bluuebunny/crossref_metadata_2025 huggingface dataset:
Optothermal Modeling of Plasmonic Nanofocusing Structures With Nonlocal Optical Response and Ballistic Heat Transport
Authors: Chen Chen , Du Zhidong , Pan Liang
Published: December 2014

Nanoscale optical energy focusing using plasmonic structures is crucial for many applications, such as imaging and lithography. Thermal management for these nanostructures is of great importance to maintain their reliabilities but has not been investigated extensively yet, especially when the strong nonlocalities present in the nanostructures. Here, we report a multiphysics model to study the coupled optical and thermal responses of plasmonic nanofocusing structures. We applied the hydrodynamic Drude model to describe the nonlocality in the optical response and derived ballistic–diffusive equations for both electrons and phonons to model the nonlocal thermal transport. Strong nonlocal optothermal responses were observed.
Mechanical Behavior and Performance of the Onager
Authors: Messina Arcangelo , Rossi Cesare
Published: December 2014

In this paper, the mechanical behavior and performance of the onager, an ancient war machine, are analyzed. This study is based on torsional motors, as previously described. Because the onager has been investigated very little in modern times and the details given by ancient engineers are very scarce, this study starts from the available literature of both ancient and modern times. The mathematical models are developed through analytical mechanics along with integrations carried out numerically. Simulations performed provide interesting results which are in good agreement with the information recorded by ancient historians, and thus validating conjectures regarding the design of these machines. Finally, this investigation clarifies the role and effectiveness of these machines in ancient warfare, helping to understand many aspects of both ancient engineering design and historical events.
Above Ground Petroleum Product Storage Tank Fires: A Numerical Analysis of Thermal Radiation for Developing Fire Prevention Strategy
Authors: Feng Wenxing , Wu Chaopeng , Li Shuxin , Long Xiaodong , Xi Jingjun
Published: December 2014

Above ground petroleum product storage tanks are tanks or other containers that are above ground, partially buried, bunkered, or in a subterranean vault. These are built to store petroleum product for pipeline system, oilfield and refinery.

Tank fires are one of the most terrible accidents in oil pipeline transportation stations. Tank fires pose a significant hazard to people, buildings, process piping, the environment and other facilities as a result of thermal radiation exposure. It is necessary and meaningful to study the distribution of the thermal radiation of a tank fire for emergency response, prevention and reducing loss.

To analyze potential tank fire incidents at a pipeline station, a three-dimensional station model was built using a computational fluid dynamics (Abbreviated as CFD, is a branch of fluid mechanics that uses numerical methods and algorithms to solve and analyze problems that involve fluid flows) software package to evaluate the thermal radiation distribution under different conditions. Numerical simulations were carried out for a total of six simulation scenarios to analyze 3 types of potential fires for 2 different liquid products (gasoline and diesel). The three kinds of fires that were modeled included: 1) disk pool fire on top of the tank; 2) ring pool fire on the top of a tank; and 3) pool fire in a dike. The simulation evaluates the effect of the thermal radiation on facilities and people.

The simulation results show that the water cooling system is effective at decreasing the magnitude of thermal radiation exposure and as a result is effective at protecting nearby tanks and facilities. Without water protection, the disk fire or ring fire can destroy or damage nearby structures significantly. The results of the simulation also show that the dike pool fire can have a catastrophic consequence to nearby facilities. Further the analysis showed that environmental wind does not change the thermal radiation distribution significantly. The results of the simulation point out countermeasure activities to enhance fire prevention at oil pipeline transportation stations in a scientific way.
Assessment of Circumferential SCC on an Ethane Pipeline
Authors: Beauregard Yannick , Edwards Cody
Published: December 2014

This paper describes the analysis conducted on circumferential SCC found on a high vapour pressure ethane pipeline. The damaged section of pipe was located near a road crossing and was cut out before failure. A total of 146 cracks were identified with lengths ranging from a 1 mm to 50 mm. Three different techniques were evaluated for crack depth measurement: balanced field electromagnetic technique (BFET), sequential grinding, and microscopic cross-section examination. Crack depths of up to 2.6 mm (52% wall thickness) were identified. The failure pressure was determined by a burst test. The pipe began leaking at a pressure of 16 865 kPa, well in excess of the maximum operating pressure of 9930 kPa. The results of the burst test are compared to failure pressure calculations for an undamaged pipe and a pipe containing an axial crack with dimensions similar to the actual failed crack.
Pipeline Leak Detection Using Four Mode Fibre-Optic Based Distributed Sensing
Authors: Godfrey Alastair , Hill David , Minto Chris , Williams John , Worsley Jerry
Published: December 2014

Fibre-optic based Distributed Acoustic Sensing (DAS), is now commonly used around the world for providing pipeline operators with real-time and early warning of intrusions on their pipeline Right of Ways. Also open to analysis within the DAS signal return are multiple signatures derived from the egress of product leaking from pipelines. Over the last three years, focussing attention on these alternative signals, OptaSense have developed a novel 4-mode External Leak Detection capability, fusing outputs from both DAS, Negative Pressure Pulse (NPP) and Distributed Temperature Gradient Sensing (DTGS) signals (the latter not to be confused with Distributed Temperature Sensing or DTS). The first commercially deployed 4-mode Leak Detection products are now being seen on the market, for both gas and liquids pipelines.

