scholarly journals Korozja pokrycia samolotu i względy bezpieczeństwa konstrukcyjnego

2021 ◽  
Vol 7 (2) ◽  
Author(s):  
Jan Pila ◽  
Jarosław Kozuba ◽  
Frantisek Martinec
Keyword(s):  
Dynamic Stress ◽  
Structural Integrity ◽  
Corrosion Damage ◽  
Structural Elements ◽  
Surface Protection ◽  
Design Elements ◽  
Load Factors ◽  
Aircraft Skin ◽  
External Forces ◽  
The Impact

The aim of this article is to point out some peculiarities of airframe corrosion, the impact of external forces on aircraft skin elements and their impact on structural integrity. The corrosion process is generally associated with fatigue of aircraft structural elements due to the effect of many factors such as the type of loading, the properties of the materials, the corro-sive environment, etc. The article is not focused on corrosion processes, but on load factors that are specific to aircraft wing design elements and their influence on corrosion of critical struc-tural elements. Corrosion of the wing is perceived as a consequence of environmental impact on damaged surface protection of the skin and connecting parts (rivets, screws, and welded joints) caused by static and dynamic stress of the wing and also by the interaction of the indi-vidual structural elements as a whole. The dynamics of operation of individual structural ele-ments is further enhanced by the fatigue of the material. Early detection of corrosion processes has generally been and is crucial to overall safety of the aircraft. The proposals presented in the article are formulated in order to improve the system of work to ensure the safety of aircraft operation in terms of resistance to corrosion damage.

scholarly journals Management of Airframe In-Service Pitting Corrosion by Decoupling Fatigue and Environment

2021 ◽  
Vol 2 (3) ◽  
pp. 493-511
Author(s):  
Loris Molent ◽  
Russell Wanhill
Keyword(s):  
Corrosion Fatigue ◽  
Pitting Corrosion ◽  
Structural Integrity ◽  
Corrosion Damage ◽  
Fatigue Loading ◽  
Cost Driver ◽  
Service Environments ◽  
Corrosion Pits ◽  
The Impact ◽  
Fatigue Corrosion

Corrosion-induced maintenance is a significant cost driver and availability degrader for aircraft structures. Although well-established analyses enable assessing the corrosion impact on structural integrity, this is not the case for fatigue nucleation and crack growth. This forces fleet managers to directly address detected corrosion to maintain flight safety. Corrosion damage occurs despite protection systems, which inevitably degrade. In particular, pitting corrosion is a common potential source of fatigue. Corrosion pits are discontinuities whose metrics can be used to predict the impact on the fatigue lives of structural components. However, a damage tolerance (DT) approach would be more useful and flexible. A potential hindrance to DT has been the assumption that corrosion-induced fatigue nucleation transitions to corrosion fatigue, about which little is known for service environments. Fortunately, several sources indicate that corrosion fatigue is rare for aircraft, and corrosion is largely confined to ground situations because aircraft generally fly at altitudes with low temperature and humidity Thus, it is reasonable to propose the decoupling of corrosion from the in-flight dynamic (fatigue) loading. This paper presents information to support this proposition, and provides an example of how a DT approach can allow deferring corrosion maintenance to a more opportune time.

Corrosion damage evolution of the aircraft aluminum alloy 2024 T3

2016 ◽  
Vol 7 (1) ◽  
pp. 25-46 ◽  
Author(s):  
Spiros Pantelakis ◽  
Dorothea Setsika ◽  
Apostolos Chamos ◽  
Anna Zervaki
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Damage Evolution ◽  
Structural Integrity ◽  
Corrosion Damage ◽  
Tensile Tests ◽  
Content Type ◽  
Experimental Database ◽  
Aluminum Alloy 2024 ◽  
The Impact

