668,979 research outputs found

    Turbocharger Structural Integrity

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    Since the introduction of Euro VI in January 2014, all new diesel powered commercial vehicles have been equipped with turbocharged engines. It is virtually impossible to meet these emission regulations without using a turbocharger. Similarly, in the passenger car sector both on diesel and petrol (gasoline) powered vehicles, legislative pressure to reduce emissions of carbon dioxide are seeing the introduction of turbochargers across almost all new power units. Future legislation will continue this trend with engine manufacturers becoming increasingly reliant on turbocharging. As well as increasing the requirement for turbochargers, these external factors are also demanding that turbochargers become more responsive with reduced rotor inertia and lower thermal inertias. This in turn makes the task of ensuring that turbocharger components remain fit for purpose for the life of the turbocharger that much more difficult. In this paper some of the recent developments in turbocharger technology will be identified and the demands that these place on the structural components will be explored. The limitations of current methods of structural integrity assessment for some of these components will be discussed. Future developments of these methods will then be proposed

    Structural integrity of hierarchical composites

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    Interface mechanical problems are of paramount importance in engineering and materials science. Traditionally, due to the complexity of modelling their mechanical behaviour, interfaces are often treated as defects and their features are not explored. In this study, a different approach is illustrated, where the interfaces play an active role in the design of innovative hierarchical composites and are fundamental for their structural integrity. Numerical examples regarding cutting tools made of hierarchical cellular polycrystalline materials are proposed, showing that tailoring of interface properties at the different scales is the way to achieve superior mechanical responses that cannot be obtained using standard material

    Reliability and structural integrity

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    An analytic model is developed to calculate the reliability of a structure after it is inspected for cracks. The model accounts for the growth of undiscovered cracks between inspections and their effect upon the reliability after subsequent inspections. The model is based upon a differential form of Bayes' Theorem for reliability, and upon fracture mechanics for crack growth

    NASA airframe structural integrity program

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    NASA initiated a research program with the long-term objective of supporting the aerospace industry in addressing issues related to the aging of the commercial transport fleet. The program combines advanced fatigue crack growth prediction methodology with innovative nondestructive examination technology with the focus on multi-stage damage (MSD) at rivited connections. A fracture mechanics evaluation of the concept of pressure proof testing the fuselage to screen for MSD was completed. A successful laboratory demonstration of the ability of the thermal flux method to detect disbonds at rivited lap splice joints was conducted. All long-term program elements were initiated, and the plans for the methodology verification program are being coordinated with the airframe manufacturers

    Transverse cracking in metal/ceramic composites with lamellar microstructure

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    Open Access funded by European Structural Integrity SocietyPeer reviewedPublisher PD

    Structural integrity assessment of superheater outlet penetration tubeplate

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    In recent years, the Linear Matching Method (LMM) has been well developed for the integrity assessment of the component subjected to cyclic thermal and mechanical loads. In this paper, the fatigue damage of a superheater outlet penetration tubeplate is assessed in detail using the LMM with an ABAQUS 3D finite element model. The significant thermal transients of the component are due to the out of phase steam temperature oscillations. The primary loading on the component is from pressure (steam and gas) and system moment on the penetration and tail pipes. A transient thermal analysis is performed in the first step to determine the component temperature history during the cycle. Then these temperature solutions are used as an input to the structural analysis to obtain the elastic stress history caused by these temperature loads. A shakedown analysis is thereafter carried out and the evaluation of the steady cyclic behaviour of tubeplate during the steady state cycle is then achieved using the LMM. The elastic, plastic and total strain ranges over the steady state cycle are evaluated for the fatigue damage assessment. Both the constant and changing residual stress solutions associated with the steady state cycle are obtained. The comparisons of stress and strain range calculations for out of phase temperature oscillations by the LMM and other methodologies are given in the paper. Finally, a LMM ratchet limit analysis is carried out to assess the capacity of the component subjected to the existing thermal transients to withstand an additional primary loads including both pressure and moment. The temperature dependent elastic-plastic properties are adopted throughout the LMM assessment

    Space shuttle: Structural integrity and assessment study

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    A study program was conducted to determine the nondestructive evaluation (NDE) requirements and to develop a preliminary nondestructive evaluation manual for the entire space shuttle vehicle. The rationale and guidelines for structural analysis and NDE requirements development are discussed. Recommendations for development of NDE technology for the orbiter thermal protection system and certain structural components are included. Recommendations to accomplish additional goals toward space shuttle inspection are presented

    Space shuttle structural integrity and assessment study

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    Potential nondestructive evaluation (NDE) requirements for the space shuttle vehicle during structural inspection in the refurbishment/turnaround period, are defined. Data are given on NDE limitations and defect characterization by the process. Special attention was given to the determination of fatigue cracks, stress corrosion cracks, corrosion, and adhesive disbonds of airframes

    Providing structural modules with self-integrity monitoring

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    With the advent of complex space structures (i.e., U.S. Space Station), the need for methods for remotely detecting structural damage will become greater. Some of these structures will have hundreds of individual structural elements (i.e., strut members). Should some of them become damaged, it could be virtually impossible to detect it using visual or similar inspection techniques. The damage of only a few individual members may or may not be a serious problem. However, should a significant number of the members be damaged, a significant problem could be created. The implementation of an appropriate remote damage detection scheme would greatly reduce the likelihood of a serious problem related to structural damage ever occurring. This report presents the results of the research conducted on remote structural damage detection approaches and the related mathematical algorithms. The research was conducted for the Small Business Innovation and Research (SBIR) Phase 2 National Aeronautics and Space Administration (NASA) Contract NAS7-961

    Menorah Review (No. 22, Spring, 1991)

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    The Christian-Jewish Encounter -- Hooked on Academic Freedom and Integrity -- Genesis and Semiosis: Structural Reading of a Biblical Book -- Book Briefing
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