful for future engine designers.
In-Situ Thermophysical Properties of an Evolving Carbon Nanoparticle Based Deposit Layer Utilizing a Novel Infrared and Optical Methodology
Authors: Salvi Ashwin A. , Hoard John , Styles Dan , Assanis Dennis
Published: January 2016

The use of exhaust gas recirculation (EGR) in internal combustion engines has significant impacts on engine combustion and emissions. EGR can be used to reduce in-cylinder NOx production, reduce fuel consumption, and enable advanced forms of combustion. To maximize the benefits of EGR, the exhaust gases are often cooled with liquid to gas heat exchangers. However, the build up of a fouling deposit layer from exhaust particulates and volatiles result in the decrease of heat exchanger efficiency, and increase the outlet temperature of the exhaust gases, and decrease the advantages of EGR.

This paper presents experimental data from a novel in-situ measurement technique in a visualization rig during the development of a 378 micron thick deposit layer. Measurements were performed every 6 hours for up to 24 hours. Results show a non-linear increase in deposit thickness with an increase in layer surface area as deposition continued. Deposit surface temperature and temperature difference across the thickness of the layer was shown to increase with deposit thickness while heat transfer decreased. The provided measurements combine to produce deposit thermal conductivity.

A thorough uncertainty analysis of the in-situ technique is presented and suggests higher measurement accuracy at thicker deposit layers and with larger temperature differences across the layer. The interface and wall temperature measurements are identified as the strongest contributors to the measurement uncertainty. Due to instrument uncertainty, the influence of deposit thickness and temperature could not be determined. At an average deposit thickness of 378 microns and at a temperature of 100°C, the deposit thermal conductivity was determined to be 0.044 ± 0.0062 W/mK at a 90% confidence interval based on instrument accuracy.
Characterization of N-Butanol High Pressure Injection From Modern Common Rail Injection System
Authors: Gao Tongyang , Xie Kelvin , Yu Shui , Han Xiaoye , Wang Meiping , Zheng Ming
Published: January 2016

Increasing attention has being paid to alternative fuels that have the potential to reduce overall greenhouse gas emissions and fossil fuel dependence. The alcohol fuel n-butanol, as one of the advanced biofuels, can be potentially utilized as a partial or complete substitute for the diesel fuel in diesel engines. Experimental results from literature, as well as from the authors’ previous research, have shown promising trend of low soot and nitrogen oxides emissions from the combustion with n-butanol high pressure direct injection. However, due to the significant fuel property differences between n-butanol and diesel, the fuel delivery mechanism and combustion control algorithm need to be optimized for n-butanol use. A better understanding of the high pressure n-butanol injection characteristics, such as the injector opening/closing delays and spray droplet sizes, can provide the guidance for the control optimization and insights to the empirical observations of engine combustion and emissions. Meanwhile, the experimental data could be used for the model development of the n-butanol high pressure fuel injection events.

In this work, injection rate measurement, high-speed video direct imaging, and phase Doppler anemometry (PDA) analysis of neat n-butanol and diesel fuel have been conducted with a light-duty high pressure common-rail fuel injection system. The injection rate measurement was performed with an offline injection rate analyzer at 20 bar backpressure to obtain the key parameters of the injector opening/closing delays, and the instantaneous pressure rise. The spray direct imaging was carried out in a pressurized chamber, and the PDA measurement was conducted on a test bench at ambient temperature and pressure. The injector dynamics and spray behavior with respect to the different fuels, variation of injection pressures, and variation of injection durations are discussed.
Analysis of Engine Vibration and Noise Induced by a Valve Train Element Combined With the Dynamic Behaviors
Authors: Guo J. , Cao Y. P. , Zhang W. P. , Zhang X. Y.
Published: January 2016

The engine vibration and noise induced by a valve train element are analyzed through the modeling and experiment method. The valve train dynamics are firstly studied to make clear the sources of the valve train noise. The component flexibility and inertia of mass are all taken into consideration as well as the contact or impact behaviors. The contact or impact forces are applied on the combined model of a combined structure. The resulting vibration responses at the outer surfaces are considered to be the boundary conditions of the acoustic model. The acoustic model is built by the boundary element method. The analysis results show the noise induced by the valve train element is mainly in the 500–800Hz 1/3 octave bands. The noise in this frequency range is related to not only the resonance of oil pan and valve cover but the overall combined structure stiffness. And moreover, the resonance of the valve train element excited by the harmonic of the camshaft rotational frequency has heightened the noise radiation in this frequency range. The noise in the low frequency range is determined by the exciting components of the cam profile, and that in the high frequency range are produced mainly by the valve-seat impact and by the cam-tappet impact. The analysis results are proved well by comparison with the experimental results. Thus the results are very useful for understanding the source characteristics of valve train noise.
Management of Climate Threat and External Forces Based on Knowledge Management
Authors: Aristizábal Ceballos Jaime Hernán , Rojas Martínez Janeth Andrea
Published: January 2016