In this paper, we report how DAS can be used to provide these four modes of leak detection — including (listed in order of typical detection latency, fastest to slowest)

i) negative pressure waves created in the pipeline product from the leak event

ii) acoustic noise from turbulent flow through the leak orifice

iii) temperature gradients in the soil due to the presence of the leaked product (positive and negative), and

iv) local strain/ground heave due to soil displacement by the leaked product.

These acoustic, temperature and strain measurements using a fibre-optic cable buried next to a pipeline can be fused together to provide highly sensitive and reliable alerts for pipeline leaks. The pipeline industry has always sought to detect smaller leaks faster, with better locational accuracy. This paper, which draws upon industry sponsored test results and commercial deployment data, provides an update to the industry on leak detection possibilities using DAS.
Safe and Successful Isolations and Interventions
Authors: Gower Stephen R. , Allen Derek C.
Published: December 2014

Pipeline isolations and interventions using hot taps and in-line isolation tools are used widely across the oil and gas industry for the maintenance of pipelines, platforms and process plants. They may also be used to facilitate tie-ins for the connection of new facilities or the diversion of operating pipelines. They require a clear understanding of risk and the factors that can lead to failure, which can have a safety, environmental or business impact affecting both the operator and supplier.

A fresh look at the risks and how they can be effectively managed was carried out. The reviews showed that whilst there was a strong emphasis on personal safety and technical standards there was a need to maintain an emphasis on overall process safety.

Using a global contract for the provision of services for isolations and interventions BP has worked closely with leading Suppliers (Furmanite, STATS Group, TD Williamson, TEAM Industrial Services) in this area to develop a framework for driving improvement and consistent delivery of these services.

The work builds on some of the best practices developed with improving success rates with In-Line Inspection (ILI) and develops the process from the definition of safe and successful isolations through to the importance of capturing lessons learnt.

The paper develops the processes for the definition of safe and successful isolations and interventions by addressing:

• Definition of success

• The engagement process and requirements for information.

• Development of a common risk model based on failure data across all of the Suppliers

• Use of effective quality management systems and key performance metrics

• Development of an industry competency framework for technicians

• Use of a clear lessons learnt process and the importance of performance reviews.

Safe and successful isolations and interventions require effective management, clear communication and systematic engagement. They are achieved through a relationship between the operator and the supplier that is built on trust, open conversation and a willingness to improve; where both operator and supplier work together with common objectives and a common understanding of risk.

The process outlined in this paper creates an opportunity to raise standards across the industry, building on knowledge, experience and best practices.
Automatic Linear Disturbance Footprint Extraction Based on Dense Time-Series Landsat Imagery
Authors: Chen Zhaohua , Jefferies Bill , Adlakha Paul , Salehi Bahram , Power Des
Published: December 2014

Linear disturbances from the construction of pipelines, roads and seismic lines for oil and gas extraction and mining have caused landscape changes in Western Canada; however these linear features are not well recorded. Inventory maps of pipelines, seismic lines and temporary access routes created by resource exploration are essential to understanding the processes causing ecological changes in order to coordinate resource development, emergency response and wildlife management. Mapping these linear disturbances traditionally relies on manual digitizing from very high resolution remote sensing data, which usually limits results to small operational area. Extending mapping to large areas is challenging due to complexity of image processing and high logistical costs. With increased availability of low cost satellite data, more frequent and regular observations are available and offer potential solutions for extracting information on linear disturbances.

This paper proposes a novel approach to incorporate spectral, geometric and temporal information for detecting linear features based on time series data analysis of regularly acquired, and low cost satellite data. This approach involves two steps: multi-scale directional line detection and line updating based on time series analysis. This automatic method can effectively extract very narrow linear features, including seismic lines, roads and pipelines. The proposed method has been tested over three sites in Alberta, Canada by detecting linear disturbances occurring over the period of 1984–2013 using Landsat imagery. It is expected that extracted linear features would be used to facilitate preparation of baseline maps and up-to-date information needed for environmental assessment, especially in extended remote areas.
Stress Analysis of Lifting and Lowering-In Process
Authors: Zhang Fan , Liu Ming , Wang Yong-Yi , Bruce William A.
Published: December 2014

