Distinguishing the Degradation of the Interdigital Piezoelectric Fibre Transducers From Structural Damage in Multifunctional Composites

2012 ◽  
Author(s):  
Mohammad Mehdizadeh ◽  
Sabu John ◽  
Chun H. Wang ◽  
Kamran Ghorbani ◽  
Wayne S. T. Rowe
Keyword(s):  
Electrical Properties ◽  
Structural Damage ◽  
Structural Changes ◽  
Fatigue Loading ◽  
Operational Environment ◽  
Multifunctional Composites ◽  
The Status ◽  
Safety And Reliability ◽  
Thermal Features ◽  
Sensor Degradation

The next-generation design of structural components involves combining multiple functions. The goal of such Multi-functional structures (MFS) is to incorporate various tasks and functions such as structural, electrical and thermal features within a structural housing. The performance and behaviour characteristics of the multi-functional structures can be affected by degradation of any of the sub-components. This can have consequences on the safety, cost, and operational capability. Therefore, the timely and accurate detection, characterization and monitoring of the degradation in these sub-components are major concerns in the operational environment. This calls for Structural Health Monitoring (SHM) as a possible method to improve the safety and reliability of structures and thereby reduce their operational cost. As the application of SHM systems to monitor the status of the MFS increase, it will be increasingly important to determine the durability, reliability, and reparability of the components of SHM system such as sensors. The sensors themselves must be reliable enough so that they do not require replacement at intervals less than the economic lifetime of the structures and components they are monitoring. This is especially important when the deleterious structural changes in the sensor occurs without any discernible change in the structure being monitored In the present work, an assessment is carried out to quantify the degradation in the electric and electromechanical characteristics of polymer composite PZT sensors, under fatigue loading. Changes in the electrical properties of these sensors such as capacitance and inductance have been measured. The strain measurements of the sensor have also been compared to the theoretically calculated strain. The results show that the delineation of structural damage from sensor degradation is possible by monitoring the changes in the key electrical properties of the sensor components such as electrodes and PZT fibers as well as the comparison of experimentally measured and theoretically calculated strain values.

Degradation of Sensor Systems in Multifunctional Composites

2010 ◽  
Author(s):  
Mohammad Mehdizadeh ◽  
Sabu John ◽  
Chun Wang ◽  
Michael Bannister ◽  
Viktor Verijenko
Keyword(s):  
Electrical Properties ◽  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Structural Changes ◽  
Reliability Assessment ◽  
Fatigue Loading ◽  
Piezoelectric Sensors ◽  
Multifunctional Composites ◽  
Aerospace Structures ◽  
Sensory Data

Structural health monitoring (SHM) systems are increasingly being considered for implementation in aerospace structures. As the application of SHM systems increase, it will be important to define standardized procedures to test durability, reliability, and longevity of the systems. The work presented in this paper is some preliminary work on the integrity of Piezoelectric sensors itself when used to monitor the strains in structures. This study involved the measurements of pertinent electrical properties of these sensors over 100,000 cycles of fatigue loading. Marked changes in the capacitance and inductance of these sensors highlighted deleterious structural changes in the sensor itself without any discernible change in the structure it is supposed to monitor. This might have significant implications in the reliability assessment of sensory data from SHM systems.

Characterization of Piezo Fiber-Based Sensors Responses in Multifunctional Composites

2011 ◽  
Vol 409 ◽  
pp. 633-638
Author(s):  
Mohammad Mehdizadeh ◽  
Sabu John ◽  
Chun H. Wang ◽  
Viktor Verijenko ◽  
Paul Callus
Keyword(s):  
Structural Damage ◽  
Structural Changes ◽  
Fibre Composite ◽  
Fatigue Loading ◽  
Civil Infrastructure ◽  
Sensor Failure ◽  
Multifunctional Composites ◽  
Wide Range ◽  
Health Monitoring Systems

Structural health monitoring systems (SHMS) are increasingly being considered for implementation in a wide range of industries, including transport, civil infrastructure, and energy production. As the application of SHM systems increase, it will be increasingly important to quantify the durability, reliability, and reparability of the SHM system. This paper investigates the electrical and electro-mechanical characteristics of piezoelectric sensors in an attempt to distinguish sensor failure from structural damage [10]. This study involved the measurements of pertinent electrical properties for MFC (Macro Fibre Composite) sensor under fatigue loading and comparison of the strain measurements to characterize the degradation of the structure as well as the MFC. Changes in the capacitance and inductance of this sensor have been recorded, highlighting deleterious structural changes in the sensor itself without any discernible change in the structure being monitored.

