Sample records for aeroengines surface damage

  1. Luster Polish Strengthening Treatment for Raceway Surface of Aeroengine Bearings

    Institute of Scientific and Technical Information of China (English)

    DENG Si-er; TENG Hong-fei; MA Fu-jian; HAO Jian-jun; CHEN Tao


    A new surface strengthening technology, luster polish strengthening treatnent, was proposed to treat the raceway surface of aeroengine bearings (9Cr18Mo) with the centrifugal strengthening machine exclusively designed for luster polish strengthening treatment. The experimental results showed that luster polish strengthening treatment produced a compressive residual stress layer with a depth of over 80 μm below the surface of the bearing raceway, and thus effectively removed the metamorphic layer in the raceway surface. After luster polish strengthening treatment, the average surface hardness of the aeroengine bearing raceway was increased from 61.02 HRC to 63.01 HRC, the surface roughness was reduced from 0.06 μm to 0.03 μm, and the contact fatigue life of the aeroengine bearings was improved by about 90%, with the dispersion of fatigue life being reduced remarkably.Theoretical calculation result agrees with that obtained by experiment.

  2. Foreign Object Damage to Fan Rotor Blades of Aeroengine Part Ⅰ: Experimental Study of Bird Impact

    Institute of Scientific and Technical Information of China (English)


    The conditions of experiment for bird impact to blades have been improved. The experiment of bird impact to the fan rotor blades of an aeroengine is carried out. Through analyzing the transient state response of blades impacted by bird and the change of blade profile before and after the impact, the anti-bird impact performance of blades in the first fan rotor is verified. The basis of anti-foreign object damage design for the fan rotor blades of an aeroengine is provided.

  3. Vibration reliability analysis for aeroengine compressor blade based on support vector machine response surface method

    Institute of Scientific and Technical Information of China (English)

    GAO Hai-feng; BAI Guang-chen


    To ameliorate reliability analysis efficiency for aeroengine components, such as compressor blade, support vector machine response surface method (SRSM) is proposed. SRSM integrates the advantages of support vector machine (SVM) and traditional response surface method (RSM), and utilizes experimental samples to construct a suitable response surface function (RSF) to replace the complicated and abstract finite element model. Moreover, the randomness of material parameters, structural dimension and operating condition are considered during extracting data so that the response surface function is more agreeable to the practical model. The results indicate that based on the same experimental data, SRSM has come closer than RSM reliability to approximating Monte Carlo method (MCM); while SRSM (17.296 s) needs far less running time than MCM (10958 s) and RSM (9840 s). Therefore, under the same simulation conditions, SRSM has the largest analysis efficiency, and can be considered a feasible and valid method to analyze structural reliability.

  4. Foreign Object Damage to Fan Rotor Blades of Aeroengine Part Ⅱ: Numerical Simulation of Bird Impact

    Institute of Scientific and Technical Information of China (English)

    Guan Yupu; Zhao Zhenhua; Chen Wei; Gao Deping


    Bird impact is one of the most dangerous threats to flight safety. The consequences of bird impact can be severe and, therefore, the aircraft components have to be certified for a proven level of bird impact resistance before being put into service. The fan rotor blades of aeroengine are the components being easily impacted by birds. It is necessary to ensure that the fan rotor blades should have adequate resistance against the bird impact, to reduce the flying accidents caused by bird impacts. Using the contacting-impacting algorithm, the numerical simulation is carried out to simulate bird impact. A three-blade computational model is set up for the fan rotor blade having shrouds. The transient response curves of the points corresponding to measured points in experiments, displacements and equivalent stresses on the blades are obtained during the simulation. From the comparison of the transient response curves obtained from numerical simulation with that obtained from experiments, it can be found that the variations in measured points and the corresponding points of simulation are basically the same. The deforming process, the maximum displacements and the maximum equivalent stresses on blades are analyzed. The numerical simulation verifies and complements the experiment results.

  5. Surface integrity of GH4169 affected by cantilever finish grinding and the application in aero-engine blades

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    Li Xun


    Full Text Available GH4169 is the main material for aero-engine blades and integrated blisks. Because GH4169 has a poor milling performance, the profile precision and surface integrity of blades and integrated blisks are difficult to be met by utilizing the conventional milling process, which directly influence the global performance and reliability of aero-engines. Through grinding experiments on parameters and surface integrity optimization, the helical cantilever grinding process utilizing a 300# CBN RB wheel is presented and applied in finish machining of GH4169 blades. The profile errors of the blade surface are within ±0.01 mm, the roughness is less than 0.4 μm, the residual compressive stresses and the hardening rate are appropriate, there are no phenomena of burr and smearing with the grinding chips, and the leading/trailing edge can be smoothly connected with the suction/pressure surface. All the experimental results indicate that this grinding process is greatly suitable for the profile finish machining of GH4169 blades.

  6. Reliability analysis for aeroengine turbine disc fatigue life with multiple random variables based on distributed collaborative response surface method

    Institute of Scientific and Technical Information of China (English)

    高海峰; 白广忱; 高阳; 鲍天未


    The fatigue life of aeroengine turbine disc presents great dispersion due to the randomness of the basic variables, such as applied load, working temperature, geometrical dimensions and material properties. In order to ameliorate reliability analysis efficiency without loss of reliability, the distributed collaborative response surface method (DCRSM) was proposed, and its basic theories were established in this work. Considering the failure dependency among the failure modes, the distributed response surface was constructed to establish the relationship between the failure mode and the relevant random variables. Then, the failure modes were considered as the random variables of system response to obtain the distributed collaborative response surface model based on structure failure criterion. Finally, the given turbine disc structure was employed to illustrate the feasibility and validity of the presented method. Through the comparison of DCRSM, Monte Carlo method (MCM) and the traditional response surface method (RSM), the results show that the computational precision for DCRSM is more consistent with MCM than RSM, while DCRSM needs far less computing time than MCM and RSM under the same simulation conditions. Thus, DCRSM is demonstrated to be a feasible and valid approach for improving the computational efficiency of reliability analysis for aeroengine turbine disc fatigue life with multiple random variables, and has great potential value for the complicated mechanical structure with multi-component and multi-failure mode.

  7. Surface integrity of GH4169 affected by cantilever finish grinding and the application in aero-engine blades

    Institute of Scientific and Technical Information of China (English)

    Li Xun; Ma Shuang; Meng Fanjun


    GH4169 is the main material for aero-engine blades and integrated blisks. Because GH4169 has a poor milling performance, the profile precision and surface integrity of blades and integrated blisks are difficult to be met by utilizing the conventional milling process, which directly influence the global performance and reliability of aero-engines. Through grinding experiments on parameters and surface integrity optimization, the helical cantilever grinding process utilizing a 300# CBN RB wheel is presented and applied in finish machining of GH4169 blades. The profile errors of the blade surface are within ±0.01 mm, the roughness is less than 0.4 lm, the residual compressive stresses and the hardening rate are appropriate, there are no phenomena of burr and smearing with the grinding chips, and the leading/trailing edge can be smoothly connected with the suction/pressure surface. All the experimental results indicate that this grinding process is greatly suitable for the profile finish machining of GH4169 blades.

  8. Laser ablation and optical surface damage (United States)

    Chase, L. L.; Hamza, A. V.; Lee, H. W. H.

    Laser ablation usually accompanies optical surface damage to bare surfaces and coatings. Investigations of optical damage mechanisms by observation of ablation processes at laser fluences very close to the optical damage threshold are described. Several promising surface characterization methods for investigating damage mechanisms are also described. The possible role of laser ablation in initiating or promoting optical surface damage is discussed.

  9. Laser ablation mechanisms and optical surface damage (United States)

    Chase, L. L.; Hamza, A. V.; Lee, H. W. H.


    Laser ablation usually accompanies optical surface damage to bare surfaces and coatings. Investigations of optical damage mechanisms by observation of ablation processes at laser fluences very close to the optical damage threshold are described. Several promising surface characterization methods for investigating damage mechanisms are also described. The possible role of laser ablation in initiating or promoting optical surface damage is discussed.

  10. Directivity of a simplified aeroengine


    Mattei, Pierre-Olivier


    International audience; This paper presents theoretical and numerical results on the high frequency directivity of an aeroengine under flight conditions. In this paper, two different theories, based on a Kirchhoff approximation for semi-infinite cylinders, are combined to obtain the far field sound pressure radiated into the whole surrounding space. Although the geometric description of the engine is simplified - in particular, the annular exhaust is not taken into account - it includes some ...

  11. Failure Analysis towards Reliable Performance of Aero-Engines

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    T. Jayakumar


    Full Text Available Aero-engines are critical components whose reliable performance decides the primary safety of anaircrafthelicopter. This is met by rigorous maintenance schedule with periodic inspection/nondestructive testingof various engine components. In spite of these measures, failure of areo-engines do occur rather frequentlyin comparison to failure of other components. Systematic failure analysis helps one to identify root causeof the failure, thus enabling remedial measures to prevent recurrence of such failures. Turbine blades madeof nickel or cobalt-based alloys are used in aero-engines. These blades are subjected to complex loadingconditions at elevated temperatures. The main causes of failure of blades are attributed to creep, thermalfatigue and hot corrosion. Premature failure of blades in the combustion zone was reported in one of theaero-engines. The engine had both the compressor and the free-turbine in a common shaft. Detailedfailure analysis revealed the presence of creep voids in the blades that failed. Failure of turbine bladeswas also detected in another aero-engine operating in a coastal environment. In this failure, the protectivecoating on the blades was cracked at many locations. Grain boundary spikes were observed on these locations.The primary cause of this failure was the hot corrosion followed by creep damage

  12. A multiaxial incremental fatigue damage formulation using nested damage surfaces

    Directory of Open Access Journals (Sweden)

    Marco Antonio Meggiolaro


    Full Text Available Multiaxial fatigue damage calculations under non-proportional variable amplitude loadings still remains a quite challenging task in practical applications, in part because most fatigue models require cycle identification and counting to single out individual load events before quantifying the damage induced by them. Moreover, to account for the non-proportionality of the load path of each event, semi-empirical methods are required to calculate path-equivalent ranges, e.g. using a convex enclosure or the MOI (Moment Of Inertia method. In this work, a novel Incremental Fatigue Damage methodology is introduced to continuously account for the accumulation of multiaxial fatigue damage under service loads, without requiring rainflow counters or path-equivalent range estimators. The proposed approach is not based on questionable Continuum Damage Mechanics concepts or on the integration of elastoplastic work. Instead, fatigue damage itself is continuously integrated, based on damage parameters adopted by traditional fatigue models well tested in engineering practice. A framework of nested damage surfaces is introduced, allowing the calculation of fatigue damage even for general 6D multiaxial load histories. The proposed approach is validated by non-proportional tensiontorsion experiments on tubular 316L stainless steel specimens.

  13. Hail damage to typical aircraft surfaces. (United States)

    Hayduk, R. J.


    Severe structural damage can occur when aircraft collide with hailstones. Consequently, methods of predicting hail damage to airplane surfaces are needed by the aircraft designer. This paper describes an analytical method of predicting the dent depth and final deformed shape for simple structural components impacted by hailstones. The solution was accomplished by adapting the DEPROSS computer program to the problem of normal impact of hail on flat metallic sheets and spherical metallic caps. Experimental data and analytical predictions are presented for hail damage to typical aircraft surfaces along with a description of the hail gun and hail simulation technique used in the experimental study.

  14. Reliability analysis of aero-engine blades considering nonlinear strength degeneration

    Institute of Scientific and Technical Information of China (English)

    Lin Jiewei; Zhang Junhong; Yang Shuo; Bi Fengrong


    To comprehensively consider the effects of strength degeneration and failure correlation,an improved stress-strength interference (SSI) model is proposed to analyze the reliability of aeroengine blades with the fatigue failure mode.Two types of TC4 alloy experiments are conducted for the study on the damage accumulation law.All the parameters in the nonlinear damage model are obtained by the tension-compression fatigue tests,and the accuracy of the nonlinear damage model is verified by the damage tests.The strength degeneration model is put forward on the basis of the Chaboche nonlinear damage theory and the Griffith fracture criterion,and determined by measuring the fatigue toughness during the tests.From the comparison of two kinds of degeneration models based on the Miner's linear law and the nonlinear damage model respectively,the nonlinear model has a significant advantage on prediction accuracy especially in the later period of life.A time-dependent SSI reliability model is established.By computing the stress distribution using the finite element (FE) technique,the reliability of a single blade during the whole service life is obtained.Considering the failure correlation of components,a modified reliability model of aero-engine blades with common cause failure (CCF) is presented.It shows a closer and more reasonable process with the actual working condition.The improved reliability model is illustrated to be applied to aero-engine blades well,and the approach purposed in this paper is suitable for any actual machinery component of aero-engine rotor systems.

  15. How surface damage removal affects fatigue life (United States)

    Jeelani, S.; Scott, M. A.


    The effect of the removal of work hardened surface layers from specimens of 2024-T4 aluminum alloy and AISI-4130 steel on their fatigue lives has been investigated. Specimens were fatigued at selected stress levels for a given number of cycles, and the surface layer was removed followed by subsequent fatigue cycling. Results confirm that when a material is subjected to fatigue loading, damage accumulates in the surface layers in the form of work hardening. Removal of the surface layer brings the specimen back to its pre-fatigued condition.

  16. Recent trends in superalloys research for critical aero-engine components

    Energy Technology Data Exchange (ETDEWEB)

    Remy, Luc [Mine ParisTech, CNRS UMR 7633, 91 - Evry (France). Centre des Materiaux; Guedou, Jean-Yves [Snecma Safran Group, Moissy-Cramayel (France). Materials and Processes Dept.


    This paper is a brief survey of common research activity on superalloys for aero-engines between Snecma and Mines ParisTech Centre des Materiaux during recent years. First in disks applications, the development of new powder metallurgy superalloys is shown. Then grain boundary engineering is investigated in a wrought superalloy. Secondly, design oriented research on single crystals blades is shown: a damage model for low cycle fatigue is used for life prediction when cracks initiated at casting pores. The methodology developed for assessing coating life is illustrated for thermal barrier coating deposited on AMI single crystal superalloy. (orig.)

  17. [Remote passive sensing of aeroengine exhausts using FTIR system]. (United States)

    Xia, Qing; Zuo, Hong-Fu; Li, Shao-Cheng; Wen, Zhen-Hua; Li, Yao-Hua


    The traditional method of measuring the aeroengine exhausts is intrusive gas sampling analysis techniques. The disadvantages of the techniques include complex system, difficult operation, high costs and potential danger because of back-pressure effects. The non-intrusive methods have the potential to overcome these problems. So the remote FTIR passive sensing is applied to monitor aeroengine exhausts and determine the concentration of the exhausts gases of aeroengines. The principle of FTIR remote passive sensing is discussed. The model algorithm for the calibration of FTIR system, the radiance power distribution and gas concentration are introduced. TENSOR27 FTIR-system was used to measure the spectra of infrared radiation emitted by the hot gases of exhausts in a test rig. The emission spectra of exhausts were obtained under different thrusts. By analyzing the spectra, the concentrations of CO2, CO and NO concentration were calculated under 4 thrusts. Researches on the determination of concentration of the exhausts gases of aeroengines by using the remote FTIR sensing are still in early stage in the domestic aeronautics field. The results of the spectra and concentration in the aeroengine test are published for the first time. It is shown that the remote FTIR passive sensing techniques have a great future in monitoring the hot gas of the aeroengines exhausts.

  18. Exogenous glycosaminoglycans coat damaged bladder surfaces in experimentally damaged mouse bladder

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    Hurst Robert E


    Full Text Available Abstract Background Interstital cystitis is often treated with exogenous glycosaminoglycans such as heparin, chondroitin sulphate (Uracyst, hyaluronate (Cystistat or the semi-synthetic pentosan polysulphate (Elmiron. The mechanism of action is presumed to be due to a coating of the bladder surface to replace the normally present chondroitin sulphate and heparan sulphate lost as a result of the disease. This study used fluorescent labelled chondroitin sulphate to track the distribution of glycosaminoglycans administered intravesically to mouse bladder that had been damaged on the surface. Methods The surfaces of mouse bladders were damaged by 3 mechanisms – trypsin, 10 mM HCl, and protamine sulphate. Texas Red-labeled chondroitin sulphate was instilled into the bladders of animals with damaged bladders and controls instilled only with saline. Bladders were harvested, frozen, and sectioned for examination by fluorescence. Results The normal mouse bladder bound a very thin layer of the labelled chondroitin sulphate on the luminal surface. Trypsin- and HCl-damaged bladders bound the labelled chondroitin sulphate extensively on the surface with little penetration into the bladder muscle. Protamine produced less overt damage, and much less labelling was seen, presumably due to loss of the label as it complexed with the protamine intercalated into the bladder surface. Conclusion Glycosaminoglycan administered intravesically does bind to damaged bladder. Given that the changes seen following bladder damage resemble those seen naturally in interstitial cystitis, the mechanisms proposed for the action of these agents is consistent with a coating of damaged bladder.

  19. Experimental Technique of Titanium Fire in Aero-engine

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    MI Guangbao


    Full Text Available Titanium fire is the typical catastrophic fault in the aero-engine. Aiming at the urgent demand for experimental technique of titanium fire from advanced high thrust-weight ratio aero-engine, the combustion technology and theory of titanium alloy based on friction oxygen concentration method (FOC were systematically studied. The evaluation method of fireproof property and the friction ignition model were built, and the fireproof mechanism was illustrated. By generalizing recent progress in experimental technique of titanium fire from three levels, including evolutionary rule, mechanism and prevention and control technology, the ideas and directions of experimental technique associated with the application research of titanium fire in the future were proposed, namely overall evaluation of fireproof property close to air flow environment of the aero-engine, prediction model of fireproof property and experimental verification of fireproof technique under the air flow environment of aero-engine. It is necessary to establish the prevention system of titanium fire in aero-engine, which contributes to the realization of "full titanium" in compressor and to the increase of high thrust-weight ratio.

  20. Multidisciplinary Design Optimization on Conceptual Design of Aero-engine (United States)

    Zhang, Xiao-bo; Wang, Zhan-xue; Zhou, Li; Liu, Zeng-wen


    In order to obtain better integrated performance of aero-engine during the conceptual design stage, multiple disciplines such as aerodynamics, structure, weight, and aircraft mission are required. Unfortunately, the couplings between these disciplines make it difficult to model or solve by conventional method. MDO (Multidisciplinary Design Optimization) methodology which can well deal with couplings of disciplines is considered to solve this coupled problem. Approximation method, optimization method, coordination method, and modeling method for MDO framework are deeply analyzed. For obtaining the more efficient MDO framework, an improved CSSO (Concurrent Subspace Optimization) strategy which is based on DOE (Design Of Experiment) and RSM (Response Surface Model) methods is proposed in this paper; and an improved DE (Differential Evolution) algorithm is recommended to solve the system-level and discipline-level optimization problems in MDO framework. The improved CSSO strategy and DE algorithm are evaluated by utilizing the numerical test problem. The result shows that the efficiency of improved methods proposed by this paper is significantly increased. The coupled problem of VCE (Variable Cycle Engine) conceptual design is solved by utilizing improved CSSO strategy, and the design parameter given by improved CSSO strategy is better than the original one. The integrated performance of VCE is significantly improved.

  1. Time-evolving statistics of cavitation damage on metallic surfaces. (United States)

    Diodati, P; Marchesoni, F


    The statistics of surface damage on polycrystalline aluminium plates caused by acoustic cavitation is studied experimentally as a function of time. Cavitation is shown to produce a uniform distribution of crater-like holes with different depth, area and eccentricity. Most notably, the size distribution of such craters evolves with time from a gamma function into a power law. By contrast, on the surface of a martensitic Cu-Ni-Al crystal cavitation damage generates ramified patterns, reminiscent of a fractal object.

  2. A Rapid Method to Achieve Aero-Engine Blade Form Detection

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    Bin Sun


    Full Text Available This paper proposes a rapid method to detect aero-engine blade form, according to the characteristics of an aero-engine blade surface. This method first deduces an inclination error model in free-form surface measurements based on the non-contact laser triangulation principle. Then a four-coordinate measuring system was independently developed, a special fixture was designed according to the blade shape features, and a fast measurement of the blade features path was planned. Finally, by using the inclination error model for correction of acquired data, the measurement error that was caused by tilt form is compensated. As a result the measurement accuracy of the Laser Displacement Sensor was less than 10 μm. After the experimental verification, this method makes full use of optical non-contact measurement fast speed, high precision and wide measuring range of features. Using a standard gauge block as a measurement reference, the coordinate system conversion data is simple and practical. It not only improves the measurement accuracy of the blade surface, but also its measurement efficiency. Therefore, this method increases the value of the measurement of complex surfaces.

  3. Tailoring radiation damage in ZnO by surface modification (United States)

    Myers, M. T.; Charnvanichborikarn, S.; Myers, M. A.; Lee, J. H.; Wang, H.; Biener, M. M.; Shao, L.; Kucheyev, S. O.


    Heavy-ion irradiation of (0 0 0 1) ZnO crystals results in unusual damage buildup, including an additional (intermediate) peak in damage-depth profiles measured by ion channeling, the formation of near-surface nanocavities, and stoichiometric imbalance. All these effects are thought to be associated with the influence of the sample surface on dynamic annealing processes. Here, by using ion channeling and transmission electron microscopy, we find that placing an ~7 nm thick AlO(OH) layer on the (0 0 0 1) ZnO surface results in (i) suppression of cavity formation, (ii) a reduced intermediate defect peak intensity, and (iii) a decreased level of disorder extending up to ~100 nm from the ZnO surface for room-temperature bombardment with 500 keV Xe ions. Our results demonstrate the potential to control radiation damage in ZnO by surface manipulation.

  4. Influence of Damage Evolution on the Failure Surface of Concrete

    Institute of Scientific and Technical Information of China (English)

    LUO Xin; WEI Jun


    The damage which represents the alternation of internal state of material was introduced to concrete strength theory according to the theory of mechanics of continuous medium and the failure criterion of deteriorated concrete was discussions. In the tests, ultrasonic velocity is used to establish the damage variable and to establish the damage-coupled failure criterion of concrete under freeze-thaw. The results show that the failure surface is gradually shrinking with the increase of freeze-thaw times. Furthermore, by the comparison between the theoretical data and the testing data from the literature, the rationality of strength theory proposed in the paper acquire confirmation. The damagecoupled failure criterion presented here can indicate the influence of damage evolution on the failure surface of concrete.

  5. Generic methods for aero-engine exhaust emission prediction

    NARCIS (Netherlands)

    Shakariyants, S.A.


    In the thesis, generic methods have been developed for aero-engine combustor performance, combustion chemistry, as well as airplane aerodynamics, airplane and engine performance. These methods specifically aim to support diverse emission prediction studies coupled with airplane and engine simulation

  6. Flood damage claims reveal insights about surface runoff in Switzerland (United States)

    Bernet, D. B.; Prasuhn, V.; Weingartner, R.


    A few case studies in Switzerland exemplify that not only overtopping water bodies frequently cause damages to buildings. Reportedly, a large share of the total loss due to flooding in Switzerland goes back to surface runoff that is formed and is propagating outside of regular watercourses. Nevertheless, little is known about when, where and why such surface runoff occurs. The described process encompasses surface runoff formation, followed by unchannelised overland flow until a water body is reached. It is understood as a type of flash flood, has short response times and occurs diffusely in the landscape. Thus, the process is difficult to observe and study directly. A promising source indicating surface runoff indirectly are houseowners' damage claims recorded by Swiss Public Insurance Companies for Buildings (PICB). In most of Switzerland, PICB hold a monopoly position and insure (almost) every building. Consequently, PICB generally register all damages to buildings caused by an insured natural hazard (including surface runoff) within the respective zones. We have gathered gapless flood related claim records of most of all Swiss PICB covering more than the last two decades on average. Based on a subset, we have developed a methodology to differentiate claims related to surface runoff from other causes. This allows us to assess the number of claims as well as total loss related to surface runoff and compare these to the numbers of overtopping watercourses. Furthermore, with the good data coverage, we are able to analyze surface runoff related claims in space and time, from which we can infer spatial and temporal characteristics of surface runoff. Although the delivered data of PICB are heterogeneous and, consequently, time-consuming to harmonize, our first results show that exploiting these damage claim records is feasible and worthwhile to learn more about surface runoff in Switzerland.

  7. Transfer element method with application to acoustic design of aeroengine nacelle

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    Wang Xiaoyu


    Full Text Available In the present survey, various methods for the acoustic design of aeroengine nacelle are first briefly introduced along with the comments on their advantages and disadvantages for practical application, and then detailed analysis and discussion focus on a kind of new method which is called “transfer element method” (TEM with emphasis on its application in the following three problems: turbomachinery noise generations, sound transmission in ducts and radiation from the inlet and outlet of ducts, as well as the interaction between them. In the theoretical frame of the TEM, the solution of acoustic field in an infinite duct with stator sound source or liner is extended to that in a finite domain with all knows and unknowns on the interface plane, and the relevant acoustic field is solved by setting up matching equation. In addition, based on combining the TEM with the boundary element method (BEM by establishing the pressure and its derivative continuum conditions on the inlet and outlet surface, the sound radiation from the inlet and outlet of ducts can also be investigated. Finally, the effects of various interactions between the sound source and acoustic treatment have been discussed in this survey. The numerical examples indicate that it is quite important to consider the effect of such interactions on sound attenuation during the acoustic design of aeroengine nacelle.

  8. Research on Time-Synchronization-Based Test and Control System of Aeroengine

    Institute of Scientific and Technical Information of China (English)

    WU Wen-jie; QIN Dong-xing; DONG Wei


    This paper presents a method of NTP-based time synchronization and a strategy of master-slave server structured time synchronization to ensure the test and control system of aeroengine to be time-synchronized. Based on time synchronization, the hierarchy and the integration of the measurement and control system of aeroengine are investigated. In result, our method is successfully applied for multiple front-end tests in a simulative altitude test facility of aeroengine.

  9. Thermal annealing of laser damage precursors on fused silica surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Shen, N; Miller, P E; Bude, J D; Laurence, T A; Suratwala, T I; Steele, W A; Feit, M D; Wang, L L


    Previous studies have identified two significant precursors of laser damage on fused silica surfaces at fluenes below {approx} 35 J/cm{sup 2}, photoactive impurities in the polishing layer and surface fractures. In the present work, isothermal heating is studied as a means of remediating the highly absorptive, defect structure associated with surface fractures. A series of Vickers indentations were applied to silica surfaces at loads between 0.5N and 10N creating fracture networks between {approx} 10{micro}m and {approx} 50{micro}m in diameter. The indentations were characterized prior to and following thermal annealing under various times and temperature conditions using confocal time-resolved photo-luminescence (CTP) imaging, and R/1 optical damage testing with 3ns, 355nm laser pulses. Significant improvements in the damage thresholds, together with corresponding reductions in CTP intensity, were observed at temperatures well below the glass transition temperature (T{sub g}). For example, the damage threshold on 05.N indentations which typically initiates at fluences <8 J/cm{sup 2} could be improved >35 J/cm{sup 2} through the use of a {approx} 750 C thermal treatment. Larger fracture networks required longer or higher temperature treatment to achieve similar results. At an annealing temperature > 1100 C, optical microscopy indicates morphological changes in some of the fracture structure of indentations, although remnants of the original fracture and significant deformation was still observed after thermal annealing. This study demonstrates the potential of using isothermal annealing as a means of improving the laser damage resistance of fused silica optical components. Similarly, it provides a means of further understanding the physics associated with optical damage and related mitigation processes.

  10. Application of Interval Multi-attribute Decision-Making Method to Aeroengine Performance Ranking

    Institute of Scientific and Technical Information of China (English)

    Zhang Haijun; Zuo Hongfu; Liang Jian


    In view of the uncertainty of the monitored performance parameters of aeroengines, the fluctuating scope of the monitored informarion during a period is taken as interval numbers, and the interval multi-attribute decision-making method is employed to predict the performance of aeroengine. The synthetic weights of interval numbers are obtained by calculating deviation degree and possibility degree. As an example of application, 5 performance parameters monitored on 10 CF6 aeroengines of China Eastern Airlines Co.,Ltd are adopted as decision attributes to verify the algorithm. The obtained synthetic ranking result shows the effectiveness and rationality of the proposed method in reflecting the performance status of aeroengins.

  11. Laser-induced surface ablation as a probe of optical surface damage mechanisms (United States)

    Chase, L. L.


    The phenomenon of laser surface damage is briefly reviewed, with an emphasis on the fundamental physical mechanisms of the interaction of laser light with the surface. Recent measurements of laser ablation of charged and neutral surface constituents and impurities are described, and it is shown that these experiments can he used to investigate optical damage mechanisms. Crystalline ZnS is used as the primary example of this work.

  12. Diamond Processing by Focused Ion Beam - Surface Damage and Recovery

    CERN Document Server

    Bayn, Igal; Cytermann, Catherine; Meyler, Boris; Richter, Vladimir; Salzman, Joseph; Kalish, Rafi


    The Nitrogen Vacancy color center (NV-) in diamond is of great interest for novel photonic applications. Diamond nano-photonic structures are often implemented using Focused-Ion-Beam (FIB) processing, leaving a damaged surface which has a detrimental effect on the color center luminescence. The FIB processing effect on single crystal diamond surfaces and their photonic properties is studied by Time of Flight Secondary Ion Mass Spectrometry (TOF-SIMS) and photoluminescence (PL). Exposing the processed surface to hydrogen plasma, followed by chemical etching, drastically decreases implanted Ga concentration, resulting in a recovery of the NV- photo-emission and in a significant increase of the NV-/NV0 ratio.

  13. Net-Shape Processing Applied to Aero-Engine Components (United States)


    sustainable in the aero-engine business as the cost of key materials such as titanium and nickel alloys is escalating, fuelled by the seemingly...have deformed to consolidate the powder is removed by rough machining and/or pickling to reveal the net-shape component. The key to producing net...being relatively expensive in terms of cost and environmental impact, mainly due to the cost of machining the mild steel tooling and having to pickle

  14. Laser induced surface emission of neutral species and its relationship to optical surface damage processes (United States)

    Chase, L. L.; Smith, L. K.


    The laser-induced emission of neutral constituents and impurities from surfaces of several optical materials is shown to be correlated with optical surface damage thresholds. The characteristics of the emission can be utilized to investigate physical processes involved in the absorption of laser energy at the surface. Examples are given of neutral emission correlated with catastrophic surface heating, changes in surface stoichiometry, and thermally-induced cracking.

  15. Damage identification in beams by a response surface based technique

    Directory of Open Access Journals (Sweden)

    Teidj S.


    Full Text Available In this work, identification of damage in uniform homogeneous metallic beams was considered through the propagation of non dispersive elastic torsional waves. The proposed damage detection procedure consisted of the following sequence. Giving a localized torque excitation, having the form of a short half-sine pulse, the first step was calculating the transient solution of the resulting torsional wave. This torque could be generated in practice by means of asymmetric laser irradiation of the beam surface. Then, a localized defect assumed to be characterized by an abrupt reduction of beam section area with a given height and extent was placed at a known location of the beam. Next, the response in terms of transverse section rotation rate was obtained for a point situated afterwards the defect, where the sensor was positioned. This last could utilize in practice the concept of laser vibrometry. A parametric study has been conducted after that by using a full factorial design of experiments table and numerical simulations based on a finite difference characteristic scheme. This has enabled the derivation of a response surface model that was shown to represent adequately the response of the system in terms of the following factors: defect extent and severity. The final step was performing the inverse problem solution in order to identify the defect characteristics by using measurement.

  16. [Passive detection of aeroengine exhaust based on Fourier transform infrared system]. (United States)

    Li, Shao-cheng; Zuo, Hong-fu; Xia, Qing


    Since the composition and concentration of aeroengine exhaust can reflect the combustion efficiency, they can provide the basis for condition based maintenance, and also the basis for the analysis of environment pollution caused by aeroengine exhaust. So the importance of aeroengine exhaust detection is evident. Up to now, the measurement of aeroengine exhaust is based on sampling analysis which is not convenient and can't meet the detection requirements when an aeroplane is flying-off or flying in the sky. Hence, new methods of exhaust detection must be studied. The passive measurement technology based on Fourier transform infrared spectroscopy (FTIR) was applied to the measurement of aeroengine exhaust in the present paper. At first, the principle of passive measurement based on FTIR was introduced in detail. On this basis, a model algorithm for gas concentration calculation was deduced based on the principle of infrared transmission. Then the feasibility of aeroengine exhaust measurement based on passive FTIR was analyzed, and the passive measurement method of aeroengine exhaust based on FTIR was given. In the end, an experiment of aeroengine exhaust passive measurement was carried out by a FTIR with the type of Tensor 27 produced by BRUKER. Good quality spectra of the exhaust and the background were measured. Based on the model algo rithm of passive measurement, the absorbance spectra of CO and NO were obtained respectively, and the concentrations of CO and NO were figured out. To check up the veracity of this method, a comparison was made with another apparatus. There were only little differences between the results of the two experiments, showing that the passive measurement technology based on FTIR could meet the requirements of aeroengine exhaust detection.

  17. Probing and repairing damaged surfaces with nanoparticle-containing microcapsules (United States)

    Kratz, Katrina; Narasimhan, Amrit; Tangirala, Ravisubhash; Moon, Sungcheal; Revanur, Ravindra; Kundu, Santanu; Kim, Hyun Suk; Crosby, Alfred J.; Russell, Thomas P.; Emrick, Todd; Kolmakov, German; Balazs, Anna C.


    Nanoparticles have useful properties, but it is often important that they only start working after they are placed in a desired location. The encapsulation of nanoparticles allows their function to be preserved until they are released at a specific time or location, and this has been exploited in the development of self-healing materials and in applications such as drug delivery. Encapsulation has also been used to stabilize and control the release of substances, including flavours, fragrances and pesticides. We recently proposed a new technique for the repair of surfaces called `repair-and-go'. In this approach, a flexible microcapsule filled with a solution of nanoparticles rolls across a surface that has been damaged, stopping to repair any defects it encounters by releasing nanoparticles into them, then moving on to the next defect. Here, we experimentally demonstrate the repair-and-go approach using droplets of oil that are stabilized with a polymer surfactant and contain CdSe nanoparticles. We show that these microcapsules can find the cracks on a surface and selectively deliver the nanoparticle contents into the crack, before moving on to find the next crack. Although the microcapsules are too large to enter the cracks, their flexible walls allow them to probe and adhere temporarily to the interior of the cracks. The release of nanoparticles is made possible by the thin microcapsule wall (comparable to the diameter of the nanoparticles) and by the favourable (hydrophobic-hydrophobic) interactions between the nanoparticle and the cracked surface.

  18. Aero-Engine Fault Diagnosis Using Improved Local Discriminant Bases and Support Vector Machine

    Directory of Open Access Journals (Sweden)

    Jianwei Cui


    Full Text Available This paper presents an effective approach for aero-engine fault diagnosis with focus on rub-impact, through combination of improved local discriminant bases (LDB with support vector machine (SVM. The improved LDB algorithm, using both the normalized energy difference and the relative entropy as quantification measures, is applied to choose the optimal set of orthogonal subspaces for wavelet packet transform- (WPT- based signal decomposition. Then two optimal sets of orthogonal subspaces have been obtained and the energy features extracted from those subspaces appearing in both sets will be selected as input to a SVM classifier to diagnose aero-engine faults. Experiment studies conducted on an aero-engine rub-impact test system have verified the effectiveness of the proposed approach for classifying working conditions of aero-engines.

  19. Hydroxyapatite coating on damaged tooth surfaces by immersion

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Byoung-Ki; Ryu, Su-Chak [Department of Nanomaterials Engineering, College of Nanoscience and Nanotechnology, Pusan National University, Miryang, 607-706 (Korea, Republic of); Sun, Fangfang; Koh, Kwangnak; Han, Dong-Wook; Lee, Jaebeom, E-mail: [Department of Nanomedical Engineering, College of Nanoscience and Nanotechnology, Pusan National University, Miryang, 607-706 (Korea, Republic of)


    Hydroxyapatite (HAp) was coated on scratched areas of a human tooth and HAp disks by the immersion method in a HAp colloidal solution (<=20{mu}m of average diameter dispersed in DI water). The surface morphologies of the scratched area after immersion for 1-3 months were investigated showing that the damaged surfaces were remarkably recovered. Then, the mechanical property and chemical stability of the HAp coating layers on both specimens were determined via the Vickers hardness test and concentration measurement of extracted Ca{sup 2+} ions, respectively, after strong acidic treatment. The cellular behavior of mouse calvaria-derived pre-osteoblastic cells (MC3T3-E1) was also examined on the HAp layers regenerated on micro-scratched HAp disks for the purpose of their potential applications on maxillofacial bone conservation and reconstruction for prosthetic dentistry, and artificial disk preparation of a vertebral column. The notable loss of Ca{sup 2+} ions under a highly acidic condition was not observed in the layers coated by HAp adsorption, indicating that the coating surface was well adhered with the original surfaces of the respective specimen. Moreover, the HAp adsorption did not adversely affect the adhesion, growth and proliferation of MC3T3-E1 cells on the coated HAp layers for up to 21 days. These results suggest that the HAp coating on the scratched areas of the tooth would be effectively applicable for the development of long-term prevention of micro-cleavage and tooth health supporters to reduce discoloration and further maxillofacial and orthopedic applications.

  20. Influence of high rotational speeds on heat transfer and oil film thickness in aero-engine bearing chambers (United States)

    Wittig, S.; Glahn, A.; Himmelsbach, J.


    Increasing the thermal loading of bearing chambers in modern aero-engines requires advanced techniques for the determination of heat transfer characteristics. In the present study, film thickness and heat transfer measurements have been carried out for the complex two-phase oil/air flow in bearing chambers. In order to ensure real engine conditions, a new test facility has been built up, designed for rotational speeds up to n = 16,000 rpm and maximum flow temperatures of T(sub max) = 473 K. Sealing air and lubrication oil flow can be varied nearly in the whole range of aero-engine applications. Special interest is directed toward the development of an ultrasonic oil film thickness measuring technique, which can be used without any reaction on the flow inside the chamber. The determination of local heat transfer at the bearing chamber housing is based on a well-known temperature gradient method using surface temperature measurements and a finite element code to determine temperature distributions within the bearing chamber housing. The influence of high rotational speed on the local heat transfer and the oil film thickness is discussed.

  1. Corin/Dorin: A WDM-Enabled Platform for Aero-Engine Control Systems


    Xia, Ming; Moslehi, Behzad; Mukherjee, Biswanath; Behbahani, Alireza; Millar, Richard


    The Full Authority Digital Electronic Control (FADEC) centralized architecture has become the norm in aero-engine control systems. With a centralized system, changes are costly and complex [1]. The goal of this work is to develop the architectural design concept for a distributed supporting network called Coarse WDM Optical Ring Network (CORIN) appropriate for aero-engine performance monitoring. A CORIN features high bandwidth, reliability, modularity, scalability, flexibility, an...

  2. Fault Diagnosis of Demountable Disk-Drum Aero-Engine Rotor Using Customized Multiwavelet Method


    Jinglong Chen; Yu Wang; Zhengjia He; Xiaodong Wang


    The demountable disk-drum aero-engine rotor is an important piece of equipment that greatly impacts the safe operation of aircraft. However, assembly looseness or crack fault has led to several unscheduled breakdowns and serious accidents. Thus, condition monitoring and fault diagnosis technique are required for identifying abnormal conditions. Customized ensemble multiwavelet method for aero-engine rotor condition identification, using measured vibration data, is developed in this paper. Fir...

  3. Surface Damage Mechanism of Monocrystalline Si Under Mechanical Loading (United States)

    Zhao, Qingliang; Zhang, Quanli; To, Suet; Guo, Bing


    Single-point diamond scratching and nanoindentation on monocrystalline silicon wafer were performed to investigate the surface damage mechanism of Si under the contact loading. The results showed that three typical stages of material removal appeared during dynamic scratching, and a chemical reaction of Si with the diamond indenter and oxygen occurred under the high temperature. In addition, the Raman spectra of the various points in the scratching groove indicated that the Si-I to β-Sn structure (Si-II) and the following β-Sn structure (Si-II) to amorphous Si transformation appeared under the rapid loading/unloading condition of the diamond grit, and the volume change induced by the phase transformation resulted in a critical depth (ductile-brittle transition) of cut (˜60 nm ± 15 nm) much lower than the theoretical calculated results (˜387 nm). Moreover, it also led to abnormal load-displacement curves in the nanoindentation tests, resulting in the appearance of elbow and pop-out effects (˜270 nm at 20 s, 50 mN), which were highly dependent on the loading/unloading conditions. In summary, phase transformation of Si promoted surface deformation and fracture under both static and dynamic mechanical loading.

  4. Effect of Random Clustering on Surface Damage Density Estimates

    Energy Technology Data Exchange (ETDEWEB)

    Matthews, M J; Feit, M D


    Identification and spatial registration of laser-induced damage relative to incident fluence profiles is often required to characterize the damage properties of laser optics near damage threshold. Of particular interest in inertial confinement laser systems are large aperture beam damage tests (>1cm{sup 2}) where the number of initiated damage sites for {phi}>14J/cm{sup 2} can approach 10{sup 5}-10{sup 6}, requiring automatic microscopy counting to locate and register individual damage sites. However, as was shown for the case of bacteria counting in biology decades ago, random overlapping or 'clumping' prevents accurate counting of Poisson-distributed objects at high densities, and must be accounted for if the underlying statistics are to be understood. In this work we analyze the effect of random clumping on damage initiation density estimates at fluences above damage threshold. The parameter {psi} = a{rho} = {rho}/{rho}{sub 0}, where a = 1/{rho}{sub 0} is the mean damage site area and {rho} is the mean number density, is used to characterize the onset of clumping, and approximations based on a simple model are used to derive an expression for clumped damage density vs. fluence and damage site size. The influence of the uncorrected {rho} vs. {phi} curve on damage initiation probability predictions is also discussed.

  5. Surface analysis of transition metal oxalates: Damage aspects

    Energy Technology Data Exchange (ETDEWEB)

    Chenakin, S.P., E-mail: [Université Libre de Bruxelles (ULB), Chimie-Physique des Matériaux, B-1050 Bruxelles (Belgium); Institute of Metal Physics, Nat. Acad. Sci. of Ukraine, Akad. Vernadsky Blvd. 36, 03680 Kiev (Ukraine); Szukiewicz, R. [Université Libre de Bruxelles (ULB), Chimie-Physique des Matériaux, B-1050 Bruxelles (Belgium); Barbosa, R.; Kruse, N. [Université Libre de Bruxelles (ULB), Chimie-Physique des Matériaux, B-1050 Bruxelles (Belgium); Voiland School of Chemical Engineering and Bioengineering, Washington State University, 155 Wegner Hall, Pullman, WA 99164-6515 (United States)


    Highlights: • Gas evolution from the Mn, Co, Ni and Cu oxalate hydrates in vacuum, during exposure to X-rays and after termination of X-ray irradiation is studied. • A comparative study of the damage caused by X-rays in NiC{sub 2}O{sub 4} and CuC{sub 2}O{sub 4} is carried out. • Effect of Ar{sup +} bombardment on the structure and composition of CoC{sub 2}O{sub 4} is studied. - Abstract: The behavior of transition metal oxalates in vacuum, under X-ray irradiation and low-energy Ar{sup +} ion bombardment was studied. A comparative mass-spectrometric analysis was carried out of gas evolution from the surface of Mn, Co, Ni and Cu oxalate hydrates in vacuum, during exposure to X-rays and after termination of X-ray irradiation. The rates of H{sub 2}O and CO{sub 2} liberation from the oxalates were found to be in an inverse correlation with the temperatures of dehydration and decomposition, respectively. X-ray photoelectron spectroscopy (XPS) was employed to study the X-ray induced damage in NiC{sub 2}O{sub 4} and CuC{sub 2}O{sub 4} by measuring the various XP spectral characteristics and surface composition of the oxalates as a function of time of exposure to X-rays. It was shown that Cu oxalate underwent a significantly faster degradation than Ni oxalate and demonstrated a high degree of X-ray induced reduction from the Cu{sup 2+} to the Cu{sup 1+} chemical state. 500 eV Ar{sup +} sputter cleaning of CoC{sub 2}O{sub 4} for 10 min was found to cause a strong transformation of the oxalate structure which manifested itself in an appreciable alteration of the XP core-level and valence band spectra. The analysis of changes in stoichiometry and comparison of XP spectra of bombarded oxalate with respective spectra of a reference carbonate CoCO{sub 3} implied that the bombardment-induced decomposition of CoC{sub 2}O{sub 4} gave rise to the formation of CoO-like and disordered CoCO{sub 3}-like phases.

  6. Super plastic forming technology applied to aeroengine and space equipment (United States)

    Mandai, Katsumi


    Titanium alloys, especially Ti-6Al-4V, are widely used for the aeroengine and space equipment because of their high strength ratio and excellent resistance to heat and corrosion. But this material is difficult to manufacture by conventional plastic forming technology. It has been reported that Ti-6Al-4V shows extensive ductility (superplasticity), more than 1000 percent under the condition of both low straining rate and high temperature ranges. Superplastic forming technology applying this characteristic is widely known as one of the most cost-effective methods to save material. At the plant, gas argon blowing equipment for the superplastic forming technology has been developed and 'V2500 nose fairing' and 'fuel tank of the H-II rocket second stage reaction control system' have been manufactured. This paper describes the superplastic forming equipment and the two products above.

  7. Investigation Of Breakdown Induced Surface Damage On 805 Mhz Pillbox Cavity Interior Surfaces

    CERN Document Server

    Jana, M R; Leonova, M; Moretti, A; Tollestrup, A; Yonehara, K; Freemire, B; Torun, Y; Bowring, D; Flanagan, G


    The MuCool Test Area (MTA) at Fermilab is a facility to develop the technology required for ionization cooling for a future Muon Collider and/or Neutrino Factory. As part of this research program, we have tested two 805 MHz vacuum RF cavities in a multi-Tesla magnetic field to study the effects of the static magnetic field on the cavity operation. This study gives useful information on field emitters in the cavity, dark current, surface conditioning, breakdown mechanisms and material properties of the cavity. All these factors determine the maximum accelerating gradient in the cavity. This paper discusses the image processing technique for quantitative estimation of spark damage spot distribution on cavity interior surfaces. The distribution is compared with the electric field distribution predicted by a computer code calculation. The local spark density is proportional to probability of surface breakdown and shows a power law dependence on the maximum electric field (E). This E dependence is consistent with ...

  8. The apparent effect of sample surface damage on the dielectric parameters of GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Engelbrecht, J.A.A. [Physics Department, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa)], E-mail:; Hashe, N.G. [Physics Department, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa); Hillie, K.T. [CSIR-NML Laboratory, P.O. Box 395, Pretoria 0001 (South Africa); Claassens, C.H. [Physics Department, University of the Free State, Bloemfontein 9300 (South Africa)


    The dielectric and optical parameters determined by infrared reflectance spectroscopy and computer simulation of a set of GaAs substrates of various surface topologies are reported. The influence of surface damage on the parameters is noted.

  9. 75 FR 45160 - SKF Aeroengine Falconer a Subsidiary of AB SKF Including On-Site Leased Workers From Manpower... (United States)


    ..., Falconer, New York. The notice was published in the Federal Register on March 12, 2010 (75 FR 11924). At... Employment and Training Administration SKF Aeroengine Falconer a Subsidiary of AB SKF Including On-Site... February 4, 2010, applicable to workers of SKF Aeroengine Falconer, a subsidiary of AB SKF, including...

  10. Fault Diagnosis of Demountable Disk-Drum Aero-Engine Rotor Using Customized Multiwavelet Method

    Directory of Open Access Journals (Sweden)

    Jinglong Chen


    Full Text Available The demountable disk-drum aero-engine rotor is an important piece of equipment that greatly impacts the safe operation of aircraft. However, assembly looseness or crack fault has led to several unscheduled breakdowns and serious accidents. Thus, condition monitoring and fault diagnosis technique are required for identifying abnormal conditions. Customized ensemble multiwavelet method for aero-engine rotor condition identification, using measured vibration data, is developed in this paper. First, customized multiwavelet basis function with strong adaptivity is constructed via symmetric multiwavelet lifting scheme. Then vibration signal is processed by customized ensemble multiwavelet transform. Next, normalized information entropy of multiwavelet decomposition coefficients is computed to directly reflect and evaluate the condition. The proposed approach is first applied to fault detection of an experimental aero-engine rotor. Finally, the proposed approach is used in an engineering application, where it successfully identified the crack fault of a demountable disk-drum aero-engine rotor. The results show that the proposed method possesses excellent performance in fault detection of aero-engine rotor. Moreover, the robustness of the multiwavelet method against noise is also tested and verified by simulation and field experiments.

  11. Investigation of Surface Damage in Forming of High Strength and Galvanized Steel Sheets

    Institute of Scientific and Technical Information of China (English)

    Zhongqi Yu; Yingke Hou; Haomin Jiang; Xinping Chen; Weigang Zhang


    Powdering/exfoliating of coatings and scratching are the main forms of surface damage in the forming of galvanized steels and high strength steels (HSS), which result in increased die maintenance cost and scrap rate.In this study, a special rectangular box was developed to investigate the behavior and characteristics of surface damage in sheet metal forming (SMF) processes.U-channel forming tests were conducted to study the effect of tool hardness on surface damage in the forming of high strength steels and galvanized steels (hot-dip galvanized and galvannealed steels).Experimental results indicate that sheet deformation mode influences the severity of surface damage in SMF and surface damage occurs easily at the regions where sheet specimen deforms under the action of compressive stress.Die corner is the position where surface damage initiates.For HSS sheet, surface damage is of major interest due to high forming pressure.The HSS and hot-dip galvanized steels show improved ability of damage-resistance with increased hardness of the forming tool.However, for galvannealed steel it is not the forming tool with the highest hardness value that performs best.

  12. The improvement of laser induced damage resistance of optical workpiece surface by hydrodynamic effect polishing (United States)

    Peng, Wenqiang; Guan, Chaoliang; Li, Shengyi; Wang, Zhuo


    Surface and subsurface damage in optical element will greatly decrease the laser induced damage threshold (LIDT) in the intense laser optical system. Processing damage on the workpiece surface can be inevitably caused when the material is removed in brittle or plastic mode. As a non-contact polishing technology, hydrodynamic effect polishing (HEP) shows very good performance on generating an ultra-smooth surface without damage. The material is removed by chemisorption between nanoparticle and workpiece surface in the elastic mode in HEP. The subsurface damage and surface scratches can be effectively removed after the polishing process. Meanwhile ultra-smooth surface with atomic level surface roughness can be achieved. To investigate the improvement of LIDT of optical workpiece, polishing experiment was conducted on a magnetorheological finishing (MRF) silica glass sample. AFM measurement results show that all the MRF directional plastic marks have been removed clearly and the root-mean-square (rms) surface roughness has decreased from 0.673nm to 0.177nm after HEP process. Laser induced damage experiment was conducted with laser pulse of 1064nm wavelength and 10ns time width. Compared with the original state, the LEDT of the silica glass sample polished by HEP has increased from 29.78J/cm2 to 45.47J/cm2. It demonstrates that LIDT of optical element treated by HEP can be greatly improved for ultra low surface roughness and nearly defect-free surface/subsurface.