For typical cross-country pipelines not expected to experience ground movement hazards, the longitudinal stresses experienced during lifting and lowering-in are typically the highest that they experience in their entire service life. Vertical bending stresses are produced by the curvature created from the upward lifting forces of the sidebooms and the downward force of the pipe weight. Horizontal bending stresses are produced due to the lateral movement of the pipe when the pipe string is moved from its support position on the side of trench to the center of the trench. It is critical to limit the stresses during lifting and lowering-in so that potential damage to the pipeline is avoided. For pipelines constructed using an engineering critical assessment (ECA) based flaw acceptance criteria, stresses must be controlled below the limit established during the development of the flaw acceptance criteria. However, there is little in the way of formal guidance in current codes and standards for controlling stresses during the lifting and lowering-in process. This paper is part of a long-term effort being sponsored primarily by Pipeline Research Council International (PRCI) to develop general construction guidelines that can be used to manage lifting and lowering-in stresses during pipeline construction. In this paper, the stresses during lifting and lowering-in on normally flat terrain were studied. The component of stress due to bending in the horizontal plane was determined through an analytical method. The component of stress due to the bending in the vertical plane was studied by finite element analysis (FEA). The FEA determined the stresses under various profiles. Recommended lifting profiles in the format of lifting height ranges were developed. The combined stress was then determined from the two components. In addition, FEA was used to simulate the lifting and lowering-in process of a pipe string including a field side bend. The results show that the side bend produces a very slight increase in the stress level. More work is being performed to investigate various other scenarios of field and pipe string conditions.
Learnings From Implementing a Management System Approach to Managing Research and Development (R&D): A Case Study on Implementing Structured Processes
Authors: Taylor Seema , Sahney Reena , Jonsson Katherine , Robeson Nicole
Published: December 2014

Enbridge Pipelines believes that a strong research and development (R&D) program is critical to ensure leading-edge safety and operational practices. As such, the Pipeline Integrity Department has launched an initiative to clearly identify, develop, and manage processes and practices to improve the transfer of knowledge from its R&D program to key operational challenges.

The Integrity Solutions group within the Pipeline Integrity Department supports the R&D program from idea generation to operationalization (including knowledge integration) into existing programs. This approach begins with scanning the horizon to enable future opportunity areas and challenges to be captured through facilitation of “blue sky sessions”. Technology roadmaps are developed for each major threat category and used to prioritize R&D projects. Project execution is managed from project proposal to close-out through a stage-gate style process that allows the department to plan, organize, and execute projects that directly link to integrity-related threats. The final stage is operationalization, where R&D knowledge is transferred into pipeline operation practices and project execution lessons learned are captured and addressed.

Through execution of the overall process supporting multi-year initiatives, Pipeline Integrity has gained experience and insight into specific strategies and tactics that are effective in overcoming the barriers presented in a well-managed R&D Program. This insight will be shared as a summary of a successful and practical management system approach to R&D initiatives.

This paper describes the Management System approach:

• Requirements: expectations and requirements for managing R&D.

• Design: developing the system.

• Implementation: deployment of the system.

• Performance: data collection and reporting.

• Continuous Improvement: analysis of results and lessons learned, including next steps.
Full Gas Burst Test for HFW Linepipe at Low Temperature
Authors: Igi Satoshi , Yabumoto Satoru , Mitsuya Masaki , Sumikura Yuya , Takeuchi Mikihiro
Published: December 2014

A full gas burst test at low temperature below −40°C was performed using a high frequency welded (HFW) linepipe with high-quality weld seam, “MightySeam®,” [1–4] in order to verify the applicability of the Drop Weight Tear Test (DWTT). Residual stress exists in the pipe body of HFW linepipe because the manufacturing method includes a sizing process. Therefore, it is necessary to clarify the difference between the arrestability in the DWTT without residual stress in the specimen and that in the full gas burst test with residual stress in the pipe body.

The full gas burst test is performed using a test pipe specimen in which a notch is introduced into the base material by an explosive cutter. In addition, a test pipe specimen with a notch introduced into the weld seam was used in this study because the developed HFW linepipe, “MightySeam®,” has excellent low-temperature toughness as a result of control of the morphology and distribution of oxides generated in the welding process by temperature and deformation distribution control. The Charpy transition temperature of “Mighty Seam®” was much lower than −45 °C.

Ductile cracks were initiated from the initial explosive notch, and these cracks were arrested after ductile crack propagation of about 1 m in base material on both sides. The fracture behavior was similar in appearance in the DWTT without residual stress and the full gas burst test with residual stress.
Development and Prioritization Portfolio of Natural-Gas Compression-Station Projects
Authors: Candian Lívia Matheus , Alves Leandro da Rosa , Amorim Ana Gabriela Portela , Pires Flavio Dupim
Published: December 2014

The Compression Stations constructions were finished between 2009 and 2011 by PETROBRAS Engineering Department. TRANSPETRO had taken part in the whole design process, and is now responsible for the operation and maintenance of these stations, which were delivered with some items pending categorized as improvements.

