Impedance-based non-destructive evaluation of additively manufactured parts

2017 ◽  
Vol 23 (3) ◽  
pp. 589-601 ◽  
Author(s):  
Mohammad I. Albakri ◽  
Logan D. Sturm ◽  
Christopher B. Williams ◽  
Pablo A. Tarazaga
Keyword(s):  
Complex Geometry ◽  
Cost Effective ◽  
Learning Context ◽  
Content Type ◽  
Electromechanical Impedance ◽  
Internal Porosity ◽  
Non Destructive Evaluation ◽  
The Impact ◽  
Non Destructive ◽  
Am Processes

Purpose This work proposes the utilization of electromechanical impedance measurements as a means of non-destructive evaluation (NDE) for additive manufacturing (AM). The effectiveness and sensitivity of the technique for a variety of defect types commonly encountered in AM are investigated. Design/methodology/approach To evaluate the feasibility of impedance-based NDE for AM, the authors first designed and fabricated a suite of test specimens with build errors typical of AM processes, including dimensional inaccuracies, positional inaccuracies and internal porosity. Two polymer AM processes were investigated in this work: material jetting and extrusion. An impedance-based analysis was then conducted on all parts and utilized, in a supervised learning context, for identifying defective parts. Findings The newly proposed impedance-based NDE technique has been proven to be an effective solution for detecting several types of print defects. Specifically, it was shown that the technique is capable of detecting print defects resulting in mass change (as small as 1 per cent) and in feature displacement (as small as 1 mm) in both extruded nylon parts and jetted VeroWhitePlus parts. Internal porosity defects were also found to be detectable; however, the impact of this defect type on the measured impedance was not as profound as that of dimensional and positional inaccuracies. Originality/value Compared to currently available NDE techniques, the newly proposed impedance-based NDE is a functional-based technique with the advantages of being cost-effective, sensitive and suitable for inspecting AM parts of complex geometry and deeply embedded flaws. This technique has the potential to bridge the existing gaps in current NDE practices, hence paving the road for a wider adoption of AM to produce mission-critical parts.

scholarly journals Evaluating undergraduate research conferences as vehicles for novice researcher development

2016 ◽  
Vol 7 (2) ◽  
pp. 159-177 ◽  
Author(s):  
Pauline Kneale ◽  
Andrew Edwards-Jones ◽  
Helen Walkington ◽  
Jennifer Hill
Keyword(s):  
Undergraduate Students ◽  
Undergraduate Research ◽  
Skills Development ◽  
Learning Context ◽  
Content Type ◽  
Research Conference ◽  
Researcher Development ◽  
Development Framework ◽  
Wide Range ◽  
The Impact

Purpose This paper aims to focus on the undergraduate research conference as its sphere of study and investigate the impact of significance of participation and socialisation in such activities on student attitudes and professional development. Using situated learning to theoretically position the undergraduate research conference as an authentic learning context, connection is also made with the concept of graduate attributes. Design/methodology/approach The Vitae (2014) Researcher Development Framework (RDF) is used to provide a template for charting the experiences and development of undergraduate students as researchers. This can be applied to short-term activities and programmes and to long-term career plans. The insights from 90 undergraduate students participating in three national undergraduate research conferences were obtained through interviews, and thematically analysed to map the students’ skills development against the RDF criteria. Findings Three main aspects of undergraduate research conference participation were considered particularly important by the students: the value of paper presentations, the value of poster presentations and the value of the overall conference experience. Within these themes, participants identified a wide range of skills and attributes they felt they had developed as a result of either preparing for or participating in the conferences. The majority of these skills and attributes could be mapped against the different domains of the RDF, using a public engagement lens for comparing actual with expected developmental areas. Research limitations/implications This research helps undergraduate research conference organisers construct programme content and form it in such a way that students’ skill development can be maximised prior to, and during, the course of an event. Learning developers can also use these findings to help understand the support needs of students preparing to deliver papers at such conferences. So far, little empirical research has examined students’ skills development within the undergraduate research conference arena. Originality/value The outcomes of this study show the diversity of the skills that students developed and the value of the conference format for offering networking practice and enhancing the communication skills which employers value.