  13. Frequency-domain Model Matching PID Controller Design for Aero-engine (United States)

    Liu, Nan; Huang, Jinquan; Lu, Feng


    The nonlinear model of aero-engine was linearized at multiple operation points by using frequency response method. The validation results indicate high accuracy of static and dynamic characteristics of the linear models. The improved PID tuning method of frequency-domain model matching was proposed with the system stability condition considered. The proposed method was applied to the design of PID controller of the high pressure rotor speed control in the flight envelope, and the control effects were evaluated by the nonlinear model. Simulation results show that the system had quick dynamic response with zero overshoot and zero steadystate error. Furthermore, a PID-fuzzy switching control scheme for aero-engine was designed, and the fuzzy switching system stability was proved. Simulations were studied to validate the applicability of the multiple PIDs fuzzy switching controller for aero-engine with wide range dynamics.

  14. Application of Small Sample Analysis in Life Estimation of Aeroengine Components

    Institute of Scientific and Technical Information of China (English)

    NIE Ting


    The samples of fatigue life tests for aeroengine components are usually less than 5, so the evaluation of these samples belongs to small sample analysis. The Weibull distribution is known to describe the life data accurately, and the Weibayes method (developed from Bayesian method) expands on the experiential data in the small sample analysis of fatigue life in aeroengine. Based on the Weibull analysis, a program was developed to improve the efficiency of the reliability analysis for aeroengine compgnents. This program has complete cycle fatigue life was evaluated by this program. From the results, the following conclusions were drawn: (a) that this program could be used for the engineering applications, and (b) while a lack of former test data lowered the validity of evaluation results, the Weibayes method ensured the results of small sample analysis did not deviate from the truth.

  15. Surface roughness and removal rate in magnetorheological finishing of a subsurface damage free surface

    Institute of Scientific and Technical Information of China (English)

    CHENG Haobo; WANG Yingwei; FENG Zhijing; CHENG Kai


    Based on computer-controlled optical surfacing, a new technique called magnetorheological finishing (MRF), is presented. The new technique combines the features of conventional loose abrasive machining with a wheel shaped polishing tool. The tool incorporates a host of features and has unprecedented fabricating versatility. The pre-polishing and fine polishing processes can be performed only by adjusting different parameters. The material removal function is studied theoretically and the results of simulation present a Gaussian distribution feature. Based on the established theoretical model, material removal rate experiments involving a parabolic mirror are designed and carried out to determine the effect of controllable parameters on size of the gap between the workpiece and the polishing wheel,rotating speed of the polishing wheel, concentration of volume fraction of non-magnetic particles and polishing time. Further experiments are carried out on the surface microstructure of the workpiece, the final surface roughness with an initial value of 10.98 nm reaches 1.22 nm root mean square (RMS) after 20 min of polishing. The subsurface damage experiment and the atomic force microscopy (AFM)measurement on the polished surface can also verify the feasibility of the MRF technique.

  16. Radiation-Induced Nano-Explosions at the Solid Surface:Near Surface Radiation Damage in CR-39 Polymer

    Institute of Scientific and Technical Information of China (English)

    Mukhtar Ahmed Rana


    @@ New measurements of fission fragment and alpha particle induced surface damage in the most sensitive and commonly used nuclear track detector CR-39 are presented here.Precisely designed and optimized exposure and chemical etching experiments are employed to unfold the structure of radiation induced surface damage (RISD).Delay in the startup of the chemical etching of latent tracks or surface radiation damage is measured and is found to contain important information about the structure of the surface damage.Simple atomic scale pictures of RISD and its chemical etching are developed in an empirical manner.Theoretical model and experimental findings coherently compose a realistic picture of early or ferntosecond evolution of RISD.

  17. A Virtual Assembly System for Aero-engines Based on VR

    Institute of Scientific and Technical Information of China (English)

    GAO Ying; GUO Yun-peng; SHAO Ya-nan; XU Zhi-guo


    In this paper, a synthesized technique is explored through design of a virtual experiment system for main aeroengine based on VR, which attempts to integrate some VR techniques, such as 3D stereo simulation and modeling, 3D scene management and human-computer virtual assembly based on data glove and collision detection. The geometry modeling and instantiation technique, virtual hand modeling and data glove interaction technique are discussed chiefly. Finally, taking aim at assembling and dismantling experiment system of a certain aero-engine, interface technology is expounded also.

  18. Free surface damage induced by irradiation of BCC iron (United States)

    Korchuganov, Aleksandr V.


    The influence of the crystallographic orientation of bcc iron samples on the character of structural changes near the free surface irradiated with ions was studied in the framework of a molecular dynamics method. Irradiation of the (111) surface leads to the formation of craters surrounded by atoms escaped on the surface (adatoms). In the case of the (110) surface irradiation, a vacancy-type dislocation loop with the Burgers vector a or a/2 was formed. The number of adatoms and survived point defects was greater in the sample with the (110) surface than in the sample with the (111) surface for the atomic displacement cascade energies lower than 20 keV. The influence of the irradiated surface orientation on the number of generated point defects decreased with the increasing atomic displacement cascade energy.

  19. Morphology of surface damage resulting from static and dynamic contacts


    Vongbandit, Pratip


    This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University. Contact fatigue damages resulting either from static or dynamic contact are of interest for understanding the failure modes and mechanisms leading to improvement of the components’ performances in tribological applications. The objective of this research was to ascertain how and to what extent the counterface materials, loading conditions, contact configuration, lubrication, and the environme...

  20. Particle impact tests. [simulation of micrometeoroid damage to orbiter surface (United States)

    Komatsu, G. K.


    Particle impact tests were performed on three types of orbiter surface with a micrometeoroid facility. The test equipment electrostatically accelerated micron sized particles to high velocities simulating micrometeoroid impacts. Test particles were titanium diboride with typical velocities in the range 1 to 2.3 km x sec/1 and equivalent particle diameters in the range 4 to 16 microns. Impact angles to the material surface were 90, 60 and 30 degrees. The particle impact sites were located on the sample surfaces and craters were photographed with a magnification of 400X.

  1. Laser annealing of plasma-damaged silicon surface

    Energy Technology Data Exchange (ETDEWEB)

    Sameshima, T., E-mail: [Tokyo University of Agriculture and Technology, Tokyo, 184-8588 (Japan); Hasumi, M. [Tokyo University of Agriculture and Technology, Tokyo, 184-8588 (Japan); Mizuno, T. [Kanagawa University, Kanagawa, 259-1293 (Japan)


    Highlights: • Ar plasma irradiation caused serious damage at SiO{sub 2}/Si interfaces. • The light induced minority carrier effective lifetime (τ{sub eff}) was decreased to 1.7 × 10{sup −5} s by Ar plasma irradiation. • The density of charge injection type interface traps at 9.1 × 10{sup 11} cm{sup −2} eV{sup −1} was formed. • 940-nm laser irradiation at 3.7 × 10{sup 4} W/cm{sup 2} for 4 × 10{sup −3} s cured the interface. • It increased τ{sub eff} to 1.7 × 10{sup −3} s and decreased D{sub it} to 2.1 × 10{sup 10} cm{sup −2} eV{sup −1}. - Abstract: 13.56 MHz capacitance coupled Ar plasma irradiation at 50 W for 120 s caused serious damage at SiO{sub 2}/Si interfaces for n-type 500-μm-thick silicon substrates. The 635-nm-light induced minority carrier effective lifetime (τ{sub eff}) was decreased from 1.7 × 10{sup −3} (initial) to 1.0 × 10{sup −5} s by Ar plasma irradiation. Moreover, the capacitance response at 1 MHz alternative voltage as a function of the bias voltage (C–V) was changed to hysteresis characteristic associated with the density of charge injection type interface traps at the mid gap (D{sub it}) at 9.1 × 10{sup 11} cm{sup −2} eV{sup −1}. Subsequent 940-nm laser annealing at 3.7 × 10{sup 4} W/cm{sup 2} for 4.0 × 10{sup −3} s markedly increased τ{sub eff} to 1.7 × 10{sup −3} s and decreased D{sub it} to 2.1 × 10{sup 10} cm{sup −2} eV{sup −1}. The hysteresis phenomenon was reduced in C–V characteristics. Laser annealing effectively decreased the density of plasma induced carrier recombination and trap states. However, laser annealing with a high power intensity of 4.0 × 10{sup 4} W/cm{sup 2} seriously caused a thermal damage associated with a low τ{sub eff} and a high D{sub it} with no hysteresis characteristic.


    Institute of Scientific and Technical Information of China (English)

    G.Q. Zhang


    The status of research, development of superalloys and materials processing & fabrication technologies for aero-engine applications in China Aviation Industry, with an emphasis on recent achievements at BIAM including directionally solidified and single crystal superalloys for blade and vane applications, wrought superalloys for aero-engine disks and rings, and powder metallurgy (PM) superalloys for high performance disk applications were described. It was also reviewed the development of new class of high temperature structural materials, such as structural intermetallics, and advanced material processing technologies including rapid solidification,spray forming and so on. The trends of research and development of the above mentioned superalloys and processing technologies are outlined. Cast, wrought and PM superalloys are the workhorse materials for the hot section of current aero-engines. New high temperature materials and advanced processing technologies have been and will be the subject of study. It is speculated that high performance, high purity and low cost superalloys and technologies will play key roles in aero-engines.

  3. Recognition and practice on remanufacturing engineering management of military aero-engines

    Institute of Scientific and Technical Information of China (English)

    Xiang Qiao


    The technologies of design, manufacture and MRO (maintenance, repair and overhaul) tor the mili- tary aero-engines, particularly for the fighters, are much more difficult to be mastered than those for any other aero-engines. They have been monopolized by only a few countries and the core technologies have never been transferred due to high risk, high investment, high barrier and high cost. Therefore, our country has long relied on mapping and copying the others' engines to satisfy the domestic demand due to not having our own indepen- dent technologies for the design and manufacture of military aero-engines. However, through over 20 years of unremitting effort, the independent MRO has been achieved for all the Chinese fighter engines, covering in- R&D (research and development) and in-service engines; and the MRO technologies, capabilities, quality, cost-efficiency have reached or exceeded those of original manufacturers. It has grown out of nothing, and then from weak to strong. In particular, dozens of projects concerning the R&D and engineering application of re- manufacturing have obtained the independent intellectual property rights and are playing an irreplaceable role in achieving leaping improvement of independent MRO for Chinese military aero-engines.

  4. Investigation of transient temperature's influence on damage of high-speed sliding electrical contact rail surface (United States)

    Zhang, Yuyan; Sun, Shasha; Guo, Quanli; Yang, Degong; Sun, Dongtao


    In the high speed sliding electrical contact with large current, the temperature of contact area rises quickly under the coupling action of the friction heating, the Joule heating and electric arc heating. The rising temperature seriously affects the conductivity of the components and the yield strength of materials, as well affects the contact state and lead to damage, so as to shorten the service life of the contact elements. Therefore, there is vital significance to measure the temperature accurately and investigate the temperature effect on damage of rail surface. Aiming at the problem of components damage in high speed sliding electrical contact, the transient heat effect on the contact surface was explored and its influence and regularity on the sliding components damage was obtained. A kind of real-time temperature measurement method on rail surface of high speed sliding electrical contact is proposed. Under the condition of 2.5 kA current load, based on the principle of infrared radiation non-contact temperature sensor was used to measure the rail temperature. The dynamic distribution of temperature field was obtained through the simulation analysis, further, the connection between temperature changes and the rail surface damage morphology, the damage volume was analyzed and established. Finally, the method to reduce rail damage and improve the life of components by changing the temperature field was discussed.

  5. Damage surfaces of cooper, niobium and titanium under micrometeorites impact

    Institute of Scientific and Technical Information of China (English)


    @@ Structure of near-crater regions of copper, niobium and titanium samples exposed in the outer space was studied. Flat Cu, Nb, Ti specimens 1 cm× 1 cm and 1 mm thickness were placed on the out-side surface of "MIR" space orbit station and exposed during 1.5 year. The samples than was studied by scanning electron microscopy with X-ray analysis.

  6. Damage surfaces of cooper, niobium and titanium under micrometeorites impact

    Institute of Scientific and Technical Information of China (English)

    Nikitushkina; O.; N.


    Structure of near-crater regions of copper, niobium and titanium samples exposed in the outer space was studied. Flat Cu, Nb, Ti specimens 1 cm× 1 cm and 1 mm thickness were placed on the out-side surface of "MIR" space orbit station and exposed during 1.5 year. The samples than was studied by scanning electron microscopy with X-ray analysis.……

  7. Entry and exit facet laser damage of optical windows with random antireflective surface structures (United States)

    Sapkota, Gopal; Case, Jason R.; Potter, Matthew G.; Busse, Lynda E.; Shaw, L. Brandon; Sanghera, Jasbinder S.; Aggarwal, Ishwar D.; Poutous, Menelaos K.


    Nanosecond duration, high intensity and high average power laser pulses induce damage on uncoated optics, due to localized field enhancement at the exit surface of the components. Anti-reflection (AR) coated optics, due to their (multiple) thin film boundaries, have similar field enhancement regions, which lead to laser damage on both entry and exit sides. Nano-scale structured optical interfaces with AR performance (ARSS) have been widely demonstrated, and found to have higher laser damage resistance than conventional AR coatings. Comprehensive tests of optical entry and exit structured-surface laser damage using nanosecond pulses for ARSS are not widely available. We measured the laser damage of random anti-reflective surface structures (rARSS), on planar, optical quality, fused silica substrates, using single 6-8ns duration pulses at 1064 nm wavelength. The single-sided rARSS substrates were optimized for Fresnel reflectance suppression at 1064 nm, and the measured transmittance at normal incidence was increased by 3.2%, with a possible theoretical maximum of 3.5%. The high energy laser beam was focused to increase the incident intensity, in order to probe values above and below the damage thresholds reported in the literature. The source laser Q-switch durations were used to directly control incident fluence. Multiple locations were tested for each Q-switch setting, to build a statistical relationship between the fluence and damaging events. Single-sided, AR random surface structured substrates were tested, using entry and exit side orientations, to determine any effects the random structures may have in the damage induced by the field enhancement on the exit side. We found that the AR randomly structured surfaces have a higher resistance, to the onset of laser damage, when they are located at the entry (structured) side of the substrates. In comparison, when the same AR random structures are in the beam exit side of the substrates, the onset of laser damage

  8. Measurements and TCAD Simulations of Bulk and Surface Radiation Damage Effects

    CERN Document Server

    F. Moscatelli; G. M. Bilei; A. Morozzi; G.-F. Dalla Betta; R. Mendicino; M. Boscardin; N. Zorzi; L. Servoli; P. Maccagnani


    In this work we propose the application of a radiation damage model based on the introduction of deep level traps/recombination centers suitable for device level numerical simulation of radiation detectors at very high fluences (e.g. 1÷2×1016 1-MeV equivalent neutrons per square centimeter) combined with a surface damage model developed by using experimental parameters extracted from measurements from gamma irradiated p-type dedicated test structures.

  9. Measurements and TCAD Simulations of Bulk and Surface Radiation Damage Effects in Silicon Detectors

    CERN Document Server

    Moscatelli, F; Passeri, D; Bilei, G M; Servoli, L; Morozzi, A; Betta, G -F Dalla; Mendicino, R; Boscardin, M; Zorzi, N


    In this work we propose the application of a radiation damage model based on the introduction of deep level traps/recombination centers suitable for device level numerical simulation of radiation detectors at very high fluences (e.g. 1{\\div}2 10^16 1-MeV equivalent neutrons per square centimeter) combined with a surface damage model developed by using experimental parameters extracted from measurements from gamma irradiated p-type dedicated test structures.

  10. Effect of Vacuum on the Occurrence of UV-Induced Surface Photoluminescence, Transmission Loss, and Catastrophic Surface Damage

    Energy Technology Data Exchange (ETDEWEB)

    Burnham, A K; Runkel, M; Demos, S G; Kozlowski, M R; Wegner, P J


    Vacuum degrades the transmittance and catastrophic damage performance of fused-silica surfaces, both bare and silica-sol anti-reflective coated. These effects may be important in certain space application of photonics devices. When exposed to hundreds of 355-rim, 10-ns laser pulses with fluences in the 2-15 J/cm{sup 2} range, transmittance loss is due to both increased reflectance and absorption at the surface. Spectroscopic measurements show that the absorbed light induces broadband fluorescence from the visible to infrared and that the peak photoluminescence wavelength depends cumulative fluence. The effect appears to be consistent with the formation of surface SiO{sub x} (x<2) with progressively lower x as cumulative fluence increases. Conversely, low fluence CW UV irradiation of fluorescent sites in air reduces the fluorescence signal, which suggests a photochemical oxidation reaction back to Si0{sub 2}. The occurrence of catastrophic damage (craters that grow on each subsequent pulse) also increases in a vacuum relative to air for both coated and uncoated samples. In both cases, the 50% damage probability for 100 one-mm sites decreases from about 45 to 35 J/cm{sup 2} for superpolished fused silica at pressures in the 10{sup -6} Torr range. The damage probability distribution in 10 Torr of air is close to that at one atmosphere of air. The damage morphology of the crater formed in vacuum differs substantially from that in air and has a more melted appearance and does not show cracking and flaking. These differences are possibly due to more coupling of the plasma shock wave into the surface with air present but slower heat dissipation in a vacuum. While it is attractive to propose that formation of sub-stoichiometric silica on the surface in a vacuum environment enhances the probability of catastrophic damage, initial experiments have not yet been able to establish a mechanistic link between the two phenomena.

  11. Luminescence Investigation of SiO2 Surfaces Damaged by 0.35 mm Laser Illumination

    Energy Technology Data Exchange (ETDEWEB)

    Kozlowski, M.; Battersby, C.L.; Demos, S.G.


    Following initiation at absorbing surface flaws, UV laser-induced damage to polished fused-silica surfaces continues to grow upon subsequent illumination. In this study photoluminescence spectroscopy was used to detect the formation of a modified, absorbing layer of silica that could be responsible for the continued growth of the damage site. For damage sites created with pulsed 355 nm illumination, three characteristic photoluminescence peaks are detected within the damage sites when excited with a 351 nm CW beam. Two of the peaks are likely due to the well-known E' and NBOHC defects associated with oxygen vacancies and broken Si-0 bonds, respectively. The third, and dominant, peak at 560 nm has not been clearly identified, but is likely associated with a change in stoichiometry of the silica. The relative intensities of the peaks are non-uniform across individual damage sites. The photoluminescence data is being combined with insights from various optical and electron microscopies to develop an understanding of laser-induced damage sites. The objective is to develop strategies to slow or stop the growth of the damage sites.

  12. Relationship between subsurface damage and surface roughness of ground optical materials

    Institute of Scientific and Technical Information of China (English)

    LI Sheng-yi; WANG Zhuo; WU Yu-lie


    A theoretical model of relationship between subsurface damage and surface roughness was established to realize rapid and non-destructive measurement of subsurface damage of ground optical materials. Postulated condition of the model was that subsurface damage depth and peak-to-valley surface roughness are equal to depth of radial and lateral cracks in brittle surface induced by small-radius (radius≤200 μm) spherical indenter, respectively. And contribution of elastic stress field to the radial cracks propagation was also considered in the loading cycle. Subsurface damage depth of ground BK7 glasses was measured by magnetorheological finishing spot technique to validate theoretical ratio of subsurface damage to surface roughness. The results show that the ratio is directly proportional to load of abrasive grains and hardness of optical materials, while inversely proportional to granularity of abrasive grains and fracture toughness of optical materials. Moreover, the influence of the load and fracture toughness on the ratio is more significant than the granularity and hardness, respectively. The measured ratios of 80 grit and 120 grit fixed abrasive grinding of BK7 glasses are 5.8 and 5.4, respectively.

  13. Full Aperture CO2 Laser Process to Improve Laser Damage Resistance of Fused Silica Optical Surface

    Directory of Open Access Journals (Sweden)

    Wei Liao


    Full Text Available An improved method is presented to scan the full-aperture optical surface rapidly by using galvanometer steering mirrors. In contrast to the previous studies, the scanning velocity is faster by several orders of magnitude. The velocity is chosen to allow little thermodeposition thus providing small and uniform residual stress. An appropriate power density is set to obtain a lower processing temperature. The proper parameters can help to prevent optical surface from fracturing during operation at high laser flux. S-on-1 damage test results show that the damage threshold of scanned area is approximately 40% higher than that of untreated area.

  14. Analysis of experimental result and fault diagnosis for aeroengine rotating shaft (United States)

    Zhao, Baoqun; Wang, Yuanyang


    To increase the accuracy of applying traditional fault diagnosis method to aeroengine vibrant faults, a novel approach based on wavelet neural network is proposed. The effective signal features are acquired by wavelet transform with multi-resolution analysis. These feature vectors then are applied to the neural network for training and testing. The synthesized method of recursive orthogonal least squares algorithm is used to fulfill the network structure and parameter initialization. By means of choosing enough practical samples to verify the proposed network performance, the information representing the faults is inputted into the trained network. According to the output result the fault pattern can be determined. The simulation results and actual applications show that the method can effectively diagnose and analyze the vibrant fault patterns of aeroengine and the diagnosis result is correct.

  15. Analytical Redundancy Design for Aeroengine Sensor Fault Diagnostics Based on SROS-ELM

    Directory of Open Access Journals (Sweden)

    Jun Zhou


    Full Text Available Analytical redundancy technique is of great importance to guarantee the reliability and safety of aircraft engine system. In this paper, a machine learning based aeroengine sensor analytical redundancy technique is developed and verified through hardware-in-the-loop (HIL simulation. The modified online sequential extreme learning machine, selective updating regularized online sequential extreme learning machine (SROS-ELM, is employed to train the model online and estimate sensor measurements. It selectively updates the output weights of neural networks according to the prediction accuracy and the norm of output weight vector, tackles the problems of singularity and ill-posedness by regularization, and adopts a dual activation function in the hidden nodes combing neural and wavelet theory to enhance prediction capability. The experimental results verify the good generalization performance of SROS-ELM and show that the developed analytical redundancy technique for aeroengine sensor fault diagnosis based on SROS-ELM is effective and feasible.

  16. Studies on dynamic characteristics of the joint in the aero-engine rotor system (United States)

    Shuguo, Liu; Yanhong, Ma; Dayi, Zhang; Jie, Hong


    The joint as a major part of the aero-engine rotating shafts directly influences its rotordynamics and state stability. This paper studies the dynamic effects of structure parameters and the external load on the stiffness and contact state of the rotor joints with nonlinear finite-element method and experiments. And a sensitivity analysis of critical speeds and vibration modes with respect to typical parameters (stiffness of the spline joints) is performed with finite difference methods, through two approaches, i.e. relative sensitivity analysis and absolute sensitivity analysis. The study results show that the stiffness and contact state of joints vary with external loads and geometry structures, and affect the rotor system operating. It is advisable to consider the influence of the position, structural parameter and external load of the rotor joints on aero-engine structure dynamics design.

  17. Therapeutic Effects of Sodium Hyaluronate on Ocular Surface Damage Induced by Benzalkonium Chloride Preserved Anti-glaucoma Medications

    Directory of Open Access Journals (Sweden)

    Xing Liu


    Conclusions: SH significantly improved both symptoms and signs of ocular surface damage in patients with BAC-preserved anti-glaucoma medications treatment. SH could be proposed as a new attempt to reduce ocular surface toxicity, and alleviate symptoms of ocular surface damage in BAC-preserved anti-glaucoma medications treatment.

  18. EB-PVD thermal barrier coatings for aeroengines and gas turbines

    Energy Technology Data Exchange (ETDEWEB)

    Peters, M.; Leyens, C.; Schulz, U.; Kaysser, W.A. [DLR, Koeln (Germany). Inst. of Materials Research


    High pressure turbine blades and vanes of aeroengines are among the most highly loaded parts in engineering components. For these demanding applications only high temperature Ni-base superalloys can be considered. These alloys have matured over the years from wrought to cast, then to directionally solidified alloys, whereas in the latest generation of turbines for the most demanding applications, like the rotating turbine components, single crystal material is employed. (orig.)

  19. Analytical Redundancy Design for Aeroengine Sensor Fault Diagnostics Based on SROS-ELM


    Jun Zhou; Yuan Liu; Tianhong Zhang


    Analytical redundancy technique is of great importance to guarantee the reliability and safety of aircraft engine system. In this paper, a machine learning based aeroengine sensor analytical redundancy technique is developed and verified through hardware-in-the-loop (HIL) simulation. The modified online sequential extreme learning machine, selective updating regularized online sequential extreme learning machine (SROS-ELM), is employed to train the model online and estimate sensor measurement...

  20. An Investigation of Unipolar Arcing Damage on Stainless Steel and Titanium Carbide Coated Surfaces. (United States)


    STAINLESS STEEL AND TITANIUM CARBIDE COATED SURFACES by Michael Thomas Keville and Robert William Lautrup June 1980 Thesis Advisors: F. Schwirzke K.D...rd"ll SU108016) V " 111. ’Cato .: "? : :V lI . An Investigation of Unipolar Arcing Master’s esis Damage on Stainless Steel and Titanium , Carbide Coated...on Stainless Steel and Titanium Carbide Coated Surfaces by Michael Thomas Keville Lieutenant, United States Navy B.S., United States Naval Academy

  1. Surface Irregularity Factor as a Parameter to Evaluate the Fatigue Damage State of CFRP

    Directory of Open Access Journals (Sweden)

    Pablo Zuluaga-Ramírez


    Full Text Available This work presents an optical non-contact technique to evaluate the fatigue damage state of CFRP structures measuring the irregularity factor of the surface. This factor includes information about surface topology and can be measured easily on field, by techniques such as optical perfilometers. The surface irregularity factor has been correlated with stiffness degradation, which is a well-accepted parameter for the evaluation of the fatigue damage state of composite materials. Constant amplitude fatigue loads (CAL and realistic variable amplitude loads (VAL, representative of real in- flight conditions, have been applied to “dog bone” shaped tensile specimens. It has been shown that the measurement of the surface irregularity parameters can be applied to evaluate the damage state of a structure, and that it is independent of the type of fatigue load that has caused the damage. As a result, this measurement technique is applicable for a wide range of inspections of composite material structures, from pressurized tanks with constant amplitude loads, to variable amplitude loaded aeronautical structures such as wings and empennages, up to automotive and other industrial applications.

  2. Recognition and practice on remanufacturing engineering management of military aero-engines

    Institute of Scientific and Technical Information of China (English)

    Xiang Qiao


    The technologies of design,manufacture and MRO (maintenance,repair and overhaul) for the mili-tary aero-engines,particularly for the fighters,are much more difficult to be mastered than those for any other aero-engines. They have been monopolized by only a few countries and the core technologies have never been transferred due to high risk,high investment,high barrier and high cost. Therefore,our country has long relied on mapping and copying the others’engines to satisfy the domestic demand due to not having our own indepen-dent technologies for the design and manufacture of military aero-engines. However,through over 20 years of unremitting effort,the independent MRO has been achieved for all the Chinese fighter engines,covering in-R&D (research and development) and in-service engines;and the MRO technologies,capabilities,quality, cost-efficiency have reached or exceeded those of original manufacturers. It has grown out of nothing,and then from weak to strong. In particular,dozens of projects concerning the R&D and engineering application of re-manufacturing have obtained the independent intellectual property rights and are playing an irreplaceable role in achieving leaping improvement of independent MRO for Chinese military aero-engines.

  3. Mode shape description of an aero-engine casing structure using Zernike moment descriptors

    Institute of Scientific and Technical Information of China (English)

    LIU Ying-chao; ZANG Chao-ping


    Vibration mode shape description of an aero-engine casing structure using Zernike moment descriptor (ZMD) was introduced in this paper. The mode shapes of the aero-engine casing structure can be decomposed as a linear combination of a series of Zernike polynomials, with the feature of each Zernike polynomial reflecting a part of characteristic of mode shapes, based on Zernike moment transformation. Meanwhile, the reconstruction of mode shapes with ZMD was explored and its ability to filtering the noise contaminated in the mode shapes was studied. Simulation of the aero-engine casing structure indicated the advantage of this method to depict the mode shapes of a symmetric structure. Results demonstrate that the Zernike moment description of the mode shapes can effectively describe the double modes in the symmetric structure and also has the ability to remove or significantly reduce the influence of noise in the mode shapes. Such feature shows great practical value for further research on the correlation, model updating and model validation of the symmetric structure's finite element model.

  4. The Brief Introduction of Different Laser Diagnostics Methods Used in Aeroengine Combustion Research

    Directory of Open Access Journals (Sweden)

    Fei Xing


    Full Text Available Combustion test diagnosis has always been one of the most important technologies for the development of aerospace engineering. The traditional methods of measurement have been unable to meet the requirements of accurate capture of the flow field in the development process of the aeroengine combustor. Therefore, the development of high-precision measurement and diagnostic techniques to meet the needs of the aeroengine combustor design is imperative. Laser diagnostics techniques developed quickly in the past several years. They are used to measure the parameters of the combustion flow field such as velocity, temperature, and components concentration with high space and time resolution and brought no disturbance. Planar laser-induced fluorescence, coherent anti-Stokes Raman scattering, tunable diode laser absorption spectroscopy, and Raman scattering were introduced systemically in this paper. After analysis of their own advantages and disadvantages, the authors considered validated Raman scattering system and Tunable Diode Laser Absorption Tomography are more suitable for research activities on aeroengine combustion systems.

  5. HF-based etching processes for improving laser damage resistance of fused silica optical surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Suratwala, T I; Miller, P E; Bude, J D; Steele, R A; Shen, N; Monticelli, M V; Feit, M D; Laurence, T A; Norton, M A; Carr, C W; Wong, L L


    The effect of various HF-based etching processes on the laser damage resistance of scratched fused silica surfaces has been investigated. Conventionally polished and subsequently scratched fused silica plates were treated by submerging in various HF-based etchants (HF or NH{sub 4}F:HF at various ratios and concentrations) under different process conditions (e.g., agitation frequencies, etch times, rinse conditions, and environmental cleanliness). Subsequently, the laser damage resistance (at 351 or 355 nm) of the treated surface was measured. The laser damage resistance was found to be strongly process dependent and scaled inversely with scratch width. The etching process was optimized to remove or prevent the presence of identified precursors (chemical impurities, fracture surfaces, and silica-based redeposit) known to lead to laser damage initiation. The redeposit precursor was reduced (and hence the damage threshold was increased) by: (1) increasing the SiF{sub 6}{sup 2-} solubility through reduction in the NH4F concentration and impurity cation impurities, and (2) improving the mass transport of reaction product (SiF{sub 6}{sup 2-}) (using high frequency ultrasonic agitation and excessive spray rinsing) away from the etched surface. A 2D finite element crack-etching and rinsing mass transport model (incorporating diffusion and advection) was used to predict reaction product concentration. The predictions are consistent with the experimentally observed process trends. The laser damage thresholds also increased with etched amount (up to {approx}30 {micro}m), which has been attributed to: (1) etching through lateral cracks where there is poor acid penetration, and (2) increasing the crack opening resulting in increased mass transport rates. With the optimized etch process, laser damage resistance increased dramatically; the average threshold fluence for damage initiation for 30 {micro}m wide scratches increased from 7 to 41 J/cm{sup 2}, and the statistical

  6. Surface damage characteristics of CFC and tungsten with repetitive ELM-like pulsed plasma irradiation (United States)

    Kikuchi, Y.; Nishijima, D.; Nakatsuka, M.; Ando, K.; Higashi, T.; Ueno, Y.; Ishihara, M.; Shoda, K.; Nagata, M.; Kawai, T.; Ueda, Y.; Fukumoto, N.; Doerner, R. P.


    Surface damage of carbon fiber composite (CFC) and tungsten (W) due to repetitive ELM-like pulsed plasma irradiation has been investigated by using a magnetized coaxial plasma gun. CX2002U CFC and stress-relieved W samples were exposed to repetitive pulsed deuterium plasmas with duration of ˜0.5 ms, incident ion energy of ˜30 eV, and surface absorbed energy density of ˜0.3-0.7 MJ/m2. Bright spots on a CFC surface during pulsed plasma exposures were clearly observed with a high-speed camera, indicating a local surface heating. No melting of a W surface was observed under a single plasma pulse exposure at energy density of ˜0.7 MJ/m2, although cracks were formed. Cracking of the W surface grew with repetitive pulsed plasma exposures. Subsequently, the surface melted due to localized heat absorption.

  7. Effects of rice harvest moisture on kernel damage and milled rice surface free fatty acid levels. (United States)

    Parker, Amanda M; Proctor, Andrew; Eason, Robert L; Jain, Vishal


    Surface free fatty acid (FFA) on milled rice is a key factor in determining rice quality and acceptability to the brewing industry. Rice FFA oxidizes, causing off-flavors and odors to develop, compromising the brewing quality of milled rice. The effect of harvest moisture (13%, 16%, and 20%), harvester type (1688 Case and 9500 John Deere), and rice variety (Cocodrie and Bengal) on harvest damaged rough rice and milled rice surface FFA after drying to 12% moisture and 6 mo rough rice storage was examined. The Case harvester produced more damaged kernels than the John Deere harvester, but this was not reflected in surface FFA development. There were no significant FFA differences in variety or harvester type. Rice harvested at a higher moisture content (20%) produced significantly greater FFA values, with a peak near 0.1%, than rice harvested at lower moisture contents (13% and 16%), which had FFA values near 0.08%. Retention of bran by damaged kernels at high harvest moisture probably was responsible for promoting surface FFA development, but if bran was lost at lower harvest moistures, surface FFA, development was limited. Harvest moisture affected milled rice FFA, although rough rice was dried to 12% immediately after harvesting.

  8. Localized CO2 laser treatment and post-heating process to reduce the growth coefficient of fused silica surface damage

    Institute of Scientific and Technical Information of China (English)

    Shizhen Xu; Xiaotao Zu; Xiaodong Yuan


    The lifetime of optical components in high-fluence ultraviolet (UV) laser applications is typically limited by laser-initiated damage and its subsequent growth. Using 10.6-μm CO2 laser pulses, we successfully mitigate 355-nm laser induced damage sites on fused silica surface with dimensions less than 200 μm.The damage threshold increases and the damage growth mitigates. However, the growth coefficients of new damage on the CO2 laser processed area are higher than those of the original sample. The damage grows with crack propagation for residual stress after CO2 laser irradiation. Furthermore, post-heating is beneficial to the release of residual stress and slows down the damage growth.%@@ The lifetime of optical components in high-fluence ultraviolet (UV) laser applications is typically limited by laser-initiated damage and its subsequent growth.Using 10.6-μm CO2 laser pulses, we successfully mitigate 355-nm laser induced damage sites on fused silica surface with dimensions less than 200 μm.The damage threshold increases and the damage growth mitigates.However, the growth coefficients of new damage on the CO2 laser processed area are higher than those of the original sample.The damage grows with crack propagation for residual stress after CO2 laser irradiation.Furthermore, post-heating is beneficial to the release of residual stress and slows down the damage growth.

  9. Experimental study of surface quality and damage when drilling unidirectional CFRP composites

    Directory of Open Access Journals (Sweden)

    Eshetu D. Eneyew


    Full Text Available In this study, an experimental investigation on the drilling of unidirectional carbon fiber reinforced plastic (UD-CFRP composite was conducted using polycrystalline diamond (PCD tipped eight facet drill. The quality of the drilled hole surface was examined through surface roughness measurements and surface damage by scanning electron microscopy (SEM. It was found that fiber pullout occurred in two specific sectors relative to the angle between the cutting direction and the fiber orientation. The thrust force was highly influenced by the feed rate than the cutting speed and it shows a significant variation throughout the rotation of the drill.

  10. The effect of laser pulse width on laser-induced damage at K9 and UBK7 components surface (United States)

    Zhou, Xinda; Ba, Rongsheng; Zheng, Yinbo; Yuan, Jing; Li, Wenhong; Chen, Bo


    In this paper, we investigated the effects of laser pulse width on laser-induced damage. We measured the damage threshold of K9 glass and UBK7 glass optical components at different pulse width, then analysis pulse-width dependence of damage threshold. It is shown that damage threshold at different pulse width conforms to thermal restriction mechanism, Because of cm size laser beam, defect on the optical component surface leads to laser-induced threshold decreased.

  11. Probing the molecular structures of plasma-damaged and surface-repaired low-k dielectrics. (United States)

    Zhang, Xiaoxian; Myers, John N; Lin, Qinghuang; Bielefeld, Jeffery D; Chen, Zhan


    Fully understanding the effect and the molecular mechanisms of plasma damage and silylation repair on low dielectric constant (low-k) materials is essential to the design of low-k dielectrics with defined properties and the integration of low-k dielectrics into advanced interconnects of modern electronics. Here, analytical techniques including sum frequency generation vibrational spectroscopy (SFG), Fourier transform infrared spectroscopy (FTIR), contact angle goniometry (CA) and X-ray photoelectron spectroscopy (XPS) have been employed to provide a comprehensive characterization of the surface and bulk structure changes of poly(methyl)silsesquioxane (PMSQ) low-k thin films before and after O2 plasma treatment and silylation repair. O2 plasma treatment altered drastically both the molecular structures and water structures at the surfaces of the PMSQ film while no bulk structural change was detected. For example, ∼34% Si-CH3 groups were removed from the PMSQ surface, and the Si-CH3 groups at the film surface tilted toward the surface after the O2 plasma treatment. The oxidation by the O2 plasma made the PMSQ film surface more hydrophilic and thus enhanced the water adsorption at the film surface. Both strongly and weakly hydrogen bonded water were detected at the plasma-damaged film surface during exposure to water with the former being the dominate component. It is postulated that this enhancement of both chemisorbed and physisorbed water after the O2 plasma treatment leads to the degradation of low-k properties and reliability. The degradation of the PMSQ low-k film can be recovered by repairing the plasma-damaged surface using a silylation reaction. The silylation method, however, cannot fully recover the plasma induced damage at the PMSQ film surface as evidenced by the existence of hydrophilic groups, including C-O/C[double bond, length as m-dash]O and residual Si-OH groups. This work provides a molecular level picture on the surface structural changes of low

  12. Surface and subsurface damage detection in cement-based materials using electrical resistance tomography (United States)

    Ruan, T.; Poursaee, A.


    Cement-based materials are widely used in infrastructure facilities. However, often the degradation of structures leads to the failures earlier than designed service life. Thus, non-destructive testing techniques are urgently needed to evaluate the health information of the structures. In this paper, the implementation of Electrical Resistance Tomography (ERT) was investigated. This low cost, radiation free and easy to perform modality is based on measuring the electrical properties of the material under test and using that to evaluate the existence of defects in that material. It uses a set of boundary potentials and injected current to reconstruct the conductivity distribution. An automatic measurement system was developed and surface damages as well as subsurface damages on mortar specimens were investigated. The reconstructed images were capable to show the presence and the location of the damages.

  13. Low-damage surface smoothing of laser crystallized polycrystalline silicon using gas cluster ion beam (United States)

    Tokioka, H.; Yamarin, H.; Fujino, T.; Inoue, M.; Seki, T.; Matsuo, J.


    Surface smoothing of laser crystallized polycrystalline silicon (poly-Si) films using gas cluster ion beam (GCIB) technology has been studied. It is found that both SF6-GCIB and O2-GCIB decrease the height of hillocks and reduce the surface roughness of the irradiated films. The mean surface roughness value of poly-Si films was reduced from 10.8 nm to 2.8 nm by SF6-GCIB irradiation at 80°. Ultraviolet reflectance measurement reveals that GCIB irradiation causes damage near-surface of the poly-Si films. Formation of the damage, however, can be suppressed by using GCIB irradiation at high incident angle. Effect of GCIB irradiation in a metal-insulator-semiconductor (MIS) capacitor has also been investigated. The capacitance-voltage curves of MIS capacitor with SF6-GCIB irradiation are distorted. On the contrary, the distortion is reduced by O2-GCIB irradiation at 80, which suggests that electrical-activated damage of the films can be decreased by using O2-GCIB irradiation.

  14. Revisiting the potential for bursting bubbles to damage cells below the free surface (United States)

    Walls, Peter; Bird, James


    The rapid motion associated with bubbles bursting at the surface of a liquid is known to cause damage to cells in a suspension, which is particularly problematic in bioreactors that require continuous injection of oxygen to sustain the cells. It is generally accepted that cells directly attached to the bubble's interface will experience lethal levels of damage. To prevent cells from initially attaching to the bubble's surface, surfactants are widely used. However, the potential for bursting bubbles to damage nearby, but not directly attached, cells is less clear. Previous numerical studies have predicted maximum energy dissipation rates (EDR) as high as 1010 W/m3 for bubbles with radii less than 1 mm; lethal to the commonly used mammalian CHO cell. Here we show that these studies tend to underestimate the generated EDR levels by several orders of magnitude due to limited numerical mesh resolution. Furthermore, we demonstrate how a downward traveling jet can cause damage away from the interface. We validate our numerical model with high-speed bubble bursting experiments and relate the dynamics of this downward jet to the boundary layer equations. We anticipate our results will be an integral step towards developing more efficient aeration platforms. We acknowledge support from Biogen Inc.

  15. Dynamical mechanism in aero-engine gas path system using minimum spanning tree and detrended cross-correlation analysis (United States)

    Dong, Keqiang; Zhang, Hong; Gao, You


    Identifying the mutual interaction in aero-engine gas path system is a crucial problem that facilitates the understanding of emerging structures in complex system. By employing the multiscale multifractal detrended cross-correlation analysis method to aero-engine gas path system, the cross-correlation characteristics between gas path system parameters are established. Further, we apply multiscale multifractal detrended cross-correlation distance matrix and minimum spanning tree to investigate the mutual interactions of gas path variables. The results can infer that the low-spool rotor speed (N1) and engine pressure ratio (EPR) are main gas path parameters. The application of proposed method contributes to promote our understanding of the internal mechanisms and structures of aero-engine dynamics.

  16. Surface damage through grazing incidence ions investigated by scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Redinger, Alex


    Surface damage, caused by grazing incidence ions, is investigated with variable temperature scanning tunneling microscopy. The experiments are carried out on a Pt(111) crystal. The kinetic energy of noble gas ions is varied between 1-15 keV and the angle of incidence can be adjusted between {theta} = 78.5 and {theta} = 90 measured with respect to the surface normal. The damage patterns of single ion impacts, on flat terraces and at step edges of monoatomic height, are investigated at low surface temperatures. Ions hitting a flat terrace are usually specular reflected. The energy transfer from the ion to the crystal atoms is small and only little damage is produced. In contrast, at ascending step edges, which are illuminated by the ion beam, large angle scattering events occur. Sputtering, adatom and vacancy production is induced. However, a significant fraction of the ions, which hit step edges, enter the crystal and are guided in between two atomic layers parallel to the surface via small angle binary collisions. This steering process is denoted as subsurface channeling. The energy loss per length scale of the channeled particles is low, which results in long ion trajectories (up to 1000A). During the steering process, the ions produce surface damage. Depending on the ion species and the ion energy, adatom and vacancies or surface vacancy trenches of monoatomic width are observed. The surface damage can be used to track the path of the ion. This makes the whole trajectory of single ions with keV energy visible. The number of sputtered atoms per incident ion at ascending step edges, i.e. the step edge sputtering yield, is measured experimentally for different irradiation conditions. For {theta} = 86 , the sputtering yield is determined from the fluence dependent retraction of pre-existing illuminated step edges. An alternative method for the step edge sputtering yield determination, is the analysis of the concentration of ascending steps and of the removed amount

  17. Damage and reliability of Y-TZP after cementation surface treatment. (United States)

    Guess, P C; Zhang, Y; Kim, J-W; Rekow, E D; Thompson, V P


    Zirconia-based restorations are widely used in prosthetic dentistry, but their susceptibility to post-sintering cementation surface treatments remains controversial. We hypothesized that grinding (600-grit) and alumina abrasion (50 microm, 5 sec, 0.5 MPa) affect the damage modes and reliability of zirconia core material. Monolithic CAD/CAM-machined and sintered Y-TZP plates (0.5 mm thickness) were adhesively cemented to dentin-like composite substrates. Uni-axial mouth-motion cyclic contact was applied through a tungsten carbide spherical indenter (r = 3.18 mm). Results showed that zirconia core ceramic is vulnerable to lower surface radial fracture after grinding or alumina abrasion, while the as-received control chiefly fractured from load-application surface cone fracture. Significantly lower reliability of ground and alumina-abraded compared with the as-received zirconia core ceramic can be attributed to damage induced on the cementation surface. Clinical relevance concerning surface treatment protocols for zirconia framework materials prior to cementation is addressed.

  18. Femtosecond laser surface ablation of transparent solids: understanding the bulk filamentation damage (United States)

    Kudryashov, Sergey I.; Joglekar, A.; Mourou, G.; Ionin, A. A.; Zvorykin, V. D.; Hunt, A. J.


    Direct SEM examination reveals a complex nanoscale structure of deep narrow central channels within shallow wide external craters produced by single-shot high-intensity femtosecond laser radiation on Corning 0211 glass and sapphire surfaces. These internal narrow channels are not expected from ordinary surface melt spallation and expulsion processes characteristic of the external surface nanocraters, but exhibit nearly the same appearance threshold. Surprisingly, the nanochannel radiuses rapidly saturate versus incident laser intensity indicating bulk rather than surface character of laser energy deposition, in contrast to the external craters extending versus laser intensity in a regular manner. These facts may be explained by channeling of electromagnetic radiation by near-surface ablative filamentary propagation of intense femtosecond laser pulses in the highly electronically excited dielectrics, by spherical aberrations in the surface layer, or deep drilling of the samples by short-wavelength Bremsstrahlung radiation of relatively hot surface electron-hole or electron-ion plasma. The double structure of ablated surface nano-features is consistent with similar structures observed for bulk damage features fabricated by femtosecond laser pulses at supercritical laser powers, but much lower laser intensities.

  19. Laser damage initiation and growth of antireflection coated S-FAP crystal surfaces prepared by pitch lap and magnetorheological finishing

    Energy Technology Data Exchange (ETDEWEB)

    Stolz, C J; Menapace, J A; Schaffers, K I; Bibeau, C; Thomas, M D; Griffin, A J


    Antireflection (AR) coatings typically damage at the interface between the substrate and coating. Therefore the substrate finishing technology can have an impact on the laser resistance of the coating. For this study, AR coatings were deposited on Yb:S-FAP [Yb{sup 3+}:Sr{sub 5}(PO{sub 4}){sub 3}F] crystals that received a final polish by both conventional pitch lap finishing as well as magnetorheological finishing (MRF). SEM images of the damage morphology reveals laser damage originates at scratches and at substrate coating interfacial absorbing defects. Previous damage stability tests on multilayer mirror coatings and bare surfaces revealed damage growth can occur at fluences below the initiation fluence. The results from this study suggest the opposite trend for AR coatings. Investigation of unstable HR and uncoated surface damage morphologies reveals significant radial cracking that is not apparent with AR damage due to AR delamination from the coated surface with few apparent cracks at the damage boundary. Damage stability tests show that coated Yb:S-FAP crystals can operate at 1057 nm at fluences around 20 J/cm{sup 2} at 10 ns; almost twice the initiation damage threshold.

  20. Temperature and heat flux measurement techniques for aeroengine fire test: a review (United States)

    Mohammed, I.; Abu Talib, A. R.; Sultan, M. T. H.; Saadon, S.


    This review is made of studies whereby some types of fire test measuring instrument were compared based on their mode of operation, sensing ability, temperature resistance and their calibration mode used for aero-engine applications. The study discusses issues affecting temperature and heat flux measurement, methods of measurement, calibration and uncertainties that occur in the fire test. It is found that the temperature and heat flux measurements of the flame from the standard burner need to be corrected and taken into account for radiation heat loss. Methods for temperature and heat flux measurements, as well as uncertainties analysis, were also discussed.

  1. An integration system for investment casting mould design of aeroengine turbine blade

    Institute of Scientific and Technical Information of China (English)

    Jiang Ruisong; Zhang Dinghua; Wang Wenhu; Shi Huajie


    An integration system was developed to satisfy the need of information integration in the process of designing,investment casting and monitoring aero-engine's turbo blade.The general architecture is detailed presented in this paper.The system mainly comprises of product master model,design information management,anti-deformation design of mould cavity,intelligence mould design and blade testing.The developed system can manage mould design and blade test data flow,optimize mould design process and achieve the goal of integration design.

  2. A feasibility study of a 3-D finite element solution scheme for aeroengine duct acoustics (United States)

    Abrahamson, A. L.


    The advantage from development of a 3-D model of aeroengine duct acoustics is the ability to analyze axial and circumferential liner segmentation simultaneously. The feasibility of a 3-D duct acoustics model was investigated using Galerkin or least squares element formulations combined with Gaussian elimination, successive over-relaxation, or conjugate gradient solution algorithms on conventional scalar computers and on a vector machine. A least squares element formulation combined with a conjugate gradient solver on a CDC Star vector computer initially appeared to have great promise, but severe difficulties were encountered with matrix ill-conditioning. These difficulties in conditioning rendered this technique impractical for realistic problems.

  3. An analysis of the generation of subharmonics in aeroengine ducts and methods of their prevention (United States)

    Vaidya, P. G.; Wang, K. S.


    When the fans of aero-engine ducts go supersonic they often produce radiation at the subharmonics of blade passage frequency known as Multiple Pure Tones. It has been shown that the conventional explanation that these MPTs are created by the shock waves is inadequate. An alternative mechanism based on the concept of 'strong interaction' between the harmonics during resonance is proposed. Expression for the governing equation for such an interaction is derived. The results show an improved agreement with observed data. The analysis has also led to several practical suggestions for the suppression of noise.

  4. Volcanic ash ingestion by a large gas turbine aeroengine: fan-particle interaction (United States)

    Vogel, Andreas; Clarkson, Rory; Durant, Adam; Cassiani, Massimo; Stohl, Andreas


    Airborne particles from explosive volcanic eruptions are a major safety threat for aviation operations. The fine fraction of the emitted particles ( 20 microns) tend to be transported into the bypass duct of the engine (by the centrifugal effect of the fan), whereas the smaller particles follow the fluid flow streamlines and are distributed homogenously in the engine (bypass ducts and core region). This result is significant as it indicates that the absolute ash mass that causes issues for aeroengine operation is a fraction of the ambient (observed or forecast) ash quantity.