The principle objective of this study is to choose and adapt a method, based on portfolio management methodology, to undertake a portfolio of Natural-Gas Compression-Station projects with decision making supported by standardized criteria and developed scenarios, so that the needs of the company are satisfied with a good cost/benefit relationship.

The Analytic Hierarchy Process was the method chosen for prioritization and selection of projects to be undertaken from the portfolio. The necessity to adapt this method to insert new projects throughout the year into the current portfolio was identified in order to attend the operational and maintenance demands.
The Misconception of Employing CVN Toughness as Key-Measure in Ductile Crack Arrest Prediction for Modern Line-Pipe Steels
Authors: Völling Alexander , Kalwa Christoph , Erdelen-Peppler Marion
Published: December 2014

Since the late 1960s’ the Battelle Two-curve (BTC) model is the standard method applied in setting up design requirements with regard to the prevention of long-running ductile fracture in pipelines. It is a straightforward tool employing Charpy-V notch (CVN) toughness as key-measure for material resistance against crack propagation. On basis of pipe dimensions, material strength, and under consideration of decompression behavior of the transferred media, it enables to set up requirements for a minimum CVN toughness level to achieve crack arrest. Overall applicability of the BTC model is based on calibration of the underlying equations to a sound data-base, including both full-scale burst test results and small-scale laboratory testing data involving typical line-pipe grades at that period, i.e. up to grade X70 steels with below 100 J upper-shelf CVN toughness. Now over the last decades, mechanical behavior of line-pipe steels was improved significantly. Responding to market demands, higher grades were designed and also toughness levels were raised as outcome of R&D efforts within the steel industry. Unfortunately, stepping outside the original material data-base from BTC model calibration, this method did forfeit its reliability. At the beginning, mispredictions were mainly related to higher grade steels and elevated operating pressures. But more recent full-scale tests did reveal discrepancies in application of the BTC model also for so-called new vintage steels, i.e. grades actually being inside the original data base for model calibration but from current production routes.

With regard to applicability/reliability of BTC model based predictions for crack arrest, the origin of uncertainty has particularly been traced back to the involved material toughness measure. Nowadays, it is common sense that the CVN upper-shelf toughness value inadequately describes the resistance against running ductile fracture. More recent thoughts coherently argue towards closer involving stress-strain response and plastic deformation capacities of the material. On basis of results for grades X65, X80 and X100, the general relation between ductility and toughness is discussed. Finally, an elastic-plastic fracture mechanics related analytical approach is introduced which enables to quantify the resistance against ductile fracture propagation. The objective is to provide a reliable procedure for crack arrest prediction in line-pipe steels.
Managing Water Crossings From an Operator’s Perspective
Authors: Nguyen Nikki , Ireland Yvanna
Published: December 2014

Effectively managing watercourse crossings is critical for pipeline operators since a failure in a watercourse can not only cause significant environmental damage, but it can also affect the safety of the public and damage public perception. This paper describes the steps that two liquids operating pipeline companies, Spectra Energy Liquids and Kinder Morgan Canada, take in the management of their watercourse crossing programs. It describes four main phases of the program including taking inventory of the water crossings, completing a hazard assessment of the water crossings to determine which hazards could pose a threat to the pipeline integrity if the crossings were to become exposed, completing engineering assessments to determine the actual risk of failure from static or dynamic loading or vortex shedding if the pipe were to become exposed, and finally prioritizing the mitigation of water crossings. This paper also describes steps to be taken to ensure the integrity of the pipeline during flood events.
Girth Weldability Evaluation of SAWH Pipes Produced From 23.7mm Thick, High-Nb Containing X70 Linepipe Steel
Authors: Güngör Özlem E. , Liebeherr Martin , Luccioni Hervé
Published: December 2014

In the energy market, there is an increasing demand for oil & gas transmission pipelines with larger wall thicknesses and from higher strength linepipe steels. Addition of niobium (Nb) to the steel chemistry in combination with thermo-mechanical controlled processing allow increasing the thickness of the linepipe steels on coil while maintaining good strength and toughness. However, pipeline construction companies often indicate their concerns about the weldability of high Nb containing linepipe steels and in addition, Nb levels are restricted in some of the steel specifications for linepipe applications.