Purpose – The purpose of this paper is to quantify the corrosion damage evolution that has occurred on the aircraft aluminum alloy 2024 after the exposure to Exfoliation Corrosion Test (EXCO) solution. Moreover, the effect of the evolving corrosion damage on the materials mechanical properties has been assessed. The relevance of the corrosion damage induced by the exposure to the laboratory EXCO for linking it to the damage developed after the exposure of the material on several outdoor corrosive environments or in service is discussed. Design/methodology/approach – To induce corrosion damage the EXCO has been used. For the quantification of corrosion damage the metallographic features considered have been pit depth, diameter, pitting density and pit shape. The effect of the evolving corrosion damage on the materials mechanical properties has been assessed by means of tensile tests on pre corroded specimens. Findings – The results have shown that corrosion damage starts from pitting and evolves to exfoliation, after the development of intergranular corrosion. This evolution is expressed by the increase of the depth of attack, as well as through the significant growth of the diameter of the damaged areas. The results of the tensile tests performed on pre corroded material made an appreciable decrease of the materials tensile properties evident. The decrease of the tensile ductility may become dramatic and increases on severity with increasing corrosion exposure time. SEM fractography revealed a quasi-cleavage zone beneath the depth of corrosion attack. Originality/value – The results underline the impact of corrosion damage on the mechanical behavior of the aluminum alloy 2024 T3 and demonstrate the need for further investigation of the corrosion effect on the structural integrity of the material. This work provides an experimental database concerning the quantification of corrosion damage evolution and the loss of material properties due to corrosion.

Structural Impact Assessment of Flaws Detected During Ultrasonic Examination of a Radioactive Waste Tank

2003 ◽  
Author(s):  
B. J. Wiersma ◽  
J. B. Elder
Keyword(s):  
Radioactive Waste ◽  
Residual Stresses ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Structural Integrity ◽  
Corrosion Damage ◽  
Corrosion Cracking ◽  
Crack Behavior ◽  
The Impact ◽  
Vapor Space

Ultrasonic (UT) inspection of an underground storage tank containing radioactive waste was conducted at the Savannah River Site (SRS). Ten cracks were identified during this examination. A critical review of the information describing stress corrosion crack behavior for the SRS waste tanks, as well as a summary review of the service history this tank, was performed. Each crack was then evaluated for service exposure history, consistency of the crack behavior with the current understanding of stress corrosion cracking, and present and future impact to the structural integrity of the tank. In all cases, the crack behavior was determined to be consistent with the previous understanding of stress corrosion cracking in the SRS waste tank environment. The length of the cracks was limited due to the short-range nature of the residual stresses near seam, repair and attachment welds. In many cases the cracks were associated with exposure to fresh waste from the SRS canyons as previously observed. However, cases in which the crack was observed to go through-wall while located in the vapor space above the waste were also observed. The time of initiation and propagation rate of these cracks is unknown. A re-examination of these cracks will determine whether these cracks are continuing to grow while in the vapor space. The impact of these cracks on the future service of this tank was also assessed. A bounding loading condition due waste removal of the sludge at the bottom of Tank 15 was considered for this analysis. The analysis showed that the combination of hydrostatic and weld residual stresses do not drive any of the cracks identified during the UT inspection to instability. For all cracks the instability length was more than 10 times the actual flaw length. The re-examination of this tank is scheduled for 2007. This examination would provide information to determine whether any additional detectable degradation is occurring and to supplement the basis for specification of conditions that are non-aggressive to tank corrosion damage for similar tanks at SRS.

Influence of the distribution of the shear walls on the seismic response of the buildings

2020 ◽  
Vol 15 (1) ◽  
pp. 37-44
Author(s):  
El Mehdi Echebba ◽  
Hasnae Boubel ◽  
Oumnia Elmrabet ◽  
Mohamed Rougui
Keyword(s):  
Structural Analysis ◽  
Seismic Response ◽  
Natural Frequency ◽  
Structural Design ◽  
Structural Response ◽  
Shear Walls ◽  
Structural Elements ◽  
Analysis Software ◽  
Ansys Apdl ◽  
The Impact

Abstract In this paper, an evaluation was tried for the impact of structural design on structural response. Several situations are foreseen as the possibilities of changing the distribution of the structural elements (sails, columns, etc.), the width of the structure and the number of floors indicates the adapted type of bracing for a given structure by referring only to its Geometric dimensions. This was done by studying the effect of the technical design of the building on the natural frequency of the structure with the study of the influence of the distribution of the structural elements on the seismic response of the building, taking into account of the requirements of the Moroccan earthquake regulations 2000/2011 and using the ANSYS APDL and Robot Structural Analysis software.

