Capacitive Imaging for Adhesive Bonds and Quality Evaluation

2020 ◽  
Author(s):  
Xuhui Huang ◽  
Ciaron Hamilton ◽  
Zonglin Li ◽  
Lalita Udpa ◽  
Satish S. Udpa ◽  
...  
Keyword(s):  
Dielectric Property ◽  
Electrical Properties ◽  
Structural Integrity ◽  
Capacitance Measurement ◽  
Adhesive Bonds ◽  
Mechanics Of Materials ◽  
Abrupt Changes ◽  
Practical Standpoint ◽  
Degraded Adhesion

Defective adhesive bonds pose significant threats towards structural integrity due to reduced joint strength. While the nature of the adhesion of two solids remains poorly understood since adhesion phenomenon is relevant to so many scientific and technological areas. A concept that has been gaining our attention from the perspective of nondestructive testing is the properties discontinuity of the adhesion. Discontinued properties depend significantly on the quality of the interface that is formed between adhesive and substrate. In this research, discontinued electrical properties at the interface are considered. The simplified model is free from multidisciplinary knowledge of chemistry, fracture mechanics, mechanics of materials, rheology and other subjects. From a practical standpoint, this emphasizes the need to establish a good relationship between electrical properties of adhesive bonds and corresponding measurements. Capacitive Imaging (CI) is a technique where the dielectric property of an object is determined from external capacitance measurements. Thus, it is potentially promising since adhesive and substrate differ in terms of dielectric property. At the interface between adhesive and substrate, discontinuity of the dielectric properties causes abrupt changes in electric field spatial distribution and thus alters capacitance measurement. By simulating defects in adhesive joints regarding permittivity uncertainties. Further understanding of the cause of degraded adhesion quality can be obtained

Capacitive imaging for adhesive bonds and quality evaluation

2020 ◽  
Vol 378 (2182) ◽  
pp. 20190590
Author(s):  
Xuhui Huang ◽  
Ciaron Hamilton ◽  
Zonglin Li ◽  
Lalita Udpa ◽  
Satish S. Udpa ◽  
...  
Keyword(s):  
Dielectric Property ◽  
Electrical Properties ◽  
Structural Integrity ◽  
Capacitance Measurement ◽  
Destructive Testing ◽  
Adhesive Bonds ◽  
Mechanics Of Materials ◽  
Practical Standpoint ◽  
Degraded Adhesion ◽  
Non Destructive

Defective adhesive bonds pose significant threats towards structural integrity due to reduced joint strength. The nature of the adhesion of two solids remains poorly understood since the adhesion phenomenon is relevant to so many scientific and technological areas. A concept that has been gaining our attention from the perspective of non-destructive testing is the properties discontinuity of the adhesion. Discontinued properties depend significantly on the quality of the interface that is formed between adhesive and substrate. In this research, discontinued electrical properties at the interface are considered. The simplified model is free from multidisciplinary knowledge of chemistry, fracture mechanics, mechanics of materials, rheology and other subjects. From a practical standpoint, this emphasizes the need to establish a good relationship between electrical properties of adhesive bonds and corresponding measurements. Capacitive imaging (CI) is a technique where the dielectric property of an object is determined from external capacitance measurements. Thus, it is potentially promising since adhesive and substrate differ in terms of dielectric property. At the interface between adhesive and substrate, discontinuity of the dielectric properties causes abrupt changes in electric field spatial distribution and thus alters capacitance measurement by simulating defects in adhesive joints regarding permittivity uncertainties. Further understanding of the cause of degraded adhesion quality can be obtained. This article is part of the theme issue ‘Advanced electromagnetic non-destructive evaluation and smart monitoring’.

scholarly journals Does Tenure Security Reduce Disaster Risk? A Comparative Study of the Nairobi Settlements of Kibera and Kawangware