Differentiating Structural Damage From Piezo-Fibre-Based Sensor Damage in Multifunctional Composites

2011 ◽  
Author(s):  
Mohammad Mehdizadeh ◽  
Sabu John ◽  
Chun H. Wang ◽  
Viktor Verijenko ◽  
Wayne Rowe ◽  
...  
Keyword(s):  
Structural Damage ◽  
Energy Production ◽  
Structural Changes ◽  
Fatigue Loading ◽  
Piezoelectric Sensors ◽  
Civil Infrastructure ◽  
Sensor Failure ◽  
Multifunctional Composites ◽  
Wide Range ◽  
Health Monitoring Systems

Structural health monitoring systems (SHMS) are increasingly being considered for implementation in a wide range of industries, including transport, civil infrastructure, and energy production. As the application of SHM systems increase, it will be increasingly important to quantify the durability, reliability, and reparability of the SHM system. This paper investigates the electrical and electro-mechanical characteristics of piezoelectric sensors in an attempt to distinguish sensor failure from structural damage. This study involved the measurements of pertinent electrical properties for three various types of advanced piezoelectric sensors under fatigue loading. Changes in the capacitance and inductance of these sensors have been recorded, highlighting the deleterious structural changes in the sensor itself without any discernible change in the structure being monitored.

Evaluation of single-electron movies of glutamine synthetase molecules

1983 ◽  
Vol 41 ◽  
pp. 280-281
Author(s):  
W. Kunath ◽  
E. Zeitler ◽  
M. Kessel
Keyword(s):  
Electron Microscope ◽  
Glutamine Synthetase ◽  
Electron Irradiation ◽  
Structural Damage ◽  
Structural Changes ◽  
Single Electron ◽  
Continuous Series ◽  
Digital Recording ◽  
Recording Device ◽  
Low Exposure

The features of digital recording of a continuous series (movie) of singleelectron TV frames are reported. The technique is used to investigate structural changes in negatively stained glutamine synthetase molecules (GS) during electron irradiation and, as an ultimate goal, to look for the molecules' “undamaged” structure, say, after a 1 e/Å2 dose.The TV frame of fig. la shows an image of 5 glutamine synthetase molecules exposed to 1/150 e/Å2. Every single electron is recorded as a unit signal in a 256 ×256 field. The extremely low exposure of a single TV frame as dictated by the single-electron recording device including the electron microscope requires accumulation of 150 TV frames into one frame (fig. lb) thus achieving a reasonable compromise between the conflicting aspects of exposure time per frame of 3 sec. vs. object drift of less than 1 Å, and exposure per frame of 1 e/Å2 vs. rate of structural damage.

scholarly journals Imaging of Joint and Soft Tissue Involvement in Systemic Lupus Erythematosus

2021 ◽  
Vol 23 (9) ◽  
Author(s):  
Andrea Di Matteo ◽  
Gianluca Smerilli ◽  
Edoardo Cipolletta ◽  
Fausto Salaffi ◽  
Rossella De Angelis ◽  
...  
Keyword(s):  
Systemic Lupus Erythematosus ◽  
Soft Tissue ◽  
Lupus Erythematosus ◽  
Structural Damage ◽  
Structural Changes ◽  
Soft Tissues ◽  
Imaging Techniques ◽  
Joint Involvement ◽  
Systemic Lupus ◽  
Muscle Involvement

Abstract Purpose of Review To highlight the potential uses and applications of imaging in the assessment of the most common and relevant musculoskeletal (MSK) manifestations in systemic lupus erythematosus (SLE). Recent Findings Ultrasound (US) and magnetic resonance imaging (MRI) are accurate and sensitive in the assessment of inflammation and structural damage at the joint and soft tissue structures in patients with SLE. The US is particularly helpful for the detection of joint and/or tendon inflammation in patients with arthralgia but without clinical synovitis, and for the early identification of bone erosions. MRI plays a key role in the early diagnosis of osteonecrosis and in the assessment of muscle involvement (i.e., myositis and myopathy). Conventional radiography (CR) remains the traditional gold standard for the evaluation of structural damage in patients with joint involvement, and for the study of bone pathology. The diagnostic value of CR is affected by the poor sensitivity in demonstrating early structural changes at joint and soft tissue level. Computed tomography allows a detailed evaluation of bone damage. However, the inability to distinguish different soft tissues and the need for ionizing radiation limit its use to selected clinical circumstances. Nuclear imaging techniques are valuable resources in patients with suspected bone infection (i.e., osteomyelitis), especially when MRI is contraindicated. Finally, dual energy X-ray absorptiometry represents the imaging mainstay for the assessment and monitoring of bone status in patients with or at-risk of osteoporosis. Summary Imaging provides relevant and valuable information in the assessment of MSK involvement in SLE.