What's Left of the Law of Integration?

2018 ◽  
Author(s):  
Julio Baquero Cruz
Keyword(s):  
International Law ◽  
Fundamental Rights ◽  
Structural Elements ◽  
The European Union ◽  
Difficult Situation ◽  
Court Of Justice ◽  
Structural Connections ◽  
The Law ◽  
Constitutional Pluralism ◽  
The Impact

This book discusses the impact of the difficult situation the European Union is currently going through on some structural elements of its legal order, looking for symptoms of decay, exploring examples of resistance, and assessing its overall state of health. The original choices made by the drafters of the Treaties and by the Court of Justice are put in their proper historical perspective, understanding Union law as a tool of civilization, and explaining its current problems, at least in part, as a consequence of the waning of the initial impetus behind integration. The concrete themes to be explored are the following: primacy, the national resistance to it and constitutional pluralism; the preliminary rulings procedure; Union citizenship, equality, and human dignity; the scope of the Charter and the standard of protection of fundamental rights; and the rigidity and fragmentation of the Union system in connection with the recent occasional use of international law as an alternative to Union law. The book looks at the development of the law throughout the decades, inevitably losing much detail, but hopefully also uncovering structural connections and continuities.

scholarly journals Potential and limitations of finite element modelling in assessing structural integrity of coralline algae under future global change

2015 ◽  
Vol 12 (19) ◽  
pp. 5871-5883 ◽  
Author(s):  
L. A. Melbourne ◽  
J. Griffin ◽  
D. N. Schmidt ◽  
E. J. Rayfield
Keyword(s):  
Climate Change ◽  
Finite Element ◽  
Structural Integrity ◽  
Geometric Model ◽  
Algal Growth ◽  
Coralline Algae ◽  
Rocky Shores ◽  
Element Analysis ◽  
Scan Data ◽  
The Impact

Abstract. Coralline algae are important habitat formers found on all rocky shores. While the impact of future ocean acidification on the physiological performance of the species has been well studied, little research has focused on potential changes in structural integrity in response to climate change. A previous study using 2-D Finite Element Analysis (FEA) suggested increased vulnerability to fracture (by wave action or boring) in algae grown under high CO2 conditions. To assess how realistically 2-D simplified models represent structural performance, a series of increasingly biologically accurate 3-D FE models that represent different aspects of coralline algal growth were developed. Simplified geometric 3-D models of the genus Lithothamnion were compared to models created from computed tomography (CT) scan data of the same genus. The biologically accurate model and the simplified geometric model representing individual cells had similar average stresses and stress distributions, emphasising the importance of the cell walls in dissipating the stress throughout the structure. In contrast models without the accurate representation of the cell geometry resulted in larger stress and strain results. Our more complex 3-D model reiterated the potential of climate change to diminish the structural integrity of the organism. This suggests that under future environmental conditions the weakening of the coralline algal skeleton along with increased external pressures (wave and bioerosion) may negatively influence the ability for coralline algae to maintain a habitat able to sustain high levels of biodiversity.

scholarly journals Conceptualising natural and quasi experiments in public health

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Frank de Vocht ◽  
Srinivasa Vittal Katikireddi ◽  
Cheryl McQuire ◽  
Kate Tilling ◽  
Matthew Hickman ◽  
...  
Keyword(s):  
Public Health ◽  
Study Design ◽  
Grey Literature ◽  
Public Health Research ◽  
Natural Experiments ◽  
Target Trial ◽  
Design Elements ◽  
Randomized Controlled ◽  
Study Designs ◽  
The Impact