2021 ◽  
Author(s):  
Rónán McDermott ◽  
Pat Gibbons ◽  
Dalmas Ochieng ◽  
Charles Owuor Olungah ◽  
Desire Mpanje
Keyword(s):  
Structural Integrity ◽  
Disaster Risk ◽  
Comparative Case Study ◽  
Complex Relationship ◽  
Tenure Security ◽  
Household Level ◽  
Urban Informal Settlements ◽  
The Relationship

AbstractWhile scholarship suggests that improving tenure security and housing significantly reduces disaster risk at the household level within urban settings, this assertion has not been adequately tested. Tenure security can be conceived as being composed of three interrelated and overlapping forms: tenure security as determined by legal systems; de facto tenure security; and tenure security as perceived by residents. This article traces the relationship between tenure security, the quality of housing, and disaster risk on the basis of a mixed methods comparative case study of the settlements of Kawangware and Kibera in Nairobi. Although the findings suggest that owner-occupancy is associated with the structural integrity of dwellings to a greater extent than tenantship, no association was found between the length of occupancy by households and the structural integrity of the dwelling. Moreover, tenantship is not found to be closely associated with fires and flooding affecting the dwelling as extant scholarship would suggest. Formal ownership is linked with greater investment and upgrading of property with significant implications for disaster risk. Our findings highlight the complex relationship between tenure security and disaster risk in urban informal settlements and provide impetus for further investigation.

Effect of Crystallographic Quality of Grain Boundaries on Both Mechanical and Electrical Properties of Electroplated Copper Thin Film Interconnections

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Naokazu Murata ◽  
Naoki Saito ◽  
Kinji Tamakawa ◽  
Ken Suzuki ◽  
Hideo Miura
Keyword(s):  
Electrical Properties ◽  
Grain Boundaries ◽  
Fatigue Fracture ◽  
High Crystallinity ◽  
Mechanical And Electrical Properties ◽  
Copper Interconnection ◽  
Electroplated Copper ◽  
Two Parameters ◽  
Low Crystallinity

Effects of crystallographic quality of grain boundaries on mechanical and electrical properties were investigated experimentally. A novel method using two parameters of image quality (IQ) and confidence index (CI) values based on electron back-scattering diffraction (EBSD) analysis was proposed in order to evaluate crystallographic quality of grain boundaries. IQ value was defined as an index to evaluate crystallinity in region irradiated with electron beam. CI value determined existence of grain boundaries in the region. It was found that brittle intergranular fatigue fracture occurred in the film without annealing and the film annealed at 200 °C because network of grain boundaries with low crystallinity remained in these films. On the other hand, the film annealed at 400 °C caused only ductile transgranular fatigue fracture because grain boundaries with low crystallinity almost disappeared. From results of measurement of electrical properties, electrical resistivity of copper interconnection annealed at 400 °C with high crystallinity (2.09 × 10−8 Ωm) was low and electron migration (EM) resistance was high compared with an copper interconnection without annealing with low crystallinity (3.33 × 10−8 Ωm). It was clarified that the interconnection with high crystallinity had superior electrical properties. Thus, it was clarified that the crystallographic quality of grain boundaries has a strong correlation of mechanical and electrical reliability.

Structural Integrity Assessment of Free-Fall Lifeboats by Combining Fast Monte-Carlo Simulations With CFD by Means of Proxy Load Variables

2016 ◽  
Author(s):  
Sébastien Fouques ◽  
Ole Andreas Hermundstad
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Structural Integrity ◽  
Free Fall ◽  
Integrity Assessment ◽  
Proxy Variables ◽  
Pressure Load ◽  
Calm Water ◽  
Measured Pressure

The paper is concerned with the launch of free-fall lifeboats (FFL). It proposes a method that complies with the DNV-OS-E406 standard in order to select characteristic launches from Monte Carlo simulations for further structural load assessment with CFD and FEM. Proxy variables derived from kinematic parameters and aiming at predicting pressure load indicators are computed with the VARUNA launch simulator developed by MARINTEK. The statistical distributions of the proxy variables obtained from the Monte Carlo simulations are used to identify critical scenarios, and characteristic launches can then be selected from a chosen probability level. The feasibility of the proposed method is documented in the paper for several types of pressure loads. Existing model test data from various FFL-launch campaigns in calm water and in waves are used to compute the proxy variables as it would be done in the VARUNA simulator. Scatter diagrams showing the correlation with actual measured pressure load indicators are then established to assess the quality of the chosen proxy variables.