  5. Surface damage of metallic implants due to mechanical loading and chemical reactions (United States)

    Ryu, Jaejoong

    The present study investigates interfacial damage mechanism of modular implants due to synergetic action of mechanical contact loading and corrosion. Modular implants are manufactured such that surfaces have a characteristic degree of roughness determined by tool tip size and motion of tool path or feeding speed. The central hypothesis for this work is that during contact loading of metallic implants, mechanisms of damage and dissolution are determined by contact loads, plastic deformation, residual stresses and environmental conditions at the nanoscale surface asperities; while during subsequent rest periods, mechanism of metallic dissolution is determined by the environmental conditions and residual stress field induced due to long range elastic interactions of the plastically deformed asperities. First part of the thesis is focused on investigating the mechanisms underlying surface roughness evolution due to stress-assisted dissolution during the rest period. The latter part is focused on investigating material removal mechanisms during single asperity contact of implant surfaces. Experimental study was performed to elucidate the roughness evolution mechanism by combined effect of multi-asperity contact and environmental corrosion. Cobalt-chromium-molybdenum specimen was subjected to either contact loading alone or alternating contact loading and exposure to reactive environment. Roughness of the specimen surface was monitored by optical profilometry and Fast Fourier Transform (FFT) calculation was used to characterize the evolving behavior of roughness modes. Finite element analysis (FEA) was employed to identify influences of surface morphological configurations and contact pressures on the residual stress development. Analytical model of multi-asperity contact has been developed for prediction of residual stress field for different roughness configurations during varying magnitude of contact loads based on elastic inclusion theory. Experimental results

  6. Type of Ground Surface during Plyometric Training Affects the Severity of Exercise-Induced Muscle Damage

    Directory of Open Access Journals (Sweden)

    Hamid Arazi


    Full Text Available The purpose of this study was to compare the changes in the symptoms of exercise-induced muscle damage from a bout of plyometric exercise (PE; 10 × 10 vertical jumps performed in aquatic, sand and firm conditions. Twenty-four healthy college-aged men were randomly assigned to one of three groups: Aquatic (AG, n = 8, Sand (SG, n = 8 and Firm (FG, n = 8. The AG performed PE in an aquatic setting with a depth of ~130 cm. The SG performed PE on a dry sand surface at a depth of 20 cm, and the FG performed PE on a 10-cm-thick wooden surface. Plasma creatine kinase (CK activity, delayed onset muscle soreness (DOMS, knee range of motion (KROM, maximal isometric voluntary contraction (MIVC of the knee extensors, vertical jump (VJ and 10-m sprint were measured before and 24, 48 and 72 h after the PE. Compared to baseline values, FG showed significantly (p < 0.05 greater changes in CK, DOMS, and VJ at 24 until 48 h. The MIVC decreased significantly for the SG and FG at 24 until 48 h post-exercise in comparison to the pre-exercise values. There were no significant (p > 0.05 time or group by time interactions in KROM. In the 10-m sprint, all the treatment groups showed significant (p < 0.05 changes compared to pre-exercise values at 24 h, and there were no significant (p > 0.05 differences between groups. The results indicate that PE in an aquatic setting and on a sand surface induces less muscle damage than on a firm surface. Therefore, training in aquatic conditions and on sand may be beneficial for the improvement of performance, with a concurrently lower risk of muscle damage and soreness.

  7. Structurally Integrated, Damage Tolerant Thermal Spray Coatings: Processing Effects on Surface and System Functionalities (United States)

    Vackel, Andrew

    Thermal Spray (TS) coatings have seen extensive application as protective surfaces to enhance the service life of substrates prone to damage in their operating environment (wear, corrosion, heat etc.). With the advent of high velocity TS processes, the ability to deposit highly dense (>99%) metallic and cermet coatings has further enhanced the protective ability of these coatings. In addition to surface functionality, the influence of the coating application on the mechanical performance of a coated component is of great concern when such a component will experience either static or cyclic loading during service. Using a process mapping methodology, the processing-property interplay between coating materials meant to provide damage tolerant surface or for structural restoration are explored in terms of relevant mechanical properties. Most importantly, the residual stresses inherent in TS deposited coatings are shown to play a significant role in the integrated mechanical performance of these coatings. Unique to high velocity TS processes is the ability to produce compressive stresses within the deposit from the cold working induced by the high kinetic energy particles upon impact. The extent of these formation stresses are explored with different coating materials, as well as processing influence. The ability of dense TS coatings to carry significant structural load and synergistically strengthen coated tensile specimens is demonstrated as a function of coating material, processing, and thickness. The sharing of load between the substrate and otherwise brittle coating enables higher loads before yield for the bi-material specimens, offering a methodology to improve the tensile performance of coated components for structural repair or multi-functionality (surface and structure). The concern of cyclic fatigue damage in coated components is explored, since the majority of service application are designed for loading to be well below the yield point. The role of

  8. Sub-surface damage issues for effective fabrication of large optics (United States)

    Tonnellier, X.; Shore, P.; Morantz, P.; Baldwin, A.; Walker, D.; Yu, G.; Evans, R.


    A new ultra precision large optics grinding machine, BoX® has been developed at Cranfield University. BoX® is located at the UK's Ultra Precision Surfaces laboratory at the OpTIC Technium. This machine offers a rapid and economic solution for grinding large off-axis aspherical and free-form optical components. This paper presents an analysis of subsurface damage assessments of optical ground materials produced using diamond resin bonded grinding wheels. The specific materials used, Zerodur® and ULE® are currently under study for making extremely large telescope (ELT) segmented mirrors such as in the E-ELT project. The grinding experiments have been conducted on the BoX® grinding machine using wheels with grits sizes of 76 μm, 46 μm and 25 μm. Grinding process data was collected using a Kistler dynamometer platform. The highest material removal rate (187.5 mm3/s) used ensures that a 1 metre diameter optic can be ground in less than 10 hours. The surface roughness and surface profile were measured using a Form Talysurf. The subsurface damage was revealed using a sub aperture polishing process in combination with an etching technique. These results are compared with the targeted form accuracy of 1 μm p-v over a 1 metre part, surface roughness of 50-150 nm RMS and subsurface damage in the range of 2-5 μm. This process stage was validated on a 400 mm ULE® blank and a 1 metre hexagonal Zerodur® part.

  9. Evaluation of Bulk and Surface Radiation Damage of Silicon Sensors for the ATLAS Upgrade

    CERN Document Server

    Mikeštíková, Marcela; Št'astný, Jan


    The electrical characteristics of different types of end-cap miniature n + -in- p strip sensors, ATLAS12A, were evaluated in Institute of Physics in Prague before and after proton and gamma irradiation. We report here on the bulk damage aspects, including the increase of leakage current and evaluation of the full depletion voltage and the surface damage, including the decrease of inter-strip resistance, changes in inter-strip capacitance and the effectiveness of punch-through protection structure. It was verified that different geometries of end-cap sensors do not influence their stability; the sensors should provide acceptable strip isolation and n ew gate PTP structure functions well even at the highest tested proton fluence 2× 10 15 n eq / cm 2

  10. Apparatus and method for atmospheric pressure reactive atom plasma processing for shaping of damage free surfaces (United States)

    Carr; Jeffrey W.


    Fabrication apparatus and methods are disclosed for shaping and finishing difficult materials with no subsurface damage. The apparatus and methods use an atmospheric pressure mixed gas plasma discharge as a sub-aperture polisher of, for example, fused silica and single crystal silicon, silicon carbide and other materials. In one example, workpiece material is removed at the atomic level through reaction with fluorine atoms. In this example, these reactive species are produced by a noble gas plasma from trace constituent fluorocarbons or other fluorine containing gases added to the host argon matrix. The products of the reaction are gas phase compounds that flow from the surface of the workpiece, exposing fresh material to the etchant without condensation and redeposition on the newly created surface. The discharge provides a stable and predictable distribution of reactive species permitting the generation of a predetermined surface by translating the plasma across the workpiece along a calculated path.

  11. Aero-engine fault diagnosis applying new fast support vector algorithm

    Institute of Scientific and Technical Information of China (English)

    XU Qi-hua; GENG Shuai; SHI Jun


    A new fast learning algorithm was presented to solve the large-scale support vector machine ( SVM ) training problem of aero-engine fault diagnosis.The relative boundary vectors ( RBVs ) instead of all the original training samples were used for the training of the binary SVM fault classifiers.This pruning strategy decreased the number of final training sample significantly and can keep classification accuracy almost invariable.Accordingly , the training time was shortened to 1 / 20compared with basic SVM classifier.Meanwhile , owing to the reduction of support vector number , the classification time was also reduced.When sample aliasing existed , the aliasing sample points which were not of the same class were eliminated before the relative boundary vectors were computed.Besides , the samples near the relative boundary vectors were selected for SVM training in order to prevent the loss of some key sample points resulted from aliasing.This can improve classification accuracy effectively.A simulation example to classify 5classes of combination fault of aero-engine gas path components was finished and the total fault classification accuracy reached 96.1%.Simulation results show that this fast learning algorithm is effective , reliable and easy to be implemented for engineering application.

  12. Research and Development of Some Advanced High Temperature Titanium Alloys for Aero-engine

    Directory of Open Access Journals (Sweden)

    CAI Jian-ming


    Full Text Available Some advanced high temperature titanium alloys are usually selected to be manufactured into blade, disc, case, blisk and bling under high temperature environment in compressor and turbine system of a new generation high thrust-mass ratio aero-engine. The latest research progress of 600℃ high temperature titanium alloy, fireproof titanium alloy, TiAl alloy, continuous SiC fiber reinforced titanium matrix composite and their application technology in recent years in China were reviewed in this paper. The key technologies need to be broken through in design, processing and application of new material and component are put forward, including industrial ingot composition of high purified and homogeneous control technology, preparation technology of the large size bar and special forgings, machining technology of blisk and bling parts, material property evaluation and application design technique. The future with the continuous application of advanced high temperature titanium alloys, will be a strong impetus to the development of China's aero-engine technology.

  13. Vibration Analysis of Aeroengine Blisk Structure Based on a Prestressed CMS Super-Element Method

    Directory of Open Access Journals (Sweden)

    Zhijun Li


    Full Text Available For vibration analysis of aeroengine blisk structure, a prestressed component modal synthesis (CMS super-element method is put forward with the fixed interface prestressing and free interface super-element approach. Based on this method, natural vibration characteristics of blisk structure are calculated at different modal truncation numbers. Comparing with the accurate result of global method, the selection principle of modal truncation number is obtained which affects the accuracy of prestressed CMS super-element method. Vibration response of two-stage blisk structure is calculated by this method, and the effects of different blade aspect ratios have been discussed on vibration characteristics. The results show that prestressed CMS super-element method is in the high accuracy and efficiency on blisk vibration analysis. Resonant frequencies in vibration response are nearly the same between the first-stage blisk and the second-stage blisk, and they are both approximately located in the range 588 Hz–599 Hz. The maximum displacement and dynamic stress are at blade tip and root of the first-stage blisk, respectively. Blade aspect ratio is a key factor of blisk vibration; the effects of blade aspect ratio on natural frequencies are different in the conditions of fixed width and fixed length. This research provides the theoretical basis for dynamic design of aeroengine compressor rotor system.

  14. The Chaotic Prediction for Aero-Engine Performance Parameters Based on Nonlinear PLS Regression

    Directory of Open Access Journals (Sweden)

    Chunxiao Zhang


    Full Text Available The prediction of the aero-engine performance parameters is very important for aero-engine condition monitoring and fault diagnosis. In this paper, the chaotic phase space of engine exhaust temperature (EGT time series which come from actual air-borne ACARS data is reconstructed through selecting some suitable nearby points. The partial least square (PLS based on the cubic spline function or the kernel function transformation is adopted to obtain chaotic predictive function of EGT series. The experiment results indicate that the proposed PLS chaotic prediction algorithm based on biweight kernel function transformation has significant advantage in overcoming multicollinearity of the independent variables and solve the stability of regression model. Our predictive NMSE is 16.5 percent less than that of the traditional linear least squares (OLS method and 10.38 percent less than that of the linear PLS approach. At the same time, the forecast error is less than that of nonlinear PLS algorithm through bootstrap test screening.

  15. A contactless ultrasonic surface wave approach to characterize distributed cracking damage in concrete. (United States)

    Ham, Suyun; Song, Homin; Oelze, Michael L; Popovics, John S


    We describe an approach that utilizes ultrasonic surface wave backscatter measurements to characterize the volume content of relatively small distributed defects (microcrack networks) in concrete. A simplified weak scattering model is used to demonstrate that the scattered wave field projected in the direction of the surface wave propagation is relatively insensitive to scatterers that are smaller than the propagating wavelength, while the scattered field projected in the opposite direction is more sensitive to sub-wavelength scatterers. Distributed microcracks in the concrete serve as the small scatterers that interact with a propagating surface wave. Data from a finite element simulation were used to demonstrate the viability of the proposed approach, and also to optimize a testing configuration to collect data. Simulations were validated through experimental measurements of ultrasonic backscattered surface waves from test samples of concrete constructed with different concentrations of fiber filler (0.0, 0.3 and 0.6%) to mimic increasing microcrack volume density and then samples with actual cracking induced by controlled thermal cycles. A surface wave was induced in the concrete samples by a 50kHz ultrasonic source operating 10mm above the surface at an angle of incidence of 9°. Silicon-based miniature MEMS acoustic sensors located a few millimeters above the concrete surface both behind and in front of the sender were used to detect leaky ultrasonic surface waves emanating from concrete. A normalized backscattered energy parameter was calculated from the signals. Statistically significant differences in the normalized backscattered energy were observed between concrete samples with varying levels of simulated and actual cracking damage volume.

  16. Bragg-case limited projection topography study of surface damage in diamond-crystal plates

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Y; Krasnicki, S; Macrander, A T; Chu, Y S; Maj, J [Advanced Photon Source, Argonne National Laboratory, Argonne (United States)


    To characterize diamond monochromators for synchrotron radiation beamlines, images for a region 25 {mu}m below the surface were obtained. Topographical images of a Bragg-diffracted beam having a scattering angle (twice the Bragg angle) of 90 deg. were obtained from asymmetric reflections with a CCD area detector. A 25 {mu}m incident slit was used to section the sample topographically. Patchwork images for the full surface area, but limited in depth to the slit size, were assembled from microbeam images. The small extinction depths provided by the asymmetric reflection geometry, namely, 2.8 {mu}m and 3.5 {mu}m for ideal diamond crystals set for the (224) and (044) reflections, respectively, permitted data analyses for a region near the surface. The diamonds were synthetic type Ib (yellowish due to nitrogen impurities). They were in the shape of plates sized 6 x 5 mm and were 0.5 mm thick. Measurements were made using monochromatic bending magnet radiation at the Advanced Photon Source at 12.04 keV and 13.90 keV. Data obtained before and after chemical etching demonstrate that damage visible as contrast from saw grooves is largely removed by etching. Dislocation etch pits were observed after etching for the (111) surface but not for the (100) surface.

  17. AFM assessment of the surface nano/microstructure on chemically damaged historical and model glasses

    Energy Technology Data Exchange (ETDEWEB)

    Carmona, Noemi [Centro Nacional de Investigaciones Metalurgicas, CSIC, Avda. Gregorio del Amo, 8, 28040 Madrid (Spain); Kowal, Andrzej [Institute of Catalysis and Surface Chemistry, PAN, ul. Niezapominajek 8, 30239 Cracow (Poland); Rincon, Jesus-Maria [Instituto Eduardo Torroja de Ciencias de la Construccion, CSIC, C. Serrano Galvache s/n, 28033 Madrid (Spain); Villegas, Maria-Angeles, E-mail: [Centro Nacional de Investigaciones Metalurgicas, CSIC, Avda. Gregorio del Amo, 8, 28040 Madrid (Spain); Instituto de Historia, Centro de Ciencias Humanas y Sociales, CSIC, C. Albasanz, 26-28, 28037 Madrid (Spain)


    Surface chemical damage on selected historical glasses from 13th to 19th centuries was evaluated by means of atomic force microscopy (AFM). Nano- and microstructure, roughness and topography of ancient glass samples have been compared with those of model glasses prepared by conventional melting at the laboratory with similar compositions to those most frequently found in historical glass pieces. The results obtained allow discussing the chemical degradation mechanisms in terms of the acid and/or basic chemical attack carried out by the combination of gaseous pollutants and environmental humidity. Even though deep corrosion features escape to the observation order of magnitude of the AF microscope used, the AFM technique proves to be quite useful for the study and evaluation of the most common surface pathologies of historical glasses with different compositions once submitted to natural weathering.

  18. Surface Contaminant Control Technologies to Improve Laser Damage Resistance of Optics

    Directory of Open Access Journals (Sweden)

    Xiaofeng Cheng


    Full Text Available The large high-power solid lasers, such as the National Ignition Facility (NIF of America and the Shenguang-III (SG-III laser facility of China, can output over 2.1 MJ laser pulse for the inertial confinement fusion (ICF experiments. Because of the enhancement of operating flux and the expansion of laser driver scale, the problem of contamination seriously influences their construction period and operation life. During irradiation by intense laser beams, the contaminants on the metallic surface of beam tubes can be transmitted to the optical surfaces and lead to damage of optical components. For the high-power solid-state laser facilities, contamination control focuses on the slab amplifiers, spatial filters, and final-optical assemblies. In this paper, an effective solution to control contaminations including the whole process of the laser driver is put forward to provide the safe operation of laser facilities, and the detailed technical methods of contamination control such as washing, cleanliness metrology, and cleanliness protecting are also introduced to reduce the probability of laser-induced damage of optics. The experimental results show that the cleanliness level of SG-III laser facility is much better to ensure that the laser facility can safely operate at high energy flux.

  19. Transparency and damage tolerance of patternable omniphobic lubricated surfaces based on inverse colloidal monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, N; Belisle, RA; Hatton, B; Wong, TS; Aizenberg, J


    A transparent coating that repels a wide variety of liquids, prevents staining, is capable of self-repair and is robust towards mechanical damage can have a broad technological impact, from solar cell coatings to self-cleaning optical devices. Here we employ colloidal templating to design transparent, nanoporous surface structures. A lubricant can be firmly locked into the structures and, owing to its fluidic nature, forms a defect-free, self-healing interface that eliminates the pinning of a second liquid applied to its surface, leading to efficient liquid repellency, prevention of adsorption of liquid-borne contaminants, and reduction of ice adhesion strength. We further show how this method can be applied to locally pattern the repellent character of the substrate, thus opening opportunities to spatially confine any simple or complex fluids. The coating is highly defect-tolerant due to its interconnected, honeycomb wall structure, and repellency prevails after the application of strong shear forces and mechanical damage. The regularity of the coating allows us to understand and predict the stability or failure of repellency as a function of lubricant layer thickness and defect distribution based on a simple geometric model.

  20. High-resolution 3-D imaging of surface damage sites in fused silica with Optical Coherence Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Guss, G; Bass, I; Hackel, R; Mailhiot, C; Demos, S G


    In this work, we present the first successful demonstration of a non-contact technique to precisely measure the 3D spatial characteristics of laser induced surface damage sites in fused silica for large aperture laser systems by employing Optical Coherence Tomography (OCT). What makes OCT particularly interesting in the characterization of optical materials for large aperture laser systems is that its axial resolution can be maintained with working distances greater than 5 cm, whether viewing through air or through the bulk of thick optics. Specifically, when mitigating surface damage sites against further growth by CO{sub 2} laser evaporation of the damage, it is important to know the depth of subsurface cracks below the damage site. These cracks are typically obscured by the damage rubble when imaged from above the surface. The results to date clearly demonstrate that OCT is a unique and valuable tool for characterizing damage sites before and after the mitigation process. We also demonstrated its utility as an in-situ diagnostic to guide and optimize our process when mitigating surface damage sites on large, high-value optics.

  1. Development on Thin-film Thermocouples Technology for Foreign Aeroengine%国外航空发动机薄膜热电偶技术发展研究

    Institute of Scientific and Technical Information of China (English)

    黄春峰; 蒋明夫; 毛茂华


    The performance and technical characteristics for thin-film thermocouple were analysed.The method of sensitive film making,technologic method,quality control for thin-film thermocouple,and application and development of new technology were expatiated.The investigation results at home and abroad demonstrate that the advanced thin-film thermocouple technology can endure a hostile environment for aeroengine testing.It is a perfect method to successfully solve the surface temperature measurement for aeroengine blade and vane.%分析了薄膜热电偶的性能和技术特点,阐述了敏感膜的制作方法、薄膜热电偶工艺方法和质量控制,以及有关新技术的应用与发展。国内外研究结果表明:先进的薄膜热电偶能够承受恶劣的试验环境,是成功解决航空发动机涡轮叶片表面温度测量的理想方法。

  2. Methoxychlor and estradiol induce oxidative stress DNA damage in the mouse ovarian surface epithelium. (United States)

    Symonds, Daniel A; Merchenthaler, Istvan; Flaws, Jodi A


    Estrogenic compounds such as 17beta-estradiol (E(2)) and methoxychlor (MXC) induce oxidative stress damage in breast cells and mouse ovarian follicles, respectively. However, little is known about whether estrogenic compounds cause oxidative stress in the ovarian surface epithelium (OSE). Thus, this work tested the hypothesis that E(2) and MXC cause oxidative stress in the OSE. To test this hypothesis, we employed an improved mouse tissue culture assay in which OSE cells were treated with hydrogen peroxide (H2O2; positive control), MXC, or E(2) +/- the anti-oxidant vitamin E, or progesterone. The cells then were subjected to a novel direct immunofluorescent assay in which cells in the microtiter plate were reacted with antibodies that detect oxidative damage to DNA (8-hydroxy-2'-deoxyguanosine). The signal was identified with a tyramide Alexa Fluor fluorescent probe and quantified by microfluorimetry. Correction for cellularity was carried out for each well with a fluorescent DNA dye system (CyQuant) at a different wavelength. After 24 h, the mean Alexa Fluor CyQuant ratio was 11.3 +/- 0.9 for controls, 132 +/- 15 for H2O2 treated positive control cells (p < or = 0.01 from control), 105 +/- 6.6 for E(2) treated cells (p < or = 0.01 from control), and 64 +/- 5.1 for MXC-treated cells (p < or = 0.01 from control). After 72 h, the mean ratio was 121 +/- 10.6 for controls, 391 +/- 23 for H2O2 treated cells (p < or = 0.01 from control), 200 +/- 15 for E(2) treated cells (p < or = 0.03), and 228 +/- 21 for MXC-treated cells (p < or = 0.01). Further, vitamin E, but not progesterone, protected OSE cells from E(2)- and MXC-induced oxidative damage. This study demonstrates the feasibility of direct immunofluorescent quantitation of DNA adducts in cell cultures without DNA extraction. Moreover, these data indicate that E(2) and MXC produce oxidative DNA damage in the OSE, and that this damage is prevented by the anti-oxidant vitamin E.

  3. Qualification of Indigenously Developed Special Coatings for Aero-Engine Components

    Directory of Open Access Journals (Sweden)

    V. Sambasiva Rao


    Full Text Available The demand for higher performance and reliability of aero-engiaes necessitates its components to worksatisfactorily under severe operating conditions. The durability of various components in these environmentis often enhanced by applying suitable coatings. The development of new materials/processing methods andalso various coatings to protect the components have been driven by the ever-increasing severity of theaero-engine internal environment. While the selection of a coating is dictated by the operating conditionsand the nature of the environment and also on the substrate, the durability of the coating depends uponthe mode of degradation of the coating and substrate in service.Though certification of an aero-engine after developmt obviously includes: validation of the componentsand its coatings, indigenous substitution of an already-qualified component system requires a re-orientationof the qualification methodology. This paper describes an approach for qualification of indigenously developedspecial coatings processes for application on aero-engine components. This approach has been adoptedsuccesshlly in validating several indigenous coatingslpmcesses, viz, aluminium-silicon diffusion coating appliedby pack cementation for oxidationhot comsion resistance, cobalt-chromium carbide coating by electrodepositionfor wear resistance, chromium carbide-nickel chromium coating applied by detonation gun and yttria-stabilisedzirconia thermal barrier coating applied by plasma spray.The approaih consists of a series of validation tests configured to assess the coating-substrate system.The rationale in evolving the qualification tests based on the type of coating, coating process, operating conditionsfor the components, probable failure modes and coating-base metal interaction, are described. In addition,comparison of the test results obtained on the test specimens coated with indigenously developed coatingsand imported coatings is also enumerated to show

  4. Quantification of acute vocal fold epithelial surface damage with increasing time and magnitude doses of vibration exposure.

    Directory of Open Access Journals (Sweden)

    Tsuyoshi Kojima

    Full Text Available Because the vocal folds undergo repeated trauma during continuous cycles of vibration, the epithelium is routinely susceptible to damage during phonation. Excessive and prolonged vibration exposure is considered a significant predisposing factor in the development of vocal fold pathology. The purpose of the present study was to quantify the extent of epithelial surface damage following increased time and magnitude doses of vibration exposure using an in vivo rabbit phonation model. Forty-five New Zealand white breeder rabbits were randomized to nine groups and received varying phonation time-doses (30, 60, or 120 minutes and magnitude-doses (control, modal intensity phonation, or raised intensity phonation of vibration exposure. Scanning electron microscopy and transmission electron microscopy was used to quantify the degree of epithelial surface damage. Results revealed a significant reduction in microprojection density, microprojection height, and depth of the epithelial surface with increasing time and phonation magnitudes doses, signifying increased epithelial surface damage risk with excessive and prolonged vibration exposure. Destruction to the epithelial cell surface may provide significant insight into the disruption of cell function following prolonged vibration exposure. One important goal achieved in the present study was the quantification of epithelial surface damage using objective imaging criteria. These data provide an important foundation for future studies of long-term tissue recovery from excessive and prolonged vibration exposure.

  5. Investigation of laser-surface interactions and optical damage mechanisms using excitation by pairs of picosecond laser pulses (United States)

    Chase, L. L.; Lee, H. W. H.; Hughes, Robert S.


    It is demonstrated that laser-surface interactions that cause optical surface damage of nominally transparent materials can be investigated by observing the effects of excitation by pairs of picosecond pulses separated by a variable time delay. Laser-induced emission of neutrals is used as the detection mechanism in the present experiments.

  6. Characterization of thermomechanical damage on tungsten surfaces during long-duration plasma transients (United States)

    Rivera, David; Crosby, Tamer; Sheng, Andrew; Ghoniem, Nasr M.


    A new experimental facility constructed at UCLA for the simulation of high heat flux effects on plasma-facing materials is described. The High Energy Flux Test Facility (HEFTY) is equipped with a Praxair model SG-100 plasma gun, which is nominally rated at 80 kW of continuous operation, of which approximately 30 kW reaches the target due to thermal losses. The gun is used to impart high intermittent heat flux to metal samples mounted within a cylindrical chamber. The system is capable of delivering an instantaneous heat flux in the range of 30-300 MW/m2, depending on sample proximity to the gun. The duration of the plasma heat flux is in the range of 1-1000 s, making it ideal for studies of mild plasma transients of relatively long duration. Tungsten and tungsten-copper alloy metal samples are tested in these transient heat flux conditions, and the surface is characterized for damage evaluation using optical, SEM, XRD, and micro-fabrication techniques. Results from a Finite Element (FE) thermo-elastoplasticity model indicate that during the heat-up phase of a plasma transient pulse, the majority of the sample surface is under compressive stresses leading to plastic deformation of the surface. Upon sample cooling, the recovered elastic strain of cooler parts of the sample exceeds that from parts that deformed plastically, resulting in a tensile surface self-stress (residual surface stress). The intensity of the residual tensile surface stress is experimentally correlated with the onset of complex surface fracture morphology on the tungsten surface, and extending below the surface region. Micro-compression mechanical tests of W micro-pillars show that the material has significant plasticity, failing by a "barreling" mode before plasma exposure, and by normal dislocation slip and localized shear after plasma exposure. Ongoing modeling of the complex thermo-fracture process, coupled with elasto-plasticity is based on a phase field approach for distributed fracture, and

  7. Assessing Expected Fractional Damage of Above-ground Buildings from Air-to-surface Weapons based on Indirect Fire Concept

    Directory of Open Access Journals (Sweden)

    Jong Yil Park


    Full Text Available For the expected fractional damage of building targets from air-to-surface weapons, the US has used the JMEM/AS method, which is based on the direct-fire concept. However, the damage redistribution assumption in the direct-fire concept could induce serious errors in damage estimation of building targets. In this paper, a method for the expected fractional damage of building targets is proposed based on the indirect-fire concept. From the proposed model, it is shown that the joint munitions effectiveness manuals/air-to-surface (JMEM/AS method is not appropriate for building targets, especially for attacks with multiple aiming points. It is recommended that the indirect-fire concept should be adopted for weaponeering even for air-to-surface weapons. fire concept could induce serious errors in damage estimation of building targets. In this paper, a method for the expected fractional damage of building targets is proposed based on the indirect-fire concept. From the proposed model, it is shown that the JMEM/AS method is not appropriate for building targets, especially for attacks with multiple aiming points. It is recommended that the indirect-fire concept should be adopted for weaponeering even for air-to-surface weapons.Defence Science Journal, 2010, 60(5, pp.491-496, DOI:

  8. Detection of a milling-induced surface damage by the magnetic Barkhausen noise (United States)

    Stupakov, A.; Neslušan, M.; Perevertov, O.


    The potential of the magnetic Barkhausen noise method for a non-destructive evaluation of the steel surface damage cased by milling was comprehensively investigated. A typical bearing steel was heat treated to three different hardnesses and then machined using the cutting tools with different degrees of the flank wear. The magnetic low-frequency measurements with a high reading depth were performed using a unique laboratory system providing a full control of the magnetization process. The high-frequency measurements were performed using a commercial Rollscan device. To study the induced magnetic anisotropy, the measurements were performed in two magnetization directions. In the feeding direction, the Barkhausen noise profiles showed a second high-field peak ascribed to an induced hardened surface layer, a so-called white layer. The most reliable results were obtained with the controlled waveform of the surface magnetic field measured directly by Hall sensors. In the perpendicular rotation direction, formation of the preferentially oriented matrix resulted in an enormously high Barkhausen noise activity. Based on these results, new magnetic parameters were proposed for the non-destructive evaluation of the white layer formation.

  9. Mussel Coating Protein-Derived Complex Coacervates Mitigate Frictional Surface Damage. (United States)

    Miller, Dusty Rose; Das, Saurabh; Huang, Kuo-Ying; Han, Songi; Israelachvili, Jacob N; Waite, J Herbert


    The role of friction in the functional performance of biomaterial interfaces is widely reckoned to be critical and complicated but poorly understood. To better understand friction forces, we investigated the natural adaptation of the holdfast or byssus of mussels that live in high-energy surf habitats. As the outermost covering of the byssus, the cuticle deserves particular attention for its adaptations to frictional wear under shear. In this study, we coacervated one of three variants of a key cuticular component, mussel foot protein 1, mfp-1 [(1) Mytilus californianus mcfp-1, (2) rmfp-1, and (3) rmfp-1-Dopa], with hyaluronic acid (HA) and investigated the wear protection capabilities of these coacervates to surfaces (mica) during shear. Native mcfp-1/HA coacervates had an intermediate coefficient of friction (μ ∼0.3) but conferred excellent wear protection to mica with no damage from applied loads, F⊥, as high as 300 mN (pressure, P, > 2 MPa). Recombinant rmfp-1/HA coacervates exhibited a comparable coefficient of friction (μ ∼0.3); however, wear protection was significantly inferior (damage at F⊥ > 60 mN) compared with that of native protein coacervates. Wear protection of rmfp-1/HA coacervates increased 5-fold upon addition of the surface adhesive group 3,4-dihydroxyphenylalanine, (Dopa). We propose a Dopa-dependent wear protection mechanism to explain the differences in wear protection between coacervates. Our results reveal a significant untapped potential for coacervates in applications that require adhesion, lubrication, and wear protection. These applications include artificial joints, contact lenses, dental sealants, and hair and skin conditioners.

  10. Ultrastructural analysis of miltefosine-induced surface membrane damage in adult Schistosoma mansoni BH strain worms. (United States)

    Bertão, Humberto Gonçalves; da Silva, Renata Alexandre Ramos; Padilha, Rafael José R; de Azevedo Albuquerque, Mônica Camelo Pessôa; Rádis-Baptista, Gandhi


    Schistosomiasis is an infectious parasitic disease caused by helminths from the genus Schistosoma; it affects over 200 million people globally and is endemic in 70 countries. In Brazil, 6 million individuals are infected with Schistosoma mansoni. Furthermore, as the prevalence of S. mansoni infections is increasing, approximately 26 million citizens in 19 Brazilian states are at risk for infection. Schistosomiasis disease control involves predominately the administration of a single drug, praziquantel. Although praziquantel exhibits chemotherapeutic efficacy and safety, its massive use in endemic zones, the possibility of the emergence of drug-resistant Schistosoma parasites, and the lack of another efficacious antischistosomal drug demand the discovery of new schistosomicidal compounds. First developed as anti-tumor drug, miltefosine is an alkylphospholipid derivative that exhibits bioactivity against Leishmania and Trypanosoma parasites, free-living protozoa, bacteria, and fungi. With its anti-parasite activity, miltefosine was the first orally administered drug against visceral and cutaneous leishmaniasis approved. Previously, by means of the MTT cytotoxic assay and a DNA fragmentation test, we verified that, at doses of 100 and 200 μM (40 and 80 μg/mL), miltefosine exhibited in vitro schistosomicidal activity against adult S. mansoni worms. Here, we present ultrastructural evidence of rapid, severe miltefosine-induced surface membrane damage in S. mansoni following drug treatment. The number of dead parasites was concentration- and time-dependent following miltefosine treatment. At a miltefosine concentration of 200 μM (∼80 μg/mL), in vitro parasite killing was initiated as early as 3 h post-incubation, and it was maximal after 24 h of treatment. The parasite death was preceded by progressive surface membrane damage, characterized by tegument peeling, spine reduction and erosion, blister formation and rupture, and the emergence of holes. According to our

  11. Mussel Coating Protein-Derived Complex Coacervates Mitigate Frictional Surface Damage (United States)


    The role of friction in the functional performance of biomaterial interfaces is widely reckoned to be critical and complicated but poorly understood. To better understand friction forces, we investigated the natural adaptation of the holdfast or byssus of mussels that live in high-energy surf habitats. As the outermost covering of the byssus, the cuticle deserves particular attention for its adaptations to frictional wear under shear. In this study, we coacervated one of three variants of a key cuticular component, mussel foot protein 1, mfp-1 [(1) Mytilus californianus mcfp-1, (2) rmfp-1, and (3) rmfp-1-Dopa], with hyaluronic acid (HA) and investigated the wear protection capabilities of these coacervates to surfaces (mica) during shear. Native mcfp-1/HA coacervates had an intermediate coefficient of friction (μ ∼0.3) but conferred excellent wear protection to mica with no damage from applied loads, F⊥, as high as 300 mN (pressure, P, > 2 MPa). Recombinant rmfp-1/HA coacervates exhibited a comparable coefficient of friction (μ ∼0.3); however, wear protection was significantly inferior (damage at F⊥ > 60 mN) compared with that of native protein coacervates. Wear protection of rmfp-1/HA coacervates increased 5-fold upon addition of the surface adhesive group 3,4-dihydroxyphenylalanine, (Dopa). We propose a Dopa-dependent wear protection mechanism to explain the differences in wear protection between coacervates. Our results reveal a significant untapped potential for coacervates in applications that require adhesion, lubrication, and wear protection. These applications include artificial joints, contact lenses, dental sealants, and hair and skin conditioners. PMID:26618194

  12. Self-Restoration of Superhydrophobicity on Shape Memory Polymer Arrays with Both Crushed Microstructure and Damaged Surface Chemistry. (United States)

    Lv, Tong; Cheng, Zhongjun; Zhang, Enshuang; Kang, Hongjun; Liu, Yuyan; Jiang, Lei


    Recently, self-healing superhydrophobic surfaces have become a new research focus due to their recoverable wetting performances and wide applications. However, until now, on almost all reported surfaces, only one factor (surface chemistry or microstructure) can be restored. In this paper, a new superhydrophobic surface with self-healing ability in both crushed microstructure and damaged surface chemistry is prepared by creating lotus-leaves-like microstructure on the epoxy shape memory polymer (SMP). Through a simple heating process, the crushed surface microstructure, the damaged surface chemistry, and the surface superhydrophobicity that are destroyed under the external pressure and/or O2 plasma action can be recovered, demonstrating that the obtained superhydrophobic surface has a good self-healing ability in both of the two factors that govern the surface wettability. The special self-healing ability is ascribed to the good shape memory effect of the polymer and the reorganization effect of surface molecules. This paper reports the first use of SMP material to demonstrate the self-healing ability of surface superhydrophobicity, which opens up some new perspectives in designing self-healing superhydrophobic surfaces. Given the properties of this surface, it could be used in many applications, such as self-cleaning coatings, microfluidic devices, and biodetection.

  13. The Electrochemical Machining Analysis of Aeroengine Blade Based on Isogeometric Method

    Directory of Open Access Journals (Sweden)

    Neng Wan


    Full Text Available Electrochemical machining is an important method for the blade in aeroengine. Analysis of electric field in machining gap is the basis of cathode design. For solving the low precision problem for sensitive boundary which is caused by traditional numerical analysis method, this paper proposed a method of promoting the analysis precision by using the isogeometric analysis. The NURBS basis functions are used to replace the Lagrange basis function for establishing the solving equations of the electrochemical machining gap. The problem of the noninterpolation feature belonging to the NURBS basis functions, which could bring the error for imposing Dirichlet boundary condition, is settled. At last, the superiority, including precision and the rate of convergence, of the isogeometric analysis is proved by the comparison test.

  14. Superplasticity in Aeroengine Titanium Alloy VT-9 and its Modified Compositions

    Directory of Open Access Journals (Sweden)

    Abhijit Dutta


    Full Text Available The alloy (Ti-6.5AL-3.3 Mo-1.6Zr-O.3Si is a Soviet composition designated VT-9. Excellent superplastic characteristics found by us in this alloy prompted us to explore the possibility of use of Si-free VT-9 in sheet form for superplastic forming. An optimum thermomechanical processing produced a microstructure that resulted in an elongation of 1700 per cent at a fairly high deformation rate (2 X 10-3 set-1. Thus, the same aeroengine alloy (VT-9 can be used for superplastically formed airframe parts in the Si-free condition. The present study also shows that for making the forming process commercially viable, deformation temperature could be lowered by temporarily alloying with hydrogen in a particular concentration range (0.1 to 0.2 wt per cent.

  15. Unified Multi-speed analysis (UMA) for the condition monitoring of aero-engines (United States)

    Nembhard, Adrian D.; Sinha, Jyoti K.


    For rotating machinery in which speeds and dynamics constantly change, performing vibration-based condition monitoring can be challenging. Thus, an effort is made here to develop a Unified Multi-speed fault diagnosis technique that can exploit useful vibration information available at various speeds from a rotating machine in a single analysis. Commonly applied indicators are computed from data collected from a rig at different speeds for a baseline case and different faults. Four separate analyses are performed: single speed at a single bearing, integrated features from multiple speeds at a single bearing, single speed for integrated features from multiple bearings and the proposed Unified Multi-speed analysis. The Unified Multi-speed approach produces the most conspicuous separation and isolation among the conditions tested. Observations made here suggest integration of more dynamic features available at different speeds improves the learning process of the tool which could prove useful for aero-engine condition monitoring.

  16. Automated analysis of damages for radiation in plastics surfaces; Analisis automatizado de danos por radiacion en superficies plasticas

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, C.; Camacho M, E.; Tavera, L.; Balcazar, M. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)


    Analysis of damages done by the radiation in a polymer characterized by optic properties of polished surfaces, of uniformity and chemical resistance that the acrylic; resistant until the 150 centigrade grades of temperature, and with an approximate weight of half of the glass. An objective of this work is the development of a method that analyze in automated form the superficial damages induced by radiation in plastic materials means an images analyst. (Author)

  17. Results of applying a non-evaporative mitigation technique to laser-initiated surface damage on fused-silica

    Energy Technology Data Exchange (ETDEWEB)

    Adams, J J; Bolourchi, M; Bude, J D; Guss, G M; Matthews, M J; Nostrand, M C


    We present results from a study to determine an acceptable CO{sub 2} laser-based non-evaporative mitigation protocol for use on surface damage sites in fused-silica optics. A promising protocol is identified and evaluated on a set of surface damage sites created under ICF-type laser conditions. Mitigation protocol acceptability criteria for damage re-initiation and growth, downstream intensification, and residual stress are discussed. In previous work, we found that a power ramp at the end of the protocol effectively minimizes the residual stress (<25 MPa) left in the substrate. However, the biggest difficulty in determining an acceptable protocol was balancing between low re-initiation and problematic downstream intensification. Typical growing surface damage sites mitigated with a candidate CO{sub 2} laser-based mitigation protocol all survived 351 nm, 5 ns damage testing to fluences >12.5 J/cm{sup 2}. The downstream intensification arising from the mitigated sites is evaluated, and all but one of the sites has 100% passing downstream damage expectation values. We demonstrate, for the first time, a successful non-evaporative 10.6 {micro}m CO{sub 2} laser mitigation protocol applicable to fused-silica optics used on fusion-class lasers like the National Ignition Facility (NIF).

  18. Gear Fault Detection Effectiveness as Applied to Tooth Surface Pitting Fatigue Damage (United States)

    Lewicki, David G.; Dempsey, Paula J.; Heath, Gregory F.; Shanthakumaran, Perumal


    A study was performed to evaluate fault detection effectiveness as applied to gear-tooth-pitting-fatigue damage. Vibration and oil-debris monitoring (ODM) data were gathered from 24 sets of spur pinion and face gears run during a previous endurance evaluation study. Three common condition indicators (RMS, FM4, and NA4 [Ed. 's note: See Appendix A-Definitions D were deduced from the time-averaged vibration data and used with the ODM to evaluate their performance for gear fault detection. The NA4 parameter showed to be a very good condition indicator for the detection of gear tooth surface pitting failures. The FM4 and RMS parameters perfomu:d average to below average in detection of gear tooth surface pitting failures. The ODM sensor was successful in detecting a significant 8lDOunt of debris from all the gear tooth pitting fatigue failures. Excluding outliers, the average cumulative mass at the end of a test was 40 mg.

  19. An investigation of the chemical and physical properties of pristine, electrochromically damaged, and photochromically damaged KTiOPO{sub 4} (KTP) using surface analytical and optical spectroscopic techniques

    Energy Technology Data Exchange (ETDEWEB)

    Quagliano, J.R.; Petrin, R.R.; Trujillo, T.C.; Cockroft, N.J.; Paffett, M.T.; Havrilla, G.; Maggiore, C.J. [Los Alamos National Lab., NM (United States); Jacco, J.C. [Philips Components, Saugerties, NY (United States)


    Single-crystal KTiOPO{sub 4} (KTP) is widely used as a nonlinear optical material in optics and lasers, but it can suffer irreversible damage from intense electric and electromagnetic fields; impurities, defects, vacancies, and electron/hole transfers are probably involved. This report shows results of surface and near-surface (bulk) studies using SIMS, Rutherford backscattering, PIXE, channeling, and XRF. The electrochromic damage may occur upon reduction of Ti{sup 4+} to Ti{sup 3+} by trapping electrons passing through the ion channels. Jahn-Teller distortions and Ti{sup 3+} absorption could produce the dark macroscopi damage. The claim that Ag ions could travel through the ion channels, is discounted by the RBS and SIMS data. RBS does suggest Ti ion migration, but this is not likely, according to the KTP structure and lack of Ti ion enhancement in the white residue. The 355 nm radiation could be absorbed into the UV band edge to inititate a photochemical process (gray tracking), which could be the charge transfer from the oxide ligand to Ti{sup 4+} to create Ti{sup 3+}.

  20. Wavelet Correlation Feature Scale Entropy and Fuzzy Support Vector Machine Approach for Aeroengine Whole-Body Vibration Fault Diagnosis

    Directory of Open Access Journals (Sweden)

    Cheng-Wei Fei


    Full Text Available In order to correctly analyze aeroengine whole-body vibration signals, Wavelet Correlation Feature Scale Entropy (WCFSE and Fuzzy Support Vector Machine (FSVM (WCFSE-FSVM method was proposed by fusing the advantages of the WCFSE method and the FSVM method. The wavelet coefficients were known to be located in high Signal-to-Noise Ratio (S/N or SNR scales and were obtained by the Wavelet Transform Correlation Filter Method (WTCFM. This method was applied to address the whole-body vibration signals. The WCFSE method was derived from the integration of the information entropy theory and WTCFM, and was applied to extract the WCFSE values of the vibration signals. Among the WCFSE values, the WFSE1 and WCFSE2 values on the scale 1 and 2 from the high band of vibration signal were believed to acceptably reflect the vibration feature and were selected to construct the eigenvectors of vibration signals as fault samples to establish the WCFSE-FSVM model. This model was applied to aeroengine whole-body vibration fault diagnosis. Through the diagnoses of four vibration fault modes and the comparison of the analysis results by four methods (SVM, FSVM, WESE-SVM, WCFSE-FSVM, it is shown that the WCFSE-FSVM method is characterized by higher learning ability, higher generalization ability and higher anti-noise ability than other methods in aeroengine whole-vibration fault analysis. Meanwhile, this present study provides a useful insight for the vibration fault diagnosis of complex machinery besides an aeroengine.

  1. Flood Damage Analysis: First Floor Elevation Uncertainty Resulting from LiDAR-Derived Digital Surface Models

    Directory of Open Access Journals (Sweden)

    José María Bodoque


    Full Text Available The use of high resolution ground-based light detection and ranging (LiDAR datasets provides spatial density and vertical precision for obtaining highly accurate Digital Surface Models (DSMs. As a result, the reliability of flood damage analysis has improved significantly, owing to the increased accuracy of hydrodynamic models. In addition, considerable error reduction has been achieved in the estimation of first floor elevation, which is a critical parameter for determining structural and content damages in buildings. However, as with any discrete measurement technique, LiDAR data contain object space ambiguities, especially in urban areas where the presence of buildings and the floodplain gives rise to a highly complex landscape that is largely corrected by using ancillary information based on the addition of breaklines to a triangulated irregular network (TIN. The present study provides a methodological approach for assessing uncertainty regarding first floor elevation. This is based on: (i generation an urban TIN from LiDAR data with a density of 0.5 points·m−2, complemented with the river bathymetry obtained from a field survey with a density of 0.3 points·m−2. The TIN was subsequently improved by adding breaklines and was finally transformed to a raster with a spatial resolution of 2 m; (ii implementation of a two-dimensional (2D hydrodynamic model based on the 500-year flood return period. The high resolution DSM obtained in the previous step, facilitated addressing the modelling, since it represented suitable urban features influencing hydraulics (e.g., streets and buildings; and (iii determination of first floor elevation uncertainty within the 500-year flood zone by performing Monte Carlo simulations based on geostatistics and 1997 control elevation points in order to assess error. Deviations in first floor elevation (average: 0.56 m and standard deviation: 0.33 m show that this parameter has to be neatly characterized in order

  2. A GM (1, 1 Markov Chain-Based Aeroengine Performance Degradation Forecast Approach Using Exhaust Gas Temperature

    Directory of Open Access Journals (Sweden)

    Ning-bo Zhao


    Full Text Available Performance degradation forecast technology for quantitatively assessing degradation states of aeroengine using exhaust gas temperature is an important technology in the aeroengine health management. In this paper, a GM (1, 1 Markov chain-based approach is introduced to forecast exhaust gas temperature by taking the advantages of GM (1, 1 model in time series and the advantages of Markov chain model in dealing with highly nonlinear and stochastic data caused by uncertain factors. In this approach, firstly, the GM (1, 1 model is used to forecast the trend by using limited data samples. Then, Markov chain model is integrated into GM (1, 1 model in order to enhance the forecast performance, which can solve the influence of random fluctuation data on forecasting accuracy and achieving an accurate estimate of the nonlinear forecast. As an example, the historical monitoring data of exhaust gas temperature from CFM56 aeroengine of China Southern is used to verify the forecast performance of the GM (1, 1 Markov chain model. The results show that the GM (1, 1 Markov chain model is able to forecast exhaust gas temperature accurately, which can effectively reflect the random fluctuation characteristics of exhaust gas temperature changes over time.

  3. Effect of Cavitation on Surface Damage of 16.7Cr-10Ni-2Mo Stainless Steel in Marine Environment

    Energy Technology Data Exchange (ETDEWEB)

    Chong, Sang-Ok; Han, Min-Su; Kim, Seong-Jong [Mokpo National Maritime University, Mokpo (Korea, Republic of)


    Stainless steel is generally known to have characteristics of excellent corrosion resistance and durability, but in a marine environment it can suffer from localized corrosion due to the breakdown of passivity film due to chloride ion in seawater. Furthermore, the damage behaviors are sped up under a cavitation environment because of complex damage from electrochemical corrosion and cavitation-erosion. In this study the characteristics of electrochemical corrosion and cavitation erosion behavior were evaluated on 16.7Cr-10Ni-2Mo stainless steel under a cavitation environment in natural seawater. The electrochemical experiments have been conducted at both static conditions and dynamic conditions inducing cavitation with different current density parameters. The surface morphology and damage behaviors were compared after the experiment. After the cavitation test with time variables morphological examinations on damaged specimens were analyzed by using a scanning electron microscope and a 3D microscope. the galvanostatic experiment gave a cleaner surface morphology presented with less damage depth at high current density regions. It is due to the effect of water cavitation peening under the cavitation condition. In the cavitation experiment, with amplitude of 30 μm and seawater temperature of 25 ℃, weight loss and cavitation-erosion damage depth were dramatically increased after 5 hours inducing cavitation.

  4. Combined Bulk and Surface Radiation Damage Effects at Very High Fluences in Silicon Detectors: Measurements and TCAD Simulations

    CERN Document Server

    Moscatelli, F; Morozzi, A; Mendicino, Roberto; Betta, G -F Dalla; Bilei, G M


    In this work we propose a new combined TCAD radiation damage modelling scheme, featuring both bulk and surface radiation damage effects, for the analysis of silicon detectors aimed at the High Luminosity LHC. In particular, a surface damage model has been developed by introducing the relevant parameters (NOX, NIT) extracted from experimental measurements carried out on p-type substrate test structures after gamma irradiations at doses in the range 10-500 Mrad(Si). An extended bulk model, by considering impact ionization and deep-level cross-sections variation, was included as well. The model has been validated through the comparison of the simulation findings with experimental measurements carried out at very high fluences (2 10^16 1 MeV equivalent n/cm^2) thus fostering the application of this TCAD approach for the design and optimization of the new generation of silicon detectors to be used in future HEP experiments.

  5. Combined Bulk and Surface Radiation Damage Effects at Very High Fluences in Silicon Detectors: Measurements and TCAD Simulations

    CERN Document Server

    Moscatelli, F; Morozzi, A; Mendicino, R; Dalla Betta, G F; Bilei, G M


    In this work we propose a new combined TCAD radiation damage modelling scheme, featuring both bulk and surface radiation damage effects, for the analysis of silicon detectors aimed at the High Luminosity LHC. In particular, a surface damage model has been developed by introducing the relevant parameters (NOX, NIT) extracted from experimental measurements carried out on p-type substrate test structures after gamma irradiations at doses in the range 10-500 Mrad(Si). An extended bulk model, by considering impact ionization and deep-level cross-sections variation, was included as well. The model has been validated through the comparison of the simulation findings with experimental measurements carried out at very high fluences (2×1016 1 MeV equivalent n/cm2) thus fostering the application of this TCAD approach for the design and optimization of the new generation of silicon detectors to be used in future HEP experiments.