Abstract Background Natural or quasi experiments are appealing for public health research because they enable the evaluation of events or interventions that are difficult or impossible to manipulate experimentally, such as many policy and health system reforms. However, there remains ambiguity in the literature about their definition and how they differ from randomized controlled experiments and from other observational designs. We conceptualise natural experiments in the context of public health evaluations and align the study design to the Target Trial Framework. Methods A literature search was conducted, and key methodological papers were used to develop this work. Peer-reviewed papers were supplemented by grey literature. Results Natural experiment studies (NES) combine features of experiments and non-experiments. They differ from planned experiments, such as randomized controlled trials, in that exposure allocation is not controlled by researchers. They differ from other observational designs in that they evaluate the impact of events or process that leads to differences in exposure. As a result they are, in theory, less susceptible to bias than other observational study designs. Importantly, causal inference relies heavily on the assumption that exposure allocation can be considered ‘as-if randomized’. The target trial framework provides a systematic basis for evaluating this assumption and the other design elements that underpin the causal claims that can be made from NES. Conclusions NES should be considered a type of study design rather than a set of tools for analyses of non-randomized interventions. Alignment of NES to the Target Trial framework will clarify the strength of evidence underpinning claims about the effectiveness of public health interventions.

scholarly journals Codon harmonization reduces amino acid misincorporation in bacterially expressed P. falciparum proteins and improves their immunogenicity

AMB Express ◽  
2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Neeraja Punde ◽  
Jennifer Kooken ◽  
Dagmar Leary ◽  
Patricia M. Legler ◽  
Evelina Angov
Keyword(s):  
Protein Structure ◽  
Amino Acid ◽  
Codon Usage ◽  
Dna Sequences ◽  
Structural Integrity ◽  
Host Cells ◽  
Loss Of Function ◽  
Species Specific ◽  
And Function ◽  
The Impact

Abstract Codon usage frequency influences protein structure and function. The frequency with which codons are used potentially impacts primary, secondary and tertiary protein structure. Poor expression, loss of function, insolubility, or truncation can result from species-specific differences in codon usage. “Codon harmonization” more closely aligns native codon usage frequencies with those of the expression host particularly within putative inter-domain segments where slower rates of translation may play a role in protein folding. Heterologous expression of Plasmodium falciparum genes in Escherichia coli has been a challenge due to their AT-rich codon bias and the highly repetitive DNA sequences. Here, codon harmonization was applied to the malarial antigen, CelTOS (Cell-traversal protein for ookinetes and sporozoites). CelTOS is a highly conserved P. falciparum protein involved in cellular traversal through mosquito and vertebrate host cells. It reversibly refolds after thermal denaturation making it a desirable malarial vaccine candidate. Protein expressed in E. coli from a codon harmonized sequence of P. falciparum CelTOS (CH-PfCelTOS) was compared with protein expressed from the native codon sequence (N-PfCelTOS) to assess the impact of codon usage on protein expression levels, solubility, yield, stability, structural integrity, recognition with CelTOS-specific mAbs and immunogenicity in mice. While the translated proteins were expected to be identical, the translated products produced from the codon-harmonized sequence differed in helical content and showed a smaller distribution of polypeptides in mass spectra indicating lower heterogeneity of the codon harmonized version and fewer amino acid misincorporations. Substitutions of hydrophobic-to-hydrophobic amino acid were observed more commonly than any other. CH-PfCelTOS induced significantly higher antibody levels compared with N-PfCelTOS; however, no significant differences in either IFN-γ or IL-4 cellular responses were detected between the two antigens.

scholarly journals Effect of Lipopolysaccharides (LPS) and Lipoteichoic acid (LTA) on the Inflammatory Response in Rumen Epithelial Cells (REC) and the Impact of LPS on Claw Explants