Causes of Structural Failures with Steel Structures

2017 ◽  
Author(s):  
Goran Alpsten
Keyword(s):  
Structural Damage ◽  
Human Error ◽  
Structural Reliability ◽  
Steel Structures ◽  
Fatigue Loading ◽  
Structural Instability ◽  
Human Errors ◽  
Collapse Mode ◽  
Load Carrying ◽  
Structural Failures

This paper is based on the experience from investigating over 400 structural collapses, incidents and serious structural damage cases with steel structures which have occurred over the past four centuries. The cause of the failures is most often a gross human error rather than a combination of “normal” variations in parameters affecting the load-carrying capacity, as considered in normal design procedures and structural reliability analyses. Human errors in execution are more prevalent as cause for the failures than errors in the design process, and the construction phase appears particularly prone to human errors. For normal steel structures with quasi-static (non-fatigue) loading, various structural instability phenomena have been observed to be the main collapse mode. An important observation is that welds are not as critical a cause of structural steel failures for statically loaded steel structures as implicitly understood in current regulations and rules for design and execution criteria.

New Strategies for Preparing Electrically Conductive Langmuir-Blodgett Films

1992 ◽  
Vol 247 ◽  
Author(s):  
J. H. Cheung ◽  
R. B. Rosner ◽  
M. F. Rubner
Keyword(s):  
Electrical Properties ◽  
Stearic Acid ◽  
Structural Changes ◽  
Solid State Reactions ◽  
Emeraldine Base ◽  
Structure Property ◽  
Electrically Conductive ◽  
Lb Films ◽  
Langmuir Blodgett ◽  
Langmuir Blodgett Films

ABSTRACTThe fabrication, structure and electrical properties of new electrically conductive Langmuir-Blodgett (LB) films of polyaniline and polypyrrole have been investigated. Polyaniline in its emeraldine-base form was mixed with stearic acid (PAN-B/SA) to produce stable films at the air-water interface (5/1 or 10/1 mole ratio of PAN-B/SA). These films were then transferred into multilayer films which were found to exhibit conductivities of about 1 S/cm upon doping with hydrochloric acid. The alkyl chains of the stearic acid molecules were found to be distributed randomly throughout the LB film thereby exerting a minimal influence on the electrical properties of the polyaniline phase. In addition to this mixed monolayer approach, a novel method of fabricating highly conductive polypyrrole LB films has been developed. This method is based on the sequential exposure of ferric stéarate LB films to hydrogen chloride (HC1) gas and pyrrole vapor. Each of these two solid state reactions was found to impart dramatic chemical and structural changes to the film. Polypyrrole LB films with conductivities as high as 5 S/cm were produced via this process. The electrical and optical properties of films made by both techniques were examined in order to elucidate their structure/property relationships.

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.

Implications of OPA 90 in General and Its Effect on the T-AO 187 Class Oilers in Particular

1994 ◽  
Vol 31 (03) ◽  
pp. 175-182
Author(s):  
Hans Hofmann ◽  
George Kapsilis ◽  
Eric Smith ◽  
Robert Wasalaski
Keyword(s):  
United States ◽  
Structural Changes ◽  
Oil Pollution ◽  
The United States ◽  
Coast Guard ◽  
International Maritime Organization ◽  
The Status ◽  
Oil Tankers ◽  
The U.S ◽  
Hull Construction

The Oil Pollution Act of 1990 has mandated that by the year 2015 all oil tankers operating in waters subject to jurisdiction of the United States must have double hulls. This paper examines the Act and the status of regulatory initiatives it has generated. Guidance for new hull construction and retrofit of existing vessels is outlined, and both IMO (International Maritime Organization) and U.S. Coast Guard requirements are discussed. Finally, the structural changes necessary to convert the U.S. Navy's T-AO Class oil tankers to meet the requirements of the Act are specified and illustrated.

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