    Institute of Scientific and Technical Information of China (English)

    张海军; 左洪福; 梁剑


    An aero-engine is a typically repairable and complex system and its maintenance level has a close relationship with the maintenance cost. The inaccurate measurement for the maintenance level of an aero-engine can induce higher overhaul maintenance costs. Variable precision rough set (VPRS) theory is used to determine the maintenance level of an aero-engine. According to the relationship between condition information and performance parameters of aero-engine modules, decision rules are established for reflecting the real condition of an aeroengine when its maintenance level needs to be determined. Finally, the CF6 engine is used as an example to illustrate the method to be effective.%应用变精度粗糙集理论研究了发动机状态信息与单元体性能参数之间的关系,提出了一种基于信息熵属性约简的航空公司发动机维修等级决策方法,从而在维修决策时能够更加客观地反映发动机实际损伤程度.最后以CF6型发动机维修等级决策规则生成为例说明了该决策方法的有效性.

  7. Study of Current Status and Method of Aeroengine Blisk Finishing%航空发动机整体叶轮光整加工现状及方法研究

    Institute of Scientific and Technical Information of China (English)

    张宏友; 吴鸣宇


    The paper expounds finishing technology current status of aeroengine blisks at home and abroad and the position in the mechanical manufacturing industry, brings for ward a kind of extruding abrasive flowing method which is used to form the roughness surface gradually and has a preliminary discussion on the abrasive flowing machine of the blisk.%论述了国内外航空发动机整体叶轮的光整加工技术研究现状,以其在机械制造业中的地位,提出了挤压磨料流的加工方法来形成渐变粗糙度表面的方法,并对整体叶轮的磨料流设备做了初步的探讨.

  8. Investigation of surface characteristics evolution and laser damage performance of fused silica during ion-beam sputtering (United States)

    Xu, Mingjin; Dai, Yifan; Zhou, Lin; Shi, Feng; Wan, Wen; Xie, Xuhui; Sui, Tingting


    Surface characteristics have great influence on the optical properties especially the laser radiation resistivity of optics. In this paper, the surface characteristics evolutions of fused silica during ion-beam sputtering and their effects on the laser damage performance were investigated. The results show that roughness change is strongly removal depth dependent and a super-smooth surface (0.25 nm RMS) can be obtained by the ion-induced smoothing effect. The concentration of metal impurities (especially Ce element) in subsurface can be effectively decreased after the removal of polishing re-deposition layer. During ion-beam sputtering process, the plastic scratches can be removed while the brittle cracks can be broadened and passivated without increase in the depth direction. Laser damage threshold of fused silica improved by 36% after ion-beam sputtering treatment. Research results have a guiding significance for ion-beam sputtering process technology of fused silica optics.

  9. Surface-based reconstruction and diffusion MRI in the assessment of gray and white matter damage in multiple sclerosis (United States)

    Caffini, Matteo; Bergsland, Niels; LaganÃ, Marcella; Tavazzi, Eleonora; Tortorella, Paola; Rovaris, Marco; Baselli, Giuseppe


    Despite advances in the application of nonconventional MRI techniques in furthering the understanding of multiple sclerosis pathogenic mechanisms, there are still many unanswered questions, such as the relationship between gray and white matter damage. We applied a combination of advanced surface-based reconstruction and diffusion tensor imaging techniques to address this issue. We found significant relationships between white matter tract integrity indices and corresponding cortical structures. Our results suggest a direct link between damage in white and gray matter and contribute to the notion of gray matter loss relating to clinical disability.

  10. Numerical Prediction of Flow and Heat Transfer on lubricant Supplying and Scavenging Flow Path of an Aero-Engine Lubrication System (United States)

    Huang, S. Q.; Liu, Z. X.; Lv, Y. G.; Zhang, L. F.; Xu, T.

    This paper presents a numerical model of internal flows on lubricant supplying and scavenging flow path of an aero-engine lubrication system. The numerical model was built in the General Analysis Software of Aero-engine Lubrication System (GASLS), developed by Northwestern Polytechnical University. The lubricant flow flux, pressure and temperature distribution at steady state were calculated. GASLS is a general purpose computer program employed a ID steady state network algorithm for analyzing flowrates, pressures and temperatures in a complex flow network. All kinds of aero-engine lubrication systems can be divided into finite correlative typical elements and nodes from which the calculation network is developed in GASLS. Special emphasis is put on how to use combinational elements which is a type of typical elements to replace some complex components such as bearing compartments, accessory drive gearboxes or heat exchangers. This method can reduce network complexity and improve calculation efficiency. The computational results show good agreement with experimental data.

  11. Direct Surge Margin Control for Aeroengines Based on Improved SVR Machine and LQR Method

    Directory of Open Access Journals (Sweden)

    Haibo Zhang


    Full Text Available A novel scheme of high stability engine control (HISTEC on the basis of an improved linear quadratic regulator (ILQR, called direct surge margin control, is derived for super-maneuver flights. Direct surge margin control, which is different from conventional control scheme, puts surge margin into the engine closed-loop system and takes surge margin as controlled variable directly. In this way, direct surge margin control can exploit potential performance of engine more effectively with a decrease of engine stability margin which usually happened in super-maneuver flights. For conquering the difficulty that aeroengine surge margin is undetectable, an approach based on improved support vector regression (SVR machine is proposed to construct a surge margin prediction model. The surge margin modeling contains two parts: a baseline model under no inlet distortion states and the calculation for surge margin loss under supermaneuvering flight conditions. The previous one is developed using neural network method, the inputs of which are selected by a weighted feature selection algorithm. Considering the hysteresis between pilot input and angle of attack output, an online scrolling window least square support vector regression (LSSVR method is employed to firstly estimate inlet distortion index and further compute surge margin loss via some empirical look-up tables.

  12. Active generalized predictive control of turbine tip clearance for aero-engines

    Institute of Scientific and Technical Information of China (English)

    Peng Kai; Fan Ding; Yang Fan; Fu Qiang; Li Yong


    Active control of turbine blade tip clearance continues to be a concern in design and con-trol of gas turbines. Ever increasing demands for improved efficiency and higher operating temper-atures require more stringent tolerances on turbine tip clearance. In this paper, a turbine tip clearance control apparatus and a model of turbine tip clearance are proposed;an implicit active generalized predictive control (GPC), with auto-regressive (AR) error modification and fuzzy adjustment on control horizon, is presented, as well as a quantitative analysis method of robust per-turbation radius of the system. The active clearance control (ACC) of aero-engine turbine tip clear-ance is evaluated in a lapse-rate take-off transient, along with the comparative and quantitative analysis of the stability and robustness of the active tip clearance control system. The results show that the resultant active tip clearance control system with the improved GPC has favorable steady-state and dynamic performance and benefits of increased efficiency, reduced specific fuel consump-tion, and additional service life.

  13. 3 D FEM analysis of welding residual stress and deformation of aero-engine blisk

    Institute of Scientific and Technical Information of China (English)

    杨建国; 周号; 雷靖; 方洪渊; 张学秋; 曲伸


    Aero-engine blisk welded by electron beam welding(EBW)method is a complicated structure.Fixtures were used to control the deformation ofblisk during its manufacturing process.Finite element method was utilized to study the evolution of the welding residual stress and deformation of this structure.In which an attenuation function was applied to the double ellipsoid heat source model based on the characteristic ofEBW,and the effects offixtures on the welding residual stresses and deforamtion were also reserached.The simulation results showed that the temperature contour ofweld cross section vertical to the weld centerline followed a “V”shape.Moreover,large welding residual stress and distortion were found in the interface between blisk and fixtures.The stress concentration was reduced sufficiently in starting and end part ofweldment as the fixtures were removed after welding process,while the removing operation had almost no effects on the welding residual stress in the middle section ofweld bead.

  14. CFD predictions of LBO limits for aero-engine combustors using fuel iterative approximation

    Institute of Scientific and Technical Information of China (English)

    Hu Bin; Huang Yong; Wang Fang; Xie Fa


    Lean blow-out (LBO) is critical to operational performance of combustion systems in propulsion and power generation.Current predictive tools for LBO limits are based on decadesold empirical correlations that have limited applicability for modern combustor designs.According to the Lefebvre's model for LBO and classical perfect stirred reactor (PSR) concept,a load parameter (LP) is proposed for LBO analysis of aero-engine combustors in this paper.The parameters contained in load parameter are all estimated from the non-reacting flow field of a combustor that is obtained by numerical simulation.Additionally,based on the load parameter,a method of fuel iterative approximation (FIA) is proposed to predict the LBO limit of the combustor.Compared with experimental data for 19 combustors,it is found that load parameter can represent the actual combustion load of the combustor near LBO and have good relativity with LBO fuel/air ratio (FAR).The LBO FAR obtained by FIA shows good agreement with experimental data,the maximum prediction uncertainty of FIA is about ± 17.5%.Because only the non-reacting flow is simulated,the time cost of the LBO limit prediction using FIA is relatively low (about 6 h for one combustor with computer equipment of CPU 2.66 GHz × 4 and 4 GB memory),showing that FIA is reliable and efficient to be used for practical applications.

  15. Remaining useful life prognostics for aeroengine based on superstatistics and information fusion

    Institute of Scientific and Technical Information of China (English)

    Liu Junqiang; Zhang Malan; Zuo Hongfu; Xie Jiwei


    Remaining useful life (RUL) prognostics is a fundamental premise to perform condition-based maintenance (CBM) for a system subject to performance degradation. Over the past decades, research has been conducted in RUL prognostics for aeroengine. However, most of the prognostics technologies and methods simply base on single parameter, making it hard to demonstrate the spe-cific characteristics of its degradation. To solve such problems, this paper proposes a novel approach to predict RUL by means of superstatistics and information fusion. The performance degradation evolution of the engine is modeled by fusing multiple monitoring parameters, which manifest non-stationary characteristics while degrading. With the obtained degradation curve, prognostics model can be established by state-space method, and then RUL can be estimated when the time-varying parameters of the model are predicted and updated through Kalman filtering algo-rithm. By this method, the non-stationary degradation of each parameter is represented, and multi-ple monitoring parameters are incorporated, both contributing to the final prognostics. A case study shows that this approach enables satisfactory prediction evolution and achieves a markedly better prognosis of RUL.

  16. Remaining useful life prognostics for aeroengine based on superstatistics and information fusion

    Directory of Open Access Journals (Sweden)

    Liu Junqiang


    Full Text Available Remaining useful life (RUL prognostics is a fundamental premise to perform condition-based maintenance (CBM for a system subject to performance degradation. Over the past decades, research has been conducted in RUL prognostics for aeroengine. However, most of the prognostics technologies and methods simply base on single parameter, making it hard to demonstrate the specific characteristics of its degradation. To solve such problems, this paper proposes a novel approach to predict RUL by means of superstatistics and information fusion. The performance degradation evolution of the engine is modeled by fusing multiple monitoring parameters, which manifest non-stationary characteristics while degrading. With the obtained degradation curve, prognostics model can be established by state-space method, and then RUL can be estimated when the time-varying parameters of the model are predicted and updated through Kalman filtering algorithm. By this method, the non-stationary degradation of each parameter is represented, and multiple monitoring parameters are incorporated, both contributing to the final prognostics. A case study shows that this approach enables satisfactory prediction evolution and achieves a markedly better prognosis of RUL.

  17. Nonlocal sparse model with adaptive structural clustering for feature extraction of aero-engine bearings (United States)

    Zhang, Han; Chen, Xuefeng; Du, Zhaohui; Li, Xiang; Yan, Ruqiang


    Fault information of aero-engine bearings presents two particular phenomena, i.e., waveform distortion and impulsive feature frequency band dispersion, which leads to a challenging problem for current techniques of bearing fault diagnosis. Moreover, although many progresses of sparse representation theory have been made in feature extraction of fault information, the theory also confronts inevitable performance degradation due to the fact that relatively weak fault information has not sufficiently prominent and sparse representations. Therefore, a novel nonlocal sparse model (coined NLSM) and its algorithm framework has been proposed in this paper, which goes beyond simple sparsity by introducing more intrinsic structures of feature information. This work adequately exploits the underlying prior information that feature information exhibits nonlocal self-similarity through clustering similar signal fragments and stacking them together into groups. Within this framework, the prior information is transformed into a regularization term and a sparse optimization problem, which could be solved through block coordinate descent method (BCD), is formulated. Additionally, the adaptive structural clustering sparse dictionary learning technique, which utilizes k-Nearest-Neighbor (kNN) clustering and principal component analysis (PCA) learning, is adopted to further enable sufficient sparsity of feature information. Moreover, the selection rule of regularization parameter and computational complexity are described in detail. The performance of the proposed framework is evaluated through numerical experiment and its superiority with respect to the state-of-the-art method in the field is demonstrated through the vibration signals of experimental rig of aircraft engine bearings.

  18. A 5-DOF Model for Aeroengine Spindle Dual-rotor System Analysis

    Institute of Scientific and Technical Information of China (English)

    HU Qinghua; DENG Sier; TENG Hongfei


    This paper develops a five degrees of freedom (5-DOF) model for aeroengine spindle dual-rotor system dynamic analysis.In this system, the dual rotors are supported on two angular contact ball bearings and two deep groove ball bearings, one of the latter-mentioned bearings works as the inter-shaft bearing.Driven by respective motors, the dual rotors have different co-rotating speeds.The proposed model mathematically formulates the nonlinear displacements, elastic deflections and contact forces of beatings with consideration of 5-DOF and coupling of dual rotors.The nonlinear equations of motions of dual rotors with 5-DOF are solved using Runge-Kutta-Fehlberg algorithm.In order to investigate the effect of the introduced 5-DOF and nonlinear dynamic bearing model, we compare the proposed model with two models: the 3-DOF model of this system only considering three translational degrees of freedom (Gupta, 1993, rotational freedom is neglected); the 5-DOF model where the deep groove ball bearings are simplified as linear elastic spring (Guskov, 2007).The simulation results verify Gupta's prediction (1993) and show that the rotational freedom of rotors and nonlinear dynamic model of bearings have great effect on the system dynamic simulation.The quantitative results are given as well.

  19. Comparison of laser-based mitigation of fused silica surface damage using mid- versus far-infrared lasers

    Energy Technology Data Exchange (ETDEWEB)

    Yang, S T; Matthews, M J; Elhadj, S; Cooke, D; Guss, G M; Draggoo, V G; Wegner, P J


    Laser induced growth of optical damage can limit component lifetime and therefore operating costs of large-aperture fusion-class laser systems. While far-infrared (IR) lasers have been used previously to treat laser damage on fused silica optics and render it benign, little is known about the effectiveness of less-absorbing mid-IR lasers for this purpose. In this study, they quantitatively compare the effectiveness and efficiency of mid-IR (4.6 {micro}m) versus far-IR (10.6 {micro}m) lasers in mitigating damage growth on fused silica surfaces. The non-linear volumetric heating due to mid-IR laser absorption is analyzed by solving the heat equation numerically, taking into account the temperature-dependent absorption coefficient {alpha}(T) at {lambda} = 4.6 {micro}m, while far-IR laser heating is well-described by a linear analytic approximation to the laser-driven temperature rise. In both cases, the predicted results agree well with surface temperature measurements based on infrared radiometry, as well as sub-surface fictive temperature measurements based on confocal Raman microscopy. Damage mitigation efficiency is assessed using a figure of merit (FOM) relating the crack healing depth to laser power required, under minimally-ablative conditions. Based on their FOM, they show that for cracks up to at least 500 {micro}m in depth, mitigation with a 4.6 {micro}m mid-IR laser is more efficient than mitigation with a 10.6 {micro}m far-IR laser. This conclusion is corroborated by direct application of each laser system to the mitigation of pulsed laser-induced damage possessing fractures up to 225 {micro}m in depth.

  20. RHEED study of irradiation-induced surface damage processes in Si and alpha-Al sub 2 O sub 3

    CERN Document Server

    Muto, S; Tanabé, T


    Surface damaging processes of crystalline silicon and alumina (alpha-Al sub 2 O sub 3) by gas ion (H sup + , He sup + , Ar sup + , 0.5-5 keV) irradiation at a moderate temperature range (300-450 K) were examined by reflection high-energy electron diffraction (RHEED). In order to explain the changes in RHEED intensities, a phenomenological kinetic equation was extended to take a dynamical interaction between hydrogen and target atoms into account. Apparent activation energies for simultaneous recovery and the cross-sections for damage production were derived and compared for different implant species by fitting the kinetic equation to the experimental data. The obtained physical parameters showed that the surface damage by inert gas irradiation could be understood simply by the dpa (displacement per atom) rates due to nuclear stopping. In case of H sup + irradiation, on the other hand, electronic stopping and chemical interaction between hydrogen and the matrix atoms significantly affected the damaging rate an...

  1. Energetic laser cleaning of metallic particles and surface damage on silica optics: investigation of the underlying mechanisms (United States)

    Shen, Nan; Demos, Stavros G.; Negres, Raluca A.; Rubenchik, Alexander M.; Harris, Candace D.; Matthews, Manyalibo J.


    Surface particulate contamination on optics can lead to laser-induced damage hence limit the performance of high power laser system. In this work we focus on understanding the fundamental mechanisms that lead to damage initiation by metal contaminants. Using time resolved microscopy and plasma spectroscopy, we studied the dynamic process of ejecting ~30 μm stainless steel particles from the exit surface of fused silica substrate irradiated with 1064 nm, 10 ns and 355 nm, 8 ns laser pulses. Time-resolved plasma emission spectroscopy was used to characterize the energy coupling and temperature rise associated with single, 10-ns pulsed laser ablation of metallic particles bound to transparent substrates. Plasma associated with Fe(I) emission lines originating from steel microspheres was observe to cool from laser energy.

  2. Improved laser damage threshold performance of calcium fluoride optical surfaces via Accelerated Neutral Atom Beam (ANAB) processing (United States)

    Kirkpatrick, S.; Walsh, M.; Svrluga, R.; Thomas, M.


    Optics are not keeping up with the pace of laser advancements. The laser industry is rapidly increasing its power capabilities and reducing wavelengths which have exposed the optics as a weak link in lifetime failures for these advanced systems. Nanometer sized surface defects (scratches, pits, bumps and residual particles) on the surface of optics are a significant limiting factor to high end performance. Angstrom level smoothing of materials such as calcium fluoride, spinel, magnesium fluoride, zinc sulfide, LBO and others presents a unique challenge for traditional polishing techniques. Exogenesis Corporation, using its new and proprietary Accelerated Neutral Atom Beam (ANAB) technology, is able to remove nano-scale surface damage and particle contamination leaving many material surfaces with roughness typically around one Angstrom. This surface defect mitigation via ANAB processing can be shown to increase performance properties of high intensity optical materials. This paper describes the ANAB technology and summarizes smoothing results for calcium fluoride laser windows. It further correlates laser damage threshold improvements with the smoothing produced by ANAB surface treatment. All ANAB processing was performed at Exogenesis Corporation using an nAccel100TM Accelerated Particle Beam processing tool. All surface measurement data for the paper was produced via AFM analysis on a Park Model XE70 AFM, and all laser damage testing was performed at Spica Technologies, Inc. Exogenesis Corporation's ANAB processing technology is a new and unique surface modification technique that has demonstrated to be highly effective at correcting nano-scale surface defects. ANAB is a non-contact vacuum process comprised of an intense beam of accelerated, electrically neutral gas atoms with average energies of a few tens of electron volts. The ANAB process does not apply mechanical forces associated with traditional polishing techniques. ANAB efficiently removes surface

  3. System and method for laser-based, non-evaporative repair of damage sites in the surfaces of fused silica optics

    Energy Technology Data Exchange (ETDEWEB)

    Adams, John J.; Bolourchi, Masoud; Bude, Jeffrey D.; Guss, Gabriel M.; Jarboe, Jeffery A.; Matthews, Manyalibo J.; Nostrand, Michael C; Wegner, Paul J.


    A method for repairing a damage site on a surface of an optical material is disclosed. The method may involve focusing an Infrared (IR) laser beam having a predetermined wavelength, with a predetermined beam power, to a predetermined full width ("F/W") 1/e.sup.2 diameter spot on the damage site. The focused IR laser beam is maintained on the damage site for a predetermined exposure period corresponding to a predetermined acceptable level of downstream intensification. The focused IR laser beam heats the damage site to a predetermined peak temperature, which melts and reflows material at the damage site of the optical material to create a mitigated site.

  4. Earliness, leaf surface wax and sugar content predict varietal differences for thrips damage in cabbage

    NARCIS (Netherlands)

    Voorrips, R.E.; Steenhuis-Broers, M.M.; Tiemens-Hulscher, M.; Lammerts Van Bueren, E.


    When cabbage is cultivated for storage in the Netherlands, it is usually harvested around mid-October. This type of cabbage crop may be severely damaged by thrips (Thrips tabaci). The thrips population on the plants and the more severe symptoms develop mostly during September and October. Also durin


    Institute of Scientific and Technical Information of China (English)

    陆晓华; 左洪福; 蔡景


    The maintenance of an aero-engine usually includes three levels ,and the maintenance cost and period greatly differ depending on the different maintenance levels .To plan a reasonable maintenance budget program , airlines would like to predict the maintenance level of aero-engine before repairing in terms of performance parame-ters ,which can provide more economic benefits .The maintenance level decision rules are mined using the histori-cal maintenance data of a civil aero-engine based on the rough set theory ,and a variety of possible models of upda-ting rules produced by newly increased maintenance cases added to the historical maintenance case database are in-vestigated by the means of incremental machine learning .The continuously updated rules can provide reasonable guidance suggestions for engineers and decision support for planning a maintenance budget program before repai-ring .The results of an example show that the decision rules become more typical and robust ,and they are more accurate to predict the maintenance level of an aero-engine module as the maintenance data increase ,which illus-trates the feasibility of the represented method .

  6. Surface and internal microstructure damage of He-ion-irradiated CLAM steel studied by cross-sectional transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, P.P. [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Zhan, Q., E-mail: [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Fu, Z.Y.; Wei, Y.P. [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Wang, Y.M. [Faculty of Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Wang, F.M. [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Ohnuki, S. [Faculty of Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Wan, F.R. [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China)


    Good understanding of blistering and embrittlement mechanism depends on good investigation of surface and internal microstructure damage of gas-ion-irradiated materials. Internal and surface microstructure of He{sup +} ion irradiated CLAM steel were examined by cross-sectional transmission electron microscopy combining focused ion beam. Variation of helium bubble density and size distribution versus depth in CLAM steel after high dose helium irradiation at room temperature was investigated. The average size of helium bubble increased within 100–400 nm but decreased near the non-irradiated matrix with the increase of depth, while the density followed a reverse trend. The formation and growth mechanism of helium bubble is different at different irradiation depth. The formation of a zone of large bubbles under the surface is the main reason of surface blistering and flaking. Helium induced irradiation swelling and surface blistering at low temperature were also discussed. - Highlights: • Microstructure of helium irradiated CLAM steel was investigated by FIB and TEM. • The nucleation of helium bubble was controlled by both different mechanisms. • The substructure of surface blisters has been analyzed in detail by XTEM. • Helium induced surface blistering and irradiation swelling have been discussed.

  7. Simultaneous impact of neutron irradiation and sputtering on the surface structure of self–damaged ITER–grade tungsten

    Directory of Open Access Journals (Sweden)

    A. I. Belyaeva


    Full Text Available Simultaneous effects of neutron irradiation and long–term sputtering on the surface relief of ITER–grade tungsten were studied. The effects of neutron–induced displacement damage have been simulated by irradiation of tungsten target with W6 + ions of 20 MeV energy. Ar+ ions with energy 600 eV were used as imitation of charge exchange atoms in ITER. The surface relief was studied after each sputtering act. The singularity in the WJ–IG surface relief was ascertained experimentally at the first time, which determines the law of roughness extension under sputtering. As follows from the experimental data, the neutron irradiation has not to make a decisive additional contribution in the processes developing under impact of charge exchange atoms only.

  8. Characterization of surface damage of a solid plate under tensile loading using nonlinear Rayleigh waves

    Institute of Scientific and Technical Information of China (English)


    This letter reports experimental observation of a direct correlation between the acoustic nonlinearity parameter (NP) measured with nonlinear Rayleigh waves and the accumulation of plasticity damage in an AZ31 magnesium alloy plate specimen.Rayleigh waves are generated and detected with wedge transducers,and the NPs are measured at different stress levels.The results show that there is a significant increase in the NPs with monotonic tensile loads surpassing the material's yielding stress.The research sugge...

  9. Response of Split Hopkinson Bar Apparatus Signal to End-Surface Damage, Numerical and Experimental Studies (United States)


    controlled tests were Fig. 4. Aluminium AI6061-T6 tested with undamaged bars. Fig. 5. Aluminium AI 6061 -T6 tested with damaged bars. conducted using a...control tests were done using the well characterized AI 6061 -T6. Results showed that artefacts were added to the signal. This paper presents the...response, control tests were performed using the well characterized Al 6061 -T6 material. This material was chosen because it was well documented and

  10. An Improved Method of Mitigating Laser Induced Surface Damage Growth in Fused Silica Using a Rastered, Pulsed CO2 Laser

    Energy Technology Data Exchange (ETDEWEB)

    Bass, I L; Guss, G M; Nostrand, M J; Wegner, P L


    A new method of mitigating (arresting) the growth of large (>200 m diameter and depth) laser induced surface damage on fused silica has been developed that successfully addresses several issues encountered with our previously-reported large site mitigation technique. As in the previous work, a tightly-focused 10.6 {micro}m CO{sub 2} laser spot is scanned over the damage site by galvanometer steering mirrors. In contrast to the previous work, the laser is pulsed instead of CW, with the pulse length and repetition frequency chosen to allow substantial cooling between pulses. This cooling has the important effect of reducing the heat-affected zone capable of supporting thermo-capillary flow from scale lengths on the order of the overall scan pattern to scale lengths on the order of the focused laser spot, thus preventing the formation of a raised rim around the final mitigation site and its consequent down-stream intensification. Other advantages of the new method include lower residual stresses, and improved damage threshold associated with reduced amounts of redeposited material. The raster patterns can be designed to produce specific shapes of the mitigation pit including cones and pyramids. Details of the new technique and its comparison with the previous technique will be presented.

  11. Optical properties and surface damage studies of crystalline silicon caused by swift iron ions

    Energy Technology Data Exchange (ETDEWEB)

    Dubey, S.K., E-mail:


    p-Type silicon samples irradiated with 70 MeV {sup 56}Fe{sup 5+} ions for various fluences varying between 5 × 10{sup 12} and 4 × 10{sup 14} ions cm{sup −2} have been studied using spectroscopic ellipsometry and Fourier transform infrared spectroscopy. The microstructure of the irradiated samples was modeled from ellipsometric data, using a multilayer optical model and Bruggeman effective medium approximation. The values of pseudodielectric function, absorption coefficient and Penn gap energy were determined with respect to ion fluence. The effective medium analysis suggests that the superficial silicon layer can be explained as a mixture of crystalline and damaged silicon. The thickness of the damaged layer and percentage of voids present in the layer were found to increase with increase in the ion fluence. The effect of disorder on the interband optical spectra, especially on the critical point E{sub 1} at 3.4 eV was found to vary with ion fluence. A red shift in the critical point E{sub 1} with increasing ion fluence was observed. FTIR study showed of silicon samples irradiated with 70 MeV {sup 56}Fe{sup 5+} ions produced the oscillations in the spectral region 1000–400 cm{sup −1}. As irradiated sample showed more pronounced fringes, while contrast of the fringes and amplitude both were found to decrease with increase in depth.

  12. Effect and suppression of parasitic surface damage in neutron irradiated CMOS Monolithic Active Pixel Sensors

    CERN Document Server

    Deveaux, M; Scharrer, P; Stroth, J


    CMOS Monolithic Active Pixel Sensors (MAPS) were chosen as sensor technology for the vertex detectors of STAR, CBM and the upgraded ALICE-ITS. They also constitute a valuable option for tracking devices at future e+e- colliders. Those applications require a substantial tolerance to both, ionizing and non-ionizing radiation. To allow for a focused optimization of the radiation tolerance, prototypes are tested by irradiating the devices either with purely ionizing radiation (e.g. soft X-rays) or the most pure sources of non-ionizing radiation available (e.g. reactor neutrons). In the second case, it is typically assumed that the impact of the parasitic $\\gamma$-rays found in the neutron beams is negligible. We checked this assumption by irradiating MAPS with $\\gamma$-rays and comparing the radiation damage generated with the one in neutron irradiated sensors. We conclude that the parasitic radiation doses may cause non-negligible radiation damage. Based on the results we propose a procedure to recognize and to ...

  13. Surface structure, model and mechanism of an insect integument adapted to be damaged easily

    Directory of Open Access Journals (Sweden)

    Bouillard Philippe


    Full Text Available Abstract Background Several sawfly larvae of the Tenthredinidae (Hymenoptera are called easy bleeders because their whole body integument, except the head capsule, disrupts very easily at a given spot, under a slight mechanical stress at this spot. The exuding haemolymph droplet acts as a feeding deterrent towards invertebrate predators. The present study aimed to describe the cuticle surface, to consider it from a mechanistic point of view, and to discuss potential consequences of the integument surface in the predator-prey relationships. Results The integument surface of sawfly larvae was investigated by light microscopy (LM and scanning electron microscopy (SEM which revealed that the cuticle of easy bleeders was densely covered by what we call "spider-like" microstructures. Such microstructures were not detected in non-easy bleeders. A model by finite elements of the cuticle layer was developed to get an insight into the potential function of the microstructures during easy bleeding. Cuticle parameters (i.e., size of the microstructures and thickness of the epi-versus procuticle were measured on integument sections and used in the model. A shear force applied on the modelled cuticle surface led to higher stress values when microstructures were present, as compared to a plan surface. Furthermore, by measuring the diameter of a water droplet deposited on sawfly larvae, the integument of several sawfly species was determined as hydrophobic (e.g., more than Teflon®, which was related to the sawfly larvae's ability to bleed easily. Conclusion Easy bleeders show spider-like microstructures on their cuticle surface. It is suggested that these microstructures may facilitate integument disruption as well as render the integument hydrophobic. This latter property would allow the exuding haemolymph to be maintained as a droplet at the integument surface.

  14. A New Quantitative Method for the Non-Invasive Documentation of Morphological Damage in Paintings Using RTI Surface Normals

    Directory of Open Access Journals (Sweden)

    Marcello Manfredi


    Full Text Available In this paper we propose a reliable surface imaging method for the non-invasive detection of morphological changes in paintings. Usually, the evaluation and quantification of changes and defects results mostly from an optical and subjective assessment, through the comparison of the previous and subsequent state of conservation and by means of condition reports. Using quantitative Reflectance Transformation Imaging (RTI we obtain detailed information on the geometry and morphology of the painting surface with a fast, precise and non-invasive method. Accurate and quantitative measurements of deterioration were acquired after the painting experienced artificial damage. Morphological changes were documented using normal vector images while the intensity map succeeded in highlighting, quantifying and describing the physical changes. We estimate that the technique can detect a morphological damage slightly smaller than 0.3 mm, which would be difficult to detect with the eye, considering the painting size. This non-invasive tool could be very useful, for example, to examine paintings and artwork before they travel on loan or during a restoration. The method lends itself to automated analysis of large images and datasets. Quantitative RTI thus eases the transition of extending human vision into the realm of measuring change over time.

  15. A new quantitative method for the non-invasive documentation of morphological damage in paintings using RTI surface normals. (United States)

    Manfredi, Marcello; Bearman, Greg; Williamson, Greg; Kronkright, Dale; Doehne, Eric; Jacobs, Megan; Marengo, Emilio


    In this paper we propose a reliable surface imaging method for the non-invasive detection of morphological changes in paintings. Usually, the evaluation and quantification of changes and defects results mostly from an optical and subjective assessment, through the comparison of the previous and subsequent state of conservation and by means of condition reports. Using quantitative Reflectance Transformation Imaging (RTI) we obtain detailed information on the geometry and morphology of the painting surface with a fast, precise and non-invasive method. Accurate and quantitative measurements of deterioration were acquired after the painting experienced artificial damage. Morphological changes were documented using normal vector images while the intensity map succeeded in highlighting, quantifying and describing the physical changes. We estimate that the technique can detect a morphological damage slightly smaller than 0.3 mm, which would be difficult to detect with the eye, considering the painting size. This non-invasive tool could be very useful, for example, to examine paintings and artwork before they travel on loan or during a restoration. The method lends itself to automated analysis of large images and datasets. Quantitative RTI thus eases the transition of extending human vision into the realm of measuring change over time.

  16. Prevention of Ultraviolet (UV)-Induced Surface Damage and Cytotoxicity of Polyethersulfone Using Atomic Layer Deposition (ALD) Titanium Dioxide (United States)

    Petrochenko, Peter E.; Scarel, Giovanna; Hyde, G. Kevin; Parsons, Gregory N.; Skoog, Shelby A.; Zhang, Qin; Goering, Peter L.; Narayan, Roger J.


    Nanostructured surfaces are finding use in several medical applications, including tissue scaffolds and wound dressings. These surfaces are frequently manufactured from biocompatible polymers that are susceptible to ultraviolet (UV) damage. Polyethersulfone (PES) is a biocompatible polymer that undergoes oxidation and degradation when exposed to ultraviolet (UV) light. A uniform TiO2 coating can protect PES during exposure to UV sources (e.g., germicidal lamps and sunlight). The goal of this study was to determine whether atomic layer deposition (ALD) can successfully be used to grow TiO2 onto PES, protect it from UV irradiation, and reduce macrophage in vitro cytotoxicity. TiO2 was ALD-coated onto PES at 21 nm thickness. Uncoated PES exposed to UV for 30 min visibly changed color, whereas TiO2-coated PES showed no color change, indicating limited degradation. Macrophages exposed to UV-treated PES for 48 h showed reduced cell viability (via MTT assay) to 18% of control. In contrast, the cell viability for UV-treated TiO2-coated PES was 90% of control. Non-UV treated PES showed no decrease in cell viability. The results indicate that ALD of TiO2 thin films is a useful technique to protect polymers from UV damage and to retain low cytotoxicity to macrophages and other types of cells that are involved in wound healing. TiO2- coated PES membranes also have potential use in direct methanol fuel cells and in wastewater treatment membranes.

  17. A study on optimization and rehabilitation of damaged land of surface mining

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Sun Duck; Lee, Hyun Joo [Korea Institute of Geology Mining and Materials, Taejon (Korea)


    The demand of nonmetal minerals is ever increasing according to the expansion of national economy. Especially, limestone takes more than 75% of total production of nonmetal minerals, and 125 limestone mines are producing 84,740,000 tones annually 90% of which are adopting open pit mining system. However, recently, open pit mining systems are being discouraged by the stringent environmental regulations. In this research, general survey for present status and difficulties in view of operational and regulatory point of view. Considering production scale, shape of deposit, topography and quality, new mining system has been researched for minimizing environmental impacts and maximizing economical viability. Two sample mines were chosen and the model design were suggested one of which steeply inclined deposit producing 500,000 m{sup 3}/year and the other one is mildly inclines deposit producing 2,040,000 m{sup 3}/year. In case of former one, replacing stationary crusher by portable one, 14,440 cm{sup 2} of forest damage could be reduced and cost savings of 698.53 won/m{sup 3}, internal rate of return of 22.98% and pay back period of 4.3 year could be achieved respectively. On the other hand, in case of latter one, by redesign of blasting methods and hauling route, 207,192 m{sup 2} of forest damage could be reduced and cost savings of 999 won/m{sup 3}, internal rate of return of 96.2% and pay back period of 1.0 year could be achieved respectively. (author). 16 refs., 54 tabs., 35 figs.

  18. Therapeutic Effects of Sodium Hyaluronate on Ocular Surface Damage Induced by Benzalkonium Chloride Preserved Anti-glaucoma Medications

    Institute of Scientific and Technical Information of China (English)

    Xing Liu; Fen-Fen Yu; Yi-Min Zhong; Xin-Xing Guo; Zhen Mao


    Background:Long-term use of benzalkonium chloride (BAC)-preserved drugs is often associated with ocular surface toxicity.Ocular surface symptoms had a substantial impact on the glaucoma patients' quality of life and compliance.This study aimed to investigate the effects of sodium hyaluronate (SH) on ocular surface toxicity induced by BAC-preserved anti-glaucoma medications treatment.Methods:Fifty-eight patients (101 eyes),who received topical BAC-preserved anti-glaucoma medications treatment and met the severe dry eye criteria,were included in the analysis.All patients were maintained the original topical anti-glaucoma treatment.In the SH-treated group (56 eyes),unpreserved 0.3% SH eye drops were administered with 3 times daily for 90 days.In the control group (55 eyes),phosphate-buffered saline were administered with 3 times daily for 90 days.Ocular Surface Disease Index (OSDI) questionnaire,break-up time (BUT) test,corneal fluorescein staining,corneal and conjunctival rose Bengal staining,Schirmer test,and conjunctiva impression cytology were performed sequentially on days 0 and 91.Results:Compared with the control group,SH-treated group showed decrease in OSDI scores (Kruskal-Wallis test:H =38.668,P < 0.001),fluorescein and rose Bengal scores (Wilcoxon signed-ranks test:z =-3.843,P< 0.001,and z =-3.508,P < 0.001,respectively),increase in tear film BUT (t-test:t =-10.994,P < 0.001) and aqueous tear production (t-test:t =-10.328,P < 0.001) on day 91.The goblet cell density was increased (t-test:t =-9.981,P < 0.001),and the morphology of the conjunctival epithelium were also improved after SH treatment.Conclusions:SH significantly improved both symptoms and signs of ocular surface damage in patients with BAC-preserved anti-glaucoma medications treatment.SH could be proposed as a new attempt to reduce ocular surface toxicity,and alleviate symptoms of ocular surface damage in BAC-preserved anti-glaucoma medications treatment.

  19. Chatter stability prediction in four-axis milling of aero-engine casings with bull-nose end mill

    Institute of Scientific and Technical Information of China (English)

    Zhou Xu; Zhang Dinghua; Luo Ming; Wu Baohai


    An analytical model for chatter stability prediction in bull-nose end milling of aero-engine casings is presented in this paper. And the mechanics and dynamics variations due to the complex cutter and workpiece geometry are considered by analyzing the effects of the lead angle on the milling process. Firstly, the tool-workpiece engagement region is obtained by using a previously developed method and divided into several disk elements along the tool-axis direction. Secondly, a 3D dynamic model for stability limit calculation is developed and simplified into a 1D model in normal direction considering only the dominant mode of the workpiece. Then the cutting force coefficients, the start and exit angles corresponding to each disk element are determined. And the total stability lobe diagram is calculated using an iterative algorithm. Finally, several experimental tests are carried out to validate the feasibility and effectiveness of the proposed prediction approach.

  20. Chatter stability prediction in four-axis milling of aero-engine casings with bull-nose end mill

    Directory of Open Access Journals (Sweden)

    Zhou Xu


    Full Text Available An analytical model for chatter stability prediction in bull-nose end milling of aero-engine casings is presented in this paper. And the mechanics and dynamics variations due to the complex cutter and workpiece geometry are considered by analyzing the effects of the lead angle on the milling process. Firstly, the tool-workpiece engagement region is obtained by using a previously developed method and divided into several disk elements along the tool-axis direction. Secondly, a 3D dynamic model for stability limit calculation is developed and simplified into a 1D model in normal direction considering only the dominant mode of the workpiece. Then the cutting force coefficients, the start and exit angles corresponding to each disk element are determined. And the total stability lobe diagram is calculated using an iterative algorithm. Finally, several experimental tests are carried out to validate the feasibility and effectiveness of the proposed prediction approach.

  1. Analysis of surface damage produced by pulsed laser ablation on metal Al and semiconductor Si

    Institute of Scientific and Technical Information of China (English)

    ManBao-Yuan; LiuAi-Hua; 等


    The suraface morphological changesd produced by Nd:YAG pulsed laser ablation of metal Al and semiconductor Si were carefully examined and analyzed by using scanning elkectron microscope.The formation mechanism of the droplets was discussed.and the reasons for formation of the microcracks on the laser irradiated area of the target surface were analyzed by calculating the thermal stress,the vapor pressure and the shock pressure induced by the laser supported detonation.

  2. Surface modification of basalt with silane coupling agent on asphalt mixture moisture damage

    Energy Technology Data Exchange (ETDEWEB)

    Min, Yahong; Fang, Ying; Huang, Xiaojun; Zhu, Yinhui; Li, Wensheng [College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082 (China); Yuan, Jianmin [College of Materials Engineering, Hunan University, Changsha, 410082 (China); Tan, Ligang [College of Mechanical and Vehicle Engineering, Hunan University, Changsha, 410082 (China); Wang, Shuangyin [State Key Laboratory of Chem/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082 (China); Wu, Zhenjun, E-mail: [College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082 (China)


    Graphical abstract: - Highlights: • A new silane coupling agent was synthesized based on KH570. • Basalt surface was modified using the new silane coupling agent. • Chemical bond between basalt and the new silane coupling agent was formed. • Asphalt mixture which used modified basalt show superior water stability. - Abstract: A new silane coupling agent was synthesized based on γ-(methacryloyloxy) propyltrimethoxysilane (KH570). The surface of basalt rocks was modified by KH570 and the new silane coupling agent (NSCA), and the interfacial interaction between silane coupling agent and basalt was also studied. Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis showed that the silane coupling agent molecule bound strongly with basalt rocks. Scanning electronic microscopy (SEM) observation showed that a thin layer of coupling agent was formed on the surface of modified basalt. The boiling test and immersion Marshall test confirmed that the moisture sensitivity of basalt modified with the new silane coupling agent increased more significantly than that untreated and treated with KH570. The Retained Marshall Strength of basalt modified with the new coupling agent increased from 71.74% to 87.79% compared with untreated basalt. The results indicated that the new silane coupling agent played an important role in improving the interfacial performance between basalt and asphalt.

  3. Mechanics and mechanisms of surface damage in Al-Si alloys under ultra-mild wear conditions (United States)

    Chen, Ming

    Al-Si alloys intended for use in engine components must operate under ultra-mild wear (UMW) conditions to fit an acceptable amount of wear during a typical vehicle life. This study simulated surface damage in a UMW regime on five chemically etched Al-Si alloy surfaces using a pin-on-disc tribometer at low loads (0.5-2.0 N) under boundary lubricated conditions. The five alloys contained 11 to 25 wt.% Si and differed in matrix hardness, silicon particle morphology, and size. The mechanisms leading to the UMW damage and the role that the matrix hardness and microstructure play on said mechanisms were studied. Quantitative measurement methods based on statistical analysis of particle height changes and material loss from elevated aluminum using a profilometer technique were developed and used to assess UMW. The Greenwood and Tripp's numerical model was adapted to analyze the contact that occurred between Al-Si alloys with silicon particles protruding above the aluminum and steel balls. The estimation of the real contact pressure applied to the silicon particles was used to rationalize the damage mechanisms. The UMW mechanisms consisted of (i) abrasive wear on the top of the silicon particle surfaces; (ii) sinking-in of the silicon particles; (iii) piling-up of the aluminium around sunken-in particles and (vi) wear of the aluminium by the counterface, which eventually led to the initiation of UMW-II. Increasing the size or areal density of silicon particles with small aspect ratios delayed the onset of UMW-II by providing resistance against the silicon particles sinking-in and the aluminum piling-up. The UMW wear rates, however, began to decrease after long sliding cycles once an oil residue layer supported by hardened ultra-fine subsurface grains formed on the deformed aluminium matrix. The layer formation depended on the microstructure and applied load. Overall experimental observations suggested that Al-11% Si with small silicon particles exhibited optimal long

  4. Ameliorated Chrysotille—induced DNA Damage in Human Embryo Lung Cells by Surface Modification of Chrysotile With Rare Earth Compounds

    Institute of Scientific and Technical Information of China (English)



    Objective:In view of the fact that asbestos is not only a key occupational hazard,but also an important enviromental pollutant,it is necessary to develop a proper method to decrease the carcinogenectiy of asbestos fibers.This study was designed to determine if the surface modification of chrysotile asbestos fiber(CAF)with rare earth compounds(REC) can ameliorate CAF-induced DNA damages in human embryo lung(HEL)cells,Methods:After incubation with REC solution at different concentrations at room temperature for 1h,natural and REC-pretreated CAF was added to cell culture at various doses.At the selected time as the experiment designed ,DNA damages of the HEL cells were detected by Unscheduled DNA Synthesis(UDS) and Single Cell Gel Electrophoresis(SCGE) assays.Results:The UDS induced by natural CAF was elevated with the increase of CAF doses,There was a good dose-response relationship between the UDS and the amount of CAF in the mdeium and the coefficient of correlation(R) was 0.958 at P<0.05,In REC-pretreated CAF groups,the use declined with the increase of REC doses.Both catalase(CAT) and dimethylsulfoxide(DMSO)also reduced the CAF-induced enhancement of UDS.In SCGE assay,CAF induced DNA chain breakage and the magnitude of DNA chain breakage increased in a dosedependent manner and the coefficient of correlation(R))was 0.992 at P<0.01,while REC-pretreated CAF significantly decreased the induction of DNA chain breakage in a dose-dependent manner(r=0.989,P<0.05).Conclusion:It can be concluded that CAF-induced DNA damages in HEL cells may be partly mediated by oxygen derivatives,and the surface modification of CAF with REC might hide critical sites on the fiber surface ,thereby reducing the fiber-mediated production of oxygen derivation and lowering the CAF-induced UDS and DNA chani breakage in HEL cells.

  5. Ameliorated Chrysotile-induced DNA Damage in Human Embryo Lung Cells by Surface Modification of Chrysotile With Rare Earth Compounds

    Institute of Scientific and Technical Information of China (English)


    Objective In view of the fact that asbestos is not only a key occupational hazard, but also an important environmental pollutant, it is necessary to develop a proper method to decrease the carcinogenecity of asbestos fibers. This study was designed to determine if the surface modification of chrysotile asbestos fiber (CAF) with rare earth compounds (REC) can ameliorate CAF-induced DNA damages in human embryo lung (HEL) cells. Methods After incubation with REC solution at different concentrations at room temperature for 1 h, natural and REC-pretreated CAF was added to cell culture at various doses. At the selected time as the experiment designed, DNA damages of the HEL cells were detected by Unscheduled DNA Synthesis (UDS) and Single Cell Gel Electrophoresis (SCGE) assays. Results The UDS induced by natural CAF was elevated with the increase of CAF doses. There was a good dose-response relationship between the UDS and the amount of CAF in the medium and the coefficient of correlation (R) was 0.958 at P<0.05. In REC-pretreated CAF groups, the UDS declined with the increase of REC doses. Both catalase (CAT) and dimethylsulfoxide (DMSO) also reduced the CAF-induced enhancement of UDS. In SCGE assay, CAF induced DNA chain breakage and the magnitude of DNA chain breakage increased in a dose-dependent manner and the coefficient of correlation (R) was 0.992 at p<0.01, while REC-pretreated CAF significantly decreased the induction of DNA chain breakage in a dose-dependent manner(r=0.989, p<0.05). Conclusion It can be concluded that CAF-induced DNA damages in HEL cells may be partly mediated by oxygen derivatives, and the surface modification of CAF with REC might hide critical sites on the fiber surface, thereby reducing the fiber-mediated production of oxygen derivation and lowering the CAF-induced UDS and DNA chain breakage in HEL cells.

  6. Effect of rogue particles on the sub-surface damage of fused silica during grinding/polishing

    Energy Technology Data Exchange (ETDEWEB)

    Suratwala, T I; Steele, R; Feit, M D; Wong, L; Miller, P E; Menapace, J A; Davis, P J


    The distribution and characteristics of surface cracks (i.e., sub-surface damage or scratching) on fused silica formed during grinding/polishing resulting from the addition of rogue particles in the base slurry has been investigated. Fused silica samples (10 cm diameter x 1 cm thick) were: (1) ground by loose abrasive grinding (alumina particles 9-30 {micro}m) on a glass lap with the addition of larger alumina particles at various concentrations with mean sizes ranging from 15-30 {micro}m, or (2) polished (using 0.5 {micro}m cerium oxide slurry) on various laps (polyurethanes pads or pitch) with the addition of larger rogue particles (diamond (4-45 {micro}m), pitch, dust, or dried Ceria slurry agglomerates) at various concentrations. For the resulting ground samples, the crack distributions of the as-prepared surfaces were determined using a polished taper technique. The crack depth was observed to: (1) increase at small concentrations (>10{sup -4} fraction) of rogue particles; and (2) increase with rogue particle concentration to crack depths consistent with that observed when grinding with particles the size of the rogue particles alone. For the polished samples, which were subsequently etched in HF:NH{sub 4}F to expose the surface damage, the resulting scratch properties (type, number density, width, and length) were characterized. The number density of scratches increased exponentially with the size of the rogue diamond at a fixed rogue diamond concentration suggesting that larger particles are more likely to lead to scratching. The length of the scratch was found to increase with rogue particle size, increase with lap viscosity, and decrease with applied load. At high diamond concentrations, the type of scratch transitioned from brittle to ductile and the length of the scratches dramatically increased and extended to the edge of the optic. The observed trends can explained semi-quantitatively in terms of the time needed for a rogue particle to penetrate into a

  7. Separation of surface, subsurface and volume fatigue damage effects in AISI 348 steel for power plant applications

    Energy Technology Data Exchange (ETDEWEB)

    Klein, Martin; Nowak, David; Walther, Frank [Technical Univ. Dortmund (Germany). Dept. of Materials Test Engineering (WPT); Starke, Peter [Saarland Univ., Saarbruecken (Germany). Chair of Non-Destructive Testing and Quality Assurance; Boller, Christian [Saarland Univ., Saarbruecken (Germany). Chair of Non-Destructive Testing and Quality Assurance; Fraunhofer IZFP, Saarbruecken (Germany)


    A wide range of industries including energy, chemistry, pharmacy, textiles, food and drink, pulp and paper, etc. is using stainless steels. Metastable austenitic steels such as used in power plants and chemical industry are subjected to cyclic mechanical and thermal loading in air as well as under the influence of corrosive media. This paper provides an overview on different nondestructive and electrochemical measurement techniques, which allow differentiating fatigue damage effects in total strain controlled multiple and constant amplitude tests with respect to damage appearance on surface, in subsurface area as well as in volume of specimens or components microstructure. In addition to conventional mechanical stress-strain hysteresis curves, electrical resistance, magnetic and open circuit potential measurements have been applied to characterize the cyclic deformation behavior of the metastable austenitic steel AISI 348 (X10CrNiNb18-9) in laboratory air and in distilled water. Based on these results obtained, the paper provides an outlook on the possibility for an efficient (remaining) fatigue life evaluation approach, which is adapted to the needs of the application areas.

  8. Stage-specific, Nonlinear Surface Ozone Damage to Rice Production in China (United States)

    Carter, Colin A.; Cui, Xiaomeng; Ding, Aijun; Ghanem, Dalia; Jiang, Fei; Yi, Fujin; Zhong, Funing


    China is one of the most heavily polluted nations and is also the largest agricultural producer. There are relatively few studies measuring the effects of pollution on crop yields in China, and most are based on experiments or simulation methods. We use observational data to study the impact of increased air pollution (surface ozone) on rice yields in Southeast China. We examine nonlinearities in the relationship between rice yields and ozone concentrations and find that an additional day with a maximum ozone concentration greater than 120 ppb is associated with a yield loss of 1.12% ± 0.83% relative to a day with maximum ozone concentration less than 60 ppb. We find that increases in mean ozone concentrations, SUM60, and AOT40 during panicle formation are associated with statistically significant yield losses, whereas such increases before and after panicle formation are not. We conclude that heightened surface ozone levels will potentially lead to reductions in rice yields that are large enough to have implications for the global rice market.