Geotechnical conditions in Colombia make the Weather-related and Outside Force Threat one of the principal threats to take into account in managing hydrocarbon transmission lines. This, along with the rotation of the personnel who support the management of this threat nationwide, has led the office of the Vice-president for Transportation and Logistics (VIT) at Ecopetrol S.A. to implement a knowledge assurance strategy that will ensure the sustainability of efforts in geotechnical matters made in recent years. This paper presents the experience of how it has been possible for management of the Weather-related and Outside Force Threat, by the office of Vice-president for Transportation and Logistics of Ecopetrol S.A., to be strengthened by proposing a prospective scenario of sustainability and knowledge that for five years has been contributing to strengthening the acquisition of knowledge and the management of the threat itself.
Understanding the Relationship Between Pitch Agility and Propulsive Aerodynamic Forces in Bio-Inspired Flapping Wing Vehicles
Authors: Hasnain Zohaib , Hubbard James E. , Calogero Joseph , Frecker Mary I. , Wissa Aimy A.
Published: January 2016

Ornithopters, or flapping wing mechanical birds, represent a unique category of aerial vehicles that fill a need for small-scale, agile, long range, and payload-capable flight vehicles. This study focuses on understanding the relationship between the propulsive aerodynamic forces and pitch agility in these flapping wing vehicles. Using analytical methods, the aerodynamic moment acting upon a wing undergoing elastic flapping was calculated. A method to determine the pitch stiffness of the vehicle was then derived using a preexisting stability analysis. This method was used to demonstrate that pitch agility in flapping wing birds is intricately tied to the flapping cycle with different parts of the cycle creating stabilizing and destabilizing effects. The results indicated that pitch agility, and propulsive force generation, have a dependency on the shape of the wing, and that deformations such as bend and sweep are capable of making the vehicle more agile. Contact-aided compliant mechanisms with nonlinear stiffness were designed and inserted into the wing of an ornithopter to induce controlled morphing. These elements have varying stiffness during the upstroke and downstroke parts of the cycle which introduces an asymmetry between the two halves of the flapping cycle. The resulting flapping motion exhibited a two fold increase in horizontal propulsive force over the baseline case. A motion tracking system was used to capture the free flight response of the ornithopter in steady level flight. This information was then used to calculate the pitch stiffness of the ornithopter with a rigid spar, and, one with a nonlinear compliant element inserted into the spar to induce a desired shape change. The results revealed that an upstroke in which the aerodynamic forces are similar in magnitude to that of the downstroke, may be necessary to make the vehicle more agile, and, that there is a compromise between vehicle agility and flight propulsive forces.
Optimization of Length and Thickness of Smart Transduction Layers on Beam Structures for Control and M/NEMS Applications
Authors: Thomas Olivier , Legrand Bernard , Fuinel Cécile
Published: January 2016

This work addresses the optimization of the geometry of smart sensors and actuators on cantilever beams. Three transduction principles are studied and compared in term of efficiency: piezoelectric, electrostatic and dielectric. For the piezoelectric transduction, an active layer of a shorter length than the one of the beam is added on its surfaces. For the electrostatic transduction, the beam is made of a conducting material and it is faced with a fixed electrode at a distance called the gap. This architecture is widely used for M/NEMS (Micro/Nano ElectroMechanical Systems). The last transduction principle, new and promising, is based on the use of dielectric layers on the beam surface. In this case, the excitation is based on electrostatic forces between the charged electrodes, causing transverse deformation of the dielectric film and bending of the multilayer structure; the detection of the vibration is capacitive, based on the fluctuation of the capacitance due to the deformation of the dielectric film. This work presents the optimization of the length and the thickness of the piezoelectric/dielectric layers and, for the electrostatic case, the optimization of the length and the gap of the electrostatic cavity. The study is based on an analytic model for a laminated beam and closed-form formula of the optimization parameters (coupling factor, driving efficiency, sensing efficiency) are obtained. The application of those three transduction principles mainly focus on resonating M/NEMS sensors, whereas the case of piezoelectric transduction is also useful for vibration control of macro-structures, especially with passive shunt techniques. General results on the comparison of the transduction efficiency, as a function of the device size and of the material properties, are also derived.
Piezoelectric-Based Rotary Electrical Energy Generator for Harvesting Energy From Low and Highly Variable Rotary Motion
Authors: Wei Jun , Duan Lian
Published: January 2016