In this study, field weldability of industrially produced helical pipes made from 23.7 mm thick, high Nb containing X70 linepipe steel was evaluated. Welding procedure development was realized for narrow-groove mechanized gas metal arc welding (GMAW). Characterization of the girth welds produced revealed the suitability of the material for typical field welding procedures for onshore pipe laying. The details and the results of the investigations are presented and discussed in the paper.
Using FRP Wraps to Reinforce Buried Steel Pipelines Subjected to Permanent Ground Deformations: A Feasibility Study
Authors: Mokhtari Mojtaba , Nia Ali Alavi
Published: December 2014

In the present paper, the concept of using fiber reinforced polymer (FRP) wraps to reinforce buried steel pipelines subjected to permanent ground deformations is studied. For this purpose, the carbon-epoxy composite wrap is used on the API 5L grade X65 pipeline. Mechanical behavior of buried pipelines under strike-slip faulting is investigated using nonlinear finite element code ABAQUS. According to defined performance criteria, critical fault displacements for different thicknesses of the composite wraps and internal pressures are specified and percentage of increase in critical fault displacement compared to the non-wrapped condition is calculated. Using composite wraps with thicknesses of 1 mm and 9 mm on pressurized pipeline with diameter to thickness ratio of 96 increases the value of critical fault displacement up to 88% and 772%, respectively. According to results obtained from the present study, the concept of using FRP wraps to reinforce buried steel pipelines under permanent ground deformations can be implemented.
Modelling Shallow Dents Using Local Regression Methods and Finite Element Analysis
Authors: Lockey Aaron , Santamaria Wilson , Gonzalez Gustavo
Published: December 2014

Modern in-line inspections can detect shallow dents in pipelines, with depths less than 2% of pipeline diameter. These dents are very common in thin-walled, small diameter refined and multiproduct lines, and frequently coincide with longitudinal welds and girth welds.

Traditional dent assessment methods (such as the EPRG approach) can be conservative. Dents can have short predicted fatigue lives, but shallow dents are not known to be a major cause of pipeline failure, unless they are associated with a weld, a gouge, a crack, or severe pressure cycling. The conservatism affects both static failure assessments and fatigue assessments, resulting in high repair rates for shallow dents. This conservatism is partly due to:

• Limitations of how the dent shape is modelled in the assessment methods;

• Simplifications of the modelling of the stresses range;

• Limitations of the calculation of strains in a dent based on inspection measurements;

• Inability to model the changing cyclic stress range with changing dent shape.

This paper shows that high resolution geometry inspection data contains irregularities which need to be filtered and smoothed. Advanced local regression methods are shown to give effective smoothing by removing errors but retaining the important elements of the real dent shape. The smoothed dent shape is used with the strain estimation methodology given by ASME B31.8 Appendix R, and an appropriate strain limit (based on likely weld quality), to assess whether cracking is likely to have initiated during dent formation.

A methodology is then presented, based on Finite Element Analysis (FEA), which improves the accuracy of cyclic stress assessments of shallow smooth dents. The FEA model geometry is provided by the smoothed version of the measured dent shape. The pressure at which the dent shape was measured affects the calculated dent shape and stress as internal pressure varies: this effect is included in the model. The calculated cyclic stresses are used with S-N curves, such as those in BSI PD 5500, to estimate dent fatigue life.

This methodology is then applied to 88 dents in two pipelines operated by ExxonMobil in the UK, using detailed high resolution geometrical in-line inspection data, comprehensive pressure cycle measurement data and enhanced dent assessment using the FEA method. It is concluded that this methodology can significantly improve the operator’s pipeline integrity strategy.
Pipeline Safety Targets and the Connection to Social License
Authors: Kresic Walter , LeBlanc Len , Harron Lorna
Published: December 2014

While North American pipeline integrity codes and regulations provide substantive prescriptive or goal setting objectives, there currently is not a consistent measurement approach for defining the levels of safety achieved. Standardized targets would drive consistent operator safety culture, enhance transparency for the public, and focus industry collaboration on technologies and innovation.

This paper provides the perspective of an operator on current status of where the pipeline industry is related to safety targets and social license in addition to where the pipeline industry could go in this arena. The intent is a ‘call to action’ for the leaders in the pipeline industry to collaborate on the establishment of the technical systems which define the current industry safety condition, the targets that must be achieved, and to show that the industry is innovating for further improvements; elements considered to be important to the achievement of social license.

A review of the current practices as well as a framework for industry advancement and advocacy will be explained. This will include an examination of safety measurement systems from around the world including other notable industries such as aviation and nuclear. Several measurement models will be highlighted including qualitative, semi-quantitative and quantitative. Importantly, this paper will highlight how operators, regulators, and codes organizations can link together for this common purpose and contribute to “social license”.
Modelling and Validation of a Rotary Motor Combining Shape Memory Wires and Overrunning Clutches
Authors: Scirè Mammano Giovanni , Dragoni Eugenio
Published: December 2014