Casing Design for an Oxygen Concentrator

1999 ◽  
Author(s):  
Stephanie H. Swindle ◽  
Beth A. Todd ◽  
James F. Cuttino
Keyword(s):  
Quality Of Life ◽  
Structural Integrity ◽  
Chronic Obstructive ◽  
Gas Mixture ◽  
Improve Quality ◽  
Chronic Obstructive Pulmonary Disorder ◽  
Element Analysis ◽  
Pulmonary Disorder ◽  
Oxygen Concentrator

Abstract Human bodies depend on a steady flow of oxygen for the heart and lungs. When a person has Chronic Obstructive Pulmonary Disorder (COPD), a device called an oxygen concentrator can be used to improve quality of life. An oxygen concentrator is an electrically powered device that takes in room air and converts it to an oxygen rich gas mixture suitable for breathing. Although a few models are battery powered, oxygen concentrators are not easily portable because they are bulky and weigh between 25–50 lbs. In this study, components were identified for re design to reduce the overall weight of the device. For instance, the concentrator casing was identified as its heaviest component. Using finite element analysis, changes in wall thickness and dimensions can be investigated to reduce weight while maintaining structural integrity. By reducing the weight of the casing, the oxygen concentrator will be easier to transport.

Conductive Metakaolin Geopolymer with Steel Microfibres​

2021 ◽  
Vol 321 ◽  
pp. 59-64
Author(s):  
Cecílie Mizerová ◽  
Ivo Kusák ◽  
Pavel Rovnaník ◽  
Patrik Bayer
Keyword(s):  
Electrical Properties ◽  
Mercury Intrusion Porosimetry ◽  
Multifunctional Composites ◽  
Spectroscopy Analysis ◽  
Sem Imaging ◽  
Metakaolin Geopolymer ◽  
Fibre Matrix ◽  
Alkali Activated ◽  
Impedance Spectroscopy Analysis

Research of alkali-activated materials and geopolymers suggests their increased ability to transfer the electric charge thus indicating their suitability for self-sensing and other multifunctional composites. In this paper, the electrical properties of metakaolin geopolymer are enhanced by the incorporated steel microfibres that also improve the mechanical and fractural properties of the composite. Selected electrical properties of metakaolin geopolymer mortars with steel microfibres (up to 30 % of metakaolin wt.) were assessed via impedance spectroscopy analysis and followed by testing their compressive and flexural strength. Mercury intrusion porosimetry and SEM imaging enabled to characterize the binder microstructure and quality of fibre-matrix bonding.

Measurement of Bulk Electrical Properties Using GPR with a Variable Reflector

2018 ◽  
Vol 23 (4) ◽  
pp. 489-496
Author(s):  
J. David Redman ◽  
A. Peter Annan ◽  
Nectaria Diamanti
Keyword(s):  
Electrical Properties ◽  
Moisture Content ◽  
Ground Penetrating Radar ◽  
Arrival Time ◽  
Wood Chip ◽  
Direct Wave ◽  
Trace Data ◽  
Ground Penetrating ◽  
Prototype Instrument

Bulk electrical properties of media are important inherently for ground penetrating radar (GPR) applications and for providing a means to determine indirectly other physical properties such as moisture content. We have developed a reflector whose reflectivity can be controlled electronically. This variable reflector controlled by a GPR provides an effective method to measure bulk electrical properties of media. For sample measurements, the GPR is placed on one side of a sample and the variable reflector on the opposite side. GPR trace data are then acquired with the reflector in an on-state and in the off-state. By differencing these measurements, we improve the ability to detect the specific reflection event from the variable reflector. This process removes both the direct wave and clutter from the trace data, improving the quality of the refection event and our ability to accurately pick its arrival time and amplitude. We describe the variable reflector, a prototype instrument based on the reflector and numerical modeling performed to understand its response. We also show the results of testing applications to the measurement of wood chip moisture content and monitoring of the electrical properties of concrete during the curing process.