Non Destructive Evaluation Based on Impedance Method Using Embedded PZT Sensor

2009 ◽  
Vol 79-82 ◽  
pp. 35-38 ◽  
Author(s):  
Dong Yu Xu ◽  
Xin Cheng ◽  
Shi Feng Huang ◽  
Min Hua Jiang
Keyword(s):  
Structural Damage ◽  
Crack Depth ◽  
Impedance Method ◽  
Impedance Spectra ◽  
Electromechanical Impedance ◽  
Non Destructive Evaluation ◽  
Increasing Trend ◽  
Impedance Technique ◽  
Impedance Curve ◽  
Non Destructive

The structural damage of mortar caused by simulated crack was evaluated using embedded PZT sensor combining with dynamic electromechanical impedance technique. The influence of embedded PZT sensors layout on detecting structural damage induced by the simulated cracks was also investigated. The results indicate that with increasing the simulated crack depth, the impedance real part of PZT sensors shift leftwards accompanying with the appearance of new peaks in the spectra. When more simulated cracks occur, the shift of the impedance curve becomes more obvious, and the amounts of new peaks in the impedance spectra also increase. RMSD indices of the structures with PZT sensors embedded in them with different layout can show the structural incipient damage clearly. With increasing more simulated cracks in the mortar structures, RMSD values of the structures with different PZT sensors layout become larger, under the same depth, RMSD indices of the structures with PZT sensor embedded transversely and horizontally in them show the increasing trend.

Part Authentication Using Indirect Electromechanical Impedance Measurements

2020 ◽  
Author(s):  
Mohammad I. Albakri ◽  
Pablo A. Tarazaga
Keyword(s):  
Numerical Solutions ◽  
Numerical Models ◽  
Impedance Measurement ◽  
Piezoelectric Transducers ◽  
Frequency Range ◽  
Impedance Measurements ◽  
Manufacturing Defects ◽  
Electromechanical Impedance ◽  
Non Destructive Evaluation ◽  
Non Destructive

Abstract Motivated by its success as a structural health monitoring solution, electromechanical impedance measurements have been utilized as a means for non-destructive evaluation of conventionally and additively manufactured parts. In this process, piezoelectric transducers are either directly embedded in the part under test or bonded to its surface. While this approach has proven to be capable of detecting manufacturing anomalies, instrumentation requirements of the parts under test have hindered its wide adoption. To address this limitation, indirect electromechanical impedance measurement, through instrumented fixtures or testbeds, has recently been investigated for part authentication and non-destructive evaluation applications. In this work, electromechanical impedance signatures obtained with piezoelectric transducers indirectly attached to the part under test, via an instrumented fixture, are numerically investigated. This aims to better understand the coupling between the instrumented fixture and the part under test and its effects ON sensitivity to manufacturing defects. For this purpose, numerical models are developed for the instrumented fixture, the part under test, and the fixture/part assembly. The frequency-domain spectral element method is used to obtain numerical solutions and simulate the electromechanical impedance signatures over the frequency range of 10–50 kHz. Criteria for selecting the frequency range that is most sensitive to defects in the part under test are proposed and evaluated using standard damage metric definitions. It was found that optimal frequency ranges can be preselected based on the fixture design and its dynamic response.

Health economic analysis of pharmaceutical inventory levels

2020 ◽  
Vol 10 (4) ◽  
pp. 603-628
Author(s):  
Peter Benjamin Ellison ◽  
Robert A. Cook
Keyword(s):  
Health Economics ◽  
Cost Effective ◽  
Current Approach ◽  
Inventory Theory ◽  
Health Economic Analysis ◽  
Content Type ◽  
Wide Range ◽  
Humanitarian Supply Chain ◽  
Demand Coverage ◽  
The Impact