  9. The influence of yield surface shape and damage in the depth-dependent response of bone tissue to nanoindentation using spherical and Berkovich indenters. (United States)

    Schwiedrzik, Johann Jakob; Zysset, Philippe Kurt


    Prevention and treatment of osteoporosis rely on understanding of the micromechanical behaviour of bone and its influence on fracture toughness and cell-mediated adaptation processes. Postyield properties may be assessed by nonlinear finite element simulations of nanoindentation using elastoplastic and damage models. This computational study aims at determining the influence of yield surface shape and damage on the depth-dependent response of bone to nanoindentation using spherical and conical tips. Yield surface shape and damage were shown to have a major impact on the indentation curves. Their influence on indentation modulus, hardness, their ratio as well as the elastic-to-total work ratio is well described by multilinear regressions for both tip shapes. For conical tips, indentation depth was not statistically significant (p damage was not a significant parameter (p < 0.0001). The gained knowledge can be used for developing an inverse method for identification of postelastic properties of bone from nanoindentation.

  10. Ultrastructural analysis of β-lapachone-induced surface membrane damage in male adult Schistosoma mansoni BH strain worms. (United States)

    Aires, André de Lima; Ximenes, Eulália Camelo Pessoa Azevedo; Silva, Renata Alexandre Ramos; Barbosa, Vanessa Xavier; Góes, Alexandre José da Silva; Peixoto, Christina Alves; Souza, Valdênia Maria Oliveira; Albuquerque, Mônica Camelo Pessôa de Azevedo


    The present study provides, for the first time, conclusions on the in vitro schistosomicidal properties of β-lap. Adult male Schistosoma mansoni worms of the BH strain were used for the study. Motility, mortality, cell viability and alterations in the tegument were employed as schistosomicidal parameters. Alterations in motility were observed 6h after incubation in concentrations of 50 and 100 μM. β-lap decreased significantly the worm viability, reducing the formation of formazan in 17.7%, 27.4% and 54.8% at concentrations of 25, 50 and 100 μM, respectively. Mortality in concentrations of 50 and 100 μM was of 67% and 100%, respectively, after 24h. The death of the parasite was preceded by progressive surface membrane damage, characterized by tegument peeling, spine reduction and erosion, blister formation and rupture, and the emergence of holes. In addition to this, in the anterior portion, intense general edema, areas of cracking with a wrinkled surface, furrows and a fibrous appearance were also observed. The results of the present study thus provide a sound basis for further in-depth studies of the schistosomicidal properties of β-lap, both in the laboratory and in the field.

  11. Surface Characterizations of Fretting Fatigue Damage in Aluminum Alloy 7075-T6 Clamped Joints: The Beneficial Role of Ni–P Coatings

    Directory of Open Access Journals (Sweden)

    Reza H. Oskouei


    Full Text Available This paper aims to characterize the surface damage as a consequence of fretting fatigue in aluminum alloy 7075-T6 plates in double-lap bolted joints through XRD, surface profilometry, and SEM analyses. The main focus was on the surface roughness and chemical phase composition of the damaged zone along with the identification of fretting fatigue crack initiations over the surface of the material. The surface roughness of the fretted zone was found to increase when the joint was clamped with a higher tightening torque and tested under the same cyclic loading. Additionally, MgZn2 (η/ή precipitates and ZnO phase were found to form onto the surface of uncoated aluminum plate in the fretted and worn zones. The formation of the ZnO phase was understood to be a result of frictional heat induced between the surface of contacting uncoated Al 7075-T6 plates during cyclic loading and exposure to the air. The beneficial role of electroless nickel-phosphorous (Ni–P coatings in minimizing the fretting damage and thus improving the fretting fatigue life of the aluminum plates was also studied. The results showed that the surface roughness decreased by approximately 40% after applying Ni–P coatings to the Al 7075-T6 plates.

  12. A combined surface and bulk TCAD damage model for the analysis of radiation detectors operating at HL-LHC fluences (United States)

    Morozzi, A.; Passeri, D.; Moscatelli, F.; Dalla Betta, G.-F.; Bilei, G. M.


    In this work we present the development and the application of a new TCAD modelling scheme to simulate the effects of radiation damage on silicon radiation detectors at the very high fluence levels expected at High Luminosity LHC (up to 2 × 1016 1MeV n/cm2). In particular, we propose a combined approach for the analysis of the surface effects (oxide charge build-up and interface trap states introduction) as well as bulk effects (deep level traps and/or recombination centers introduction). Experimental measurements have been carried out aiming at: i) extraction from simple test structures of relevant parameters to be included within the TCAD model and ii) validation of the new modelling scheme through comparison with measurements of different test structures (e.g. different technologies) before and after irradiation. The good agreements between experimental measurements and simulation findings foster the suitability of the TCAD modelling approach as a predictive tool for investigating the radiation detector behavior at different fluences and operating conditions. This would allow the design and optimization of innovative 3D and planar silicon detectors for future HL-LHC High Energy Physics experiments.

  13. Monitoring the intensity of locust damage to vegetation using hyper-spectra data obtained at ground surface (United States)

    Ni, Shaoxiang; Wu, Tong


    Since 1980s of the last century, outbreak of Oriental Migratory Locust (Locusta migratoria manilensis Meyen) has rampantly emerged again in some regions of China. It is extremely important to monitor efficiently the locust damage to vegetation in order to control this kind of insect pest. In this paper, taking Huanghua County of Hebei province, China as the study area and based on the in situ hyper-spectral data, the differences in canopy reflectance spectra and the characteristic parameters of hyper-spectra were analyzed and compared for the reeds at normal growing and for those under encroaching from locusts. In addition, five models were developed to simulate the relations between the characteristic parameters of hyper-spectra and Leaf Area Index (LAI) of reeds. The result showed that among those indices the locust damage spectra index (LDSI) is mostly applicable to reflect the intensity of locust damage in the study area. Finally, a scheme for the intensity distinction of locust damage to reeds was suggested based on LDSI data, i.e., no damage if LDSI is over 62.856, slightly damage if LDSI is between 41.254 and 59.496, and seriously damage if LDSI is less than 41.254.

  14. Electron microscopic analysis of surface damaged layer in Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystal (United States)

    Kasuya, Yusuke; Sato, Yukio; Urakami, Ryosuke; Yamada, Kazuhiro; Teranishi, Ryo; Kaneko, Kenji


    Single crystals of lead magnesium niobate-lead titanate, Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT), have superior dielectric and piezoelectric properties suitable for medical ultrasound imaging. Imaging devices with superior performance can be manufactured from thinner PMN-PT single crystals by mechanical dicing and/or polishing. Although it is often a concern that a damaged layer may form during the mechanical dicing and/or thinning process, the microscopic characteristics of the damaged layer have not yet been investigated in detail. In this study, the microstructural characterization of a damaged layer was investigated by transmission electron microscopy. It was found that mechanical polishing introduced dislocation near the surface of the crystal. It was also found that the domain structure was affected by the introduction of dislocation.

  15. Influence of free surfaces on microstructure evolution of radiation damage in Fe from molecular dynamics and object kinetic Monte Carlo calculations

    Energy Technology Data Exchange (ETDEWEB)

    Aliaga, Maria J.; Caturla, Maria J. [Facultad de Ciencias, Department Fisica Aplicada, Fase II, Universidad de Alicante, 03690, Alicante (Spain); Dopico, Ignacio; Martin-Bragado, Ignacio [IMDEA Materials Institute, C/Eric Kandel 2, 28906, Getafe, Madrid (Spain)


    The influence of surfaces on the evolution of damage of irradiated Fe is studied using object kinetic Monte Carlo with input from molecular dynamics simulations and ab initio calculations. Two effects are analysed: the influence of traps and the initial distribution of damage in the cascade. These simulations show that for a trap concentration of around 100 appm, there are no significant differences between defect concentrations in bulk and thin films. However, the initial distribution of defects plays an important role not only on total defect concentration but also on defect type, for the model used in this study. Damage produced by a 100 keV Fe ion impinging a Fe thin film. Blue (dark) spheres are self-interstitials, red (light) spheres are vacancies. (copyright 2016 The Authors/Employers. Phys. Status Solidi A published by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. The effect of pulse duration on the growth rate of laser-induced damage sites at 351 nm on fused silica surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Negres, R A; Norton, M A; Liao, Z M; Cross, D A; Bude, J D; Carr, C W


    Past work in the area of laser-induced damage growth has shown growth rates to be primarily dependent on the laser fluence and wavelength. More recent studies suggest that growth rate, similar to the damage initiation process, is affected by a number of additional parameters including pulse duration, pulse shape, site size, and internal structure. In this study, we focus on the effect of pulse duration on the growth rate of laser damage sites located on the exit surface of fused silica optics. Our results demonstrate, for the first time, a significant dependence of growth rate at 351 nm on pulse duration from 1 ns to 15 ns as {tau}{sup 0.3} for sites in the 50-100 {micro}m size range.

  17. Influence of Na2SiO3 addition on surface microstructure and cavitation damage characteristics for plasma electrolytic oxidation of Al-Mg alloy (United States)

    Lee, Jung-Hyung; Son, Chang-Ryeon; Kim, Seong-Jong


    Recently, plasma electrolytic oxidation (PEO) has emerged as a promising surface modification technique to improve surface properties of Al alloys. In this study, PEO coating process for Al-Mg alloy was conducted with two different electrolyte solutions under the same electrical parameters: one was potassium hydroxide (KOH) aqueous solution, and the other involved potassium hydroxide aqueous solution with sodium silicate (Na2SiO3). The surface morphology was observed with scanning electron microscope (SEM) and elemental compositions were identified with energy dispersive spectroscopy (EDS) analysis. The chemical structures of PEO coatings were identified by X-ray diffraction analysis. Cavitation experiment was performed using ultrasonic vibratory cavitation erosion testing apparatus. Cavitation damage of PEO coatings was characterized using SEM and three-dimensional (3D) microscope. The result indicated that the surface of Al-Mg alloy were successfully modified having complete different surface morphologies by changing electrolyte composition. It was found that the surface morphology had a great influence on the cavitation damage behavior of PEO coating.

  18. Laser-induced surface ablation and optical damage of ZnS crystals caused by single- and multiple-pulse laser-irradiation (United States)

    Arlinghaus, H. F.; Calaway, W. F.; Gruen, D. M.; Chase, L. L.

    Velocity distributions and yields of neutral Zn atoms emitted from laser-irradiated ZnS crystals at power densities far below the single-pulse damage threshold have been analyzed by high-resolution two-photon laser-induced fluorescence spectroscopy and also by electron impact ionization mass spectrometry. Large differences in the measured kinetic temperatures have been found between the single- and multiple-pulse laser irradiation experiments. The high-kinetic temperatures, obtained in multiple-pulse experiments, may be caused by cumulative surface modification, such as thermally-induced cracking, leading to a reduction of the thermal conductivity compared to the bulk value. Optical damage was related to the interaction of a plasma formed at a critical combination of particle density and laser intensity, with the surface.

  19. In situ Barely Visible Impact Damage detection and localization for composite structures using surface mounted and embedded PZT transducers: A comparative study (United States)

    Dziendzikowski, M.; Kurnyta, A.; Dragan, K.; Klysz, S.; Leski, A.


    Application of guided waves excited by a network of PZT transducers integrated with a given structure is one of the promising approaches to Structural Health Monitoring (SHM). The performance of a SHM system based on PZT network is rooted in two distinct areas of the technology development, that is the hardware and the signal analysis. The first includes the type of transducers used to built a network and the way of their integration with a monitored structure. For composites, besides the possibility of the transducers attachment to a surface of an element, also embedding of PZTs into their internal structure is available. In the article Barely Visible Impact Damage (BVID) detection capabilities as well as selected physical properties of the embedded and surface mounted PZT transducers are compared in broad frequency range of the excitation. Among the compared parameters are the impedance and capacitance spectra up to 600 kHz. The damage detection capabilities are compared in the range 100-350 kHz. In addition to purely qualitative detection of damages a new algorithm of their localization is proposed and compared between the embedded and surface attached transducers for the frequency optimal to detect BVIDs.

  20. Responses of the surface membrane and excretory system of Schistosoma mansoni to damage and to treatment with praziquantel and other biomolecules. (United States)

    Oliveira, F A; Kusel, J R; Ribeiro, F; Coelho, P M Z


    Damage to the surface membrane of adult Schistosoma mansoni, and the activity of the excretory system, as shown by resorufin fluorescence, was observed following treatment with praziquantel and incubation with other molecules. Praziquantel treatment induced damage to the surface membrane as measured by the use of a variety of fluorescent compounds. The excretory system of the male worm was inhibited immediately after praziquantel treatment, but fully recovered after culture for 2 h following removal of praziquantel. The excretory system of the female, observed to be minimally active in untreated worm pairs, was often greatly activated in paired females, as shown by intense resorufin labelling, after praziquantel treatment, and this continued during recovery of the male excretory system. In experiments with normal worm pairs, the female could be activated by inhibiting the metabolic rate of the pair by a cooling procedure. The effects on the excretory system of changes in culture conditions (such as changes in pH, concentrations of bacterial lipopolysaccharide, cytokines, reactive oxygen species, compounds which remove cholesterol, such as beta-methyl cyclodextrin, and damaging basic poly-L-lysine) were also assessed. It is concluded that the extensive excretory system of the adult worm is responsive to drug treatment and to certain changes in environmental conditions. Its activity seems to be strongly linked to the integrity of the surface membrane.

  1. Aeroengine adaptive control based on adaline network%基于Adaline网的航空发动机自适应控制

    Institute of Scientific and Technical Information of China (English)

    丁凯锋; 樊思齐


    Associated with the characteristic of nonlinear,recessive anduncertain of model,a kind of aeroengine adaptive control scheme based on adaline network was presented.Two-layered linear adaline network were used both in the neural estimator and nueral controller.The weight was updated using Widrow- Hoff delta rule. Simulation results show that the scheme has the advantage of br iefness ,stability and better real-time ability.It can be used on the on-line control of aeroengine throughout the full flight envelope.%根据发动机模型非线性、关系式呈隐性和具有不确定性的工作特点,提出了一种基于Adaline网的发动机自适应控制方案,该方案中的神经网络辨识器和神经网络控制器均采用两层线性Adaline网,权值采用Widrow-Hoffδ学习规则更新。仿真结果表明这种方法具有方案简单、稳定性好、实时性好等优点,可在全飞行包线内对发动机进行在线控制。

  2. Defending the leaf surface: intra- and inter-specific differences in silicon deposition in grasses in response to damage and silicon supply

    Directory of Open Access Journals (Sweden)

    Sue Elaine Hartley


    Full Text Available Understanding interactions between grasses and their herbivores is central to the conservation of species-rich grasslands and the protection of our most important crops against pests. Grasses employ a range of defenses against their natural enemies; silicon-based defenses have been shown to be one of the most effective. Silicon (Si is laid down on the leaf surface as spines and other sharp bodies, known as phytoliths, making grasses abrasive and their foliage indigestible to herbivores. Previous studies on Si defenses found that closely related species may have similar levels of Si in the leaves but differ markedly in abrasiveness. Here we show how the number, shape and distribution of Si-rich phytoliths and spines differ within and between different grass species and demonstrate that species also differ in their ability to change the deposition and distribution of these defenses in response to damage or increases in Si supply. Specifically, we tested the response of two genotypes of Festuca arundinacea known to differ in their surface texture and 3 different grass species (F. ovina, F. rubra and Deschampsia cespitosa differing in their abrasiveness to combined manipulation of leaf damage and Si supply. F.arundinacea plants with a harsh leaf surface had higher Si content and more spines on their leaf surface than soft varieties. F. ovina and D. cespitosa plants increased their leaf Si concentration and produced an increase in the number of leaf spines and phytoliths on the leaf surface in response to Si addition. F rubra also increased leaf Si content in response to treatments, particularly in damaged leaves, but did not deposit this in the form of spines or increased densities of phytoliths. We discuss how the form in which grasses deposit Si may affect their anti-herbivore characteristics and consider the ecological and agricultural implications of the differences in allocation to Si-based defenses between grass species.

  3. Defending the leaf surface: intra- and inter-specific differences in silicon deposition in grasses in response to damage and silicon supply. (United States)

    Hartley, Sue E; Fitt, Rob N; McLarnon, Emma L; Wade, Ruth N


    Understanding interactions between grasses and their herbivores is central to the conservation of species-rich grasslands and the protection of our most important crops against pests. Grasses employ a range of defenses against their natural enemies; silicon-based defenses have been shown to be one of the most effective. Silicon (Si) is laid down on the leaf surface as spines and other sharp bodies, known as phytoliths, making grasses abrasive and their foliage indigestible to herbivores. Previous studies on Si defenses found that closely related species may have similar levels of Si in the leaves but differ markedly in abrasiveness. Here we show how the number, shape and distribution of Si-rich phytoliths and spines differ within and between different grass species and demonstrate that species also differ in their ability to change the deposition and distribution of these defenses in response to damage or increases in Si supply. Specifically, we tested the response of two genotypes of Festuca arundinacea known to differ in their surface texture and three different grass species (F. ovina, F. rubra, and Deschampsia cespitosa) differing in their abrasiveness to combined manipulation of leaf damage and Si supply. F. arundinacea plants with a harsh leaf surface had higher Si content and more spines on their leaf surface than soft varieties. F. ovina and D. cespitosa plants increased their leaf Si concentration and produced an increase in the number of leaf spines and phytoliths on the leaf surface in response to Si addition. F rubra also increased leaf Si content in response to treatments, particularly in damaged leaves, but did not deposit this in the form of spines or increased densities of phytoliths. We discuss how the form in which grasses deposit Si may affect their anti-herbivore characteristics and consider the ecological and agricultural implications of the differences in allocation to Si-based defenses between grass species.

  4. Study on characteristic parameters influencing laser-induced damage threshold of KH(2)PO(4) crystal surface machined by single point diamond turning. (United States)

    Chen, Mingjun; Li, Mingquan; Cheng, Jian; Jiang, Wei; Wang, Jian; Xu, Qiao


    It has fundamental meaning to find the elements influencing the laser-induced damage threshold (LIDT) of KH(2)PO(4) (KDP) crystal and to provide suitable characterization parameters for these factors in order to improve the LIDT of KDP. Using single-point diamond turning (SPDT) to process the KDP crystal, the machined surface quality has important effects on its LIDT. However, there are still not suitable characteristic parameters of surface quality of KDP to correspond with the LIDT nowadays. In this paper, guided by the Fourier model theory, we study deeply the relationship between the relevant characteristic parameters of surface topography of KDP crystal and the experimental LIDT. Research results indicate that the waviness rather than the roughness is the leading topography element on the KDP surface machined by the SPDT method when the LIDT is considered and the amplitude of micro-waviness has greater influence on the light intensity inside the KDP crystal within the scope of dangerous frequencies between (180 μm)(-1) and (90 μm)(-1); with suitable testing equipment, the characteristic parameters of waviness amplitude, such as the arithmetical mean deviation of three-dimensional profile S(a) or root mean square deviation of three-dimensional contour S(q), are able to be considered as suitable parameters to reflect the optical quality of the machined surface in order to judge approximately the LIDT of the KDP surface and guide the machining course.

  5. Study on CAD Method for Aeroengine Pipeline System%管路系统计算机辅助设计方法研究

    Institute of Scientific and Technical Information of China (English)

    陈志英; 唐文哲


    This paper summarizes nine principles of CAD aeroengine pipe routing and considers three approaches of CAD pipe routing.According to the complexity of aeroengine pipeline system and the features of computer-aided routing,WRS(Wide in diameter,Region,Stride) approach is provided,that is first to route tubes Wide in diameter,then in dividing Region,last tubes of Striding regions.The approach conforms to rules of routing from wide in diameter to narrow,from short in length to long,from difficult in layout to easy.It bases on the principle that optimization in local region can reach to overall optimization of pipeline system.Considering the feature of 3D view for computer-aided pipe routing,the WRS method avoids exchanging between the overall view and local view in the electronic engine mockup ,especially routing in dividing region.A pipeline system layout was successfully made on an electronic mockup by using the WRS approach.It is proven that the WRS method can gain success for only once,and shorten the period of design.The presented method is useful to aeroengine pipeline system design.%为进行计算机辅助管路系统敷设,本文归纳出9条管路CAD规则,探讨了3种管路敷设方法。为满足管路设计规则,根据管路系统的复杂性和计算机辅助敷设的特点,本文提出了先敷设粗管再分区敷设最后解决跨区域管路的WRS法。它按照先重后轻、先短后长、先难后易的敷管原则,体现了局部最优从而达到全局最佳的原理。文中着重介绍了该方法的思路,并结合在电子模型样机上的敷管实例及过程,分析了该方法的特点,为计算机辅助航空发动机管路系统敷设提供了一种可行的工程应用方法。

  6. DNA damage and oxidative stress in human liver cell L-02 caused by surface water extracts during drinking water treatment in a waterworks in China. (United States)

    Xie, Shao-Hua; Liu, Ai-Lin; Chen, Yan-Yan; Zhang, Li; Zhang, Hui-Juan; Jin, Bang-Xiong; Lu, Wen-Hong; Li, Xiao-Yan; Lu, Wen-Qing


    Because of the daily and life-long exposure to disinfection by-products formed during drinking water treatment, potential adverse human health risk of drinking water disinfection is of great concern. Toxicological studies have shown that drinking water treatment increases the genotoxicity of surface water. Drinking water treatment is comprised of different potabilization steps, which greatly influence the levels of genotoxic products in the surface water and thus may alter the toxicity and genotoxicity of surface water. The aim of the present study was to understand the influence of specific steps on toxicity and genotoxicity during the treatment of surface water in a water treatment plant using liquid chlorine as the disinfectant in China. An integrated approach of the comet and oxidative stress assays was used in the study, and the results showed that both the prechlorination and postchlorination steps increased DNA damage and oxidative stress caused by water extracts in human derived L-02 cells while the tube settling and filtration steps had the opposite effect. This research also highlighted the usefulness of an integrated approach of the comet and oxidative stress assays in evaluating the genotoxicity of surface water during drinking water treatment.

  7. Radiation damage and associated phase change effect on photodesorption rates from ices—Lyα studies of the surface behavior of CO{sub 2}(ice)

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Chunqing; Yates, John T. Jr., E-mail: [Department of Chemistry, University of Virginia, Charlottesville, VA 22904 (United States)


    Photodesorption from a crystalline film of CO{sub 2}(ice) at 75 K has been studied using Lyα (10.2 eV) radiation. We combine quantitative mass spectrometric studies of gases evolved and transmission IR studies of species trapped in the ice. Direct CO desorption is observed from the primary CO{sub 2} photodissociation process, which occurs promptly for CO{sub 2} molecules located on the outermost surface of the ice (Process I). As the fluence of Lyα radiation increases to ∼5.5 × 10{sup 17} photons cm{sup –2}, extensive damage to the crystalline ice occurs and photo-produced CO molecules from deeper regions (Process II) are found to desorb at a rapidly increasing rate, which becomes two orders of magnitude greater than Process I. It is postulated that deep radiation damage to produce an extensive amorphous phase of CO{sub 2} occurs in the 50 nm ice film and that CO (and CO{sub 2}) diffusive transport is strongly enhanced in the amorphous phase. Photodesorption in Process II is a combination of electronic and thermally activated processes. Radiation damage in crystalline CO{sub 2} ice has been monitored by its effects on the vibrational line shapes of CO{sub 2}(ice). Here the crystalline-to-amorphous phase transition has been correlated with the occurrence of efficient molecular transport over long distances through the amorphous phase of CO{sub 2}(ice). Future studies of the composition of the interstellar region, generated by photodesorption from ice layers on grains, will have to consider the significant effects of radiation damage on photodesorption rates.

  8. Enhanced Etching, Surface Damage Recovery, and Submicron Patterning of Hybrid Perovskites using a Chemically Gas-Assisted Focused-Ion Beam for Subwavelength Grating Photonic Applications. (United States)

    Alias, Mohd S; Yang, Yang; Ng, Tien K; Dursun, Ibrahim; Shi, Dong; Saidaminov, Makhsud I; Priante, Davide; Bakr, Osman M; Ooi, Boon S


    The high optical gain and absorption of organic-inorganic hybrid perovskites have attracted attention for photonic device applications. However, owing to the sensitivity of organic moieties to solvents and temperature, device processing is challenging, particularly for patterning. Here, we report the direct patterning of perovskites using chemically gas-assisted focused-ion beam (GAFIB) etching with XeF2 and I2 precursors. We demonstrate etching enhancement in addition to controllability and marginal surface damage compared to focused-ion beam (FIB) etching without precursors. Utilizing the GAFIB etching, we fabricated a uniform and periodic submicron perovskite subwavelength grating (SWG) absorber with broadband absorption and nanoscale precision. Our results demonstrate the use of FIB as a submicron patterning tool and a means of providing surface treatment (after FIB patterning to minimize optical loss) for perovskite photonic nanostructures. The SWG absorber can be patterned on perovskite solar cells to enhance the device efficiency through increasing light trapping and absorption.

  9. Enhanced Etching, Surface Damage Recovery, and Submicron Patterning of Hybrid Perovskites using a Chemically Gas-Assisted Focused-Ion Beam for Subwavelength Grating Photonic Applications

    KAUST Repository

    Alias, Mohd Sharizal


    The high optical gain and absorption of organic–inorganic hybrid perovskites have attracted attention for photonic device applications. However, owing to the sensitivity of organic moieties to solvents and temperature, device processing is challenging, particularly for patterning. Here, we report the direct patterning of perovskites using chemically gas-assisted focused-ion beam (GAFIB) etching with XeF2 and I2 precursors. We demonstrate etching enhancement in addition to controllability and marginal surface damage compared to focused-ion beam (FIB) etching without precursors. Utilizing the GAFIB etching, we fabricated a uniform and periodic submicron perovskite subwavelength grating (SWG) absorber with broadband absorption and nanoscale precision. Our results demonstrate the use of FIB as a submicron patterning tool and a means of providing surface treatment (after FIB patterning to minimize optical loss) for perovskite photonic nanostructures. The SWG absorber can be patterned on perovskite solar cells to enhance the device efficiency through increasing light trapping and absorption.

  10. Applications of Ion Implantation in Aeroengine Parts%离子注入技术在航空零件上的应用

    Institute of Scientific and Technical Information of China (English)



    This paper introduces the characteristics of ion implantation, explains the industrial application examples of ion implantation technology in aerocomponents, biomaterials, dies and cutters. The emphasis is put on the applied achievements of this technology in aeroengine bearings and fuel pumps at Chengdu Engine Company.%介绍了离子注入技术的特点及其在航空零件、生物材料、模具和刀具等产品上的应用实例,着重叙述了成都发动机公司在航空发动机轴承和燃油泵上应用离子注入技术的成果。

  11. Metallurgical investigation of defects in super alloy 718 mill forms intended for aeroengine applications; Metallurgische Schadensanalyse an Halbzeugen aus der Superlegierung 718 fuer Triebwerksapplikationen

    Energy Technology Data Exchange (ETDEWEB)

    Gopala Krishna, V.; Srinivas, M. [Defence Metallurgical Research Lab., Hyderabad (India); Janakiram, G.D. [Utah State Univ., Logan, UT (United States); Murty, C.H.V.S.; Venugopal Reddy. A. [Regional Center for Military Airworthiness (Materials), Hyderabad (India)


    Super alloy 718 finds extensive utilization, particularly in aero engine industry, due to its excellent strength, low cycle fatigue and creep resistance. The alloy was manufactured using vacuum induction melting followed by vacuum arc remelting techniques. The electrodes, after thermo-mechanical processing to hot rolled square bar and flat forms, were ultrasonically inspected prior to machining of aeroengine compressor blades. During machining, crack-like defects were noticed. Visual / Stereo microscopic examination revealed that the defect was along the length of airfoil and was located at mid airfoil width. The defects were filled with dark gray colored debris. Fractographic examination of the crack facets revealed flaky gray region containing number of cracks and bright region with dimpled rupture features covered with debris. Analysis of the debris indicated the presence of oxygen in addition to the elements present in the material, suggesting that the debris is essentially an oxide. These features were correlated with processing histories and defect morphologies. (orig.)

  12. Spray dispersion in a generic premix module for aeroengine combustors; Spray-Dispersion in einem generischen Vormischmodul fuer Flugtriebwerks-Brennkammern

    Energy Technology Data Exchange (ETDEWEB)

    Becker, J.


    The liquid fuel placement and fuel spray dispersion in an annular, swirling flow is investigated experimentally. The liquid fuel is injected into the annular airflow in the radial direction by means of plain jet nozzles in the center body. Optical measurement techniques are applied at near-realistic aeroengine operating conditions, particularly at elevated values of air pressure. An investigation of the liquid plain jet in crossflow concerning penetration, break-up and atomization using visualization techniques and phase-Doppler anemometry is followed by the actual investigation of spray dispersion. This includes detailed measurements of the airflow by laser-Doppler anemometry, yielding turbulence data such as velocity fluctuations and length scales. The Stokes number is employed to analyze and interpret the data and transfer the results to a full power operating condition that cannot be investigated experimentally. (orig.)

  13. Sputtering and surface damage of TFTR protective plate materials (Mo, TZM, graphite) by energetic D/sup +/ ion irradiation. Final report for Princeton Plasma Physics Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Kaminsky, M.; Das, S.K.; Dusza, P.


    Studies have been conducted in accordance with a service request from the Plasma Physics Laboratory (PPPL) of Princeton University to determine the total sputtering yields and the surface damage of molybdenum (a candidate material for the neutral beam injector protective plate for Princeton's Fusion Test Reactor (TFTR)) caused by the impact of D/sup +/ ions at 120-keV, 60-keV and 40-keV at fluxes and total doses agreed upon between PPPL and ANL. The irradiations have been conducted in a specified pulsed mode as well as in a dc mode. The material TZM (a molybdenum alloy) was included in some tests of surface damage, but not for the full complement of doses planned for molybdenum. According to a request by PPPL the target temperature was not to be controlled (targets were allowed to reach a temperature determined by the beam power deposition and the conductive and radiative heat losses), but the target temperature was to be monitored. The irradiations were conducted at pressures ranging from 4 x 10/sup -9/ torr to 2 x 10/sup -8/ torr.

  14. Surface morphology changes and damage in hot tungsten by impact of 80 eV - 12 keV He-ions and keV-energy self-atoms (United States)

    Hijazi, Hussein; Bannister, Mark E.; Krstic, Predrag S.; Parish, Chad M.; Meyer, Harry M., III; Meyer, Fred M.


    We report on measurements of interactions of 50 - 12,000 eV He ions with heated tungsten surfaces performed at the ORNL MIRF. Surface morphology changes, as well as nano-fuzz formation were investigated as function of flux and total fluence, for both virgin and pre-damaged W-targets. At low fluences, ordered surface structures are observed, with great grain-to-grain variability, together with blisters and pinholes, whose density and size increase with increasing fluence. At larger fluences, individual grain characteristics disappear, and the entire surface assumes a frothy appearance in FIB/SEM, with a multitude of near-surface bubbles with a broad range of sizes, and disordered whisker growth, while in SEM imaging the surface is indistinguishable from nano-fuzz produced on linear plasma devices. These features are evident at progressively lower fluences as the He-ion energy is increased, particularly above 1 keV, where the He beam serves not only to load the near-surface region with He to saturation, but to produce significant near-surface damage sites that can trap He. We also report on observations of the effects on surface morphology changes and nano-fuzz formation of pre-damage created by self-ion impact, and on MD simulations of near-surface damage using self-atoms. Research sponsored by the LDRD Program of ORNL, managed by UT-Battelle, LLC, for the US DOE.

  15. 基于UG的航空发动机管路系统流阻分析%Flow Resistance Analysis on Aeroengine Pipe System Based on UG

    Institute of Scientific and Technical Information of China (English)

    邱明星; 付鹏哲; 钟易成; 赵士洋


    Pipe modeling and flow analysis of aeroengine pipe system were performed respectively in software of CAD and CAE.A great deal of time and resources were wasted in repeated data transmission and modeling between two kinds of softwares.The UG routing models and topology information were analyzed based on the UG/Open API.The inserted modules of fluid system resistance analysis in workbench of UG NX3.0 were developed by the flow simulation software FOCUSS-FS.The real-time on-line flow analysis of aeroengine pipe modeling was achieved,which increase the efficiency of pipe design.%航空发动机外部管路系统的管路建模和流动分析分别在CAD和CAE软件中进行,在管路设计及改进时往往需在2种软件之间进行重复建模和数据传递,耗费大量时间与资源。为此,基于UG/Open API技术,通过对UG管路模型几何与拓扑信息进行研究,利用流体仿真软件FOCUSS-FS开发了UG NX3.0工作平台下的内嵌式管路流阻分析模块,实现了发动机管路建模时的实时在线流动分析,极大地提高了外部管路设计效率。

  16. Study on the role of laser surface irradiation on damage and decohesion of Al/epoxy joints

    KAUST Repository

    Alfano, Marco


    In this work we investigate the effect of laser irradiation on the bond toughness of aluminum/epoxy bonded joints. The evolution of substrate surface morphology and wettability, for various sets of laser process parameters (i.e. laser power, line spacing, scan speed), was investigated by means of Scanning Electron Microscopy (SEM) and contact angle measurements. A proper combination of power, line spacing and scan speed was then selected and adhesive bonded Al/epoxy T-peel joints were prepared and tested. For comparison, similar samples were produced using substrates with classical grit blasting surface treatment. Finally, post-failure SEM analyses of fracture surfaces were performed, and in order to typify the increase in bond toughness of the joints, finite element simulations were carried out using a potential based cohesive zone model of fracture. © 2012 Elsevier Ltd.

  17. Surface Ruptures and Building Damage of the 2003 Bam, Iran, Earthquake Mapped by Satellite Synthetic Aperture Radar Interferometric Correlation (United States)

    Fielding, Eric J.; Talebian, M.; Rosen, P. A.; Nazari, H.; Jackson, J. A.; Ghorashi, M.; Walker, R.


    We use the interferometric correlation from Envisat synthetic aperture radar (SAR) images to map the details of the surface ruptures related to the 26 December 2003 earthquake that devastated Bam, Iran. The main strike-slip fault rupture south of the city of Bam has a series of four segments with left steps shown by a narrow line of low correlation in the coseismic interferogram. This also has a clear expression in the field because of the net extension across the fault. Just south of the city limits, the surface strain becomes distributed over a width of about 500 m, probably because of a thicker layer of soft sedimentary material.

  18. Laser induced periodic surface structure formation in germanium above laser damage fluence by mid IR femtosecond laser irradiation (United States)

    Kafka, Kyle; Austin, Drake; Cheng, Jian; Trendafilov, Simeon; Shvets, Gennady; Li, Hui; Yi, Allen; Blaga, Cosmin I.; DiMauro, L. F.; Chowdhury, Enam


    Laser induced periodic surface structures (LIPSS) were generated via interaction of multiple 90 femtosecond 1900 - 3600 nm mid IR laser pulses (3 -10,000) on single crystal Ge targets. For specific laser parameters, both low and high frequency LIPSS are found together, which are oriented perpendicular to each other. Study of polarization dependence of LIPSS revealed that orientation and symmetry of interaction could be controlled by rotating polarization of laser pulses. Low frequency LIPSS formation was consistent with surface plasmon coupling of laser pulses with excited Ge.

  19. A bioluminescence ATP assay for estimating surface hydrophobicity and membrane damage of Escherichia coli cells treated with pulsed electric fields (United States)

    Pulse Electric Field (PEF) treatments, a non-thermal process have been reported to injure and inactivate bacteria in liquid foods. However, the effect of this treatment on bacterial cell surface charge and hydrophobicity has not been investigated. Apple juice (AJ, pH 3.8) purchased from a wholesale ...

  20. Correlation between surface damage and micro-defects in Si covered with insulating layer by implantation of He and H ions

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.L., E-mail: [School of Science, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Low Dimension Materials Physics and Preparing Technology, Institute of Advanced Materials Physics Faculty of Science, Tianjin 300072 (China); Li, M.K.; Wang, Z.; Gao, Y.J.; Liao, J.Q.; Zhang, D.C.; Zhang, X.L.; Shen, Y.Y. [School of Science, Tianjin University, Tianjin 300072 (China)


    Cz n-type Si (100) wafers covered with a 220 nm SiO{sub 2} layer or a 170 nm Si{sub 3}N{sub 4} layer were singly implanted with 160 keV He ions at a dose of 5 x 10{sup 16}/cm{sup 2} or successively implanted with 160 keV He ions at a dose of 5 x 10{sup 16}/cm{sup 2} and 110 keV H ions at a dose of 1 x 10{sup 16}/cm{sup 2}. Surface morphologies together with defect microstructures have been studied by means of several techniques, including optical microscopy, atomic force microscopy, and cross-sectional transmission electron microscopy (XTEM). Only surface blistering has been observed for He and H sequentially implanted SiO{sub 2}/Si samples after annealing in temperature range up to 1000 {sup o}C. However, as for the He and H implanted Si{sub 3}N{sub 4}/Si samples, surface features including blistering and the localized exfoliation of both the top Si{sub 3}N{sub 4} layer and the implanted Si layer have been well demonstrated during subsequent annealing. XTEM observations reveal quite different defect morphologies in two kinds of materials under the same implantation and annealing conditions. The possible mechanisms of surface damage in two kinds of materials have been discussed and presented based on the XTEM results.

  1. Damage Distributions

    DEFF Research Database (Denmark)

    Lützen, Marie


    the damage location, the damage sizes and the main particulars of the struck vessel. From the numerical simulation and the analyse of the damage statistics it is found that the current formulation from the IMO SLF 43/3/2 can be used as basis for determination of the p-, r-, and v-factors. Expressions...... and methods of calculation have been discussed. The damage distributions for the different vessels have been compared and analyses regarding relations between damage parameters and main particulars have been performed. The damage statistics collected in work package 1 have been analysed for relations between...... for the distribution of the non-dimensional damage location, the non-dimensional damage length and the non-dimensional penetrations have been derived. These distributions have been used as basis for a proposal for the p- and r-factors. Two proposals for the v-factor have been performed using the damage statistics...

  2. Sideband Difference Diagnostics of Local Defects for Aero-engine Intershaft Bearing%航空发动机中介轴承局部故障边带差值诊断法

    Institute of Scientific and Technical Information of China (English)

    邓巍; 廖明夫; 马振国


    Aiming at the problem of difficult to diagnose local defects of aero-engine intershaft bearing, a new diag- nosis approach of sideband difference diagnostics of local defects for aero-engine intershaft bearing was proposed in this paper. Based on operating characteristic of intershaft bearing for both inner and outer ring rotation, the ap- proach used signal modulation frequency sideband as the main fault information, and established a complete set of fault diagnosis procedure. Experiments of an aero-engine inter bearing with the outer ring failure were carried out. Using the proposed approach, the local defects of the bearing was judged accurately. The theoretical analysis and fault bearing diagnosis example showed that the method can identify local defects of intershaft bearing and is effec- tive in local defects diagnosis for the aero-engine intershaft bearing%针对航空发动机中介轴承局部故障难以诊断的问题,提出了航空发动机中介轴承局部故障边带差值诊断法。该方法利用中介轴承内外环均旋转的运转特点,将其故障振动信号的调制边频带分量作为故障信息,建立了一套完整的故障诊断步骤,在实验器上对具有外环剥落故障的某型中介轴承进行实验,准确判断了该轴承故障。理论分析和诊断实例表明,该方法可以识别中介轴承局部故障,是一种适合航空发动机中介轴承局部故障诊断的有效方法。

  3. Improvement of Laval nozzle calculation model and simulative verification in aero-engine performance calculation%拉瓦尔喷管计算模型的改进及其整机仿真验证

    Institute of Scientific and Technical Information of China (English)

    周文祥; 黄金泉; 周人治


    根据拉瓦尔喷管的典型工作状态.建立了零维拉瓦尔喷管气体动力学模型,并将其集成到发动机整机部件级模型中,开展了发动机整机加速动态仿真.仿真结果表明:①随着喷口面积的不断收小,发动机低压转速加速曲线存在一段"先降后升"区域,这与实际试车结果吻合;②贴口正激波被推出管外的瞬间,出口马赫数从亚声速突变至超声速,但喷管出口流量、发动机推力变化连续,未见突变现象.%By analyzing typical operating regimes of Laval nozzle, a zero-dimensional pneumatic model was built to evaluate the influence of Laval nozzle on the performance of aero-engine. The Laval nozzle model was integrated into a whole aero-engine component-level model. Numerical simulations were performed to study transient performance of aero-engine when nozzle throat and outlet areas decreased during accelerating process from idle to middle state. Results show that low pressure rotor speed decreases during some specific regimes, along with the reduction of Laval nozzle area in accelerating process, which also exists in real aero-engine rig tests. Besides, after normal shock clinging to nozzle outlet section was pushed out, there was a mach number break from subsonic to supersonic in nozzle outlet section, however, both the outflow rate and thrust changed smoothly without any break at the accelerating curve.

  4. Global crop yield reductions due to surface ozone exposure: 1. Year 2000 crop production losses and economic damage (United States)

    Avnery, Shiri; Mauzerall, Denise L.; Liu, Junfeng; Horowitz, Larry W.


    Exposure to elevated concentrations of surface ozone (O 3) causes substantial reductions in the agricultural yields of many crops. As emissions of O 3 precursors rise in many parts of the world over the next few decades, yield reductions from O 3 exposure appear likely to increase the challenges of feeding a global population projected to grow from 6 to 9 billion between 2000 and 2050. This study estimates year 2000 global yield reductions of three key staple crops (soybean, maize, and wheat) due to surface ozone exposure using hourly O 3 concentrations simulated by the Model for Ozone and Related Chemical Tracers version 2.4 (MOZART-2). We calculate crop losses according to two metrics of ozone exposure - seasonal daytime (08:00-19:59) mean O 3 (M12) and accumulated O 3 above a threshold of 40 ppbv (AOT40) - and predict crop yield losses using crop-specific O 3 concentration:response functions established by field studies. Our results indicate that year 2000 O 3-induced global yield reductions ranged, depending on the metric used, from 8.5-14% for soybean, 3.9-15% for wheat, and 2.2-5.5% for maize. Global crop production losses totaled 79-121 million metric tons, worth $11-18 billion annually (USD 2000). Our calculated yield reductions agree well with previous estimates, providing further evidence that yields of major crops across the globe are already being substantially reduced by exposure to surface ozone - a risk that will grow unless O 3-precursor emissions are curbed in the future or crop cultivars are developed and utilized that are resistant to O 3.

  5. Research on sub-surface damage and its stress deformation in the process of large aperture and high diameter-to-thickness ratio TMT M3MP (United States)

    Hu, Hai-xiang; Qi, Erhui; Cole, Glen; Hu, Hai-fei; Luo, Xiao; Zhang, Xue-jun


    Large flat mirrors play important roles in large aperture telescopes. However, they also introduce unpredictable problems. The surface errors created during manufacturing, testing, and supporting are all combined during measurement, thus making understanding difficult for diagnosis and treatment. Examining a high diameter-to-thickness ratio flat mirror, TMT M3MP, and its unexpected deformation during processing, we proposed a strain model of subsurface damage to explain the observed phenomenon. We designed a set of experiment, and checked the validity of our diagnosis. On that basis, we theoretical predicted the trend of this strain and its scale effect on Zerodur®, and checked the validity on another piece experimentally. This work guided the grinding-polishing process of M3MP, and will be used as reference for M3M processing as well.

  6. Surface functionalization of titanium implants with chitosan-catechol conjugate for suppression of ROS-induced cells damage and improvement of osteogenesis. (United States)

    Chen, Weizhen; Shen, Xinkun; Hu, Yan; Xu, Kui; Ran, Qichun; Yu, Yonglin; Dai, Liangliang; Yuan, Zhang; Huang, Ling; Shen, Tingting; Cai, Kaiyong


    Oxidative stress induced by reactive oxygen species (ROS) overproduction would hinder bone healing process at the interface of bone/implant, yet underlying mechanism remains to be explored. To endow titanium (Ti) substrates with antioxidant activity for enhanced bone formation, multilayered structure composing of chitosan-catechol (Chi-C), gelatin (Gel) and hydroxyapatite (HA) nanofibers was constructed on Ti substrates. Surface wettability and topography of multilayer coated Ti substrates were characterized by water contact angle measurement, scanning electron microscopy and atomic force microscopy, respectively. Chi-C containing multilayer on Ti surface effectively protected osteoblasts from ROS damage, which was revealed by high level of intracellular ROS scavenging activity and reduced oxidative damage on cellular level by regulating the expression of cell adhesion related genes (integrin αv, β3, CDH11 and CDH2). Moreover, it regulated the production of cell adhesive and anti-apoptotic related proteins (p-MYPT1, p-FAK, p-Akt and Bcl-2) and pro-apoptotic critical executioners (Bax and cleaved caspase 3). Beside, the composite multilayer of Chi-C/Gel/HA nanofibers on Ti substrates promoted osteoblasts differentiation, which was evidenced by high expression levels of alkaline phosphatase activity, collagen secretion, ECM mineralization and osteogenesis-related genes expression in vitro. The in vivo experiments of μ-CT analysis, push out test and histochemistry staining further confirmed that Chi-C multilayered implant had great potential for improved early bone healing. Overall, the study offers an effective strategy for the exploration of high quality Ti implants for orthopedic applications.

  7. Simulation of surface coating failure based on continuum damage mechanics%基于连续损伤力学的表面涂层损伤模拟

    Institute of Scientific and Technical Information of China (English)

    庄蔚敏; 陈延红


    In view of the limitations of traditional macro-mechanics in the surface coating study, the continuum damage mechanics(CDM) was introduced into the finite element analysis of the surface coating. A material model was built based on CDM, and it was embedded in the solver of the software ABAQUS through the user defined subroutine VUMAT of ABAQUS as the interface. A series of numerical simulations were carried out to analyze the mechanical behavior of the coating. By means of the proposed model not only the stress distribution in the coating could be obtained, but also the damage evolution of the coating under loading could be predicted. By studying the relationship between the reaction force and the coating thickness, a concept of a special reaction force corresponding to the crack penetrating the coating thickness was proposed to evaluate the load carrying capacity of the coating. Besides, a critical thickness derived from the relationship between the coating thickness and the crack depth as a reference for coating thickness design.%针对传统宏观力学研究涂层问题的局限性,开展了基于损伤力学的表面涂层有限元模拟方法研究。首先建立损伤力学材料模型;然后通过有限元软件ABAqus提供的子程序(VUMAT)接口,将该材料模型嵌入到ABAQUS求解器;最后对涂层进行数值模拟以分析涂层的力学性能。用该材料模型分析不仅可以得到涂层的应力分布,而且可以得到涂层在载荷作用下的损伤过程。通过研究反力与涂层厚度的关系,提出用裂纹穿透涂层时的反力来衡量涂层的承载能力。此外,还可以根据在一定载荷作用下涂层厚度与裂纹深度的关系得到涂层的临界厚度,进而为涂层厚度设计提供参考。

  8. A method for the assessment of operational severity for a high pressure turbine blade of an aero-engine (United States)

    Haslam, Anthony; Abu, Abdullahi; Laskaridis, Panagiotis


    This paper provides a tool for the estimation of the operational severity of a high pressure turbine blade of an aero engine. A multidisciplinary approach using aircraft/ engine performance models which provide inputs to a thermo-mechanical fatigue damage model is presented. In the analysis, account is taken of blade size, blade metal temperature distribution, relevant heat transfer coefficients and mechanical and thermal stresses. The leading edge of the blade is selected as the critical part in the estimation of damage severity for different design and operational parameters. The study also suggests a method for production of operational severity data for the prediction of maintenance intervals.

  9. Structured Modeling of Aeroengine Assembly Data and Its Application%航空发动机装配数据结构化建模及应用

    Institute of Scientific and Technical Information of China (English)

    李坤; 莫蓉


    Aeroengine assembly data is low degree of structure and data tracing back was dififcult. In order to deal with these problems, areoengine assembly data structure and features is analyzed. Deifnition model of assembly production preparation data and assembly pro-duction process data is proposed. Data model based on as-sembly structured data units is established. The generation process of electronic curriculum vitae is presented. Appli-cation example veriifed the effectiveness of this method.%针对航空发动机装配数据结构化程度低及数据追溯困难等问题,分析了航空发动机装配数据构成及特点,提出了一个装配生产准备数据和装配生产过程数据的定义模型。针对装配生产过程数据特点,建立了以装配数据单元为核心的装配数据模型,给出了电子化履历本的实现过程,验证了方法的有效性。

  10. Shot-peened Residual Stress of Aeroengine Titanium Alloy Blades%航空发动机钛合金叶片喷丸强化残余应力研究

    Institute of Scientific and Technical Information of China (English)

    张彩珍; 杨健; 魏磊; 李跃辉; 吕建勋; 陈林洪


    Objective The residual stress field of aeroengine titanium alloy blades was studied, and the residual stress distribu-tion of blades after shot peening and after use was mastered, in order to provide a basis for evaluating the safety and reliability of the blades, and to provide data support for predicting the residual life of the blades. Methods The surface residual stress field after shot peening, the residual stress distribution along the deep layer, and the residual stress of aeroengine fan blades and compressor blades after use were studied using X-ray diffraction technology. Results After shot peening, about 90% of residual stress of the fan blades was distributed in the range of -600~-800 MPa, and the average residual stress value was about -682 MPa. About 90% of residual stress distribution of the compressor blades was distributed in the range of-500~-700 MPa, and the average re-sidual stress was about -603 MPa. After shot peening, the surface residual stress of the fan blade and compressor blade was about-610 MPa, and there was a maximum residual stress in the subsurface layer, the values were-739 MPa at 11μm and-683 MPa at 13μm, respectively, and then the residual stress decreased gradually with increasing depth. The residual stress distribution of the fan blades was-460~-720 MPa after using for 300 hours, and-430~-700 MPa after using for 600 hours. The residual stress distribu-tion of the compressor blades was-470~-670 MPa after using for 300 hours, and-360~-620 MPa after using for 600 hours. Con-clusion The residual compressive stress of Titanium alloy blade after shot peening first decreased and then increased with the increase of the layer depth, and the depth of the residual stress field was about 50 μm. The residual stress of titanium alloy blade after use showed an attenuation trend, and the residual compressive stress attenuation increased gradually with the increase of using time.%目的 研究航空发动机钛合金叶片残余应力场,掌

  11. Modeling Cryptosporidium and Giardia in Ground and Surface Water Sources in Rural India: Associations with Latrines, Livestock, Damaged Wells, and Rainfall Patterns. (United States)

    Daniels, Miles E; Smith, Woutrina A; Schmidt, Wolf-Peter; Clasen, Thomas; Jenkins, Marion W


    Surface and groundwater contamination with fecal pathogens is a public health concern especially in low-income settings where these sources are used untreated. We modeled observed Cryptosporidium and Giardia contamination in community ponds (n = 94; 79% contaminated), deep tubewells (DTWs) (n = 107; 17%), and shallow tubewells (STWs) (n = 96; 19%) during the 2012 and 2013 monsoon seasons (June-August) in 60 villages in Puri District, India to understand sources and processes of contamination. Detection of Cryptosporidium and/or Giardia in a tubewell was positively associated with damage to the well pad for DTWs, the amount of human loading into pour-flush latrine pits nearby (≤15 m) for STWs, and the village literacy rate (for Giardia in STWs). Pond concentration levels were positively associated with the number of people practicing open defecation within 50 m and the sheep population for Cryptosporidium, and with the village illiteracy rate for Giardia. Recent rainfall increased the risk of Cryptosporidium in STWs (an extreme event) and ponds (any), while increasing seasonal rainfall decreased the risk of Giardia in STWs and ponds. Full latrine coverage in this setting is expected to marginally reduce pond Cryptosporidium contamination (16%) while increasing local groundwater protozoal contamination (87-306%), with the largest increases predicted for Cryptosporidium in STWs.