The paper presents the conceptual design, modeling and prototyping of a novel rotary motor based on shape memory alloy (SMA) wires. The basic architecture of the device capitalizes on a SMA wire wound around a low-friction cylindrical drum. The backup force to the SMA wire is provided by a beam spring which generates a nearly-constant force tangential to the drum. The electrical activation of the wire produces a contraction of the wire, hence a rotation of the drum fitted to the shaft through an overrunning clutch (free wheel). Thanks to the overrunning clutch, during the backup phase (recoiling of the wire), the drum rotates backward while the shaft does not move. Spurious backward movements of the shaft are contrasted by a second overrunning clutch linking the shaft to the frame. The paper presents a model for the quasi-static simulation of the motor and the experimental characterization of a prototype device featuring three active drums, a rotary sensor and an angular brake to apply the external load.
Determination of Angular Position in a Shape Memory Alloy Based Rotary Manipulator Using an Artificial Neural Network
Authors: Narayanan Pavanesh , Elahinia Mohammad
Published: December 2014

Shape memory alloys (SMA) when subjected to deformation at low temperature can recover their original shape by heating above a temperature called Austenite transformation temperature. This original shape is sustained till the material is deformed again by an applied stress. This property makes the SMA a unique actuator, which doesn’t require any other components. Also, the material’s resistance changes with deformation. Thus the change in resistance can be used to sense the deformation, which eliminates the requirements of additional sensors. This can make the system more compact and reduce the cost. In our study, a binary Nickel-Titanium alloy is used as a rotary actuator. The actuation is controlled by adjusting the temperature through controlled joule heating by varying the electric current. The manipulator used in this research is a single degree-of-freedom, bias type actuator. SMA actuation in this system is under a varying stress, thereby creating a complex thermo-mechanical condition which affects the transformation temperatures, significantly. Also, the resistance change during heating and cooling paths exhibit hysteresis behavior. This paper investigates the use of artificial neural network (ANN) in establishing relationship between resistance and angular position of the manipulator. To model the hysteresis behavior of the SMA, in addition to resistance of the SMA, other electric properties like voltage etc are given as input to the ANN. The obtained ANN model is able to determine the angular position of the rotary manipulator with good accuracy.
Chaotification as a Means of Broadband Energy Harvesting With Piezoelectric Materials
Authors: Geiyer Daniel , Kauffman Jeffrey L.
Published: December 2014

Component miniaturization and reduced power requirements in sensors have enabled growth in the field of low power ambient vibration energy harvesting. This work aims to increase bandwidth and power output beyond current techniques by inducing chaotic nonlinear phenomena and applying a low-power OGY controller to stabilize a chosen periodic orbit. Previously, researchers used a nonlinear piezomagnetoelastic beam in search of a large amplitude broadband voltage response, but chaos was strictly avoided. Including chaos as a desirable property allows small perturbations to alter the behavior of a system dramatically. The nonlinear piezomagnetoeleastic beam element described by a Duffing oscillator is extended to embrace chaotic motion more actively. By driving motion along a chaotic attractor, even a single excitation frequency results in a theoretically infinite number of unstable periodic orbits that can be stabilized through control. The chosen orbit will be accessible from a large range of input excitation frequencies, potentially expanding the bandwidth of operation.
Ultra-Long Barium Titanate Nanowire Arrays for Low Frequency Energy Harvesting Applications
Authors: Koka Aneesh , Sodano Henry A.
Published: December 2014

Piezoelectric nanowires (NWs) have recently attracted immense interest due to their excellent electro-mechanical coupling behavior that can efficiently enable conversion of low-intensity mechanical vibrations for powering or augmenting batteries of biomedical devices and portable consumer electronics. Specifically, nano-electromechanical systems (NEMS) composed of piezoelectric NWs offer an exciting potential for energy harvesting applications due to their enhanced flexibility, light weight, and compact size. Compared to the bulk form, high aspect ratio NWs can exhibit higher deformation to produce an enhanced piezoelectric response at a lower stress level. NEMS made of conventional semiconducting vertically aligned, ZnO NW arrays have been investigated thoroughly for energy harvesting; however, ZnO has a lower piezoelectric coupling coefficient as compared to many ferroelectric ceramics which limits its piezoelectric performance. Amidst lead-free ferroelectric materials, environmentally-friendly barium titanate (BaTiO3) possesses one of the highest piezoelectric strain coefficients and thus can enable greater energy transfer when used in vibrational energy harvesters. In this paper, a novel NEMS energy harvester is fabricated using ultra-long (∼40 μm long), vertically aligned BaTiO3 NW arrays which has a low resonant frequency (below 200 Hz) and its AC power harvesting capacity from low amplitude base vibrations (0.25 g) is demonstrated. The design and fabrication of low resonant frequency vibrational energy harvesters has been challenging in the field of MEMS/NEMS since the high stiffness of the structures results in resonant frequency often greater than 1 kHz. However, ambient mechanical vibrations usually exist in the 1 Hz to 1 kHz range and thus highly complaint ultra-long, NW arrays are beneficial to enable efficient energy conversion. Through the use of this newly developed synthesis process for the growth of highly compliant, ultra-long BaTiO3 NW arrays, it is shown that piezoelectric NWs based NEMS energy harvesters capable of harnessing this low frequency ambient vibrational energy can be conceived.
Concept for a Deployable Wing
Authors: Lachenal Xavier , Weaver Paul M. , Pirrera Alberto
Published: December 2014