Animals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 2058
Author(s):  
Nicole Reisinger ◽  
Dominik Wendner ◽  
Nora Schauerhuber ◽  
Elisabeth Mayer
Keyword(s):  
Epithelial Cells ◽  
Inflammatory Response ◽  
Structural Integrity ◽  
Animal Health ◽  
Lipoteichoic Acid ◽  
Local Inflammatory Response ◽  
Tissue Integrity ◽  
Separation Force ◽  
The Impact ◽  
Rumen Epithelial Cells

Endotoxins play a crucial role in ruminant health due to their deleterious effects on animal health. The study aimed to evaluate whether LPS and LTA can induce an inflammatory response in rumen epithelial cells. For this purpose, epithelial cells isolated from rumen tissue (RECs) were stimulated with LPS and LTA for 1, 2, 4, and 24 h. Thereafter, the expression of selected genes of the LPS and LTA pathway and inflammatory response were evaluated. Furthermore, it was assessed whether LPS affects inflammatory response and structural integrity of claw explants. Therefore, claw explants were incubated with LPS for 4 h to assess the expression of selected genes and for 24 h to evaluate tissue integrity via separation force. LPS strongly affected the expression of genes related to inflammation (NFkB, TNF-α, IL1B, IL6, CXCL8, MMP9) in RECs. LTA induced a delayed and weaker inflammatory response than LPS. In claw explants, LPS affected tissue integrity, as there was a concentration-dependent decrease of separation force. Incubation time had a strong effect on inflammatory genes in claw explants. Our data suggest that endotoxins can induce a local inflammatory response in the rumen epithelium. Furthermore, translocation of LPS might negatively impact claw health.

The Role of the Conclusions of the Council of Judges of the Russian Federation in the Prevention of the Emergence and Development of Conflicts of Legal Interests in the Judicial System of Russia

2020 ◽  
Vol 12 ◽  
pp. 56-66
Author(s):  
E. V. Ryabtseva ◽  
Keyword(s):  
Russian Federation ◽  
Judicial System ◽  
Structural Elements ◽  
Consistent System ◽  
Optimal Behavior ◽  
Regulatory Impact ◽  
The Russian Federation ◽  
The Impact ◽  
Individual Regulation

The growing role of the judicial community in reforming the judicial system actualizes the scientific problems of law enforcement associated with understanding the essence of the regulatory impact of the Councils of Judges of the Russian Federation as a body of the judicial community to prevent the emergence of conflicts of legal interests in judicial activity. The purpose of the research is to theoretically substantiate the essence of individual regulation of conflicts of legal interests by the Council of Judges of the Russian Federation, aimed at optimizing its activities to combat corruption. The worldview and methodological basis were the works of theoretical scholars and their methods of integrative understanding of law to substantiate the impact of the Council of Judges of the Russian Federation on judicial activity through individual regulation. The conclusion is substantiated that the activities of the Commission of the Council of Judges of the Russian Federation on Ethics, related to the drawing up of opinions on the assessment of conflicts of legal interests and other corruption risks for both acting judges and retired judges, is an individual regulation of legal relations through: interpretation of law; overcoming gaps and conflicts in the law; individuali zation of rights, etc. The content of the interpretation of law by the Commission of the Council of Judges of the Russian Federation on Ethics is: the application of certain norms of both international and national law in a specific legal relationship when assessing conflicts of legal interests among judges through a systematic interpretation of the norms of law as a system of elements, defining its role in law, identifying other norms, as well as the principles of law; interpretation of the principles and norms of law, through the legal-logical interpretation of a normative act as logically interconnected structural elements of a single, internally agreed and consistent system of principles and norms of law, when deciding on the presence of conflicts of legal interests in the activities of judges, etc. The paper substantiates that in relation to conflicts of legal interests, individualization should be aimed at determining by the Council of Judges of the Russian Federation typical situations of such conflicts for their correct assessment and development of recommendations related to the optimal behavior of judges, when circumstances arise that lead to conflicts of legal interests.

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