A class of piezoelectric-based rotary electrical-energy generator is presented in which a polygon-shaped gear is used to effectively couple the rotating shaft with multiple piezoelectric cantilevers. The relation between the input rotational speed and the output power production for a laboratory-scale device with an octagonal gear is systematically characterized both by experiments with DC-motor controlled rotation inputs and by finite-element analyses (FEA) with prescribed gear rotational speeds. The electric signals generated by each piezoelectric bimorph are shown in phase with each other as well as the total power output scales with the number of piezoelectric bimorphs. The generator outputs higher electric power over a significantly wider range of rotational frequencies than similar devices do using the piezoelectric transduction mechanism. The generated power increases almost linearly with the input rotational speed for input frequencies up to at least 300 RPM. The broadband feature of the present generator makes it ideal for power generation systems that operate with low frequent, broadband excitations like those that harvest energy from wind and tidal flows.
Free and Forced Vibration Analysis of Non-Local Euler-Bernoulli Beam Resting on Nonlinear Foundation
Authors: Sari Ma’en S. , Qawasmeh Bashar R.
Published: January 2016

In this study, the primary response of an Euler-Bernoulli beam resting on nonlinear elastic foundation is investigated. The beam is subjected to thermal and magnetic axial loads. The nonlocal Eringen’s elasticity theory is used to derive the mathematical model to account for the scale effect of the beam. A simply supported beam is considered in the analysis, and the multi-mode approach is used to obtain the reduced nonlinear temporal equations of motion that contain quadratic and cubic nonlinear terms. The method of multiple-scales is applied to obtain approximate analytical solutions for the nonlinear natural frequencies in addition to the primary resonance response curves. Moreover, the effective nonlinearity is obtained as a function of the natural frequencies and the coefficients of the elastic foundation. The results reveal that the scale parameter has a significant effect on the frequencies and amplitudes of the beam. The obtained results are presented over a selected range of physical parameters such as the scale effect parameter, foundation parameters, thermal and magnetic loads, and the excitation level. Time responses, phase planes and Poincaré maps are generated for the beam under consideration.
Design and Control of a Magnetorheological Elastomer Dynamic Vibration Absorber for Powertrain Mount Systems of Automobiles
Authors: Bai Xian-Xu , Xin Fu-Long , Qian Li-Jun , Kan Ping
Published: January 2016

The principle of a magnetorheological elastomer (MRE) dynamic vibration absorber (DVA) is proposed and the corresponding configuration is designed in this paper. The MRE DVA is composed of a vibration absorbing unit and a passive vibration isolation unit. The vibration absorbing unit can be utilized to mitigate the kinetic energy acting on the primary system (i.e., the system of which the vibration will be mitigated) and the passive vibration isolation unit utilized to support the primary system. The vibration absorbing unit consists of magnetic conductor, shearing sleeve, bobbin core, electromagnetic coil winding, and vulcanized MRE between the shearing sleeve and the bobbin core. The magnetic field produced by the electromagnetic coil winding starts from the bobbin core, and passes through the magnetic conductor and the shearing sleeve, then goes through the MRE and forms a closed loop. The shear storage modulus of the MRE could be tuned continuously by varying the applied current, which results in natural frequency shift of the MRE DVA. The optimal parameters of the electromagnetic circuit of the MRE DVA are calculated based on Kirchoff’s law. The finite element method is employed to validate the electromagnetic circuit of the MRE DVA and to obtain the corresponding electromagnetic characteristics. The mathematical model of the MRE DVA is also derived. In order to analyze how the parameters of the MRE DVA influence the effectiveness of the vibration control and to validate the flexibility of the control systems, the MRE DVA is employed in a powertrain mount system to replace the conventional passive mount. A single-degree-of-freedom (SDOF) dynamic model for the semi-active powertrain mount system is established. A varied step optimum algorithm is adopted to realize the vibration control of the powertrain mount system based on the MRE DVA.
Dynamic Deployment of Smart Inflatable Tsunami Airbags (TABs) for Tsunami Disaster Mitigation
Authors: Shahinpoor M. , Asanuma H.
Published: January 2016