PurposeHumanitarian crises increase vulnerability of children to pneumonia, so aid agencies store pharmaceuticals in advance of this demand. Decisions on how much to store are plagued by many diverse challenges as is common in humanitarian contexts, so this study considers storing more medications to improve the relatively poor (∼80) demand coverage at a representative aid agency.Design/methodology/approachThe paper combines inventory theory with health economics to calculate the impact inventory increases would have on the final cost of pneumonia treatment. It can then assess to what extent inventory can be increased while pneumonia treatment remains cost effective.FindingsThe study finds that more drug investment has only a small effect on the final treatment cost. Substantial drug inventory increases remain well within established guidelines for highly cost-effective treatments, so the agency should consider large increases as an efficient use of funding.Research limitations/implicationsThe study focuses on pneumonia treatment only to allow sufficient depth of analysis. Further research could look at many other treatments using the same approach, although some problem scenarios will include complicating parameters like drug perishability.Practical implicationsThe level of pharmaceutical inventory at humanitarian warehouses is a high-value decision for the aid sector. The method shows the potential for health economics to provide practical decision support for a wide range of humanitarian and ministry of health warehouse operations. While large increases in inventory investment are within guidelines, there is an asymptotically increasing cost as demand coverage approaches 100%. As a result, decision makers may want to set a target demand coverage (e.g. 99%) and allocate remaining aid funding to other projects.Originality/valueMany humanitarian supply chain decisions lack analytical support due to issues with complexity, scale or a lack of reliable input data, and this study is the first to provide analytical insights which can greatly improve the current approach to inventory control policies for pneumonia medications and beyond.

scholarly journals Real-time structural health monitoring for concrete beams: a cost-effective ‘Industry 4.0’ solution using piezo sensors

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Arka Ghosh ◽  
David John Edwards ◽  
M. Reza Hosseini ◽  
Riyadh Al-Ameri ◽  
Jemal Abawajy ◽  
...  
Keyword(s):  
Structural Health Monitoring ◽  
Real Time ◽  
Health Monitoring ◽  
Industry 4.0 ◽  
Concrete Beams ◽  
Low Cost ◽  
Cost Effective ◽  
Content Type ◽  
Structural Health ◽  
Non Destructive

PurposeThis research paper adopts the fundamental tenets of advanced technologies in industry 4.0 to monitor the structural health of concrete beam members using cost-effective non-destructive technologies. In so doing, the work illustrates how a coalescence of low-cost digital technologies can seamlessly integrate to solve practical construction problems.Design/methodology/approachA mixed philosophies epistemological design is adopted to implement the empirical quantitative analysis of “real-time” data collected via sensor-based technologies streamed through a Raspberry Pi and uploaded onto a cloud-based system. Data was analysed using a hybrid approach that combined both vibration-characteristic-based method and linear variable differential transducers (LVDT).FindingsThe research utilises a novel digital research approach for accurately detecting and recording the localisation of structural cracks in concrete beams. This non-destructive low-cost approach was shown to perform with a high degree of accuracy and precision, as verified by the LVDT measurements. This research is testament to the fact that as technological advancements progress at an exponential rate, the cost of implementation continues to reduce to produce higher-accuracy “mass-market” solutions for industry practitioners.Originality/valueAccurate structural health monitoring of concrete structures necessitates expensive equipment, complex signal processing and skilled operator. The concrete industry is in dire need of a simple but reliable technique that can reduce the testing time, cost and complexity of maintenance of structures. This was the first experiment of its kind that seeks to develop an unconventional approach to solve the maintenance problem associated with concrete structures. This study merges industry 4.0 digital technologies with a novel low-cost and automated hybrid analysis for real-time structural health monitoring of concrete beams by fusing several multidisciplinary approaches into one integral technological configuration.

scholarly journals Non-Destructive Evaluation Techniques and What They Tell Us about Wood Property Variation

Forests ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 728 ◽  
Author(s):  
Laurence Schimleck ◽  
Joseph Dahlen ◽  
Luis A. Apiolaza ◽  
Geoff Downes ◽  
Grant Emms ◽  
...  
Keyword(s):  
Multiple Scales ◽  
Wood Property ◽  
Wood Properties ◽  
Product Performance ◽  
Detailed Knowledge ◽  
Field Equipment ◽  
Property Variation ◽  
Non Destructive Evaluation ◽  
The Impact ◽  
Non Destructive