  12. Grey Comprehensive Evaluation of Cutting Tool Performance for Aero-engine Blisk%航空发动机整体叶盘刀具性能灰色综合评价

    Institute of Scientific and Technical Information of China (English)

    贾玉佩; 赵威; 李亮


    A grey comprehensive evaluation method of CNC milling tool performance was pro—posed for an aero-engine titanium alloy blisk with the CNC milling of a type of aero-engine blisk as the research obj ect.In this method,a benchmark with some typical difficult-to-machine features extracted from aero-engine blisk was designed,and the processing route was developed.In addition,grey com—prehensive evaluation models of cutting tool performance were established for roughing and finishing tools respectively.Finally,experiments of CNC milling the benchmark were carried out,and then the grey comprehensive evaluation models were used to evaluate the cutting tools.The results show that the method is convenient and effective to evaluate the cutting tool performance for aero-engine blisks.%以某型航空发动机钛合金整体叶盘的数控铣削为研究对象,提出了一种面向航空发动机整体叶盘的数控铣削刀具性能灰色综合评价方法。首先设计涵盖航空发动机整体叶盘难加工特征的基准件模型,然后基于灰色关联度分别构建了粗精加工刀具性能灰色综合评价模型,最后进行基准件的切削试验并应用所建立的灰色综合评价模型对刀具性能进行综合评价。研究结果表明,所构建的基准件模型和灰色综合评价模型可以快捷、有效地评价刀具性能。

  13. Modeling and experimental study of the mechanism of electrification from aero-engine jet%航空发动机喷流起电机理建模与试验研究

    Institute of Scientific and Technical Information of China (English)

    朱利; 刘尚合; 郑会志; 魏明; 胡小锋; 索罗金·安德烈


    以研究航空发动机喷流起电的机理以及喷流起电对飞行器整体带电特性的影响为目的,对起电机理进行了建模和实验验证。首先以流体运动方程为基础,建立了航空发动机带电粒子浓度的动态仿真模型,仿真得到发动机燃烧过程中的各类粒子浓度变化情况。其次,设计了用于发动机喷流起电探测的静电感应传感器,对装配涡扇发动机的某型飞行器进行了地面试验测试,得到了发动机启动、稳定运行、加速、减速、停止等状态的动态电位。仿真及实验结果详细地描述了发动机喷流起电的机理,以及喷流起电会使飞行器带负电的结论,为进一步分析飞行器飞行过程中整体带电特性提供了指导。%To investigate the mechanism of electrification from aero-engine jet and the electrification effect on the overall charging charac-teristics of vehicle, a simulation model of concentration of charged particles in aero-engine is build based on the equations of fluid motion. And concentration changes of various particles are simulated. To verify the simulation result, a special electrostatic induction sensor for detecting the electrification of engine jet is designed, according to the principle of the Faraday cup, to measure the dynamic potential when the turbofan engine starts, operates steadily, accelerates, decelerates and stops. The simulation and experimental re-sults show that the aircraft is negatively charged by the electrification from aero-engine jet and the mechanism of electrification from aero-engine jet is described specifically. The research may provide a guidance to the further study on analyzing the overall charging characteristics of vehicle during the flight.

  14. 瓷绝缘子表面激光损伤的数值模拟和实验研究%Numerical simulation and experiment research of laser damage of porcelain insulator surface

    Institute of Scientific and Technical Information of China (English)

    齐丽君; 朱晓; 朱长虹; 郭飞; 朱广志; 谷山强


    During the process of laser de-icing applied in the electric grid, the electrical equipment such as insulator should not be damaged by the laser. The temperature and stress field distributions of normal porcelain, alumina porcelain, zirconium oxide porcelain and cordierite porcelain after laser irradiating are obtained by using ANSYS software. The results show that alumina porcelain has advantages in characteristics of anti-damage of thermal induced stress. The experiments of surface damage of insulator with Nd: YAG laser irradiation are explored. The relations between surface temperature and irradiating time are obtained. So is the damage form. Numerical analysis and experiment results are both show that laser power density and irradiating time are considered as the important influence factors of laser damage of the insulator. Thermal damage and thermal-stress damage are the main types of laser damage of porcelain insulator, which are related to the surface temperature after laser irradiation. The anti-damage methods of aiming and controlling, combining laser de-icing with other de-icing methods to protect the insulator are also proposed.%为了防止输电线路激光除冰过程中激光损伤绝缘子等电力设备,采用有限元分析软件ANSYS对激光与普通瓷、氧化铝瓷、氧化锆瓷、堇青石瓷作用后的温度场和应力场进行了数值模拟,得到氧化铝瓷具有较好的抗热应力破坏性能,并进行了Nd∶ YAG激光照射绝缘子表面实验,得到绝缘子表面温度与照射时间和损伤类型的关系.结果表明,激光功率密度和照射时间是影响绝缘子破坏的重要因素,瓷绝缘子表面损伤包括热损伤和热应力破坏,破坏类型与表面温度相关.提出了瞄准、控制、激光除冰与其它除冰方式相结合等保护措施.这一结果对输电线路激光除冰工程应用中保障电力设施的安全是有帮助的.

  15. Ocular surface damage of Graves disease patients without eye symptoms%无眼征Graves病患者的眼表损害

    Institute of Scientific and Technical Information of China (English)

    张磊; 何彦津


    Objective To evaluate the ocular surface damage and the changes of tear film function in Graves disease ( GD) patients without eye symptoms, and investigate the function of ocular inflammation in the pathogenesis of dry eye. Methods A total of 38 patients(76 eyes) with GD without eye symptoms and 30 healthy controls(60 eyes) were included in this study. The palpebral fissure height,degree of proptosis, ocular surface disease index(OSDI) ,Schirmer I tear test,break-up time(BUT) ,corneal fluorescence staining (FL) , and conjunctival impression cytology (IC) were assessed. The results were compared between the patient and the control groups. Results The OS-DI score was 43. 34 ± 10. 32 in the GD group and 22. 56 ±11.21 in the control group, there was significant difference (P < 0. 01). The value of Schirmer I test was (13.2 ± 7.1) mm in the GD group and (22.4 ± 4. 5) mm in the control group, there was significant difference^<0.01). BUT was(7.2±2. l)s in the GD group and( 10. 4 ±2. 9)s in the control group,there was significant difference(P < 0. 01). In the cornea! fluorescence staining test,20 eyes were positive in the GD group and 6 eyes in the control group, there was statistical difference(P = 0.016). Conjunctival impress cytology showed grade 0 was in 26 eyes(36.11% ),grade 1 in 23 eyes(31.94% ),grade 2 in 17 eyes(23.61% ), grade 3 in 6 eyes(8. 33% ) in GD group,whereas grade 0 in 39 eyes(65.00% ) .grade 1 in 13 eyes(21. 67% ), grade 2 in 6 eyes ( 10. 00% ), grade 3 in 2 eyes ( 3. 33% ) in control group,there was significant difference(P=0. 008). There was no statistical difference in interpalpebral distance and protosis between two groups( t = 0.482, -0.357 ;P = 0.632,0.723). Conclusion Dry eye and ocular surface damage appear in GD without eye symptoms, which may be associated with the ocular surface inflammation.%目的 评价无眼征的Graves病(Graves disease,GD)患者的眼表损害以及泪膜功能变化,了解眼表炎症在干眼

  16. 航空发动机空气系统验算标定%Calibration of Calculation for Aero-Engine Air System

    Institute of Scientific and Technical Information of China (English)

    呼艳丽; 徐连强; 赵维维


    利用流量特性试验得到的相关流路元件的流阻计算模型,和旋转状态下阶梯齿风阻温升计算方法,通过调节封严篦齿间隙等参数,对航空发动机空气系统的压力、温度进行验算标定,并根据验算结果分析发现后续试验中存在和需要注意的问题。验算标定结果表明:通过对发动机试验工况的验算标定,可发现试验中存在的问题,较准确地模拟出后续试验中的问题和试验风险,确保发动机的工作安全,并为空气系统的进一步改进和优化提供依据。%A calibration method for aero-engine air system was presented, with the air system throttle ele-ments flow loss coefficient experiment data and the rotating step labyrinth seal windage temperature rise cal-culation method. The pressure and temperature of air system were calibrated by adjusting the labyrinth seal clearance. Some possible and noteworthy problems in the following tests were found out according to the cal-ibrated results. The results show that through the calibration of experimental conditions, the problems could be revealed and the risk of the following tests can be simulated perfectly to ensure the safety of engine work-ing which could be referential for the further improvements of engine's air system.

  17. Radiation damage

    CERN Document Server

    Heijne, Erik H M; CERN. Geneva


    a) Radiation damage in organic materials. This series of lectures will give an overview of radiation effects on materials and components frequently used in accelerator engineering and experiments. Basic degradation phenomena will be presented for organic materials with comprehensive damage threshold doses for commonly used rubbers, thermoplastics, thermosets and composite materials. Some indications will be given for glass, scintillators and optical fibres. b) Radiation effects in semiconductor materials and devices. The major part of the time will be devoted to treat radiation effects in semiconductor sensors and the associated electronics, in particular displacement damage, interface and single event phenomena. Evaluation methods and practical aspects will be shown. Strategies will be developed for the survival of the materials under the expected environmental conditions of the LHC machine and detectors. I will describe profound revolution in our understanding of black holes and their relation to quantum me...

  18. Assessing Tropical Cyclone Damage (United States)

    Done, J.; Czajkowski, J.


    Landfalling tropical cyclones impact large coastal and inland areas causing direct damage due to winds, storm-surge flooding, tornadoes, and precipitation; as well as causing substantial indirect damage such as electrical outages and business interruption. The likely climate change impact of increased tropical cyclone intensity, combined with increases in exposure, bring the possibility of increased damage in the future. A considerable amount of research has focused on modeling economic damage due to tropical cyclones, and a series of indices have been developed to assess damages under climate change. We highlight a number of ways this research can be improved through a series of case study analyses. First, historical loss estimates are revisited to properly account for; time, impacted regions, the source of damage by type, and whether the damage was direct/indirect and insured/uninsured. Second, the drivers of loss from both the socio-economic and physical side are examined. A case is made to move beyond the use of maximum wind speed to more stable metrics and the use of other characteristics of the wind field such as direction, degree of gustiness, and duration is explored. A novel approach presented here is the potential to model losses directly as a function of climate variables such as sea surface temperature, greenhouse gases, and aerosols. This work is the first stage in the development of a tropical cyclone loss model to enable projections of losses under scenarios of both socio-economic change (such as population migration or altered policy) and physical change (such as shifts in tropical cyclone activity one from basin to another or within the same basin).

  19. Comparing the use of 4.6 um lasers versus 10.6 um lasers for mitigating damage site growth on fused silica surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Yang, S T; Matthews, M J; Elhadj, S; Cooke, D; Guss, G M; Draggoo, V G; Wegner, P J


    The advantage of using mid-infrared (IR) 4.6 {micro}m lasers, versus far-infrared 10.6 {micro}m lasers, for mitigating damage growth on fused silica is investigated. In contrast to fused silica's high absorption at 10.6 {micro}m, silica absorption at 4.6 {micro}m is two orders of magnitude less. The much reduced absorption at 4.6 {micro}m enables deep heat penetration into fused silica when it is heated using the mid-IR laser, which in turn leads to more effective mitigation of damage sites with deep cracks. The advantage of using mid-IR versus far-IR laser for damage growth mitigation under non-evaporative condition is quantified by defining a figure of merit (FOM) that relates the crack healing depth to laser power required. Based on our FOM, we show that for damage cracks up to at least 500 {micro}m in depth, mitigation using a 4.6 {micro}m mid-IR laser is more efficient than mitigation using a 10.6 {micro}m far-IR laser.

  20. Numerically Simulating Airflow Field Inside Aeroengine Bearing Chamber%航空发动机轴承腔气相速度场数值模拟

    Institute of Scientific and Technical Information of China (English)

    陈薄; 陈国定; 张永红; 孙恒超


    The airflow field in a typical aeroengine beating chamber has been calculated with the commercial computational fluid dynamics software CFX 11. 0, taking into consideration the sealing structure of the ventilation hole and the airflow state equations. Then the effects of erating conditions such as rotational speed, air inflow volume, gap of the bearing chamber, the the structural parameters and ophydraulic diameter of the bearing chamber on the air- flow states are analyzed. The calculation results show preliminarily but clearly that the air inflow, ventilation hole and compressible air property have significant influence on the airflow states of the bearing chamber. The nondi- mensional tangential velocity decreases along the radial direction of the bearing chamber, but the radial and axial velocities change in a complicated manner. The rotational speed of the rotor, airflow volume and the hydraulic diameter of the bearing chamber have great influence on the nondimensional velocity distribution.%考虑轴承腔密封间隙和排气孔结构,以及气相介质状态方程条件下,利用CFX软件数值计算了典型航空发动机轴承腔结构的气相流场。探讨了密封间隙和排气孔结构存在以及考虑气相介质状态方程对气相介质流动的影响,以及转子转速、进气量、轴承腔的液力直径等工况和结构参数对气相介质流动状态的影响。计算结果表明:考虑密封进气和排气孔结构以及气相介质的状态方程对气相介质流动速度分布影响较大;气相介质无量纲切向速度沿着轴承腔径向方向减小,而无量纲径向速度和轴向速度沿着径向方向变化较为复杂;转子转速、密封进气量和轴承腔液力直径对无量纲速度分布影响也较大而且很复杂。与有关文献计算结果的对比验证了本文提出的计算方法的可靠性和正确性。

  1. Convergence Analysis of the Numerical Solution for Cathode Design of Aero-engine Blades in Electrochemical Machining

    Institute of Scientific and Technical Information of China (English)

    Li Zhiyong; Niu Zongwei


    As a main difficult problem encountered in electrochemical machining (ECM), the cathode design is tackled, at present, with various numerical analysis methods such as finite difference, finite element and boundary element methods. Among them, the finite element method presents more flexibility to deal with the irregularly shaped workpieces. However, it is very difficult to ensure the convergence of finite element numerical approach. This paper proposes an accurate model and a finite element numerical approach of cathode design based on the potential distribution in inter-electrode gap. In order to ensure the convergence of finite element numerical approach and increase the accuracy in cathode design, the cathode shape should be iterated to eliminate the design errors in computational process. Several experiments are conducted to verify the macbining accuracy of the designed cathode. The experimental results have proven perfect convergence and good computing accuracy of the proposed finite element numerical approach by the high surface quality and dimensional accuracy of the machined blades.

  2. Surface modification and deuterium retention in reduced-activation steels under low-energy deuterium plasma exposure. Part II: steels pre-damaged with 20 MeV W ions and high heat flux (United States)

    Ogorodnikova, O. V.; Zhou, Z.; Sugiyama, K.; Balden, M.; Pintsuk, G.; Gasparyan, Yu.; Efimov, V.


    The reduced-activation ferritic/martensitic (RAFM) steels including Eurofer (9Cr) and oxide dispersion strengthened (ODS) steels by the addition of Y2O3 particles investigated in Part I were pre-damaged either with 20 MeV W ions at room temperature at IPP (Garching) or with high heat flux at FZJ (Juelich) and subsequently exposed to low energy (~20-200 eV per D) deuterium (D) plasma up to a fluence of 2.9  ×  1025 D m-2 in the temperature range from 290 K to 700 K. The pre-irradiation with 20 MeV W ions at room temperature up to 1 displacement per atom (dpa) has no noticeable influence on the steel surface morphology before and after the D plasma exposure. The pre-irradiation with W ions leads to the same concentration of deuterium in all kinds of investigated steels, regardless of the presence of nanoparticles and Cr content. It was found that (i) both kinds of irradiation with W ions and high heat flux increase the D retention in steels compared to undamaged steels and (ii) the D retention in both pre-damaged and undamaged steels decreases with a formation of surface roughness under the irradiation of steels with deuterium ions with incident energy which exceeds the threshold of sputtering. The increase in the D retention in RAFM steels pre-damaged either with W ions (damage up to ~3 µm) or high heat flux (damage up to ~10 µm) diminishes with increasing the temperature. It is important to mention that the near surface modifications caused by either implantation of high energy ions or a high heat flux load, significantly affect the total D retention at low temperatures or low fluences but have a negligible impact on the total D retention at elevated temperatures and high fluences because, in these cases, the D retention is mainly determined by bulk diffusion.

  3. Effect of deep structure and surface layer (a) simulation study on the heavy damage belt of the 1995 Hyogoken Nanbu earthquake; Hado simulation wo mochiita `shinsai no obi` ni tsuite no kento

    Energy Technology Data Exchange (ETDEWEB)

    Feng, S.; Ishikawa, K.; Kaji, Y. [Chuokaihatsu Corp., Tokyo (Japan)


    A simulation study was done to identify the causes for the so-called heavy damage belt observed as a result of the Hyogoken Nanbu Earthquake. This study determines distributions of the maximum amplitudes on the ground surfaces, and discusses the effects of deep structures and low-velocity surface layers, based on the simulation by the wave equation with the underground model of Higashinada-ku and its vicinity in the north-south direction, observed seismic records and artificial waves. The two-dimensional scalar wave equation is used for the analysis. The velocity structure model used for the simulation is established, based on the elastic wave seismic survey results. The focus function is drawn by expanding or contracting the time scale, using the seismic records at Kobe Port Island and artificial waves. The analysis results show that the damage belt coincides with the areas at which the focusing zone of the deep structure overlap the amplification zone in the low-velocity ground surfaces, where relative density is amplified 1.5 to 2 times. It is also observed that large peaks repeat 2 to 3 times on the time scale. 5 refs., 8 figs., 1 tab.

  4. Irradiation damage

    Energy Technology Data Exchange (ETDEWEB)

    Howe, L.M


    There is considerable interest in irradiation effects in intermetallic compounds from both the applied and fundamental aspects. Initially, this interest was associated mainly with nuclear reactor programs but it now extends to the fields of ion-beam modification of metals, behaviour of amorphous materials, ion-beam processing of electronic materials, and ion-beam simulations of various kinds. The field of irradiation damage in intermetallic compounds is rapidly expanding, and no attempt will be made in this chapter to cover all of the various aspects. Instead, attention will be focused on some specific areas and, hopefully, through these, some insight will be given into the physical processes involved, the present state of our knowledge, and the challenge of obtaining more comprehensive understanding in the future. The specific areas that will be covered are: point defects in intermetallic compounds; irradiation-enhanced ordering and irradiation-induced disordering of ordered alloys; irradiation-induced amorphization.

  5. PCA algorithm for detection, localisation and evolution of damages in gearbox bearings

    Energy Technology Data Exchange (ETDEWEB)

    Pirra, M; Gandino, E; Garibaldi, L; Machorro-Lopez, J M [Dipartimento di Meccanica, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy); Torri, A, E-mail: [Avio S.p.A., Strada del Drosso 145, 10135 Torino (Italy)


    A fundamental aspect when dealing with rolling element bearings, which often represent a key component in rotating machineries, consists in correctly identifying a degraded behaviour of a bearing with a reasonable level of confidence. This is one of the main requirements a health and usage monitoring system (HUMS) should have. This paper introduces a monitoring technique for the diagnosis of bearing faults based on Principal Component Analysis (PCA). This method overcomes the problem of acquiring data under different environmental conditions (hardly biasing the data) and allows accurate damage recognition, also assuring a rather low number of False Alarms (FA). In addition, a novel criterion is proposed in order to isolate the area in which the faulty bearing stands. Another useful feature of this PCA-based method concerns the capability to observe an increasing trend in the evolution of bearing degradation. The described technique is tested on an industrial rig (designed by Avio S.p.A.), consisting of a full size aeroengine gearbox. Healthy and variously damaged bearings, such as with an inner or rolling element fault, are set up and vibration signals are collected and processed in order to properly detect a fault. Finally, data collected from a test rig assembled by the Dynamics and Identification Research Group (DIRG) are used to demonstrate that the proposed method is able to correctly detect and to classify different levels of the same type of fault and also to localise it.

  6. Mechanism of original damage of thin optical comp onents induced by surface particle contamination%表面颗粒污染物诱导薄光学元件初始损伤的机理*

    Institute of Scientific and Technical Information of China (English)

    孙晓艳; 雷泽民; 卢兴强; 范滇元


    基于光传输理论研究了前表面颗粒污染物诱导薄光学元件产生初始损伤的原因,提出了颗粒遮光效应和颗粒造成的光学元件局部热变形两者共同作用对光束进行扰动的损伤机理。研究结果表明:对于高功率激光光束,薄光学元件局部热变形对光束的扰动是产生较高光强调制的重要原因;随着激光脉冲发射次数的增加,局部热变形的表面形状、位相延迟幅度、热扩散长度不断变化,会在光学元件内不同厚度处和后表面xy方向上的不同位置处产生较高的光强调制,不仅容易引起后表面产生多个损伤点,也可能在光学元件内就产生损伤,并且在厚度方向上的损伤点是分散的。%Based on the optical transmission theory, the reason why front-surface particle contamination may induce the original damage of thin optical components is considered, and a damage mechanism is put forward: The localized thermal deformation of an optical element induced by the thermal effect of particle contamination together with the shading effect of it can disturb the laser beams. Simulated results show that for a high power laser, the localized thermal deformation of thin optical components, which disturbs the laser beam, is an important cause to produce strong light intensity modulations. The surface shape, phase delay, and thermal diffusion length of a localized thermal deformation are constantly changing with the increase of laser pulse shot number, so the highest light intensity modulation will be produced at different positions in the thickness direction or the xy direction on the rear-surface of an optical element. This not only can easily induce some damages on the rear-surface of the optical element, but also cause the interior damages scattered in the thickness direction.

  7. Fatigue-induced damage of high-strength steels (United States)

    Shetulov, D. I.; Myl'nikov, V. V.


    The issues on the estimation of the surface damage of the products produced from high-strength alloys are considered. Mathematical relationships for a numerical calculation of the surface damage are given. The peculiarities of the evaluation of the surface damage are investigated, as applied to high-strength alloys.

  8. Radiation damage tolerant nanomaterials

    Directory of Open Access Journals (Sweden)

    I.J. Beyerlein


    Full Text Available Designing a material from the atomic level to achieve a tailored response in extreme conditions is a grand challenge in materials research. Nanostructured metals and composites provide a path to this goal because they contain interfaces that attract, absorb and annihilate point and line defects. These interfaces recover and control defects produced in materials subjected to extremes of displacement damage, impurity implantation, stress and temperature. Controlling radiation-induced-defects via interfaces is shown to be the key factor in reducing the damage and imparting stability in certain nanomaterials under conditions where bulk materials exhibit void swelling and/or embrittlement. We review the recovery of radiation-induced point defects at free surfaces and grain boundaries and stabilization of helium bubbles at interphase boundaries and present an approach for processing bulk nanocomposites containing interfaces that are stable under irradiation.

  9. The influence of fault geometry and frictional contact properties on slip surface behavior and off-fault damage: insights from quasi-static modeling of small strike-slip faults from the Sierra Nevada, CA (United States)

    Ritz, E.; Pollard, D. D.


    Geological and geophysical investigations demonstrate that faults are geometrically complex structures, and that the nature and intensity of off-fault damage is spatially correlated with geometric irregularities of the slip surfaces. Geologic observations of exhumed meter-scale strike-slip faults in the Bear Creek drainage, central Sierra Nevada, CA, provide insight into the relationship between non-planar fault geometry and frictional slip at depth. We investigate natural fault geometries in an otherwise homogeneous and isotropic elastic material with a two-dimensional displacement discontinuity method (DDM). Although the DDM is a powerful tool, frictional contact problems are beyond the scope of the elementary implementation because it allows interpenetration of the crack surfaces. By incorporating a complementarity algorithm, we are able to enforce appropriate contact boundary conditions along the model faults and include variable friction and frictional strength. This tool allows us to model quasi-static slip on non-planar faults and the resulting deformation of the surrounding rock. Both field observations and numerical investigations indicate that sliding along geometrically discontinuous or irregular faults may lead to opening of the fault and the formation of new fractures, affecting permeability in the nearby rock mass and consequently impacting pore fluid pressure. Numerical simulations of natural fault geometries provide local stress fields that are correlated to the style and spatial distribution of off-fault damage. We also show how varying the friction and frictional strength along the model faults affects slip surface behavior and consequently influences the stress distributions in the adjacent material.

  10. Depth-dependent and surface damages in MgAl sub 2 O sub 4 and MgO irradiated with energetic iodine ions

    CERN Document Server

    Aruga, T; Ohmichi, T; Okayasu, S; Kazumata, Y; Jitsukawa, S


    Samples of polycrystalline ceramics of MgAl sub 2 O sub 4 irradiated at the ambient temperature with 85 MeV I sup 7 sup + iodine ions to doses up to 1x10 sup 1 sup 9 m sup - sup 2 is observed to be amorphized up to depths around 6 mu m from the ion-incident surface for a dose of 1.2x10 sup 1 sup 9 m sup - sup 2 , through a cross-sectional transmission electron microscopy. A step height of 1 mu m is formed across the border between the masked and irradiated regions of the surface. The height of the step is observed to increase sharply from the irradiated area towards the edge at the border, forming a peak as tall as 1.5 mu m. A glossy, silver-gray film with a thickness less than 0.1 mu m is unexpectedly observed to have formed on the surface of samples of MgAl sub 2 O sub 4 and MgO, in about 3.5 years aging after the irradiation to 1.2x10 sup 1 sup 9 m sup - sup 2 , being left untouched in the air. The film is easily peeled off along grain boundaries and found to be amorphous from the electron diffraction patt...

  11. Damage-dependent bounding surface model for cyclic degradation of saturated clay%考虑循环载荷下饱和黏土软化的损伤边界面模型研究

    Institute of Scientific and Technical Information of China (English)

    胡存; 刘海笑; 黄维


    研究表明,循环载荷作用下饱和黏土将发生软化,其机制主要有两个:一是孔压的积累;二是土体原有结构的不断损伤和新结构的不断重塑.针对上述机制,基于广义各向同性硬化准则建立了考虑饱和黏土循环软化的损伤单面模型.该模型在有效应力空间中引入损伤变量,表征土体结构的损伤和重塑程度,在连续的循环加载下,损伤不断累积,边界面则随着损伤的累积不断收缩,以模拟饱和黏土刚度和强度的软化;以应力反向点作为边界面的广义各向同性硬化中心和映射法则的映射中心,灵活地选择塑性模量的插值公式以模拟塑性变形和孔压的累积以及应力-应变的滞回特性.应用该模型对不排水循环三轴试验进行模拟,并且考查了循环周次、循环应力水平和固结历史对饱和黏土循环软化特性的影响,并与相关试验比较,验证了模型的有效性.%Degradation of saturated clay during cyclic loading can be assumed to be caused mainly by two mechanisms, pore water pressure build-up and the damage and remolding of soil fabric. Based on these mechanisms, a damage-dependent bounding surface model for cyclic degradation of saturated clay is proposed using the generalized isotropic hardening rule. In the model, the degree of damage and remolding of soil during cyclic loading is quantified by introducing a damage variable and the size of the bounding surface decreases with damage accumulation to characterize progressive degradation and nonlinear behavior of the saturated clay. By taking the stress reversal point as the generalized isotropic hardening center of the bounding surface as well as the mapping origin, the forms of hardening modulus can be adopted flexibly so as to predict the accumulation of plasticity deformation and pore pressure and the hysteresis property of clay. The cyclic behaviors for undrained one-way cyclic triaxial tests are predicted by the model

  12. Doping effect of L-cystine on structural, UV-visible, SHG efficiency, third order nonlinear optical, laser damage threshold and surface properties of cadmium thiourea acetate single crystal (United States)

    Azhar, S. M.; Anis, Mohd; Hussaini, S. S.; Kalainathan, S.; Shirsat, M. D.; Rabbani, G.


    The present article is focused to investigate the influence of L-cystine (LC) on linear-non-linear optical and laser damage threshold of cadmium thiourea acetate (CTA) crystal. The structural parameters of pure and LC doped CTA crystals have been determined using the single crystal X-ray diffraction technique. The functional groups of grown crystals have been identified by means of fourier transform infrared (FT-IR) analysis. The UV-visible spectral analysis has been done in the range of 200-900 nm to ascertain the uplifting influence of LC on optical properties of CTA crystal. The second harmonic generation (SHG) efficiency of LC doped CTA crystal is found to be higher than CTA and KDP crystal. The Z-scan technique has been employed to determine the third order nonlinear optical (TONLO) nature of LC doped CTA crystal at 632.8 nm. The self focusing tendency confirmed the strong kerr lensing ability of LC doped CTA crystal. The TONLO susceptibility (χ3), refraction (n2) and absorption coefficient (β) has been calculated using the Z-scan data. The laser damage threshold of pure and LC doped CTA crystals has been measured using the Q-switched Nd:YAG laser and its is found to be in range of GW/cm2. The surface analysis has been done by means of etching studies.


    Institute of Scientific and Technical Information of China (English)



    Damage of a dike may result in severe damage and suffering. To reduce downstream damage and loss of life, it is important to study the process of breaching of the damaged dike. It is not possible to understand the damage process without a clear understanding of the flow patterns encountered. In the present study, data obtained from nine experimental runs are analyzed. The flow patterns and progressive damage of dike overtopping are investigated. Two types of phenomena at the dike surface:erosion; and erosion and sliding, are observed during the overtopping event. Four stages of dike damage can be distinguished. The degradation rate of the dike crest is found to be dependent on the downstream slope of the dike. The degradation rate is higher when the downstream slope is steeper.

  14. 航空发动机对转涡轮气动设计技术研究进展%Aerodynamic Design of Counter-rotating Turbine for Aero-engine

    Institute of Scientific and Technical Information of China (English)

    周琨; 邹正平; 刘火星; 王雷


    随着航空工业的发展,民用或者军用飞行器都对航空发动机要求越来越高,对转涡轮由于其气动布局上的优势能成为未来航空发动机的关键技术之一.本文通过对国内外文献的调研,结合课题组多年研究工作,分析了对转涡轮内部的特征,并从对转涡轮速度三角形参数分析和气动设计准则、内部复杂流动机制、激波组织技术和收扩叶型造型方法等方面对其研究进展进行了论述;在此基础上考虑加工工艺、结构强度、传热冷却等多学科耦合因素,探讨了转涡轮技术在工程应用中面临的挑战及可能的解决方向,展望了转涡轮技术的发展趋势.%With the development of aviation industry, more and more requirements are submitted during the design of civil and military aero-engines, such as higher thrust-weight ratio, lower fuel consumption, more affordability, etc. The counter-rotating turbine technology provides a powerful solution for the problems. The relevant literatures are reviewed from the aspects of velocity triangle parametric analyses, aerodynamic design criteria, internal (low mechanisms, Shockwave control methods, and design techniques of convergent-divergent airfoils, respectively. By combining literature review with the research carried out in many years by authors, the characteristics of counter-rotating turbine are analyzed. However some challenges are also encountered when the counter-rotation turbine technology is applied to the aero-engines. These challenges in terms of processing technology, structural strength, heal transfer/cooling as well as their possible solutions are considered. Finally, the development trends of the technology are predicted.

  15. 套齿联轴器对航空发动机振动特性的影响%Effects of Gear Coupling on Aero-engine Vibration Characteristics

    Institute of Scientific and Technical Information of China (English)

    廖仲坤; 陈果; 王海飞


    The aero-engine gear coupling stiffness was studied herein ,and the coupling dynamic gearing forces were deduced ,the relationship among the gear coupling gearing forces and the torque , misalignment ,and the dynamic relative displacements was analyzed .According to aero-engine gearing structure characteristics ,a rotor dynamic model including gear coupling and the three supports was es-tablished ,and the effects of gear coupling stiffness on the system frequency response function were an-alyzed;under the conditions of considering the angle misalignment between two rotors ,the effects of gear stiffness on the misalignment responses were studied .The results show that the dynamic gearing stiffness model can simulate the gear coupling dynamic stiffness very correctly ,but the dynamic change range of the stiffness is not enough to change obviously the system dynamic characteristics , however ,the effects of the angle stiffness of gear coupling on the system vibration characteristics are very great .%研究了航空发动机套齿联轴器的连接刚度,推导了套齿动态啮合力计算模型,分析了随扭矩、套齿不对中和动态相对位移变化的套齿啮合力和啮合刚度。依据航空发动机套齿连接结构,建立了含套齿联轴器的三支点转子动力学模型,分析了套齿连接刚度对系统频率响应特性的影响,在考虑转轴间角度不对中的情况下,分析了套齿连接刚度对系统不对中响应的影响规律。结果发现,动态啮合力模型能够更加真实地模拟套齿连接刚度的变化,但是,当其径向啮合刚度变化不大时,其计算结果与等效刚度模型的计算结果相同,套齿角向刚度对系统动力性能影响很大,在套齿设计、装配和使用中需要重视。

  16. Abrupt fault diagnosis of aero-engine based on affinity propagation clustering%基于相似性传播聚类的航空发动机突发故障诊断

    Institute of Scientific and Technical Information of China (English)

    李丽敏; 王仲生; 姜洪开


    针对航空发动机突发故障,构建了一种基于相似性传播聚类的突发故障诊断方法。首先利用突发故障历史监测数据建立突发故障数据库,通过相似性传播聚类找到数据库中所有突发故障数据的中心,当诊断新采集数据的突发故障类型时,通过相似性传播聚类找到当前新采集数据的中心,经过与突发故障数据库中的数据中心进行匹配判断该新采集数据所对应的突发故障类型。将该突发故障诊断方法应用到发动机转子实验台的突发故障诊断中,仿真和实验结果表明该方法的可行性,并通过与其他方法比较,表明该方法具有诊断时间短和误差小的优点。%Aiming at aero-engine faults,an abrupt fault diagnosis method based on affinity propagation clustering was proposed.Abrupt fault historical monitoring data were used to establish faults database.Through affinity propagation clustering,all the exemplars of abrupt faults in the database were found and the affinity propagation clustering was applied once again to find the exemplar of the new collected data.The fault type was then identified by matching the center with the centers obtained from the faults database.The method was used in the aero-engine abrupt fault diagnosis.The simulation and experiment results show that the method is feasible to diagnose abrupt fault,and compared with other methods,it needs shorter time consuming and produces lower error.

  17. Global Crop Yield Reductions due to Surface Ozone Exposure: Crop Production Losses and Economic Damage in 2000 and 2030 under Two Future Scenarios of O3 Pollution (United States)

    Avnery, S.; Mauzerall, D. L.; Liu, J.; Horowitz, L. W.


    Field studies demonstrate that exposure to elevated concentrations of surface ozone (O3) may cause substantial reductions in the agricultural yields of many crops. As emissions of O3 precursors rise in many parts of the world over the next few decades, yield reductions from O3 exposure may increase the challenges of feeding a global population projected to grow from approximately 6 to 8 billion people between 2000 and 2030. This study estimates global yield reductions of three key staple crops (soybean, maize, and wheat) due to surface ozone exposure in 2000 and 2030 according to two trajectories of O3 pollution: the Intergovernmental Panel on Climate Change Special Report on Emissions Scenarios (IPCC SRES) A2 and B1 storylines, which represent upper- and lower-boundary projections, respectively, of most O3 precursor emissions in 2030. Our results indicate that year 2000 O3-induced global yield reductions ranged, depending on the O3 exposure metric used, from 3.9-15% for wheat, 8.5-14% for soybean, and 2.2-5.5% for maize. Global crop production losses totaled 79-121 million metric tons, worth 11-18 billion annually (USD2000). In the 2030-A2 scenario we find global O3-induced yield loss of wheat to be 5.4-26% (a further reduction in yield of +1.5-10% from year 2000 values), 15-19% for soybean (reduction of +0.9-11%), and 4.4-8.7% for maize (reduction of +2.1-3.2%) depending on the metric used, with total global agricultural losses worth 17-35 billion USD2000 annually (an increase of +6-17 billion in losses from 2000). Under the 2030-B1 scenario, we project less severe but still substantial reductions in yields: 4.0-17% for wheat (a further decrease in yield of +0.1-1.8% from 2000), 9.5-15% for soybean (decrease of +0.7-1.0%), and 2.5-6.0% for maize (decrease of+ 0.3-0.5%), with total losses worth 12-21 billion annually (an increase of +$1-3 billion in losses from 2000). Because our analysis uses crop data from the year 2000, which likely underestimates agricultural

  18. A Model for Creep and Creep Damage in the γ-Titanium Aluminide Ti-45Al-2Mn-2Nb

    Directory of Open Access Journals (Sweden)

    William Harrison


    Full Text Available Gamma titanium aluminides (γ-TiAl display significantly improved high temperature mechanical properties over conventional titanium alloys. Due to their low densities, these alloys are increasingly becoming strong candidates to replace nickel-base superalloys in future gas turbine aeroengine components. To determine the safe operating life of such components, a good understanding of their creep properties is essential. Of particular importance to gas turbine component design is the ability to accurately predict the rate of accumulation of creep strain to ensure that excessive deformation does not occur during the component’s service life and to quantify the effects of creep on fatigue life. The theta (θ projection technique is an illustrative example of a creep curve method which has, in this paper, been utilised to accurately represent the creep behaviour of the γ-TiAl alloy Ti -45Al-2Mn-2Nb. Furthermore, a continuum damage approach based on the θ-projection method has also been used to represent tertiary creep damage and accurately predict creep rupture.

  19. Improvement of interfacial adhesion and nondestructive damage evaluation for plasma-treated PBO and Kevlar fibers/epoxy composites using micromechanical techniques and surface wettability. (United States)

    Park, Joung-Man; Kim, Dae-Sik; Kim, Sung-Ryong


    Comparison of interfacial properties and microfailure mechanisms of oxygen-plasma treated poly(p-phenylene-2,6-benzobisoxazole (PBO, Zylon) and poly(p-phenylene terephthalamide) (PPTA, Kevlar) fibers/epoxy composites were investigated using a micromechanical technique and nondestructive acoustic emission (AE). The interfacial shear strength (IFSS) and work of adhesion, Wa, of PBO or Kevlar fiber/epoxy composites increased with oxygen-plasma treatment, due to induced hydrogen and covalent bondings at their interface. Plasma-treated Kevlar fiber showed the maximum critical surface tension and polar term, whereas the untreated PBO fiber showed the minimum values. The work of adhesion and the polar term were proportional to the IFSS directly for both PBO and Kevlar fibers. The microfibril fracture pattern of two plasma-treated fibers appeared obviously. Unlike in slow cooling, in rapid cooling, case kink band and kicking in PBO fiber appeared, whereas buckling in the Kevlar fiber was observed mainly due to compressive and residual stresses. Based on the propagation of microfibril failure toward the core region, the number of AE events for plasma-treated PBO and Kevlar fibers increased significantly compared to the untreated case. The results of nondestructive AE were consistent with microfailure modes.

  20. Corrosion damage evolution and residual strength of corroded aluminum alloys

    Institute of Scientific and Technical Information of China (English)

    Youhong Zhang; Guozhi Lv; Hui Wang; Bomei Si; Yueliang Cheng


    The LY12CZ aluminum alloy specimens were eurroded under the conditions of different test temperatures and exposure durations. After corrosion exposure, fatigue tests were performed. Scanning electron microscopy and optical microscope analyses on corrosion damage were carried out. The definition of surface corrosion damage ratio was provided to describe the extent of surface corrosion damage. On the basis of the measured data sets of the corrosion damage ratio, the probabilistic model of corrosion damage evolution was built. The corrosion damage decreased the fatigue life by a factor of about 1.25 to 2.38 and the prediction method of residual strength of the corroded structure was presented.

  1. Laser Damage Precursors in Fused Silica

    Energy Technology Data Exchange (ETDEWEB)

    Miller, P; Suratwala, T; Bude, J; Laurence, T A; Shen, N; Steele, W A; Feit, M; Menapace, J; Wong, L


    There is a longstanding, and largely unexplained, correlation between the laser damage susceptibility of optical components and both the surface quality of the optics, and the presence of near surface fractures in an optic. In the present work, a combination of acid leaching, acid etching, and confocal time resolved photoluminescence (CTP) microscopy has been used to study laser damage initiation at indentation sites. The combination of localized polishing and variations in indentation loads allows one to isolate and characterize the laser damage susceptibility of densified, plastically flowed and fractured fused silica. The present results suggest that: (1) laser damage initiation and growth are strongly correlated with fracture surfaces, while densified and plastically flowed material is relatively benign, and (2) fracture events result in the formation of an electronically defective rich surface layer which promotes energy transfer from the optical beam to the glass matrix.

  2. Phased Array Ultrasonic Nondestructive Testing for Aero-engine Turbine Blade%航空发动机涡轮叶片相控阵超声检测研究

    Institute of Scientific and Technical Information of China (English)

    江文文; 柏逢明


    超声波无损检测技术(UNT)是航空工件检测中应用较多的一种检测方法.本文对航空发动机涡轮叶片进行了超声波无损检测;传统检测是用反射波形和波幅特征分析检测出发动机涡轮叶片缺陷;相控阵超声检测(PAUT)是利用相位延迟达到相控效果,形成清晰的图像,和传统超声波检测相比,更能直观的显示缺陷的位置和形状.%Ultrasonic Nondestructive Testing (UNT) is widely used in aviation component test .This paper adopts UNT in aero-engine turbine blade .Traditional detection uses reflection waveform and amplitude characteristic to check out flaw in engine turbine blade . Phased Array Ultrasonic nondestructive Testing (PAUT) takes advantage of phased delay to obtain phased effect and product clear image .Comparing with traditional ultrasonic detection, PAUT shows position and sharp of flaw more directly.

  3. Laser-induced damage in optical materials

    CERN Document Server

    Ristau, Detlev


    Dedicated to users and developers of high-powered systems, Laser-Induced Damage in Optical Materials focuses on the research field of laser-induced damage and explores the significant and steady growth of applications for high-power lasers in the academic, industrial, and military arenas. Written by renowned experts in the field, this book concentrates on the major topics of laser-induced damage in optical materials and most specifically addresses research in laser damage that occurs in the bulk and on the surface or the coating of optical components. It considers key issues in the field of hi

  4. Femtosecond damage threshold of multilayer metal films (United States)

    Ibrahim, Wael M. G.; Elsayed-Ali, Hani E.; Shinn, Michelle D.; Bonner, Carl E.


    With the availability of terawatt laser systems with subpicosecond pulses, laser damage to optical components has become the limiting factor for further increases in the output peak power. Evaluation of different material structures in accordance to their suitability for high-power laser systems is essential. Multi-shot damage experiments, using 110 fs laser pulses at 800 nm, on polycrystalline single layer gold films and multi-layer (gold-vanadium, and gold-titanium) films were conducted. The laser incident fluence was varied, in both cases, from 0.1 to 0.6 J/cm2. No evidence of surface damage was apparent in the gold sample up to a fluence of 0.3 J/cm2. The multilayer sample experienced the onset of surface damage at the lowest fluence value used of 0.1 J/cm2. Damage results are in contrast with the time resolved ultrafast thermoreflectivity measurements that revealed a reduction of the thermoreflectivity signal for the multilayer films. This decrease in the thermoreflectivity signal signifies a reduction in the surface electron temperature that should translate in a lower lattice temperature at the later stage. Hence, one should expect a higher damage threshold for the multilayer samples. Comparison of the experimental results with the predictions of the Two-Temperature Model (TTM) is presented. The damage threshold of the single layer gold film corresponds to the melting threshold predicted by the model. In contrast to the single layer gold film, the multi-layer sample damaged at almost one third the damage threshold predicted by the TTM model. Possible damage mechanisms leading to the early onset of damage for the multilayer films are discussed.

  5. Localized versus diffuse damage: A variational approach (United States)

    Lancioni, Giovanni; Corinaldesi, Valeria


    A variational model based on incremental energy minimization is proposed to describe the evolution of damage in elastic materials. The model accounts for an elastic energy, depending on the damage variable, and for a damage energy, which has a local and a non-local term. The evolution of the displacement and damage fields, representing the problem unknowns, is determined by an incremental energy minimization problem, which is analytically solved in a special one-dimensional case, and numerically in a two-dimensional setting. By properly assigning the shapes of the elastic and damage energies, two different damage modes are reproduced: localized damage, consisting in a stress-softening process, in which damage forms in thin body portions and coalesces in fracture surfaces, and diffuse damage, which is characterized by a stress-hardening response, with damage spreading in large zones of the body. The former mechanism is typical of quasi-brittle materials, while the latter one is proper for ductile materials. Results of numerical simulations are presented, where the behaviors of both quasi-brittle and ductile materials are reproduced.

  6. Development mechanism of cavity damage under urban roads and its influence on road surface subsidence%城市道路地下空洞病害发展机理及对路面塌陷的影响

    Institute of Scientific and Technical Information of China (English)

    陶连金; 袁松; 安军海


    外界因素作用易引起城市道路地下空洞破坏,甚至向上发展至地面形成地层塌陷。基于离散元软件对城市道路路基下空洞的发展破坏进行数值模拟,分析空洞规模、埋深、施工振动、空洞周围土性对空洞稳定性的影响。结果表明:道路路面沉降随着空洞埋深的减小和尺寸的增大,均出现先急剧增加后趋于平缓的过程。该曲线的拐点为道路安全性预测的关键点。当空洞与扰动土层相距3 m以内时,必须考虑施工扰动的影响。沉降值随空洞所在土层的黏聚力和摩擦角均近似呈线性变化。该研究从颗粒细观角度揭示了地下空洞发展至路面塌陷的破坏机制,为地下病害研究提供了新方法。%This paper is concerned specifically with a deeper study addressing cavity disease—cavity damage more likely to occur under urban roads due to the external factors and even cause road surface subsidence. The study involves simulating the development and damage of cavity under urban road using distinct element software and analyzing the impact of the cavity size, buried depth, the vibration during construction, the property of soil around the cavity on the stability of the cavity. The study demonstrates that, as a result of the decrease of the cavity depth and the increase of size, the road surface is subjected to the typical subsidence tending to sharply increase, followed by a flat increase, suggesting that the point of inflexion holds the key to the road safety prediction; the occurrence of a 3-m-distance between cavity and disturbed soil necessitates the consideration of the influence of vibration during construction;and sur-face has subsidence value approximate to linear variation due to the cohesive force and the friction angle of soil to which the cavity is exposed. The study offers a new insight into failure mechanism behind the underground cavity and the resulting road surface subsidence thanks to


    Energy Technology Data Exchange (ETDEWEB)

    Hsu, P C; Dehaven, M; McClelland, M; Chidester, S; Maienschein, J L


    Thermal damage experiments were conducted on LX-04, LX-10, and LX-17 at high temperatures. Both pristine and damaged samples were characterized for their material properties. A pycnometer was used to determine sample true density and porosity. Gas permeability was measured in a newly procured system (diffusion permeameter). Burn rate was measured in the LLNL strand burner. Weight losses upon thermal exposure were insignificant. Damaged pressed parts expanded, resulting in a reduction of bulk density by up to 10%. Both gas permeabilities and burn rates of the damaged samples increased by several orders of magnitude due to higher porosity and lower density. Moduli of the damaged materials decreased significantly, an indication that the materials became weaker mechanically. Damaged materials were more sensitive to shock initiation at high temperatures. No significant sensitization was observed when the damaged samples were tested at room temperature.

  8. 航空发动机健康管理用户的诊断预测指标体系%Diagnostic and Prognostic Metrics of Aeroengine Health Management Users

    Institute of Scientific and Technical Information of China (English)

    尉询楷; 刘芳; 陈良峰; 朱纪洪; 杨立


    The need of different health management users must be met by the top design requirements of aeroengine health management. The user categories and design flow of the health management system were briefly introduced, and then the needs from the field users including logistics, flight, maintenance and fleet management were analyzed. In the perspective of diagnostics and prognostics for health management systems, the mapping relations between the different user requirements and the metrics for diagnostics and prognostics were analyzed, and the respective metrics were built. The results could help the military decision staffs make the research and development top requirements suite better for the field usage needs, also the industrial design engineers could benefit from making more satisfied research regulatory for the user requirements.%航空发动机健康管理的顶层设计必须要满足不同健康管理用户的使用要求。简要介绍了健康管理系统的用户分类和开发流程,重点分析了面向外场使用的后勤、飞行、维修、机群管理等军方健康管理用户的要求。从健康管理诊断和预测的技术实现出发,分别分析了军方不同用户的要求与诊断、预测指标之间的映射关系,建立了相应的诊断和预测指标体系。可为军方制定满足外场使用需求的研制总要求,工业部门制定贴合用户需求的研制规范提供借鉴。

  9. Laser Damage Inspection Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Salmon, J T; Brase, J M; Bliss, E S; Carrano, C J; Kegelmeyer, L M; Miller, M G; Orth, C D; Sacks, R A


    Large, high-power laser systems are often designed as reimaging multipass cavities to maximize the extraction of energy from the amplifiers. These multipass cavities often have vacuum spatial filters that suppress the growth of beam instability via B-integral effects. These spatial filters also relay images of laser damage, often nearly superimposing these images in common planes. Also, the fluence damage threshold limits the minimum size of the optics. When used as vacuum barriers in the spatial filters, these large optics present a safety hazard from the risk of implosion if the laser damage were sufficiently large. The objective of the project was to develop algorithms and methods for optical detection and characterization of laser-induced damage of optics. The system should detect small defects (about 5% of the critical size), track their growth over multiple laser shots, and characterize the defects accurately so that the optic can be replaced (at 25% of the critical size) and, hence, minimize the risk of implosion. The depth of field must be short enough to isolate the damaged vacuum barrier from other damaged optics in the beamline, and the system should also be capable of inspecting other optics in the beamline, since damage on one optic can subsequently damage subsequent optics. Laser induced damage starts as a small (<<1mm) crater and grows as material is removed on subsequent laser shots. The highly fractured rough surface of the crater scatters light from the illuminating inspection beam. This scattered light is imaged by the inspection system. Other types of defects may occur as well including inclusions in the bulk glass, tooling marks, and surface contamination. This report will discuss the detection and characterization of crater-like surface defects although the general techniques may prove useful for other types of defects. The work described here covers the development of an image processing approach and specific algorithms for defect detection

  10. Plate tectonics, damage and inheritance. (United States)

    Bercovici, David; Ricard, Yanick


    The initiation of plate tectonics on Earth is a critical event in our planet's history. The time lag between the first proto-subduction (about 4 billion years ago) and global tectonics (approximately 3 billion years ago) suggests that plates and plate boundaries became widespread over a period of 1 billion years. The reason for this time lag is unknown but fundamental to understanding the origin of plate tectonics. Here we suggest that when sufficient lithospheric damage (which promotes shear localization and long-lived weak zones) combines with transient mantle flow and migrating proto-subduction, it leads to the accumulation of weak plate boundaries and eventually to fully formed tectonic plates driven by subduction alone. We simulate this process using a grain evolution and damage mechanism with a composite rheology (which is compatible with field and laboratory observations of polycrystalline rocks), coupled to an idealized model of pressure-driven lithospheric flow in which a low-pressure zone is equivalent to the suction of convective downwellings. In the simplest case, for Earth-like conditions, a few successive rotations of the driving pressure field yield relic damaged weak zones that are inherited by the lithospheric flow to form a nearly perfect plate, with passive spreading and strike-slip margins that persist and localize further, even though flow is driven only by subduction. But for hotter surface conditions, such as those on Venus, accumulation and inheritance of damage is negligible; hence only subduction zones survive and plate tectonics does not spread, which corresponds to observations. After plates have developed, continued changes in driving forces, combined with inherited damage and weak zones, promote increased tectonic complexity, such as oblique subduction, strike-slip boundaries that are subparallel to plate motion, and spalling of minor plates.