Presented is an initial discussion on dynamic simulation of tsunami air bag deployment in connection with a number of smart inflatable and deployable structures, called tsunami air bags (TAB) that can be rather quickly set up and strongly anchored to the ocean floor to withstand the impact of a tsunami wave and thus protect the buildings and structures on shore. These dedicated inflatable smart structures are designed such that upon tsunami impact they can perform two smart deployment tasks. The first one is for the structure to deploy in the form of a porous structure containing internal folds and pockets and reconfigure due to tsunami impact to perform energy absorption by forcing the tsunami waves to pass through the porous inflatable structure forcing the tsunami waves to lose kinetic energy due to viscous drag and pressurizing the TABs. The second task is related to a special de sign of the inflatable structure that causes it to deploy to either further vertically rise or become a hollow inflatable dam upon the tsunami impact. In these endeavors a wave generation channel was designed and constructed to perform experiments and to simulate tsunami wave impacts on inflatable structures deploying from an underwater location. The initial observation indicates that TABs have a great potential to mitigate tsunami impacts.
Development Smart/Nervous Material With Novel Sensor Embedding Techniques: A Review
Authors: Butt Asad Muhammad , Mekid Samir
Published: January 2016

The paper discusses recent attempts to support the development of nervous materials based on structural health monitoring, augmented with corrective actions using actuators against any external effect or impending failure within the structure. This configuration features embedded sensors inside materials of structural importance e.g. metal and composites that could include comprehensive monitoring in terms of coverage area of the structure, variety of parameters to be measured, types of signals received and with fast information processing capabilities. Fast processing of information would allow the smart material to respond quickly and effectively to any external stimuli e.g. force, pressure or temperature. A review is provided to establish grounds to work on novel methods to embed off-the-shelf sensors for the development of smart material/structures. Actuation options have not been considered in this current review. Existing embedding technologies are reviewed for the sake of refining direction of research and possibilities on improvement of plausible methods. It is envisaged throughout this review to establish a clear understanding of the existing methods and develop improved and alternatives for performance improvement when developing smart and nervous materials.
The Influence of Mass Configurations on Bandwidth in Velocity Amplified Vibrational Energy Harvesters
Authors: O’Donoghue Declan , Frizzell Ronan , Punch Jeff
Published: January 2016

Vibrational energy harvesters offer an alternative to batteries for the autonomous powering of low power electronic devices, such as wireless sensors. Velocity amplified electromagnetic generators (VAEGs) utilise the velocity amplification effect in order to increase the output power and operational bandwidth of an electromagnetic generator, compared to linear resonators. This effect is achieved through sequential collisions in a system of free-moving masses. The velocity amplification achieved is controlled by the number of masses or degrees-of-freedom (dofs) and the mass ratio between them. An experimental investigation into the influence of mass ratio and number of dofs on the operational bandwidth of a VAEG at low frequencies (< 30 Hz) is presented herein. VAEG systems with 2-, 3- and 4-dofs are analysed for mass ratios in the range of 3:1 to 20:1 under sinusoidal forced excitation. It is shown that 3- and 4-dof configurations offer broader bandwidths than 2-dof configurations, particularly at higher mass ratios. At lower mass ratios, the bandwidths of the 3- and 4-dof configurations decrease, while the bandwidth of the 2-dof configuration increases. At a mass ratio of 3:1, the bandwidth of the 2-dof configuration approaches that of the 3- and 4-dof configurations. The highest half-power bandwidth of 9.3 Hz was achieved by the 3-dof mass ratio 20:1 system, at an acceleration of 1 g. The total voltage harvested over the frequency range 7–30 Hz is at a maximum at a mass ratio of 5:1 for the 3- and 4-dof configurations, and at 3:1 for the 2-dof configuration. The findings of this investigation will be significant in the development of future reduced scale VAEGs.
Exploiting Bi-Stability to Enhance Energy Capture From Turbulent Flows
Authors: Alhadidi Ali H. , Daqaq Mohammed F.
Published: January 2016

This paper investigates utilizing a nonlinear (bi-stable) restoring force to enhance the transduction of galloping energy harvesters in turbulent flows. To that end, a harvester consisting of a piezoelectric cantilever beam augmented with a square-sectioned bluff body at the free end is considered. Two repulsive magnets located at the tip of the beam are used to introduce the bi-stable restoring force. Turbulence is generated in a wind tunnel using static-grid structures located in the upstream of the bluff body. Three different mesh screens with square bars are designed with different bar and mesh widths to control the Reynolds numbers and associated turbulence intensity. A series of wind tunnel tests are then used to experimentally investigate the response of the harvester with and without the tip magnets. Results demonstrate that the bi-stable restoring force can be used to improve the output power of the harvester for sufficiently large turbulence intensities.
Enhanced Photocatalytic Activity of TiO2 Coatings by Heat Treatment in Carbon Powder
Authors: Guan Sujun , Hao Liang , Miyazawa Kohei , Lu Yun , Yoshida Hiroyuki , Asanuma Hiroshi
Published: January 2016