A concept for a novel folding wing is presented, which, using the Brazier effect, can snap from a stable, extended position to a folded configuration. A wing typical of size used in an unmanned aircraft vehicle (UAV) is examined, including manufacturing aspects as well as an analytical and a finite element model (FEM) of the structure. The wing is simply made of a glass fiber reinforced plastic (GFRP) skin stiffened by ribs at regular intervals. At the mid-span location, a cut-out is made in the leading and trailing edge in order to allow the pressure and suction sides of the wing to collapse inward when folding occurs (due to Brazier effect). The analytical model draws upon work from Brazier to predict the maximum bending moment the folding section can withstand before buckling. A FEM, using a quasi-static analysis and requiring a contact definition to allow the wing surfaces to meet, reproduces with accuracy the folding pattern seen on the prototype. A bending test of the demonstrator confirmed the validity of the models in terms of bending stiffness, bending snap through and folding radius of curvature.
Shape Memory Polymers: Energy Method Superposition Constitutive Modeling
Authors: Balogun Olaniyi A. , Mo Changki
Published: December 2014

Shape memory polymers (SMPs) have the capacity to stored strain energy under appropriate stimulus and pre-deformation conditions. Temperature is a good stimulus and predominantly used to activate the shape memory effects of SMPs. Complex engineering application use of SMPs are being developed or proposed and it becomes imperative to develop a simple but yet practical constitutive model that will capture the deformation and recovery of SMPs appropriately under different constraints and loading conditions. In this study, a thermo-mechanical constitutive model is developed for SMPs. A four step shape memorization and recovery is considered and a thermo-mechanical energy balance (first principles of thermodynamics) is done on the individual steps. For this study, the four steps considered are a) Pre-loading of the SMP at high temperature b) Constant strain at negative rate of change of temperature c) constraint release and shape fixity at low temperate and d) unconstrained free strain recovery. A free energy function is developed for the individual steps and superposition principle is used to define the storage free energy in the third step. Applying the second law of thermodynamics in Clausius-Duhem form, the stress-strain relation was developed. Also, in order to account for the polymer’s molecular architecture and morphology resulting in shape memory effect, a binding factor was approximately defined. The binding factor is primarily a function of temperature and secondarily a function of the viscosity of the material at high and low temperatures. The storage strain was assumed to be an internal variable that is generated from the mechanical loading of the SMP. The general model is reduced down to a specific viscoelastic model based on the assumption of the free energy function. The developed model is validated by comparing the predictions to experimental results in literature.
Mechanical Behaviour of Magnetic Silly Putty: Viscoelastic and Magnetorheological Properties
Authors: Spaggiari Andrea , Golinelli Nicola , Dragoni Eugenio
Published: December 2014

In this work the mechanical and viscoelastic properties of the magnetic Silly Putty are investigated. Silly Putty is a non-Newtonian material whose response depends on the rate at which it is deformed. For a rapid deformation it behaves as an elastic solid while over a relatively long time scale stress, the polymer molecules can be untangled and it flows as a fluid. The purpose of this paper is to study the behaviour of this material firstly under a quasi-static compression and shear and secondly under a dynamic shear loading. The Silly Putty under study presents a volume fraction of ferromagnetic particles. Hence, both quasi-static and dynamic stress are coupled with several values of magnetic field in order to assess the influence on the mechanical and viscoelastic properties of magnetic Silly Putty. The approach adopted in this work was based on a Design of Experiment technique so that evaluating the influence of the variables involved and their interactions is possible. The results highlight a strong dependence on the deformation rate while the influence of the magnetic field is weak especially under dynamic shear tests in which the highest deformation are predominant.
Recent Advances in Materials Development for Emerging SMA Applications
Authors: Coda Alberto , Cadelli Andrea , Butera Francesco
Published: December 2014