  11. 低能氦离子辐照对钨和钼材料的表面损伤作用%Low-energy helium-ion irradiation on the surface damage of tungsten and molybdenum

    Institute of Scientific and Technical Information of China (English)

    李月; 范红玉; 杨铭; 张义武; 牛金海


    钨和钼材料具有高熔点、高热导率、低溅射率等优点成为国际热核实验反应堆计划中面向等离子体材料的候选材料。因此研究钨和钼材料的辐照损伤行为对于认识面向等离子体材料的辐照损伤机制具有重要意义。本文采用120 eV的 He+在873 K对钨和钼材料进行辐照实验,利用纳米压痕仪与导电模式原子力显微镜(Conductive Atomic Force Microscopy, CAFM)相结合,原位比较了钨和钼材料在辐照前后的表面形貌、表面微结构以及表层缺陷分布的变化特征。结果表明,低能He+辐照会导致钨和钼材料的近表面产生纳米量级氦泡缺陷,这些氦泡缺陷的存在使得样品表面产生绒毛或波浪状结构。纳米压痕深度分析和扫描电镜的分析结果表明,低能He+辐照会对Mo材料产生明显的刻蚀作用。本工作对于进一步认识低能氦离子辐照对面向等离子体材料的辐照损伤作用具有一定的科学参考意义。%Background: Due to their high melting point, high thermal conductivity, low sputtering yield, tungsten (W) and molybdenum (Mo) have been regarded as the potential candidates for plasma facing materials in fusion reactors.Purpose: This study aims to understand the irradiation damage behavior of W and Mo for the development of key fusion reactors materials. Methods: Polycrystalline W and Mo materials have been irradiated by 120-eV He ions with the irradiation temperature at 873 K.In situ analysis of these samples was carried out using nano-identation masked technique and non-destructive conductive atomic force microscopy (CAFM). The morphology, microscopic evolution and distribution of defects of these samples before and after irradiation are compared.Results:Analysis indicated that a large number of nanometer-sized helium bubbles were formed near the sample surface. Over-high internal pressure of nanometer-sized helium bubbles may result in forming protuberances of

  12. DNA damage and autophagy

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Rocha, Humberto; Garcia-Garcia, Aracely [Redox Biology Center and School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583 (United States); Panayiotidis, Mihalis I. [School of Community Health Sciences, University of Nevada, Reno, NV 89557 (United States); Franco, Rodrigo, E-mail: [Redox Biology Center and School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583 (United States)


    Both exogenous and endogenous agents are a threat to DNA integrity. Exogenous environmental agents such as ultraviolet (UV) and ionizing radiation, genotoxic chemicals and endogenous byproducts of metabolism including reactive oxygen species can cause alterations in DNA structure (DNA damage). Unrepaired DNA damage has been linked to a variety of human disorders including cancer and neurodegenerative disease. Thus, efficient mechanisms to detect DNA lesions, signal their presence and promote their repair have been evolved in cells. If DNA is effectively repaired, DNA damage response is inactivated and normal cell functioning resumes. In contrast, when DNA lesions cannot be removed, chronic DNA damage triggers specific cell responses such as cell death and senescence. Recently, DNA damage has been shown to induce autophagy, a cellular catabolic process that maintains a balance between synthesis, degradation, and recycling of cellular components. But the exact mechanisms by which DNA damage triggers autophagy are unclear. More importantly, the role of autophagy in the DNA damage response and cellular fate is unknown. In this review we analyze evidence that supports a role for autophagy as an integral part of the DNA damage response.

  13. Damage Theory Validation

    DEFF Research Database (Denmark)

    Simonsen, Bo Cerup


    This report contains a series of validation examples for the theoretical model implemented in the computer program DAMAGE. note that the validation examples are for assembled structures.......This report contains a series of validation examples for the theoretical model implemented in the computer program DAMAGE. note that the validation examples are for assembled structures....

  14. Cumulative fatigue damage models (United States)

    Mcgaw, Michael A.


    The problem of calculating expected component life under fatigue loading conditions is complicated by the fact that component loading histories contain, in many cases, cyclic loads of widely varying amplitudes. In such a case a cumulative damage model is required, in addition to a fatigue damage criterion, or life relationship, in order to compute the expected fatigue life. The traditional cumulative damage model used in design is the linear damage rule. This model, while being simple to use, can yield grossly unconservative results under certain loading conditions. Research at the NASA Lewis Research Center has led to the development of a nonlinear cumulative damage model, named the double damage curve approach (DDCA), that has greatly improved predictive capability. This model, which considers the life (or loading) level dependence of damage evolution, was applied successfully to two polycrystalline materials, 316 stainless steel and Haynes 188. The cumulative fatigue behavior of the PWA 1480 single-crystal material is currently being measured to determine the applicability of the DDCA for this material.

  15. 基于改进混合卡尔曼滤波器的航空发动机机载自适应模型%Aeroengine on-board adaptive model based on improved hybrid Kalman filter

    Institute of Scientific and Technical Information of China (English)

    陆军; 郭迎清; 张书刚


    提出了基于改进混合卡尔曼滤波器的航空发动机机载自适应模型方法,即以机载非线性模型的输出作为分段线性卡尔曼滤波器的稳态基准值,将性能蜕化因子作为该滤波器的增广状态量进行在线估计,并反馈给机载非线性模型使其完成在线更新.同时,根据工作模式切换机制使该模型获得有效输出.通过将该方法应用于某型涡扇发动机进行一系列仿真表明,在全飞行包线内、不同工作状态以及性能蜕化严重的情况下,该模型能够始终与实际发动机相匹配,满足实际应用需求.%A method of establishing aeroengine on-board adaptive model was proposed based on improved hybrid Kalman filter(IHKF).The output of nonlinear on-board engine model(NOBEM) was regarded as the steady-state basic model of piecewise linear Kalman filter(PWKF),while its performance deterioration factor was regarded as the augmented state vector of PWKF for on-line estimation,and fed back to NOBEM for on-line updating.In addition,the switching logic of work mode was established,which could make the IHKF work better.By applying this method to a turbofan engine,a series of simulation results show that the model can always match the actual engine in the whole flight envelope,under different engine states and severe performance deterioration,thus meeting the needs of practical applications.

  16. 航空发动机轴承腔油气两相流型的一个判断准则%A Criterion of the Oil/Gas Two-phase Flow Pattern in Aeroengine Bearing Chamber

    Institute of Scientific and Technical Information of China (English)

    刘曼利; 陈国定; 张永红; 苏华


    It is a potential method of reseach on two-phase oil/gas flow lubrication in aeroengine bearing chamber based on flow pattern classification, in which the identification to oil/gas two-phase flow pattern in bearing chamber is an important work. Based on the relationships between the two-phase oil/gas flow pattern and the match of geom- etry and operating condition in bearing chamber relying on nondimensional parameters and mean splashing parame- ter, a new method was proposed to identify flow pattern flow pattern identification by the present method agreed of oil/gas two-phase flow. The results of two-phase oil/gas well with the former experimental results. The present work realized evaluation of two-phase flow pattern according to the geometry and operating condition in bearing chamber, and it is conducive to analyzing two-phase oil/gas flow lubrication and designing heat transfer.%基于流型进行航空发动机轴承腔油气两相润滑分析是一个有潜力的研究途径,通过构建轴承腔油气两相流型与结构工况的关系,形成轴承腔油气两相流型的判断准则是其中重要的基础工作。借助描述轴承腔油气两相流的流型判别参数,构建轴承腔油气两相流型与结构工况的关联关系,提出轴承腔油气两相流型的判断准则,相关的轴承腔油气两相流试验现象支持了这一准则。研究工作实现了根据轴承腔结构工况条件预估轴承腔油气两相流型的途径,有助于基于流型分类进行轴承腔润滑分析和换热设计。

  17. 近距离微型广角加力燃烧室点火过程观测系统%Micro and Wide-Angle Observation System Close to Aeroengine Afterburner for Ignition Process

    Institute of Scientific and Technical Information of China (English)

    胡智涌; 段发阶


    由于加力燃烧室尾喷口环境恶劣,难以近距离对其进行观测,传统方法采用远距离观测,成像效果不佳.本文提出一种用于可见光波段的微型广角观测系统方案,使用微型相机,与水冷保护管相结合,可直接在尾喷口后1~2 m位置对加力燃烧室点火过程进行观测.相机直径7 mm,水冷管直径可达20~30 mm,视场角最大可达50°.在模拟实验中,对靶标成像清晰,细节明显.通过视觉成像技术对航空发动机加力燃烧室内部区域工作过程进行观测,得到的观测结果可用于对点火、火焰稳定性和燃烧均匀性的定性评价.%Due to the severe environment near to the jet of the afterburner, it is hard to observe.Tradi-tional observation method is remote from the afterburner and the photos are not clear enough.In order to solve this problem, a micro and wide-angle observation system was proposed in this paper.Based on a micro camera and combined with a water-cooling tube, the system is useful for visible spectrum and can be set close to the jet with a distance of 1—2 m.The camera diameter is 7 mm and the water-cooling tube diameter reach to 20—30 mm, and the largest field angle is about 50°.Experimental results show that the images of the system for the target are clear and detailed.The result of vision observation to aero-engine afterburner inner aera is available for the evaluation of ignition and combustion stability and homo-geneity.

  18. Numerical simulation on thermal radiation enviroment of a small aeroengine combustion chamber%小型航空发动机燃烧室热辐射环境数值模拟

    Institute of Scientific and Technical Information of China (English)

    刘晗; 刘跃凡


    The radiative heat transfer of high temperature gas and particles to the inner wall in the engine combus⁃tion chamber account for a large part of the total heat transfer, and it can reach 80%of the total heat transfer for lu⁃minous flame. Relevant data show that the engine combustion chamber gas and carbon black thermal radiation can achieve 2. 3 × 105 W/m2 . The reliable numerical simulations should be very important in aeroengine combustion chamber design. In this article, a small aviation combustion chamber structure was simplified, and the commercial software FLUENT was used to simulate and obtain the concentration field, temperature field, and wall heat flux un⁃der a typical condition. By analyzing the results, it shows that the radiative heat transfer lowers more than 5%of the highest temperature inside the engine combustion chamber, reducing the temperature gradient of flow field. It also has important role in the distribution of other physical quantity.%发动机燃烧室中高温气体和粒子对内壁面的辐射传热占总传热量很大一部分,对发光火焰来说能够达到总传热量的80%,有关资料表明发动机燃烧室内气体和炭黑辐射热流能达到2.3×105 W/m2,所以在先进航空发动机燃烧室的设计中需要可靠的数值仿真支持。文拟对某小型航空发动机燃烧室结构进行适当简化,并利用商业软件FLUENT数值仿真方法计算其典型工况下燃烧室内温度、组分浓度场以及壁面热流,对计算结果进行对比分析,结果表明在发动机燃烧室中考虑燃气的辐射效应使得燃烧室内最高温度降低了5%以上,使得流场的温度梯度降低,对其他各物理量的分布也具有重要的作用。

  19. Equivalent damage validation by variable cluster analysis (United States)

    Drago, Carlo; Ferlito, Rachele; Zucconi, Maria


    The main aim of this work is to perform a clustering analysis on the damage relieved in the old center of L'Aquila after the earthquake occurred on April 6, 2009 and to validate an Indicator of Equivalent Damage ED that summarizes the information reported on the AeDES card regarding the level of damage and their extension on the surface of the buildings. In particular we used a sample of 13442 masonry buildings located in an area characterized by a Macroseismic Intensity equal to 8 [1]. The aim is to ensure the coherence between the clusters and its hierarchy identified in the data of damage detected and in the data of the ED elaborated.

  20. Diabetes and nerve damage (United States)

    Diabetic neuropathy; Diabetes - neuropathy; Diabetes - peripheral neuropathy ... In people with diabetes, the body's nerves can be damaged by decreased blood flow and a high blood sugar level. This condition is ...

  1. LSD and Genetic Damage (United States)

    Dishotsky, Norman I.; And Others


    Reviews studies of the effects of lysergic acid diethylamide (LSD) on man and other organisms. Concludes that pure LSD injected in moderate doses does not cause chromosome or detectable genetic damage and is not a teratogen or carcinogen. (JM)

  2. Bypassing damaged nervous tissue

    CERN Document Server

    Shneider, M N


    We show the principal ability of bypassing damaged demyelinated portions of nervous tissue, thereby restoring its normal function for the passage of action potentials. We carry out a theoretical analysis on the basis of the synchronization mechanism of action potential propagation along a bundle of neurons, proposed recently in [1]. And we discuss the feasibility of implement a bypass to restore damaged nervous tissue and creating an artificial neuron network.

  3. Cantilever steel post damaged by wind

    Directory of Open Access Journals (Sweden)

    Wei Sha


    Full Text Available An analysis for the cause of fracture failure of a cantilever steel sign post damaged by wind has been carried out. An unusual cause of failure has been identified, which is the subject of this paper. Microscopy and microanalysis of the fracture surface showed that the failure was due to pre-existing cracks, from the fabrication of the post. This conclusion was reached after detecting and analysing a galvanised layer on the fracture surfaces.

  4. Integrated geomechanical modelling for deep subsurface damage

    NARCIS (Netherlands)

    Wees, J.D. van; Orlic, B.; Zijl, W.; Jongerius, P.; Schreppers, G.J.; Hendriks, M.


    Government, E&P and mining industry increasingly demand fundamental insight and accurate predictions on subsurface and surface deformation and damage due to exploitation of subsurface natural resources, and subsurface storage of energy residues (e.g. CO2). At this moment deformation is difficult to

  5. Molecular Cabal Contributes to Stroke Damage

    Institute of Scientific and Technical Information of China (English)


    @@ In the neural train wreck that is stroke, the cutoff of oxygen kills brain cells through a buildup of acid, as well as by overexciting receptors on the surface of brain cells. Now, researchers exploring the detailed mechanism of this excitotoxicity and acidotoxicity have discovered how an insidious chain of molecular events contributes to its damage.

  6. The structural strength of glass: hidden damage

    NARCIS (Netherlands)

    Veer, F.A.; Rodichev, Y.M.


    We discuss “hidden damage” of glass by the rolling process, which results in heterogeneous distribution of microcracks on the edge surface of glass element, which are the fracture source deteriorating glass element strength. It is shown that removal of this damage on the edges of glass elements incr

  7. Frost damage of concrete subject to confinement

    DEFF Research Database (Denmark)

    Hasholt, Marianne Tange


    When internal frost damage is observed in real concrete structures, the usual pattern is cracks with a preferred orientation parallel to the exposed surface. When exposing concrete with poor frost resistance to a standardised freeze/thaw test in the laboratory, the orientations of the resulting...

  8. Damage prediction of HP40Nb steel with coupled creep and carburization based on the continuum damage mechanics

    Institute of Scientific and Technical Information of China (English)

    Limin SHEN; Jianming GONG; Yong JIANG; Luyang GENG


    HP40Nb steel,used as a candidate material for ethylene cracking furnace tube,suffers creep and carburization damage from the complex environment of high temperature,high carbon potential and low oxygen partial pressure,and they lead to failure of the furnace tubes ahead of designed life.In order to investigate damage evolution under the complex condition,coupled creep damage and carburization damage constitutive equations were developed according to continuum damage mechanics theory.Based on the finite element ABAQUS code,user subroutines were developed for analyzing damage evolution of ethylene furnace tube under the action of coupled creepcarburization.The results show that carburization accelerates the damage process dramatically,damage value reaches the critical value along the inner surface after serving for 75,000 h under the action of creep-carburization,meanwhile the damage value is only 0.53 along the outer surface after operating the same time under the action of creep alone,which means that microcracks are generated along the inner surface under the action of coupled creep-carburization,fracture begins along the outer surface of tube under the action of creep alone.

  9. Plasto-damage modelling for semi-brittle geomaterials

    Directory of Open Access Journals (Sweden)

    Alizadeh Ali


    Full Text Available This paper presents an elastoplastic damage model for constitutive modelling of semi-brittle geomaterials showing two irreversible mechanisms. On one hand, the model deals with the plastic behaviour of a porous medium by a new variant of Barcelona Basic Model. On the other hand, the model combines the micromechanical definition of damage and phenomenological concepts in the framework of Continuum Damage Mechanics (CDM for damage modelling. A second order tensorial damage variable is adopted for the model. Damaged effective stress variables are employed for formulation of elastoplastic behaviour laws and the plastic yield surface is a damage dependent one. The model has been validated by comparing the numerical results with experimental results of argillites.

  10. Indirect identification of damage functions from damage records

    CERN Document Server

    Steinhäuser, J Micha; Kropp, Jürgen P


    In order to assess future damage caused by natural disasters, it is desirable to estimate the damage caused by single events. So called damage functions provide -- for a natural disaster of certain magnitude -- a specific damage value. However, in general, the functional form of such damage functions is unknown. We study the distributions of recorded flood damages on extended scales and deduce which damage functions lead to such distributions when the floods obey Generalized Extreme Value statistics and follow Generalized Pareto distributions. Based on the finding of broad damage distributions we investigate two possible functional forms to characterize the data. In the case of Gumbel distributed extreme events, (i) a power-law distribution density with an exponent close to 2 (Zipf's law) implies an exponential damage function; (ii) stretched exponential distribution densities imply power-law damage functions. In the case of Weibull (Frechet) distributed extreme events we find correspondingly steeper (less st...

  11. Laser-Induced Damage Initiation and Growth of Optical Materials

    Directory of Open Access Journals (Sweden)

    Jingxia Yu


    Full Text Available The lifetime of optical components is determined by the combination of laser-induced damage initiation probability and damage propagation rate during subsequent laser shots. This paper reviews both theoretical and experimental investigations on laser-induced damage initiation and growth at the surface of optics. The damage mechanism is generally considered as thermal absorption and electron avalanche, which play dominant roles for the different laser pulse durations. The typical damage morphology in the surface of components observed in experiments is also closely related to the damage mechanism. The damage crater in thermal absorption process, which can be estimated by thermal diffusion model, is typical distortion, melting, and ablation debris often with an elevated rim caused by melted material flow and resolidification. However, damage initiated by electron avalanche is often accompanied by generation of plasma, crush, and fracture, which can be explained by thermal explosion model. Damage growth at rear surface of components is extremely severe which can be explained by several models, such as fireball growth, impact crater, brittle fracture, and electric field enhancement. All the physical effects are not independent but mutually coupling. Developing theoretical models of multiphysics coupling are an important trend for future theoretical research. Meanwhile, more attention should be paid to integrated analysis both in theory and experiment.

  12. Damage Tolerance Assessment Branch (United States)

    Walker, James L.


    The Damage Tolerance Assessment Branch evaluates the ability of a structure to perform reliably throughout its service life in the presence of a defect, crack, or other form of damage. Such assessment is fundamental to the use of structural materials and requires an integral blend of materials engineering, fracture testing and analysis, and nondestructive evaluation. The vision of the Branch is to increase the safety of manned space flight by improving the fracture control and the associated nondestructive evaluation processes through development and application of standards, guidelines, advanced test and analytical methods. The Branch also strives to assist and solve non-aerospace related NDE and damage tolerance problems, providing consultation, prototyping and inspection services.

  13. Crumpling Damaged Graphene

    CERN Document Server

    Giordanelli, I; Andrade,, J S; Gomes, M A F; Herrmann, H J


    Through molecular mechanics we find that non-covalent interactions modify the fractality of crumpled damaged graphene. Pristine graphene membranes are damaged by adding random vacancies and carbon-hydrogen bonds. Crumpled membranes exhibit a fractal dimension of $ 2.71 \\pm 0.02$ when all interactions between carbon atoms are considered, and $2.30 \\pm 0.05$ when non-covalent interactions are suppressed. The transition between these two values, obtained by switching on/off the non-covalent interactions of equilibrium configurations, is shown to be reversible and independent on thermalisation. In order to explain this transition, we propose a theoretical model that is compatible with our numerical findings. Finally, we also compare damaged graphene membranes with other crumpled structures, as for instance, polymerised membranes and paper sheets, that share similar scaling properties.

  14. Failure and damage analysis of advanced materials

    CERN Document Server

    Sadowski, Tomasz


    The papers in this volume present basic concepts and new developments in failure and damage analysis with focus on advanced materials such as composites, laminates, sandwiches and foams, and also new metallic materials. Starting from some mathematical foundations (limit surfaces, symmetry considerations, invariants) new experimental results and their analysis are shown. Finally, new concepts for failure prediction and analysis will be introduced and discussed as well as new methods of failure and damage prediction for advanced metallic and non-metallic materials. Based on experimental results the traditional methods will be revised.

  15. Thermal stress simulation of laser induced damage of fused silica by contamination on the surface%表面污染物诱导熔石英损伤的热力学数值模拟

    Institute of Scientific and Technical Information of China (English)

    苗心向; 袁晓东; 程晓锋; 贺少勃; 郑万国


    为了研究高功率固体激光装置内污染诱导光学元件损伤问题,基于有限元数值方法,结合污染物诱导熔石英损伤机理,给出了熔石英样片在高功率脉冲激光辐照下的温度场和应力场分布.结果表明,激光脉冲辐照过程中主要以污染物的温度升高为主,最高至2800K,而样片温升不大,仅为7K;在激光脉冲辐照后100μs的时间内,样片表面中心快速升温至2200K,而边缘处仅为700K,在较短的距离内温度变化剧烈,由此产生的热应力导致表面发生损伤;损伤区域中心表现为压应力,边缘为拉应力,最大可达30.73MPa.测试了污染物诱导样片损伤斑的微观显微形貌,实验结果和理论计算结果符合较好.%In order to study the laser-induced damage mechanism in inertial confinement fusion system, temperature and thermal stress distributions in the fused silica, heated by repetition frequency laser, were given by means of finite element methods. The simulated results indicate the temperature of the contaminations rise to 2800K during the pulse laser irradiation, but the fused silica' s temperature mainly rise from 300K to 2200K in 100μs after irradiation, and damage induced by the thermal stress occurs. The strong compressive in the damage region is about 30. 73MPa. The highest stress outside the damage region is deviatoric hoop stress. The damage morphologies were tested by means of optical microscopy. The simulated outcomes correspond to the experiment result.

  16. Density of oxidation-induced stacking faults in damaged silicon

    NARCIS (Netherlands)

    Kuper, F.G.; Hosson, J.Th.M. De; Verwey, J.F.


    A model for the relation between density and length of oxidation-induced stacking faults on damaged silicon surfaces is proposed, based on interactions of stacking faults with dislocations and neighboring stacking faults. The model agrees with experiments.

  17. 航空发动机高速电磁阀控制模式分析研究%Research on High Speed Duty Ratio Control Method of Solenoid on Aero-engine

    Institute of Scientific and Technical Information of China (English)

    王秋霞; 樊丁; 彭凯; 刘宇琦


    High speed solenoid is a key component of aero-engine electric control system. Two control methods applied in engineering are the variable frequency method and the steady frequency method. However, it is not easy to find the research on the comparison of these two methods both at home and abroad. To better understand the different effects these two methods have on the control of the system and offer some help on the choice of the control method in engineering, the model of high speed solenoid and typical mechanical—hydraulic control system was built with AMES-im. Based on this model, two comparisons have been made. One of them was between the settled frequency duty ratio (SFDR) control algorithm and the variable frequency duty ratio (VFDR) control algorithm. The other one was done according to the different frequency in the settled frequency control. The simulation shows that the VFDR has better quality than the SFDR in the response time, and they are nearly equal in other aspects. As the frequency grows, the response time slows down while the overshoot of the system decreases. As the frequency decreases, the result is completely opposite.%高速电磁阀是航空发动机实现电子控制部件,工程应用中通常采用定频与变频两种驱动方式,而应对控制效果方面进行对比研究.为比较两种方式对系统控制的影响,为相关控制模式选型提供参考,在AMESim环境下建立了电磁阀及典型航空发动机机械液压主燃油流量控制系统的数学模型,运用数字仿真方法,研究了定频变占空比及变频变占空比两种驱动控制模式对系统性能的影响,以及定频控制模式下不同频率对系统性能的影响.结果表明:变频控制方式在快速性方面优于定频控制,其它性能相当.定频控制模式下,驱动频率增加,系统响应的超调量减小但响应速度变慢;驱动频率降低,系统的响应速度变快但超调量增大.

  18. 带执行机构的航空发动机喷口控制器设计方法%Controller Design Methodology for Aeroengine Nozzle with Actuator

    Institute of Scientific and Technical Information of China (English)



    依据发动机非线性模型求取喷口的动态模型时,存在未建模动态对线性动态模型的建模误差,由此设计的喷口控制器较难达到设计要求,尤其在大范围飞行包线内喷口控制的动态性能将会变坏;同时由于传感器噪声问题、喷口执行机构的位置饱和限制、速率饱和限制的问题,以及PI控制中的积分饱和问题的存在,这些饱和限制等干扰将会影响PI控制器的设计性能。针对上述问题提出了一种带执行机构的喷口控制器的设计方法和抑制饱和限制干扰的喷口控制逻辑设计方法。首先获取了带执行机构的线性动态增广模型,然后针对该增广模型利用迭代线性不等式方法计算了喷口的鲁棒PI控制器,并对控制器输出进行抗饱和修正,从而提高了喷口控制器的鲁棒性。引入所述方法在发动机半物理仿真中进行了验证,在全飞行包线内获得了满意的喷口控制鲁棒性能。%In order to build a nozzle dynamic model based on aeroengine non-linear model,it will induce an error between the nnmodeling dynamics and linear model dynamics resulting in the nozzle controller hard to meet its design requirement and even worse dynamics performance in nozzle control in large range flight envelope. The PI controller design performance can be affected by the sense noise, the position and velocity saturation of the actuators and the integrator wind-up of PI controller. This paper describes a design method for nozzle controller with actuators and a method of controlling logic design to surpass the saturation limitation disturbance to address all the problems above. To improve the robustness of nozzle controller, firstly, a linear dynamic augmented model with actuator should be built. Secondly, by using iterative linear inequality the robust nozzle PI controller can be obtained through augmented model calculation and saturation correction will be applied to control

  19. 航空发动机振动应力测量的贴片可靠性及优化分析%Reliability and Optimization Analysis of Strain-Gauge Application for Aeroengine Vibration Measurements

    Institute of Scientific and Technical Information of China (English)

    蔡宁泊; 侯乃先; 张成成


    为了评估航空发动机应变片粘贴误差对振动应力测量结果的影响程度,利用有限元计算与蒙特卡洛分析方法对压气机转子叶片的贴片方案进行了研究,并提出基于可靠度的贴片方案优化准则。分析结果表明:当贴片位置由应变梯度较小的B点移动至应变梯度较大的A点时,相对应变误差增加了0.5倍,贴片可靠度降低了0.3倍;当贴片方向与最大主应变方向之间的夹角由0°增加至30°时,相对应变误差增大了0.6倍,贴片可靠度降低了0.4倍;根据可靠度准则,所选贴片方案可同时对两阶模态的振动应力进行有效测量,其可靠度达到限制值0.9以上,表明将该准则用于贴片方案寻优是合适的。%The strain-gauge application schemes were investigated through finite element analysis and Mon⁃te Carlo simulation methods, so as to evaluate the impact of sensor placement tolerances on vibratory response during aero-engine vibration test. The strain-gauge application scheme optimum criterion was put forward based on reliability theory. The analysis results show that when the strain-gauge was placed from point B to point A,be⁃cause of the raising of strain gradient,the relative strain error increased by 0.5 times,and the reliability of the scheme was decreased by 0.3 times. When the angle between strain-gauge placement orientation and maximum principle strain orientation was expanded from 0° to 30°,the relative strain error increased by 0.6 times,while the reliability of the scheme was decreased by 0.4 times. According to the reliability criterion, the selected strain-gauge application scheme could effectively measure the vibration stress of two modes simultaneously,and it’s reliability exceeded the limit value of 0.9. The research indicates that it is adequate to use the reliability crite⁃rion for the strain-gauge application scheme optimization.

  20. Loss and damage (United States)

    Huq, Saleemul; Roberts, Erin; Fenton, Adrian


    Loss and damage is a relative newcomer to the climate change agenda. It has the potential to reinvigorate existing mitigation and adaptation efforts, but this will ultimately require leadership from developed countries and enhanced understanding of several key issues, such as limits to adaptation.


    Directory of Open Access Journals (Sweden)

    Jean-Louis Chermant


    Full Text Available This paper shows how it is possible to characterize and quantify the damages in materials using classical tools of automatic image analysis. Examples presented concern ceramic matrix composites, i.e. high tech materials. It gives important information to support the deformation and rupture mechanism of materials under mechanical solicitations.

  2. Investigation of dynamic characteristics of a rotor system with surface coatings (United States)

    Yang, Yang; Cao, Dengqing; Wang, Deyou


    A Jeffcott rotor system with surface coatings capable of describing the mechanical vibration resulting from unbalance and rub-impact is formulated in this article. A contact force model proposed recently to describe the impact force between the disc and casing with coatings is employed to do the dynamic analysis for the rotor system with rubbing fault. Due to the variation of penetration, the contact force model is correspondingly modified. Meanwhile, the Coulomb friction model is applied to simulate the friction characteristics. Then, the case study of rub-impact with surface coatings is simulated by the Runge-Kutta method, in which a linear interpolation method is adopted to predict the rubbing instant. Moreover, the dynamic characteristics of the rotor system with surface coatings are analyzed in terms of bifurcation plot, waveform, whirl orbit, Poincaré map and spectrum plot. And the effects of the hardness of surface coatings on the response are investigated as well. Finally, compared with the classical models, the modified contact force model is shown to be more suitable to solve the rub-impact of aero-engine with surface coatings.

  3. Effective LiDAR Damage Detection: Comparing Two Detection Algorithms

    Institute of Scientific and Technical Information of China (English)

    BIAN Haitao; BAI Libin; WANG Xiaoyu; LIU Wangiu; CHEN Shenen; WANG Shengguo


    The health conditions of highway bridges is critical for sustained transportation operations. US federal government mandates that all bridges built with public funds are to be inspected visually every two years.There is a growing consensus that additional rapid and non-intrusive methods for bridge damage evaluation are needed. This paper explores the potential of applying ground-based laser scanners for bridge damage evaluation. LiDAR has the potential of providing high-density, full-field surface static imaging. Hence, it can generate volumetric quantification of concrete corrosion or steel erosion. By recording object surface topology, LiDAR can detect different damages on the bridge structure and differentiate damage types according to the surface flatness and smoothness. To determine the effectiveness of LiDAR damage detection, two damage detection algorithms are presented and compared using scans on actual bridge damages. The results demonstrate and validate LiDAR damage quantification, which can be a powerful tool for bridge condition evaluation.

  4. A two-scale damage model with material length (United States)

    Dascalu, Cristian


    The Note presents the formulation of a class of two-scale damage models involving a micro-structural length. A homogenization method based on asymptotic developments is employed to deduce the macroscopic damage equations. The damage model completely results from energy-based micro-crack propagation laws, without supplementary phenomenological assumptions. We show that the resulting two-scale model has the property of capturing micro-structural lengths. When damage evolves, the micro-structural length is given by the ratio of the surface density of energy dissipated during the micro-crack growth and the macroscopic damage energy release rate per unit volume of the material. The use of fracture criteria based on resistance curves or power laws for sub-critical growth of micro-cracks leads to quasi-brittle and, respectively, time-dependent damage models. To cite this article: C. Dascalu, C. R. Mecanique 337 (2009).

  5. Damage Evolution On Mechanical Parts Under Cyclic Loading (United States)

    Lestriez, P.; Bogard, F.; Shan, J. L.; Guo, Y. Q.


    This paper presents a fatigue damage model, based on the continuum damage mechanics and general thermodynamic theory, proposed by Lemaitre and Chaboche, for rolling bearings under very numerous loading cycles. A flow surface of fatigue using the Sines criterion is adopted. The coupling between the hardening plasticity and damage effects is considered in the constitutive equations. An explicit algorithm of weak coupling leads to a calculation very fast. This fatigue damage model is implemented into Abaqus/Explicit using a Vumat user's subroutine. Moreover, the damage variable in function of time is transformed into a function of number of cycles. An algorithm of cycle jump, with a criterion for choosing the number increment of cycles, is proposed, which allows to largely reduce the CPU time. The present damage simulation allows to determine the lifetime of mechanical parts under cyclic loading.

  6. A GPA diagnostic system for aeroengine applications

    Institute of Scientific and Technical Information of China (English)

    Yi-Guang Li


    In this research,a GPA(Gas Path Analysis)diagnostic system enhanced with GPA Index is described for gas path sensor and component fault diagnosis.A method of measurement correction is used in order that the measurement data obtained at un-standard ambient and operating conditions can be used for diagnostic analysis.The developed diagnostic system has been implemented into a Cranfield University gas turbine performance and diagnostic analysis software PYTHIA for gas turbine performance degradation analysis.The developed method and software have been applied to a model aero gas turbine engine to test the effectiveness of the system.The analysis shows that the developed diagnostic system can diagnose degraded sensor and components effectively using performance deviation measured at un-standard ambient and operational conditions.Theoretically,the idea of the diagnostic approach can be applied to different gas turbine engines.

  7. Net Shape Manufacturing of Aeroengine Components (United States)


    Direct laser fabrication (DLF) and Net shape HIPping are two net shape manufacturing technologies which are being studied in the IRC. The direct... laser fabrication technique can produce 3-D components from their CAD files from metal powder and using a laser, the movement of which follows the paths

  8. Experimental Replication of an Aeroengine Combustion Instability (United States)

    Cohen, J. M.; Hibshman, J. R.; Proscia, W.; Rosfjord, T. J.; Wake, B. E.; McVey, J. B.; Lovett, J.; Ondas, M.; DeLaat, J.; Breisacher, K.


    Combustion instabilities in gas turbine engines are most frequently encountered during the late phases of engine development, at which point they are difficult and expensive to fix. The ability to replicate an engine-traceable combustion instability in a laboratory-scale experiment offers the opportunity to economically diagnose the problem (to determine the root cause), and to investigate solutions to the problem, such as active control. The development and validation of active combustion instability control requires that the causal dynamic processes be reproduced in experimental test facilities which can be used as a test bed for control system evaluation. This paper discusses the process through which a laboratory-scale experiment was designed to replicate an instability observed in a developmental engine. The scaling process used physically-based analyses to preserve the relevant geometric, acoustic and thermo-fluid features. The process increases the probability that results achieved in the single-nozzle experiment will be scalable to the engine.

  9. Cavitation damage prediction for the JSNS mercury target vessel (United States)

    Naoe, Takashi; Kogawa, Hiroyuki; Wakui, Takashi; Haga, Katsuhiro; Teshigawara, Makoto; Kinoshita, Hidetaka; Takada, Hiroshi; Futakawa, Masatoshi


    The liquid mercury target system for the Japan Spallation Neutron Source (JSNS) at the Materials and Life science experimental Facility (MLF) in the Japan Proton Accelerator Research Complex (J-PARC) is designed to produce pulsed neutrons. The mercury target vessel in this system, which is made of type 316L stainless steel, is damaged by pressure wave-induced cavitation due to proton beam bombardment. Currently, cavitation damage is considered to be the dominant factor influencing the service life of the target vessel rather than radiation damage. In this study, cavitation damage to the interior surface of the target vessel was predicted on the basis of accumulated damage data from off-beam and on-beam experiments. The predicted damage was compared with the damage observed in a used target vessel. Furthermore, the effect of injecting gas microbubbles on cavitation damage was predicted through the measurement of the acoustic vibration of the target vessel. It was shown that the predicted depth of cavitation damage is reasonably coincident with the observed results. Moreover, it was confirmed that the injection of gas microbubbles had an effect on cavitation damage.

  10. The cavitation erosion damage process of dynamically loaded journal bearings

    Institute of Scientific and Technical Information of China (English)

    MA Yan-yan; CHENG Xian-hua


    The cavitation damage model was built using finite element analysis software MSC.Marc.This paper attempted to numerically analyze the action process based on damage mechanics when a jet created by bubble collapse acted on the bearing surface in the process of cavitation erosion.The numerical results show that the values of equivalent plastic strain and void volume fraction increase with time.The values of damage scalar are higher on the bearing surface and subsurface,and decrease when it approaches the interface of overlay and nickel layer.The strain history and damage evolvement of beating material acted on by jet impact load can be calculated efficiently using the proposed method,which develops a new method of analyzing cavitation erosion failure of thebearing surface.

  11. Guess-Work and Reasonings on Centennial Evolution of Surface Air Temperature in Russia. Part IV: Towards Economic Estimations of Climate-Related Damages from the Bifurcation Analysis Viewpoint (United States)

    Kolokolov, Yury; Monovskaya, Anna

    The paper completes the cycle of the research devoted to the development of the experimental bifurcation analysis (not computer simulations) in order to answer the following questions: whether qualitative changes occur in the dynamics of local climate systems in a centennial timescale?; how to analyze such qualitative changes with daily resolution for local and regional space-scales?; how to establish one-to-one daily correspondence between the dynamics evolution and economic consequences for productions? To answer the questions, the unconventional conceptual model to describe the local climate dynamics was proposed and verified in the previous parts. That model (HDS-model) originates from the hysteresis regulator with double synchronization and has a variable structure due to competition between the amplitude quantization and the time quantization. The main advantage of the HDS-model is connected with the possibility to describe “internally” (on the basis of the self-regulation) the specific causal effects observed in the dynamics of local climate systems instead of “external” description of three states of the hysteresis behavior of climate systems (upper, lower and transient states). As a result, the evolution of the local climate dynamics is based on the bifurcation diagrams built by processing the data of meteorological observations, where the strange effects of the essential interannual daily variability of annual temperature variation are taken into account and explained. It opens the novel possibilities to analyze the local climate dynamics taking into account the observed resultant of all internal and external influences on each local climate system. In particular, the paper presents the viewpoint on how to estimate economic damages caused by climate-related hazards through the bifurcation analysis. That viewpoint includes the following ideas: practically each local climate system is characterized by its own time pattern of the natural qualitative

  12. Uncertainty in urban flood damage assessment due to urban drainage modelling and depth-damage curve estimation. (United States)

    Freni, G; La Loggia, G; Notaro, V


    Due to the increased occurrence of flooding events in urban areas, many procedures for flood damage quantification have been defined in recent decades. The lack of large databases in most cases is overcome by combining the output of urban drainage models and damage curves linking flooding to expected damage. The application of advanced hydraulic models as diagnostic, design and decision-making support tools has become a standard practice in hydraulic research and application. Flooding damage functions are usually evaluated by a priori estimation of potential damage (based on the value of exposed goods) or by interpolating real damage data (recorded during historical flooding events). Hydraulic models have undergone continuous advancements, pushed forward by increasing computer capacity. The details of the flooding propagation process on the surface and the details of the interconnections between underground and surface drainage systems have been studied extensively in recent years, resulting in progressively more reliable models. The same level of was advancement has not been reached with regard to damage curves, for which improvements are highly connected to data availability; this remains the main bottleneck in the expected flooding damage estimation. Such functions are usually affected by significant uncertainty intrinsically related to the collected data and to the simplified structure of the adopted functional relationships. The present paper aimed to evaluate this uncertainty by comparing the intrinsic uncertainty connected to the construction of the damage-depth function to the hydraulic model uncertainty. In this way, the paper sought to evaluate the role of hydraulic model detail level in the wider context of flood damage estimation. This paper demonstrated that the use of detailed hydraulic models might not be justified because of the higher computational cost and the significant uncertainty in damage estimation curves. This uncertainty occurs mainly

  13. Network Using Damage Progression Trends

    Directory of Open Access Journals (Sweden)

    C. J. Keulen


    damage (RAPID technique. Two damage metrics are used with the algorithm and a comparison is made to the more commonly used signal difference coefficient (SDC metric. Best case results show that damage is detected within 12 mm. The algorithm is also run on a more sparse network with no damage detection, therefore indicating that the selected arrangement is the most sparse arrangement with this configuration.

  14. Laser induced damage in optical materials: 1989 (United States)

    Bennett, H. E.; Chase, L. L.; Guenther, A. H.; Newnam, B. E.; Soileau, M. J.


    The 21st Annual Symposium on Optical Materials for High Power Lasers was divided into sessions concerning Materials and Measurements, Mirrors and Surfaces, Thin Films, and, finally, Fundamental Mechanisms. As in previous years, the emphasis of the papers presented was directed toward new frontiers and new developments. Particular emphasis was given to materials for high power apparatus. The wavelength range of the prime interest included surface characterization, thin film substrate boundaries, and advances in fundamental laser matter threshold interactions and mechanisms. The scalling of damage thresholds with pulse duration, focal area, and wavelength was discussed in detail.

  15. Contextualizing aquired brain damage

    DEFF Research Database (Denmark)

    Nielsen, Charlotte Marie Bisgaard


    Contextualizing aquired brain damage Traditional approaches study ’communicational problems’ often in a discourse of disabledness or deficitness. With an ontology of communcation as something unique and a presupposed uniqueness of each one of us, how could an integrational approach (Integrational...... for people with aquired brain injuries will be presented and comparatively discussed in a traditional versus an integrational perspective. Preliminary results and considerations on ”methods” and ”participation” from this study will be presented along with an overview of the project's empirical data....

  16. Radiation damage in graphite

    CERN Document Server

    Simmons, John Harry Walrond


    Nuclear Energy, Volume 102: Radiation Damage in Graphite provides a general account of the effects of irradiation on graphite. This book presents valuable work on the structure of the defects produced in graphite crystals by irradiation. Organized into eight chapters, this volume begins with an overview of the description of the methods of manufacturing graphite and of its physical properties. This text then presents details of the method of setting up a scale of irradiation dose. Other chapters consider the effect of irradiation at a given temperature on a physical property of graphite. This

  17. 人工材料在急性运动骨损伤中的应用与表面修饰%Surface modified biomaterials for repairing acute exercise-induced bone damage

    Institute of Scientific and Technical Information of China (English)



    背景:选择合适的表面修饰材料,有针对性的对基质支架材料进行表面改性和表面修饰,提高材料表面的细胞黏附性以及促进细胞的增生是骨组织工程支架材料研究的重要内容.目的:概述骨组织工程支架材料的运用情况,支架材料表面修饰材料的运用以及修饰方法或途径.方法:由第一作者检索1995/2010 PubMed数据及万方数据库文章,选择与组织工程支架材料运用及表面修饰相关的文献.结果与结论:成骨细胞与支架材料的作用依赖于材料的表面特性、局部形态、表面能或化学能等,这些表面特性决定了细胞怎样吸附到材料表面、细胞的定位以及细胞的功能行为等.因此生物材料的复杂性和细胞-生物材料表面的相互作用决定着进行生物支架材料表面修饰的重要性.理想的表面修饰应该兼顾表面拓扑结构、特异性识别、亲水与疏水平衡、蛋白质吸附等各个方面才能得到功能化的新生组织.目前,应用最多的表面修饰材料是Ⅰ型胶原,未来研究中将多种表面修饰材料进行复合发挥材料的互补作用,以及基因疗法和纳米材料的发展,将成为骨组织工程学领域研究的热点问题.%BACKGROUND: The key research of bone tissue engineering scaffolds is selecting the appropriate materials for surface modification, targeting to the surface modification of matrix scaffold materials, improving the cell adhesion on the surface of materials, and promoting cell proliferation.OBJECTIVE: To overview application of bone tissue engineering scaffold materials and scaffold surface modification materials,as well as the modification method or means.METHODS: A computer-based online search of PubMed database and Wanfang database from 1995 to 2010 was performed by the first author for articles related to use of tissue engineering scaffolds and surface modification.RESULTS AND CONCLUSION: The roles of osteoblasts and scaffolds

  18. Thoracic damage control surgery. (United States)

    Gonçalves, Roberto; Saad, Roberto


    The damage control surgery came up with the philosophy of applying essential maneuvers to control bleeding and abdominal contamination in trauma patients who are within the limits of their physiological reserves. This concept was extended to thoracic injuries, where relatively simple maneuvers can shorten operative time of in extremis patients. This article aims to revise the various damage control techniques in thoracic organs that must be known to the surgeon engaged in emergency care. RESUMO A cirurgia de controle de danos surgiu com a filosofia de se aplicar manobras essenciais para controle de sangramento e contaminação abdominal, em doentes traumatizados, nos limites de suas reservas fisiológicas. Este conceito se estendeu para as lesões torácicas, onde manobras relativamente simples, podem abreviar o tempo operatório de doentes in extremis. Este artigo tem como objetivo, revisar as diversas técnicas de controle de dano em órgãos torácicos, que devem ser de conhecimento do cirurgião que atua na emergência.

  19. Damage evaluation system for materials used in fossil thermal power plants

    Energy Technology Data Exchange (ETDEWEB)

    Okamura, Hiroyuki [Science Univ. of Tokyo (Japan); Sakai, Shinsuke [Tokyo Univ. (Japan); Tomita, Akira [Japan Power Engineering and Inspection Corp., Tokyo (Japan); Koyama, Teruo [Babcock Hitachi K.K., Tokyo (Japan); Sakurai, Shigeo; Kawasaki, Yoshiya [Hitachi Ltd., Ibaraki (Japan)


    The summary of this research paper is as follows: The fundamental design of the damage evaluation system is carried out based on the basic concept. Prototype systems for boilers and turbines have been constructed: (a) Boiler: (I) Evaluation part: Outer surface of the primary pendant superheater tube; (II) Damage mode: Creep; (III) Damage evaluation method: Hardness measurement method; (b) Turbine: (I) Evaluation part: Inner surface at the center bore of high pressure turbine rotor; (II) Damage mode: Creep; (III) Damage evaluation method: Electric potential method. (orig./MM)

  20. 汽车后桥从动齿轮断齿和齿面损伤失效分析%Fatigue Analysis of Tooth Surface Damage and Fracture for Rear Axle Passive Gear of Truck

    Institute of Scientific and Technical Information of China (English)

    张红霞; 杨明; 位立刚


    采用宏观微观形貌观察、化学成分分析、金相检验、硬度测试和有效硬化层深测量等方法对失效的齿轮进行了分析.结果表明:齿轮失效因为在于齿轮齿根部有较深的切削沟槽,导致齿根部应力加大,形成裂纹源,并产生高周疲劳引起齿根部断裂,进而波及其他齿产生断裂和剥落;用户在使用时也存在齿轮润滑油选用不当等问题.%In order to find out the reason for the rear axle passive gear being failure, the macro characteristics,micro-morphology, microstructure of the damaged teeth were observed and analyzed The composition, hardness and carburized layer depth were measured The results show that the failure reason of passive gear is because the gear bottom has cutting groove in cool work, which leads to the high stress and high cycle fatigue crack, causing the start tooth broken, and thus getting other teeth broken The less important problem is that the lubricating oil of gear is unwise.

  1. A finite element modeling method of aero-engine rotor without physical prototype%一种无样机的航空发动机转子有限元建模方法

    Institute of Scientific and Technical Information of China (English)

    边杰; 梅庆; 臧朝平; 杨海


    established. As the frequency error of the reference model and tested model is within 3%, the reference model can be used to update the simplified model. Finally, a correlation was analyzed and frequency response functions between the tested model and updated simplified model were com-pared. The frequency differences of them are in 2%, and matching values of modal assurance criteri-on are higher than 81%, which verified the correctness and effectiveness of the updated simplified model updated by the reference model. When this method is used to establish finite element model of a real aero-engine without physical prototype, the calculation accuracy can be improved and the a-mount of calculation can be reduced, also the period of research and development can be shortened.

  2. Laser-Induced Damage Growth on Larger-Aperture Fused Silica Optical Components at 351 nm

    Institute of Scientific and Technical Information of China (English)

    HUANG Wan-Qing; ZHANG Xiao-Min; HAN Wei; WANG Fang; XIANG Yong; LI Fu-Quan; FENG Bin; JING Feng; WEI Xiao-Feng; ZHENG Wan-Guo


    Laser-induced damage is a key lifetime limiter for optics in high-power laser facility. Damage initiation and growth under 351 nm high-fluence laser irradiation are observed on larger-aperture fused silica optics. The input surface of one fused silica component is damaged most severely and an explanation is presented. Obscurations and the area of a scratch on it are found to grow exponentially with the shot number. The area of damage site grows linearly. Micrographs of damage sites support the micro-explosion damage model which could be used to qualitatively explain the phenomena.