The heat treatment in carbon powder is a safe and effective strategy to enhance the photocatalytic activity of titanium dioxide (TiO2) coatings. Firstly, Ti coatings were prepared by mechanical coating operation with Ti powder on alumina balls. Secondly, the target TiO2 coatings were prepared using the prepared Ti coatings by the multi-heat treatment (pretreatment in carbon powder, oxidation in air and reduction in carbon powder). During the pretreatment, thin films of Ti2CO and micro-cracks form in the surface of the Ti coatings. The formed thin films and micro-cracks are helpful for forming a nano-fiber morphology of rutile TiO2, during the subsequent oxidation. During the reduction, oxygen vacancies generated in the lattice of rutile TiO2 are in favor of narrowing the band gap. The target TiO2 coatings with a nano-fiber morphology and the narrowed band gap, effectively enhances the photocatalytic activity by more than 3 times, compared with the pristine TiO2 coatings.
Characterization of ZnO Piezoelectric Nanowires in Energy Harvesting for Fiber-Reinforced Composites
Authors: Groo LoriAnne , Chung Howard , Yari Boroujeni Ayoub , Emami Anahita , Al-Haik Marwan , Philen Michael
Published: January 2016

Structural health monitoring can enhance reliability, increase safety, and decrease maintenance costs by detecting damage at an early stage. By taking advantage of the electromechanical coupling, piezoelectric materials have the potential to harvest energy from ambient vibration sources to provide low-power electricity for self-powered electronic devices. In comparison with other piezoelectric transducers, zinc oxide (ZnO) nanowires carry the added advantages of structural flexibility, lower cost, compactness, and lighter weight. In this study, the energy harvesting capabilities of nanoscale ZnO piezoelectric nanowires (NW) grown on the surface of glass fiber fabrics are investigated experimentally. A series of cantilevered carbon fiber beams containing a controlled amount of ZnO nanowires is evaluated. The absolute electrical energy dissipation is quantified by measuring the output power over a broad spectrum of known vibratory loads and frequencies. The maximum amount of power extracted is obtained by employing resistive impedance matching. Here, a maximum peak of ∼6.7 mV was generated when the beam containing ZnO nanowires was excited at 2.90g and connected to a 10 MΩ load. At that excitation level, a maximum of 20.0 pW was generated when an optimal resistor of 1 MΩ is connected. A tip mass of ∼0.6 gram added to the sample with ZnO NWs increased the peak-voltage by 2.21 mV and increased the peak-power by 13.3 pW. A series of DC voltage applied to the ZnO sample suggests the equivalence of poling treatment, where the dipole alignment of the ZnO NWs are disrupted. Here, a maximum peak-power of 45 pW is reported, showing promising potential of scaling-up to harvest ambient energy for low-powered electronics.
Reduction of Actuation Loads in a Self-Deploying SMA-Based Slat-Cove Filler for a Transport Aircraft
Authors: Scholten William , Hartl Darren , Strganac Thomas , Turner Travis
Published: January 2016

During low speed maneuvers such as approach and landing, a significant component of the total environmental noise produced by a typical transport aircraft is associated with flow over the airframe, termed airframe noise. A key contributor to airframe noise is the leading-edge-slat, a high-lift device. Previous work showed that a slat-cove filler (SCF) may be effective at reducing the slat noise and optimal designs for an SMA-based SCF have been determined, considering stow/deploy and aerodynamic loads as well as other constraints for two realistic airframe configurations such that actuation force was minimized as the design objective. The objective of this current work is to further reduce the actuation force required to retract the SCF by an auxiliary method. The methods considered for force reduction are 1) utilization of structural instabilities in the SCF, 2) addition of auxiliary SMA actuators, and 3) replacement of selected metallic regions of the SCF with more compliant polymer-based alternatives. These methods are investigated using finite element analysis (FEA) models based on a physical bench-top model developed previously. The FEA models are also capable of modeling contact, complex load cases, and they benefit from the use of a custom user subroutine that captures the pseudoelastic response of SMA materials. For each of the three force reduction concepts considered, design optimizations are conducted using open source optimization codes and the non-dominated sorting genetic algorithm. An overall best design is proposed.