Shape Memory Alloys (SMAs) are active metallic materials classified as “smart” or “intelligent” materials along with piezoelectric ceramic and polymers, electro-active plastics, electro-rheological and magneto-rheological fluids and others. SMAs show a multitude of different and dependent properties interesting for technological applications. These properties depend on the peculiar deformation mechanisms, accounting for the so-called shape memory effect. SMAs are nowadays used in quite different fields, like thermo-mechanical devices, anti-loosening systems, biomedical applications, mechanical damping systems, in some cases employed for large scale civil engineering structures. These multifunctional materials can be naturally considered as sensor-actuator elements demonstrating large possibilities for applications in high-tech smart systems. The use of SMAs in actuators offers an excellent technological opportunity to develop reliable, robust, simple and lightweight elements within structures or as stand-alone components that can represent an alternative to electro-magnetic actuators commonly used in several fields of industrial applications, such as automotive, appliances, consumer electronics and aerospace. NiTi-based SMAs demonstrated to have the best combination of properties, especially in terms of the amount of work output per material volume and the large amount of recoverable stress and strain. However, there are several limiting factors to a widespread diffusion of SMAs to technological fields. For instance, SMAs display a critical dependence of the shape-memory related properties, like transition temperatures, on their actual composition. For this reason, a great care in the production steps, mainly based on casting processes, is required. Another critical aspect, that is to be considered when dealing with SMAs, is the strong influence of their thermo-mechanical history on their properties. This may disclose interesting perspectives of application to smart devices in which different aspects of the shape memory phenomenology, like one and two way shape memory effect, pseudoelasticity, damping capacity, etc., are used. Last, but not least, one of the most debated aspects around NiTi alloys is microcleanliness. This concept is becoming increasingly important as the industrial market moves to smaller, lower profile devices with thinner structures.

In this work a general overview about the peculiar behavior of NiTi alloys along with their main issues, the shape memory components under development, and the main efforts and directions for materials improvement will be presented and discussed. A bird’s-eye view on the future opportunities of NiTi-based shape memory actuators for industrial applications will also be given.
Structural Optimization and Form-Finding of Cylindrical Shells for Targeted Elastic Postbuckling Response
Authors: Hu Nan , Burgueño Rigoberto , Lajnef Nizar
Published: December 2014

This paper presents a finite element based numerical study on controlling the postbuckling behavior of thin-walled cylindrical shells under axial compression. With the increasing interest of various disciplines for harnessing elastic instabilities in materials and mechanical systems, the postbuckling behavior of thin-walled cylindrical shells may have a new role to design materials and structures at multiple scales with switchable functionalities, morphogenesis, etc. In the design optimization approach presented herein, the mode shapes and their amplitudes are linearly combined to generate initial geometrical designs with predefined imperfections. A nonlinear postbuckling finite element analysis evaluates the design objective function, i.e., the desired postbuckling force-displacement path. Single and multi-objective optimization problems are formulated with design variables consisting of shape parameters that scale base eigenvalue shapes. A gradient-based algorithm and numerical sensitivity evaluations are used. Results suggest that an optimized shape for a cylindrical shell can achieve a targeted response in the elastic postbuckling regime with multiple mode transitions and energy dissipation characteristics. The optimization process and the obtained geometry can be potentially used for energy harvesting and other sensing and actuation applications.
New Insights Into the Performance and Optimization of Galloping Flow Energy Harvesters
Authors: Bibo Amin , Daqaq Mohammed F.
Published: December 2014

This paper presents a generalized formulation, analysis, and optimization of energy harvesters subjected to galloping and base excitations. The harvester consists of a cantilever beam with a bluff body attached at the free end. A nondimensional lumped-parameter model which accounts for the combined loading and different electro-mechanical transduction mechanisms is presented. The aerodynamic loading is modeled using the quasi-steady assumption with polynomial approximation. A nonlinear analysis is carried out and an approximate analytical solution is obtained. A dimensional analysis is performed to identify the important parameters that affect the system’s response. It is shown that the response curves of the harvester can be generated in terms of only three dimensionless loading parameters. These curves can serve as a complete design guide for scaling and optimizing the performance of galloping-based harvesters. As a special case study, a harvester subjected to only galloping excitations is analyzed. It is shown that, for a given shape of the bluff body and under quasi-steady flow conditions, the harvester’s dimensionless response can be described by a single universal curve irrespective to the geometric, mechanical, and electrical design parameters of the harvester. The universal curve is utilized to obtain the optimal harvesting circuit design parameters, that minimize the cut-in wind speed and maximize the output power, and predict the harvester’s total conversion efficiency.
Concurrent Vibration Suppression and Energy Harvesting Using Ferrofluids: An Experimental Investigation
Authors: Alazemi Saad F. , Bibo Amin , Daqaq Mohammed F.
Published: December 2014

This paper presents an experimental study which examines the design parameters affecting the performance characteristics of a Tuned Magnetic Fluid Damper (TMFD) device designed to concurrently mitigate structural vibrations and harvest vibratory energy. The device which is mounted on a vibrating structure, consists of a rectangular container carrying a magnetized ferrofluid and a pick-up coil wound around the container to enable energy harvesting. Experiments are performed to investigate the three-way interaction between the vibrations of the structure, the sloshing of the fluid, and the harvesting circuit dynamics. In particular, the tuning and optimization is examined for several design parameters including magnetic field spatial distribution and intensity, winding direction, winding location, winding density, and ferrofluid height inside the tank. The experimental response of the device is compared against the conventional TMFD at different excitation levels and frequencies. Results demonstrating the influence of the significant parameters on the relative performance are presented and discussed in terms of vibration suppression and power generation capabilities.