To maximize utilization of our forest resources, detailed knowledge of wood property variation and the impacts this has on end-product performance is required at multiple scales (within and among trees, regionally). As many wood properties are difficult and time-consuming to measure our knowledge regarding their variation is often inadequate as is our understanding of their responses to genetic and silvicultural manipulation. The emergence of many non-destructive evaluation (NDE) methodologies offers the potential to greatly enhance our understanding of the forest resource; however, it is critical to recognize that any technique has its limitations and it is important to select the appropriate technique for a given application. In this review, we will discuss the following technologies for assessing wood properties both in the field: acoustics, Pilodyn, Resistograph and Rigidimeter and the lab: computer tomography (CT) scanning, DiscBot, near infrared (NIR) spectroscopy, radial sample acoustics and SilviScan. We will discuss these techniques, explore their utilization, and list applications that best suit each methodology. As an end goal, NDE technologies will help researchers worldwide characterize wood properties, develop accurate models for prediction, and utilize field equipment that can validate the predictions. The continued advancement of NDE technologies will also allow researchers to better understand the impact on wood properties on product performance.

Sport for development and peace snakes and ladders

2015 ◽  
Vol 18 (3) ◽  
pp. 278-297 ◽  
Author(s):  
Andrew Joseph Webb ◽  
André Richelieu
Keyword(s):  
Conceptual Model ◽  
Current Knowledge ◽  
Cost Effective ◽  
Research Field ◽  
Content Type ◽  
Sport For Development ◽  
Corporate Funding ◽  
The Impact ◽  
Practical Impact ◽  
Practical Implications

Purpose – The purpose of this paper is to better understand the factors that may improve or hinder the impact of sport for development and peace projects. Sport for development and/or peace (SDP) has been described as an emerging, yet under-theorized research field (Schnitzer et al., 2013). As such, few authors have analyzed the conditions, best practices and processes needed for achieving impact on context through SDP. The purpose of this paper is to address this gap in current knowledge. Design/methodology/approach – A literature review was chosen to analyze the focus and findings of the related body of work. Findings – A conceptual model of the dominant SDP process serves as a framework to identify and analyze concepts that may influence SDP impact on context. Moreover, this conceptual model provides insight about an apparent empirical incongruity between the theoretical and practical impact of this dominant SDP process on the ground. Practical implications – This paper opens a debate around the process currently deployed by SDP agencies to influence peace and/or development. Specifically, we question if indoctrinating sport-related values into child athletes, who then somehow influence their communities, is the most cost effective process for sport to contribute to development and/or peace. Originality/value – This paper addresses the paucity of insight about concepts that SDP agencies should implement to impact context. This contribution appears significant in a context of increased competition for funding. As growing number of SDP agencies operating in emerging markets compete for rarifying corporate funding, deploying cost-effective projects for development and peace may provide SDP agencies with a competitive advantage.

Prediction of impact response in construction safety helmet using FEA

2019 ◽  
Vol 18 (3) ◽  
pp. 557-566
Author(s):  
Mohammed Rajik Khan ◽  
Atul Sonawane
Keyword(s):  
Complex Geometry ◽  
Construction Safety ◽  
Impact Response ◽  
Fe Model ◽  
Content Type ◽  
Design Engineers ◽  
Head Injury Criteria ◽  
Clear Idea ◽  
Free Falling ◽  
The Impact

Purpose This paper aims to present 3D finite element (FE) simulations of impact loading on a construction safety helmet over a headform to improve the ventilation slots profile in helmet design. Design/methodology/approach Impact response on headforms in three different studies considering ventilation slots of varied profiles and dimensions in helmets with rectangular elliptical and circular slots is compared and analysed. Head injury criteria (HIC) and safety regulations from past literature have been considered to evaluate the impact responses. Findings Simulation results show that a helmet with rectangular ventilation slots achieves a lowest peak impact force of 5941.3 N for a slot area of 170 mm2 as compared to elliptical and circular slots. Research limitations/implications Ventilation slots of simple geometry (rectangular, elliptical and circular) have been considered in this work. Other/complex geometry slots can also be chosen to predict its effect during impact response on a helmet–headform model. Biofidelic head–neck FE model can be developed to achieve precise results. Practical implications The presented work gives a clear idea to design engineers for the selection of ventilation slot profiles to design a construction safety helmet. Social implications Construction safety (CS) helmets are used to reduce injuries on heads of workers at construction sites in the event of free-falling objects. Rectangular ventilation slots in CS helmets as suggested in the work may reduce the risk of injury. Originality/value Results are found in good agreement with the past numerical simulation of impact response on a construction safety helmet over a validated biofidelic head FE model.

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