The Electrical Properties of Polyoxide Depending on the Polycrystalline-Si Formation Conditions

1990 ◽  
Vol 182 ◽  
Author(s):  
Kyoung-Soo Yi ◽  
Deok-Ho Cho ◽  
Jeong Yong Lee ◽  
Kee-Soo Nam ◽  
Sang-Won Kang ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Dielectric Property ◽  
Electrical Properties ◽  
Low Temperature ◽  
Electric Field ◽  
Transmission Electron ◽  
Formation Conditions ◽  
Temperature Oxide ◽  
Amorphous Si ◽  
Current Electric Field

AbstractPrior to growth of polyoxide, amorphous-Si with a cap of low temperature oxide was annealed to improve the dielectric property of polyoxide. Current-electric field, critical electric field, critical electric field histogram, and Fowler-Nordheim conduction plot were evaluated. The interface of polyoxide and poly-Si was observed with a transmission electron microscope. The annealing of the amorphous-Si prior to oxidation was effective to improve the dielectric property of the polyoxide.

INFLUENCE OF RECTANGULAR STEEL SPLICE-SLEEVE FOR PRECAST CONCRETE CONNECTION

2015 ◽  
Vol 77 (12) ◽  
Author(s):  
Ahmad Baharuddin Abd Rahman ◽  
Tan Kee Hong ◽  
Izni Syahrizal Ibrahim ◽  
Roslli Noor Mohamed
Keyword(s):  
Structural Integrity ◽  
Precast Concrete ◽  
Tensile Load ◽  
Steel Plates ◽  
Steel Bar ◽  
Tensile Performance ◽  
Bond Property ◽  
The Many ◽  
Steel Sleeve

Precast concrete building system has gained its popularity in Malaysia because of the many advantages such as high quality of structural components, less labour intensive at the construction site, and shorter completion time of a project. One of the constraints in precast concrete structures is to ensure that the connections are strong enough to ensure the structural integrity and robustness of the overall frames. In this study, a total of nine rectangular steel splice-sleeve connections were tested experimentally under incremental tensile loads. Two steel plates were inserted and welded to each end of the steel splice-sleeve. The steel plates act as shear key to provide the interlocking mechanism to the grout and to enhance the bond property between the grout and the splice. These plates were adopted to prevent the grout slippage from the sleeve. The grout strength, embedded steel bar lengths and the size of the steel sleeve splice were varied among the specimens to study their effect on the tensile performance of the connection. The results showed that the higher strength of grout, longer embedded length of steel bar and smaller size of the sleeve contributes to a higher ultimate tensile load.

The Impact of Mesh Implantation on Vaginal Smooth Muscle Innervation and Contraction

2013 ◽  
Author(s):  
Zegbeh C. Jallah ◽  
Pamela Moalli ◽  
Andrew Feola ◽  
William Barone ◽  
Stacy Palcsey ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Surgical Repair ◽  
The United States ◽  
Pelvic Organ ◽  
Muscle Innervation ◽  
Vaginal Canal ◽  
The Cost ◽  
Vaginal Smooth Muscle ◽  
The Impact

Pelvic organ prolapse (POP) is a multifactorial disorder characterized by the descent of the pelvic organs into the vaginal canal. This disorder is associated with decreased quality of life, and even depression, yet 50% of women over the age of fifty are living with POP. The cost associated with the repair of POP exceeds one billion dollars annually, in the United States alone. This rather exorbitant figure includes the cost of surgery performed for symptom management, but does not include strategies which address the underlying cause of the disorder for which there are none. Because failure rates of native tissue repairs are as high as 30%, vaginal mesh is increasingly used in the surgical repair of POP. The procedure aims to reinforce the fibromuscular layer of the vagina and the paravaginal attachments, thus providing structural integrity to the weakened native tissues. However, the use of mesh is limited by mesh-related complications including exposure, erosion, pain contraction and infection.

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