  3. Progressive damage state evolution and quantification in composites (United States)

    Patra, Subir; Banerjee, Sourav


    Precursor damage state quantification can be helpful for safety and operation of aircraft and defense equipment's. Damage develops in the composite material in the form of matrix cracking, fiber breakages and deboning, etc. However, detection and quantification of the damage modes at their very early stage is not possible unless modifications of the existing indispensable techniques are conceived, particularly for the quantification of multiscale damages at their early stage. Here, we present a novel nonlocal mechanics based damage detection technique for precursor damage state quantification. Micro-continuum physics is used by modifying the Christoffel equation. American society of testing and materials (ASTM) standard woven carbon fiber (CFRP) specimens were tested under Tension-Tension fatigue loading at the interval of 25,000 cycles until 500,000 cycles. Scanning Acoustic Microcopy (SAM) and Optical Microscopy (OM) were used to examine the damage development at the same interval. Surface Acoustic Wave (SAW) velocity profile on a representative volume element (RVE) of the specimen were calculated at the regular interval of 50,000 cycles. Nonlocal parameters were calculated form the micromorphic wave dispersion curve at a particular frequency of 50 MHz. We used a previously formulated parameter called "Damage entropy" which is a measure of the damage growth in the material calculated with the loading cycle. Damage entropy (DE) was calculated at every pixel on the RVE and the mean of DE was plotted at the loading interval of 25,000 cycle. Growth of DE with fatigue loading cycles was observed. Optical Imaging also performed at the interval of 25,000 cycles to investigate the development of damage inside the materials. We also calculated the mean value of the Surface Acoustic Wave (SAW) velocity and plotted with fatigue cycle which is correlated further with Damage Entropy (DE). Statistical analysis of the Surface Acoustic Wave profile (SAW) obtained at different

  4. The Fault Geometry and Surface Ruptures, the Damage Pattern and the Deformation Field of the 6th and 7th of April 2009, Mw=6.3 and Mw=5.6 Earthquakes in L'Aquila (Central Italy) Revealed by Ground and Space Based Observations (United States)

    Papanikolaou, Ioannis; Roberts, Gerald; Foumelis, Michael; Parcharidis, Issaac; Lekkas, Efthimios; Fountoulis, Ioannis


    The 2009 Mw=6.3 L' Aquila earthquake in central Italy despite its moderate magnitude caused significant loss of life and damages, producing the highest death toll in the E.U. since the 1980 Mw=6.9 Irpinia event and the highest economic cost since the 1999 Ms=5.9 Athens earthquake. It is now recognized that such events pose a high risk in most extensional settings, such as Europe at large due both to its high rate of occurrence and proximity to human habitation, forming a typical case study scenario. The deformation pattern of the 6th and 7th of April 2009 Mw=6.3 and Mw=5.6 earthquakes in L' Aquila is revealed by DInSAR analysis and compared with earthquake environmental effects. The DInSAR predicted fault surface ruptures coincide with localities where surface ruptures have been observed in the field, confirming that the ruptures observed near Paganica village are indeed primary. These ruptures are almost one order of magnitude lower than the ruptures that have been produced by other major surrounding faults from historical earthquakes. This event ruptured a small fault segment of the fault system and not one of the major postglacial fault scarps that outcrop in the area. This explains the minor primary surface ruptures that have been reported so that the 2009 L' Aquila event can be characterized as belonging to the lower end member concerning the capacity of the existing seismic sources of the area.These faults have not been activated during the 2009 event, but have the capacity to generate significantly stronger events. DInSAR analysis shows that 66% (or 305 km2) of the area deformed has been subsided whereas the remaining 34% (or 155 km2) has been uplifted. A footwall uplift versus hangingwall subsidence ratio of about 1/3 is extracted from the mainshock. The maximum subsidence (25cm) was recorded about 4.5 km away from the primary surface ruptures and about 9km away from the epicentre. In the immediate hangingwall, subsidence did not exceeded 15cm, showing that

  5. Damage scenarios and an onboard support system for damaged ships

    Directory of Open Access Journals (Sweden)

    Choi Jin


    Full Text Available Although a safety assessment of damaged ships, which considers environmental conditions such as waves and wind, is important in both the design and operation phases of ships, in Korea, rules or guidelines to conduct such assessments are not yet developed. However, NATO and European maritime societies have developed guidelines for a safety assessment. Therefore, it is required to develop rules or guidelines for safety assessments such as the Naval Ship Code (NSC of NATO. Before the safety assessment of a damaged ship can be performed, the available damage scenarios must be developed and the safety assessment criteria must be established. In this paper, the parameters related to damage by accidents are identified and categorized when developing damage scenarios. The need for damage safety assessment criteria is discussed, and an example is presented. In addition, a concept and specifications for the DB-based supporting system, which is used in the operation phases, are proposed.

  6. Shock induced damage and damage threshold of optical K9 glass investigated by laser-driven shock wave (United States)

    Song, Yunfei; Yu, Guoyang; Jiang, Lilin; Zheng, Xianxu; Liu, Yuqiang; Yang, Yanqiang


    The shock wave driven by short laser pulse is used to study the damage of brittle material K9 glass. The damage morphology of K9 glass surface indicates that the material has experienced different loading modes, respectively, at the central area and the surrounding area of the shock wave. At the central area of shock wave, the wavefront is plane and has a uniform pressure distribution, the material mainly suffers a longitudinal shock pressure; but on the edge the shock wave, the wavefront is approximately spherical, besides longitudinal pressure, transverse tensile stress will emerge inside the material. In the latter case, the damage threshold of the material is much smaller than that in the case of compressing by longitudinal pressure only. According to the relationship between damage area and shock pressure, an experimental method is proposed to measure the damage threshold of materials under shock loading. The damage threshold of K9 glass under spherical shock wave is measured to be about 1.12 GPa; and the damage threshold under plane shock wave is estimated to be between 1.82 and 1.98 GPa. They are much bigger than the damage threshold under static pressure. This method could also be used to measure the damage threshold of other materials when loaded by dynamic pressure.

  7. Contextualizing aquired brain damage

    DEFF Research Database (Denmark)

    Nielsen, Charlotte Marie Bisgaard

    Contextualizing aquired brain damage Traditional approaches study ’communicational problems’ often in a discourse of disabledness or deficitness. With an ontology of communcation as something unique and a presupposed uniqueness of each one of us, how could an integrational approach (Integrational...... Linguistics) help facilitate a new methodological perspective on the study of problems in interpersonal communication and could such a research contribute to develop a methodology that studied ”howabledness” (a term borrowed from Pirkko Raudaskoski) rather than disabledness? A study on ”inclusion” at a centre...... for people with aquired brain injuries will be presented and comparatively discussed in a traditional versus an integrational perspective. Preliminary results and considerations on ”methods” and ”participation” from this study will be presented along with an overview of the project's empirical data....

  8. Fatigue Damage in Wood

    DEFF Research Database (Denmark)

    Clorius, Christian Odin; Pedersen, Martin Bo Uhre; Hoffmeyer, Preben;


    An investigation of fatigue failure in wood subjected to load cycles in compression parallel to grain is presented. Fatigue failure is found to depend both on the total time under load and on the number of cycles.Recent accelerated fatigue research on wood is reviewed, and a discrepancy between...... failure explanation under fatigue and static load conditions is observed. In the present study small clear specimens of spruce are taken to failure in square wave formed fatigue loading at a stress excitation level corresponding to 80% of the short term strength. Four frequencies ranging from 0.01 Hz...... to 10 Hz are used. The number of cycles to failure is found to be a poor measure of the fatigue performance of wood. Creep, maximum strain, stiffness and work are monitored throughout the fatigue tests. Accumulated creep is suggested identified with damage and a correlation between stiffness reduction...

  9. Aldosterone and vascular damage. (United States)

    Duprez, D; De Buyzere, M; Rietzschel, E R; Clement, D L


    Although the aldosterone escape mechanism is well known, aldosterone has often been neglected in the pathophysiologic consequences of the activated renin-angiotensin-aldosterone system in arterial hypertension and chronic heart failure. There is now evidence for vascular synthesis of aldosterone aside from its secretion by the adrenal cortex. Moreover, aldosterone is involved in vascular smooth muscle cell hypertrophy and hyperplasia, as well as in vascular matrix impairment and endothelial dysfunction. The mechanisms of action of aldosterone may be either delayed (genomic) or rapid (nongenomic). Deleterious effects of aldosterone leading to vascular target-organ damage include (besides salt and water retention) decreased arterial and venous compliance, increased peripheral vascular resistance, and impaired autonomic vascular control due to baroreflex dysfunction.

  10. Emotionalism Following Brain Damage

    Directory of Open Access Journals (Sweden)

    Peter Allman


    Full Text Available Emotionalism is an heightened tendency to cry, or more rarely, laugh. It is commonly associated with brain damage and is often distressing to both patients and carers. Emotionalism is easily confused with depression, and when severe it can interfere with treatment. The aetiology is poorly understood but its response to drugs with different modes of action suggests that there is more than one underlying mechanism. When the components of emotionalism are studied separately a wide range is observed and they combine in a more complex and varied way than commonly held stereotyped views suggest. Most patients with emotionalism are helped by simple education and reassurance. Some severe cases respond dramatically to tricyclic antidepressants, levodopa or fluoxetine.

  11. Multivariate pluvial flood damage models

    Energy Technology Data Exchange (ETDEWEB)

    Van Ootegem, Luc [HIVA — University of Louvain (Belgium); SHERPPA — Ghent University (Belgium); Verhofstadt, Elsy [SHERPPA — Ghent University (Belgium); Van Herck, Kristine; Creten, Tom [HIVA — University of Louvain (Belgium)


    Depth–damage-functions, relating the monetary flood damage to the depth of the inundation, are commonly used in the case of fluvial floods (floods caused by a river overflowing). We construct four multivariate damage models for pluvial floods (caused by extreme rainfall) by differentiating on the one hand between ground floor floods and basement floods and on the other hand between damage to residential buildings and damage to housing contents. We do not only take into account the effect of flood-depth on damage, but also incorporate the effects of non-hazard indicators (building characteristics, behavioural indicators and socio-economic variables). By using a Tobit-estimation technique on identified victims of pluvial floods in Flanders (Belgium), we take into account the effect of cases of reported zero damage. Our results show that the flood depth is an important predictor of damage, but with a diverging impact between ground floor floods and basement floods. Also non-hazard indicators are important. For example being aware of the risk just before the water enters the building reduces content damage considerably, underlining the importance of warning systems and policy in this case of pluvial floods. - Highlights: • Prediction of damage of pluvial floods using also non-hazard information • We include ‘no damage cases’ using a Tobit model. • The damage of flood depth is stronger for ground floor than for basement floods. • Non-hazard indicators are especially important for content damage. • Potential gain of policies that increase awareness of flood risks.

  12. Nanosecond laser damage of optical multimode fibers (United States)

    Mann, Guido; Krüger, Jörg


    For pulse laser materials processing often optical step index and gradient index multimode fibers with core diameters ranging from 100 to 600 μm are used. The design of a high power fiber transmission system must take into account limitations resulting from both surface and volume damage effects. Especially, breakdown at the fiber end faces and selffocusing in the fiber volume critically influence the fiber performance. At least operation charts are desirable to select the appropriate fiber type for given laser parameters. In industry-relevant studies the influence of fiber core diameter and end face preparation on laser-induced (surface) damage thresholds (LIDT) was investigated for frequently used all-silica fiber types (manufacturer LEONI). Experiments on preform material (initial fiber material) and compact specimens (models of the cladding and coating material) accompanied the tests performed in accordance with the relevant LIDT standards ISO 21254-1 and ISO 21254-2 for 1-on-1 and S-on-1 irradiation conditions, respectively. The relation beam diameter vs. LIDT was investigated for fused silica fibers. Additionally, laser-induced (bulk) damage thresholds of fused silica preform material F300 (manufacturer Heraeus) in dependence on external mechanical stress simulating fiber bending were measured. All experiments were performed with 10-ns laser pulses at 1064 and 532 nm wavelength with a Gaussian beam profile.

  13. Measurement of damage in systemic vasculitis: a comparison of the Vasculitis Damage Index with the Combined Damage Assessment Index

    DEFF Research Database (Denmark)

    Suppiah, Ravi; Flossman, Oliver; Mukhtyar, Chetan;


    To compare the Vasculitis Damage Index (VDI) with the Combined Damage Assessment Index (CDA) as measures of damage from vasculitis.......To compare the Vasculitis Damage Index (VDI) with the Combined Damage Assessment Index (CDA) as measures of damage from vasculitis....

  14. Wavelet Transformation for Damage Identication in Wind Turbine Blades

    DEFF Research Database (Denmark)

    Ulriksen, Martin Dalgaard; Skov, Jonas falk; Kirkegaard, Poul Henning


    The present paper documents a proposed modal and wavelet analysis-based structural health monitoring (SHM) method for damage identification in wind turbine blades. A finite element (FE) model of a full-scale wind turbine blade is developed and introduced to a transverse surface crack. Hereby, post...... of the first structural blade mode. However, due to the nature of the proposed method, it is also found that the accuracy of the damage assessment highly depends on the number of employed measurement points....

  15. Design Manual for Impact Damage Tolerant Aircraft Structure. Addendum (United States)


    extensively damaged as a result of delamination and rear surface spallation . Excessive gauges are required to minimise damage. Therefore, increasing skin...Panels. ’ 10 0 129-grain steal tube 0 12ŝ-grai steel spbere 6000 y 3/16-tech diater drilled bole 30W’ 20000 5 , 0 1 000 I t 0 3000 0 120000 J 005 OO6 0

  16. Detection of Damage in Operating Wind Turbines by Signature Distances

    Directory of Open Access Journals (Sweden)

    James F. Manwell


    Full Text Available Wind turbines operate in the atmospheric boundary layer and are subject to complex random loading. This precludes using a deterministic response of healthy turbines as the baseline for identifying the effect of damage on the measured response of operating turbines. In the absence of such a deterministic response, the stochastic dynamic response of the tower to a shutdown maneuver is found to be affected distinctively by damage in contrast to wind. Such a dynamic response, however, cannot be established for the blades. As an alternative, the estimate of blade damage is sought through its effect on the third or fourth modal frequency, each found to be mostly unaffected by wind. To discern the effect of damage from the wind effect on these responses, a unified method of damage detection is introduced that accommodates different responses. In this method, the dynamic responses are transformed to surfaces via continuous wavelet transforms to accentuate the effect of wind or damage on the dynamic response. Regions of significant deviations between these surfaces are then isolated in their corresponding planes to capture the change signatures. The image distances between these change signatures are shown to produce consistent estimates of damage for both the tower and the blades in presence of varying wind field profiles.

  17. Damage and structural defects in the surface lager of pure molybdenum induced by high-current pulsed electron beam%强流脉冲电子束辐照诱发纯钼表面的损伤效应及结构缺陷

    Institute of Scientific and Technical Information of China (English)

    季乐; 杨盛志; 蔡杰; 李艳; 王晓彤; 张在强; 侯秀丽; 关庆丰


    利用强流脉冲电子束(HCPEB)装置对纯钼表面进行辐照处理,并利用X射线衍射仪,扫描电子显微镜(SEM)、透射电子显微镜(TEM)详细分析了辐照表面的微观结构和损伤效应.1次HCPEB辐照后,纯钼表层积聚了极大的残余应力,多次辐照后表面未融化区域出现大量绝热剪切带,且局部区域发生开裂.微观结构分析显示,辐照后材料表面形成发散状的位错组态和大量空位簇缺陷;绝热剪切带内部是尺寸为1µm左右等轴状的再结晶晶粒.剪切带造成的材料表面局部软化以及间隙原子偏聚于晶界是材料发生开裂的主要原因.另外,表面熔化区域可形成尺寸为20 nm左右的纳米晶.%High-current pulsed electron beam (HCPEB) technique was applied to induce the surface irradiation of pure molybdenum. Mi-crostructures and damaging effect of the irradiated surface were investigated in detail by X-ray diffraction, scanning electron mi-croscopy (SEM) and transmission electron microscopy (TEM). After 1 pulse of HCPEB irradiation, a high level of residual stress is amassed in the irradiated surface layer, while after several pulses of irradiation, a large number of adiabatic shear bands are formed on the unmelted regions of the surface, and local cracking occurs in these regions. Microstructure observations show that scattered dislocations and large amounts of vacancy clusters are formed on the irradiated surface. The adiabatic shear bands are composed of fine recrystallized grains with an average size about 1 µm. The partial softening of the irradiated surface induced by adiabatic shear bands, and the segregation of interstitial atoms in grain boundaries are primarily responsible for the surface cracking of the material. Further, nanocrystallines (20 nm) are also formed in some melted regions of the surface.

  18. Excavation damaged zone

    Energy Technology Data Exchange (ETDEWEB)

    Poulain, S.; Sergeant, C.; Vesvres, M.H.; Simonoff, M.; Lavielle, B.; Thomas, B.; Gilabert, E. [Bordeaux-1 Univ., I and 2/CNRS and GdR FORPRO 0788, Nuclear Analytical and Bioenvironmental Chemistry 33 - Gradignan (France); Poulain, S.; Altmann, S.; Lenoir, N.; Barnichon, J.D.; Wileveau, Y.; Lebon, P. [ANDRA - Agence Nationale pour la Gestion des Dechets Radioactifs, 92 - Chatenay Malabry (France); Le Marrec, C. [Bordeaux-1 Univ., ISTAB, INRA, UMR Oenologie - ISVV, 33 - Talence (France); Vinsot, A.; Dewonck, S.; Wileveau, Y.; Armand, G.; Cruchaudet, P.; Rebours, H.; Morel, J. [Agence Nationale pour la Gestion des Dechets Radioactifs, Lab. de Souterrain de Meuse/Haute-Marne, 55 - Bure (France); Lanyon, G.W. [Fracture Systems Ltd, Tregurrian, Ayr, St Ives, Cornwall (United Kingdom); Marschall, P.; Vietor, T. [NAGRA - National Cooperative for the Disposal of Radioactive Waste, Wettingen (Switzerland); Bourdeau, C.; Dedecker, F.; Billaux, D. [ITASCA Consultants, S.A.S., 69 - Ecully (France); Lenoir, N.; Desrues, J.; Viggiani, G.; Besuelle, P. [Laboratoire 3S-R - Sols Solides Structures-Risques, 38 - Grenoble (France); Bornert, M. [Ecole Polytechnique, LMS - Lab. de Mecanique des Solides, 91 - Palaiseau (France); Arson, C.; Gatmiri, B. [CERMES, Ecole Nationale des Ponts et Chaussees, 77 - Marne-la-Vallee (France); Gatmiri, B. [University of Tehran (Iran, Islamic Republic of); Bernier, F. [ESV EURIDICE GIE - European Underground Research Infrastructure for Disposal of Nuclear Waste in Clay Environment (Belgium); Nussbaum, C.; Mori, O. [Geotechnical Institute Ltd., Fabrique de Chaux, St-Ursanne (Switzerland); Bossart, P. [Swisstopo - Federal Office of Topography, Wabern (Switzerland); Schuster, K.; Alheid, H.J. [BGR - Bundesanstalt fur Geowissenschaften und Rohstoffe, Hannover (Germany); Lavanchy, J.M.; Croise, J.; Schwarz, R. [Colenco Power Engineering AG, Groundwater Protection and Waste Disposal, Baden (Switzerland)] [and others


    This session gathers 13 articles dealing with: autochthonous and colonizing microorganisms in argillaceous underground environments (S. Poulain, C. Sergeant, C. Le Marrec, M.H. Vesvres, A. Vinsot, S. Dewonck, M. Simonoff, S. Altmann); the discrete fracture network modelling of the Hg-a experiment at the Mont Terri rock Laboratory (G.W. Lanyon, P. Marschall, T. Vietor); the discrete modelling of drift behaviour in the Meuse/Haute-Marne URL, France (C. Bourdeau, F. Dedecker, D. Billaux); the fracturing in Callovo-Oxfordian argillite under triaxial compression studied by X-ray microtomography (N. Lenoir, J. Desrues, G. Viggiani, P. Besuelle, M. Bornert, J.D. Barnichon); a general review of the damage models for the EDZ creation (C. Arson, B. Gatmiri); similarities in the Hydro-Mechanical response of Callovo-Oxfordian clay and Boom clay during gallery excavation (Y. Wileveau, F. Bernier); the different geometries of the EDZ fracture networks in the Mont Terri and Meuse/Haute-Marne rock laboratories: Structural approach (C. Nussbaum, Y. Wileveau, P. Bossart, A. Moeri, G. Armand); the characterisation of the Excavation-Damaged Zone in the Meuse/Haute-Marne Underground Research Laboratory (G. Armand, P. Lebon, M. Cruchaudet, H. Rebours, J. Morel, Y. Wileveau); the EDZ characterisation with ultrasonic interval velocity measurements in the Meuse/Haute-Marne URL, performed between depth of 85 m and 504 m (K. Schuster, H.J. Alheid); the clay formation at the Meuse Haute Marne URL: evaluation of the impact of resin filled slots on flow paths characteristics within the EDZ (J.M. Lavanchy, J. Croise, R. Schwarz, G. Armand, M. Cruchaudet); the characterisation and evolution of EDZ by extraction and analyse of noble gases in pore waters in the Meuse/Haute Marne URL site (B. Lavielle, B. Thomas, E. Gilabert); in-situ gas test for the characterisation of Excavation Disturbed Zone at the Meuse/Haute Marne URL (H. Shao, K. Schuster, J. Soennke, V. Braeuer); and the flow and reactive

  19. A stochastic model updating strategy-based improved response surface model and advanced Monte Carlo simulation (United States)

    Zhai, Xue; Fei, Cheng-Wei; Choy, Yat-Sze; Wang, Jian-Jun


    To improve the accuracy and efficiency of computation model for complex structures, the stochastic model updating (SMU) strategy was proposed by combining the improved response surface model (IRSM) and the advanced Monte Carlo (MC) method based on experimental static test, prior information and uncertainties. Firstly, the IRSM and its mathematical model were developed with the emphasis on moving least-square method, and the advanced MC simulation method is studied based on Latin hypercube sampling method as well. And then the SMU procedure was presented with experimental static test for complex structure. The SMUs of simply-supported beam and aeroengine stator system (casings) were implemented to validate the proposed IRSM and advanced MC simulation method. The results show that (1) the SMU strategy hold high computational precision and efficiency for the SMUs of complex structural system; (2) the IRSM is demonstrated to be an effective model due to its SMU time is far less than that of traditional response surface method, which is promising to improve the computational speed and accuracy of SMU; (3) the advanced MC method observably decrease the samples from finite element simulations and the elapsed time of SMU. The efforts of this paper provide a promising SMU strategy for complex structure and enrich the theory of model updating.

  20. Road Damage Following Earthquake (United States)


    Ground shaking triggered liquefaction in a subsurface layer of water-saturated sand, producing differential lateral and vertical movement in a overlying carapace of unliquified sand and slit, which moved from right to left towards the Pajaro River. This mode of ground failure, termed lateral spreading, is a principal cause of liquefaction-related earthquake damage caused by the Oct. 17, 1989, Loma Prieta earthquake. Sand and soil grains have faces that can cause friction as they roll and slide against each other, or even cause sticking and form small voids between grains. This complex behavior can cause soil to behave like a liquid under certain conditions such as earthquakes or when powders are handled in industrial processes. Mechanics of Granular Materials (MGM) experiments aboard the Space Shuttle use the microgravity of space to simulate this behavior under conditons that carnot be achieved in laboratory tests on Earth. MGM is shedding light on the behavior of fine-grain materials under low effective stresses. Applications include earthquake engineering, granular flow technologies (such as powder feed systems for pharmaceuticals and fertilizers), and terrestrial and planetary geology. Nine MGM specimens have flown on two Space Shuttle flights. Another three are scheduled to fly on STS-107. The principal investigator is Stein Sture of the University of Colorado at Boulder. Credit: S.D. Ellen, U.S. Geological Survey

  1. Damage modelling in Plasma Facing Components

    Energy Technology Data Exchange (ETDEWEB)

    Martin, E.; Camus, G. [Bordeaux-1 Univ. des Sciences et Technologies-3, LCTS, Lab. des Composites Thermostructuraux, CNRS-UMR 5801, 33 - Pessac, (France); Schlosser, J. [Association Euratom-CEA Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee


    Full text of publication follows: The plasma facing components (PFC) of controlled fusion devices are submitted to high heat fluxes in operating conditions (10 MW/m2 for Tore Supra and up to 20 MW/m{sup 2} for ITER, Cadarache, France). Active cooling is required to maintain a reasonable surface temperature and to avoid critical heat flux and melting of the components. The PFC developed for Tore Supra are made of a carbon/carbon (C/C) composite flat tile bonded to a copper alloy heat sink. Under operating conditions, because of the thermal expansion mismatch existing between the C/C composite and the copper alloy, these components withstand significant stresses which induce damage in the C/C material as well as at the copper/composite interface. Design tools are thus required in order to analyse the initiation and the propagation of damage in thermally loaded PFC. The present study describes a modelling approach aimed at predicting damage in actively cooled PFC. For this purpose, dedicated experimental procedures have been developed and sound constitutive laws taking into account the damage related non linear behaviour of both the C/C material and the Cu-C/C joint have been established. Various tests have first been performed on C/C samples in tension and compression, within the fibre axis and off-axis, as well as in shear using a Iosipescu type device, in order to carefully analyse the non-linear mechanical behaviour of this material. A constitutive law able to handle complex multiaxial loadings, established within a classical thermodynamical framework and using scalar damage variables, was then identified. Tensile and shear tests were also performed on C/C-Cu samples in order to identify a cohesive zone model representative of the damageable behaviour of the joint. These constitutive laws were then introduced in a numerical model representative of a PFC. Obtained results have evidenced the progressive development of damage which takes place in the assembly when

  2. Grounding Damage to Conventional Vessels

    DEFF Research Database (Denmark)

    Lützen, Marie; Simonsen, Bo Cerup


    The present paper is concerned with rational design of conventional vessels with regard to bottom damage generated in grounding accidents. The aim of the work described here is to improve the design basis, primarily through analysis of new statistical data for grounding damage. The current...

  3. Damage growth in aerospace composites

    CERN Document Server


    This book presents novel methods for the simulation of damage evolution in aerospace composites that will assist in predicting damage onset and growth and thus foster less conservative designs which realize the promised economic benefits of composite materials. The presented integrated numerical/experimental methodologies are capable of taking into account the presence of damage and its evolution in composite structures from the early phases of the design (conceptual design) through to the detailed finite element method analysis and verification phase. The book is based on the GARTEUR Research Project AG-32, which ran from 2007 to 2012, and documents the main results of that project. In addition, the state of the art in European projects on damage evolution in composites is reviewed. While the high specific strength and stiffness of composite materials make them suitable for aerospace structures, their sensitivity to damage means that designing with composites is a challenging task. The new approaches describ...

  4. Mitigation of organic laser damage precursors from chemical processing of fused silica. (United States)

    Baxamusa, S; Miller, P E; Wong, L; Steele, R; Shen, N; Bude, J


    Increases in the laser damage threshold of fused silica have been driven by the successive elimination of near-surface damage precursors such as polishing residue, fractures, and inorganic salts. In this work, we show that trace impurities in ultrapure water used to process fused silica optics may be responsible for the formation of carbonaceous deposits. We use surrogate materials to show that organic compounds precipitated onto fused silica surfaces form discrete damage precursors. Following a standard etching process, solvent-free oxidative decomposition using oxygen plasma or high-temperature thermal treatments in air reduced the total density of damage precursors to as low as inorganic compounds are more likely to cause damage when they are tightly adhered to a surface, which may explain why high-temperature thermal treatments have been historically unsuccessful at removing extrinsic damage precursors from fused silica.

  5. DNA damage in neurodegenerative diseases

    Energy Technology Data Exchange (ETDEWEB)

    Coppedè, Fabio, E-mail:; Migliore, Lucia, E-mail:


    Highlights: • Oxidative DNA damage is one of the earliest detectable events in the neurodegenerative process. • The mitochondrial DNA is more vulnerable to oxidative attack than the nuclear DNA. • Cytogenetic damage has been largely documented in Alzheimer's disease patients. • The question of whether DNA damage is cause or consequence of neurodegeneration is still open. • Increasing evidence links DNA damage and repair with epigenetic phenomena. - Abstract: Following the observation of increased oxidative DNA damage in nuclear and mitochondrial DNA extracted from post-mortem brain regions of patients affected by neurodegenerative diseases, the last years of the previous century and the first decade of the present one have been largely dedicated to the search of markers of DNA damage in neuronal samples and peripheral tissues of patients in early, intermediate or late stages of neurodegeneration. Those studies allowed to demonstrate that oxidative DNA damage is one of the earliest detectable events in neurodegeneration, but also revealed cytogenetic damage in neurodegenerative conditions, such as for example a tendency towards chromosome 21 malsegregation in Alzheimer's disease. As it happens for many neurodegenerative risk factors the question of whether DNA damage is cause or consequence of the neurodegenerative process is still open, and probably both is true. The research interest in markers of oxidative stress was shifted, in recent years, towards the search of epigenetic biomarkers of neurodegenerative disorders, following the accumulating evidence of a substantial contribution of epigenetic mechanisms to learning, memory processes, behavioural disorders and neurodegeneration. Increasing evidence is however linking DNA damage and repair with epigenetic phenomena, thereby opening the way to a very attractive and timely research topic in neurodegenerative diseases. We will address those issues in the context of Alzheimer's disease

  6. Evolution of the passive film on mechanically damaged nitinol. (United States)

    Schroeder, Valeska


    The corrosion behavior of Nitinol-based medical implants is critical to their success in vivo. Contemporary Nitinol-based medical implants are typically chemically passivated or electrochemically polished to form a protective passive film. However, mechanically formed surfaces caused by handling damage, fretting, or fatigue fracture may also be present on a device in vivo. In this study, mechanically polished surfaces are used to simulate mechanically damaged surfaces such that analytical techniques, including electrochemical impedance spectroscopy, open circuit potential monitoring, X-ray photoelectron spectroscopy (XPS), and Mott-Schottky analysis may be used to monitor the evolution of the passive film on mechanically damaged Nitinol. These mechanically polished Nitinol surfaces are compared with chemically passivated and electrochemically polished Nitinol surfaces and mechanically polished titanium surfaces in phosphate buffered saline solution. The mechanically polished Nitinol exhibits lower impedance at low frequencies, empirically modeled to a thinner film with lower film resistance than chemically passivated and electrochemically polished Nitinol and mechanically polished titanium. Moreover, the passive film on mechanically polished Nitinol continues to develop over time, increasing in its thickness and film resistance. This characterization demonstrates that mechanically formed surfaces may be initially less protective than chemically passivated and electrochemically polished Nitinol surfaces, but continue to become thicker and more resistant to electrochemical reactions with exposure to saline solution.


    Directory of Open Access Journals (Sweden)

    Karin Kocúrová


    Full Text Available The article deals with the analysis of a damaged part, which was designed for use in a mechanical clutch of a car. The crack in the part was found during the production inspection. The aim of metallographic and fractography analyses of the fracture surfaces was to discover the reasons for the crack. The reason for creating the crack was the formation of smaller cracks in the production during pressing process of the semiproduct. These cracks even grew after the following thermochemical treatment. The fracture was initiated during the straightening process of quenched part.


    Energy Technology Data Exchange (ETDEWEB)



    During this year we performed two major projects: I. We developed a detailed theoretical model which complements our experiments on surface DNA electrophoresis. We found that it was possible to enhance the separation of DNA chains by imposing a chemical nanoscale pattern on the surface. This approach utilized the surface interaction effect of the DNA chains with the substrate and is a refinement to our previous method in which DNA chains were separated on homogeneous flat surfaces. By introducing the nano-patterns on the surface, the conformational changes of DNA chains of different lengths can be amplified, which results in the different friction strengths with the substrate surface. Our results also show that, when compared to the DNA electrophoresis performed on homogeneous flat surfaces, nanopatterned surfaces offer a larger window in choosing different surface interactions to achieve separation. II. In collaboration with a large international manufacturer of skin care products we also embarked on a project involving photo toxicity of titanium dioxide nanoparticles, which are a key ingredient in sunscreen and cosmetic lotions. The results clearly implicated the nanoparticles in catalyzing damage to chromosomal DNA. We then used this knowledge to develop a polymer/anti-oxidant coating which prevented the photocatalytic reaction on DNA while still retaining the UV absorptive properties of the nanoparticles. The standard gel electrophoresis was not sufficient in determining the extent of the DNA damage. The conclusions of this study were based predominantly on analysis obtained with the surface electrophoresis method.

  9. Experimental verification of a progressive damage model for composite laminates based on continuum damage mechanics. M.S. Thesis Final Report (United States)

    Coats, Timothy William


    Progressive failure is a crucial concern when using laminated composites in structural design. Therefore the ability to model damage and predict the life of laminated composites is vital. The purpose of this research was to experimentally verify the application of the continuum damage model, a progressive failure theory utilizing continuum damage mechanics, to a toughened material system. Damage due to tension-tension fatigue was documented for the IM7/5260 composite laminates. Crack density and delamination surface area were used to calculate matrix cracking and delamination internal state variables, respectively, to predict stiffness loss. A damage dependent finite element code qualitatively predicted trends in transverse matrix cracking, axial splits and local stress-strain distributions for notched quasi-isotropic laminates. The predictions were similar to the experimental data and it was concluded that the continuum damage model provided a good prediction of stiffness loss while qualitatively predicting damage growth in notched laminates.

  10. Dynamics and Adaptive Control for Stability Recovery of Damaged Aircraft (United States)

    Nguyen, Nhan; Krishnakumar, Kalmanje; Kaneshige, John; Nespeca, Pascal


    This paper presents a recent study of a damaged generic transport model as part of a NASA research project to investigate adaptive control methods for stability recovery of damaged aircraft operating in off-nominal flight conditions under damage and or failures. Aerodynamic modeling of damage effects is performed using an aerodynamic code to assess changes in the stability and control derivatives of a generic transport aircraft. Certain types of damage such as damage to one of the wings or horizontal stabilizers can cause the aircraft to become asymmetric, thus resulting in a coupling between the longitudinal and lateral motions. Flight dynamics for a general asymmetric aircraft is derived to account for changes in the center of gravity that can compromise the stability of the damaged aircraft. An iterative trim analysis for the translational motion is developed to refine the trim procedure by accounting for the effects of the control surface deflection. A hybrid direct-indirect neural network, adaptive flight control is proposed as an adaptive law for stabilizing the rotational motion of the damaged aircraft. The indirect adaptation is designed to estimate the plant dynamics of the damaged aircraft in conjunction with the direct adaptation that computes the control augmentation. Two approaches are presented 1) an adaptive law derived from the Lyapunov stability theory to ensure that the signals are bounded, and 2) a recursive least-square method for parameter identification. A hardware-in-the-loop simulation is conducted and demonstrates the effectiveness of the direct neural network adaptive flight control in the stability recovery of the damaged aircraft. A preliminary simulation of the hybrid adaptive flight control has been performed and initial data have shown the effectiveness of the proposed hybrid approach. Future work will include further investigations and high-fidelity simulations of the proposed hybrid adaptive Bight control approach.

  11. An improved damaging model for structured clays

    Institute of Scientific and Technical Information of China (English)

    姜岩; 雷华阳; 郑刚; 徐舜华


    An improved damaging model formulated within the framework of bounding surface for structured clays was proposed. The model was intended to describe the effects of structure degradation due to geotechnical loading. The predictive capability of the model was compared with those of triaxial compression test on Tianjin soft clays. The results show that, by incorporating a new damage function into the model, the reduction of elastic bulk and shear modulus with elastic deformations and the reduction of plastic bulk modulus and shear modulus with plastic deformations are able to be appreciable. Before the axial strain reaches 15%, the axial strain computed from the model is smaller than that from the test under the drained condition. Under the undrained condition, after the axial strain reaches 1%, the axial strain increases quickly because of the complete loss of structure and stiffness; and the result computed from the model is nearly equal to that from the model without the incorporation of the damage function due to less plastic strain under undrained condition test.

  12. Enhanced damage characterization using wavefield imaging methods (United States)

    Blackshire, James L.


    Wavefield imaging methods are becoming a popular tool for characterizing and studying elastic field interactions in a wide variety of material systems. By using a scanning laser vibrometry detection system, the transient displacement fields generated by an ultrasonic source can be visualized and studied in detail. As a tool for quantitative nondestructive evaluation, the visualization of elastic waves provides a unique opportunity for understanding the scattering of elastic waves from insipient damage, where the detection and characterization of damage features using ultrasound can be enhanced in many instances. In the present effort, the detection and direct imaging of fatigue cracks in metals, and delaminations in composites, is described. An examination of the transient displacement fields near the scattering sites show additional details related to the local damage morphology, which can be difficult to account for using traditional far-field NDE sensing methods. A combination of forward models and experimental wavefield imaging methods were used to explore enhancement opportunities for the full 3-dimensional characterization of surface-breaking cracks and delaminations.

  13. Lightning Damage to Wind Turbine Blades From Wind Farms in the U.S

    DEFF Research Database (Denmark)

    Candela Garolera, Anna; Madsen, Søren Find; Nissim, Maya;


    This paper presents statistical data about lightning damage on wind turbine blades reported at different wind farms in the U.S. The analysis is based on 304 cases of damage due to direct lightning attachment on the blade surface. This study includes a large variety of blades with different lengths......, laminate structure, and lightning protection systems. The statistics consist of the distribution of lightning damage along the blade and classify the damage by severity. In addition, the frequency of lightning damage to more than one blade of a wind turbine after a thunderstorm is assessed. The results...

  14. Generation of Scratches and Their Effects on Laser Damage Performance of Silica Glass (United States)

    Li, Yaguo; Ye, Hui; Yuan, Zhigang; Liu, Zhichao; Zheng, Yi; Zhang, Zhe; Zhao, Shijie; Wang, Jian; Xu, Qiao


    Scratches are deleterious to precision optics because they can obscure and modulate incident laser light, which will increase the probability of damage to optical components. We here imitated the generation of brittle and ductile scratches during polishing process and endeavored to find out the possible influence of scratches on laser induced damage. Brittle scratches can be induced by spiking large sized abrasives and small abrasives may only generate ductile scratches. Both surface roughness and transmittivity are degraded due to the appearance of brittle scratches while ductile scratches make little difference to surface roughness and transmittance. However, ductile and brittle scratches greatly increase the density of damage about one order of magnitude relative to unscratched surface. In particular, ductile scratches also play an unignorable role in laser induced damage, which is different from previous knowledge. Furthermore, ZrO2 and Al2O3 polished surfaces appear to perform best in terms of damage density. PMID:27703218

  15. Seismic damage identification for steel structures using distributed fiber optics. (United States)

    Hou, Shuang; Cai, C S; Ou, Jinping


    A distributed fiber optic monitoring methodology based on optic time domain reflectometry technology is developed for seismic damage identification of steel structures. Epoxy with a strength closely associated to a specified structure damage state is used for bonding zigzagged configured optic fibers on the surfaces of the structure. Sensing the local deformation of the structure, the epoxy modulates the signal change within the optic fiber in response to the damage state of the structure. A monotonic loading test is conducted on a steel specimen installed with the proposed sensing system using selected epoxy that will crack at the designated strain level, which indicates the damage of the steel structure. Then, using the selected epoxy, a varying degree of cyclic loading amplitudes, which is associated with different damage states, is applied on a second specimen. The test results show that the specimen's damage can be identified by the optic sensors, and its maximum local deformation can be recorded by the sensing system; moreover, the damage evolution can also be identified.

  16. The distribution of subsurface damage in fused silica

    Energy Technology Data Exchange (ETDEWEB)

    Miller, P E; Suratwala, T I; Wong, L L; Feit, M D; Menapace, J A; Davis, P J; Steele, R A


    Managing subsurface damage during the shaping process and removing subsurface damage during the polishing process is essential in the production of low damage density optical components, such as those required for use on high peak power lasers. Removal of subsurface damage, during the polishing process, requires polishing to a depth which is greater than the depth of the residual cracks present following the shaping process. To successfully manage, and ultimately remove subsurface damage, understanding the distribution and character of fractures in the subsurface region introduced during fabrication process is important. We have characterized the depth and morphology of subsurface fractures present following fixed abrasive and loose abrasive grinding processes. At shallow depths lateral cracks and an overlapping series of trailing indentation fractures were found to be present. At greater depths, subsurface damage consists of a series of trailing indentation fractures. The area density of trailing fractures changes as a function of depth, however the length and shape of individual cracks remain nearly constant for a given grinding process. We have developed and applied a model to interpret the depth and crack length distributions of subsurface surface damage in terms of key variables including abrasive size and load.


    Institute of Scientific and Technical Information of China (English)

    X.Bai; D.B.Sun; H.Y.Yu; X.L.Zhang


    The influence of the surface galvanic effects of 1Cr13 SS during cavitation damage hasbeen investigated in NaCl solutions. The results show that the solution concentrationand area ratio of bubble unacted surface to the bubble-acted surface greatly influencethe cavitation damage of the alloy. The surface galvanic effects can speed up thedissolution rate of the alloy, and the mass loss per area of the alloy increases linearlywith the area ratio of bubble unacted surface to the bubble acted surface of the alloy.

  18. Clinical light damage to the eye

    Energy Technology Data Exchange (ETDEWEB)

    Miller, D.


    This book contains four sections: The Nature of Light and of Light Damage to Biological Tissues; Light Damage to the Eye; Protecting the Eye from Light Damage; and Overview of Light Damage to the Eye. Some of the paper titles are: Ultraviolet-Absorbing Intraocular Lens Implants; Phototoxic Changes in the Retina; Light Damage to the Lens; and Radiation, Light, and Sight.

  19. Low cost CCD camera protection against neutron radiation damage. (United States)

    Kok, J G M


    At a radiotherapy department cancer patients are treated with high energy electron and photon beams. These beams are produced by a linear accelerator. A closed circuit television system is used to monitor patients during treatment. Although CCD cameras are rather resistant to stray radiation, they are damaged by the low flux of neutrons which are produced by the linac as a side effect. PVC can be used to reduce damage to CCD cameras induced by neutron radiation. A box with 6 cm thick walls will extend the life of the camera at least by a factor of two. A PVC neutron shield is inexpensive. PVC is easy to obtain and the box is simple to construct. A similar box made out of PE will not reduce neutron damage to a CCD camera. Although PE is a good medium to moderate faster neutrons, thereby reducing some of the bulk defects, it will not capture thermal neutrons which induce surface damage.

  20. Infectious Keratitis: Secreted Bacterial Proteins That Mediate Corneal Damage

    Directory of Open Access Journals (Sweden)

    Mary E. Marquart


    Full Text Available Ocular bacterial infections are universally treated with antibiotics, which can eliminate the organism but cannot reverse the damage caused by bacterial products already present. The three very common causes of bacterial keratitis—Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pneumoniae—all produce proteins that directly or indirectly cause damage to the cornea that can result in reduced vision despite antibiotic treatment. Most, but not all, of these proteins are secreted toxins and enzymes that mediate host cell death, degradation of stromal collagen, cleavage of host cell surface molecules, or induction of a damaging inflammatory response. Studies of these bacterial pathogens have determined the proteins of interest that could be targets for future therapeutic options for decreasing corneal damage.

  1. Damage analysis. Product improvement through damage analysis; Schadensanalyse. Produktverbesserung durch Schadensanalyse

    Energy Technology Data Exchange (ETDEWEB)



    Within the 37th VDI annual meeting from 19th to 20th May, 2011 in Wuerzburg (Federal Republic of Germany) the following lectures and posters were presented: (1) Malpractice of material processing and heat processing of large gear wheels (P. Sommer); (2) Damages by faulty heat treatment - Case studies: Glow testing at a heat exchanger and wheel breakage of a high-strength screw connection (A. Thomas); (3) Crack formation in pole end plates of high-performance generators of a pumped-storage power plant - Causes and possibilities of remedy (J. Kinder); (4) Grind burn inspection for damage prevention at wind turbine gearboxes - Use of different processes for the investigation of peripheral-zone properties of case-hardened components (T. Griggel); (5) Damage inspection in coal mines using products from the degradation process as an example - damage - inspection - solution: This is the working method of the certification body (C. Kleine-Hegermann); (6) Damages at the sealing rings - Causes of the failure at radial shaft rings (K. Marchetti); (7) Thermal analyses at faulty plastic components (O. Jacobs); (8) Application of the micro computer tomography at damages of fibre-reinforced materials (H. Dinnebier); (9) The significance of 'material defects' from the view of lay people, lawyers and engineers - 'Material defect' in the literature, set of rules and expert opinion (C. Klinger); (10) Material defects from a legal view (P. Henseler); (11) Significance of material defects from the view of an engineering insurer (C. Harden); (12) Wear analyses by means of RNT and non-destructive surface analytics (K. Poehlmann); (13) Damages by means of non-metallic inclusions using ICE 3 as an example - Significance and localisation of single non-metallic inclusions in large components (D. Bettge); (14) Cathodic corrosion protection of pipeline steels (H.-G. Schoeneich); (15) Non-destructive and destructive investigations when assessing damages of corrosion at a

  2. Damage in fused-silica spatial-filter lenses on the OMEGA laser system (United States)

    Rigatti, Amy L.; Smith, Douglas J.; Schmid, Ansgar W.; Papernov, Semyon; Kelly, John H.


    Vacuum surface damage to fused-silica, spatial-filter lenses is the most prevalent laser-damage problem occurring on the OMEGA laser system. Approximately one-half of the stage C- input and output, D-input, E-input, and F-input spatial- filter lenses are currently damaged with millimeter-scale fracture sites. With the establishment of safe operational damage criteria, laser operation has not been impeded. These sol-gel-coated lenses see an average fluence of 2 to 4 J/cm2 at 1053 nm/1 ns. Sol-gel coatings on fused-silica glass have small-spot damage thresholds at least a factor of 2 higher than this peak operational fluence. It is now known that the vacuum surface of OMEGA's spatial-filter lenses are contaminated with vacuum pump oils and machine oils used in the manufacture of the tubes; however, development-phase damage tests were conducted on uncontaminated witness samples. Possible explanations for the damage include absorbing defects originating form ablated pinhole materials, contamination nucleated at surface defects on the coating, or subsurface defects from the polishing process. The damage does not correlate with hot spots in the beam, and the possibility of damage from ghost reflections has been eliminated. Experiments have been initiated to investigate the long-term benefits of ion etching to remove subsurface damage and to replace sol-gel layers by dielectric oxide coatings, which do not degrade with oil contamination.

  3. BDS thin film damage competition

    Energy Technology Data Exchange (ETDEWEB)

    Stolz, C J; Thomas, M D; Griffin, A J


    A laser damage competition was held at the 2008 Boulder Damage Symposium in order to determine the current status of thin film laser resistance within the private, academic, and government sectors. This damage competition allows a direct comparison of the current state-of-the-art of high laser resistance coatings since they are all tested using the same damage test setup and the same protocol. A normal incidence high reflector multilayer coating was selected at a wavelength of 1064 nm. The substrates were provided by the submitters. A double blind test assured sample and submitter anonymity so only a summary of the results are presented here. In addition to the laser resistance results, details of deposition processes, coating materials, and layer count will also be shared.

  4. Probabilistic Fatigue Damage Program (FATIG) (United States)

    Michalopoulos, Constantine


    FATIG computes fatigue damage/fatigue life using the stress rms (root mean square) value, the total number of cycles, and S-N curve parameters. The damage is computed by the following methods: (a) traditional method using Miner s rule with stress cycles determined from a Rayleigh distribution up to 3*sigma; and (b) classical fatigue damage formula involving the Gamma function, which is derived from the integral version of Miner's rule. The integration is carried out over all stress amplitudes. This software solves the problem of probabilistic fatigue damage using the integral form of the Palmgren-Miner rule. The software computes fatigue life using an approach involving all stress amplitudes, up to N*sigma, as specified by the user. It can be used in the design of structural components subjected to random dynamic loading, or by any stress analyst with minimal training for fatigue life estimates of structural components.

  5. Civil Liability for Environmental Damages

    Directory of Open Access Journals (Sweden)

    Daniela Ciochină


    Full Text Available We debated in this article the civil liability for environmental damages as stipulated in ourlegislation with reference to Community law. The theory of legal liability in environmental law is basedon the duty of all citizens to respect and protect the environment. Considering the importance ofenvironment in which we live, the liability for environmental damages is treated by the Constitution as aprinciple and a fundamental obligation. Many human activities cause environmental damages and, in linewith the principle of sustainable development, they should be avoided. However, when this is notpossible, they must be regulated (by criminal or administrative law in order to limit their adverse effectsand, according to the polluter pays principle, to internalize in advance their externalities (through taxes,insurances or other forms of financial security products. Communication aims to analyze these issues andlegal regulations dealing with the issue of liability for environmental damage.

  6. Climate change: Unattributed hurricane damage (United States)

    Hallegatte, Stéphane


    In the United States, hurricanes have been causing more and more economic damage. A reanalysis of the disaster database using a statistical method that accounts for improvements in resilience opens the possibility that climate change has played a role.


    Institute of Scientific and Technical Information of China (English)

    Huang Peizhen; Li Zhonghua; Sun Jun


    Based on the thermal kinetic and mass conservation, a series of controlling equations for the finite element are derived and related programs are developed to simulate the damage microcrack healing process controlled by surface diffusion. Two kinds of typical models for microcrack splitting are proposed, i.e., the grain boundary energy existing on the crack surface and residual stresses applying on the crack surface. And the conditions of microcrack splitting in the two models are given as a function of the microcrack aspect ratio. The microcrack with traction-free surfaces will directly evolve into a spheroid.

  8. Damage Atlas for Photographic materials

    Directory of Open Access Journals (Sweden)

    Kristel Van Camp


    Full Text Available La conservation des documents photographiques peut nécessiter des interventions préventives ou curatives. Ce choix est guidé par leur état de conservation. Une meilleure connaissance des détériorations est donc cruciale. Le répertoire présenté ici essaie de les classifier selon des caractéristiques spécifiques et leur niveau de gravité. Les différents types de dégradation sont illustrés et décrits avec une terminologie précise. L’auteur propose en regard de ceux-ci l’intervention qui semble la plus appropriée. Ce répertoire s’adresse à toutes les personnes concernées par la photographie, qu’ils soient dans le milieu de la conservation ou dans le domaine artistique, dans les musées ou dans les archives. In order to rescue a damaged photographic object, preventive or conservative actions are needed. Knowing the specific characteristics of different types of damage is crucial. A damage atlas can provide these characteristics. With this atlas the damage can be recognised and appropriate actions can be taken. This damage atlas offers a first attempt to such a characterisation in the field of photography. The damage atlas contains images and the necessary information about damage on photographic material. The atlas with special annotations about the terminology and the grade of the damage is meant for everybody who works with photographic material, as well in museums as in archives.

  9. How expensive is vole damage?


    Walther, B; Fülling, O.; Malevez, J.; Pelz, H.-J.


    Vole species, especially Arvicola terrestris and Microtus arvalis cause significant economical damage in organic pomiculture by gnawing the root system of trees. The importance of voles as pest organisms is well known. Nevertheless, the estimation of financial loss caused by voles is difficult for German fruit growers. We conducted a survey among organic fruit growers to get data on kind and amount of annual damage. Using the available publications and official statistics we calculated econom...

  10. Autologous transplantation of bone marrow mesenchymal stem cells to improve ocular surface in severely damaged cases%自体骨髓间充质干细胞移植改善重度眼表损伤临床观察

    Institute of Scientific and Technical Information of China (English)

    陈洁; 潘志强; 骆非; 接英; 彭秀军


    Objective To evaluate the effect of autologous bone marrow mesenchymal stem cells (BMSC) in treating severely damaged ocular surface.Methods Four cases of corneal chemical burn and two cases of Stenven-Johnson Syndrome were enrolled in this study.The BMSCs were obtained and cultured in vitro.The cells were harvested afler 14 days and confirmed to be BMSCs.Then the cells were placed on an amniotic membrane (AM) and expanded until 90% confluence formation before using.After the abnormal conjunctival and corneal tissues were removed from the cornea,the AM coated autologous BMSCs were transplanted onto the corneal surface.Aftersurgery,antibiotics,steroid and lubricant eye drops were used and patients were examined by slit-lamp and impression cytology.Results In all the six treated eyes,the entire corneal epithelium was intact one week after surgery.The visual acuity improved in three eyes,two eyes kept at the same level and decreased in one eye.The ocular surface was smooth,but the new blood vessels didn't show significant reduction.After twelve weeks,the epithelial cells phenotype and goblet cells appeared on corneal surface.Conclusions Autologous BMSCs can improve ocular surface condition in severely damaged patients,which show potential use for treating limbal deficiency.%目的 评价自体骨髓间充质干细胞在严重眼表损伤移植后的治疗效果.方法 选取了化学烧伤4例,Stevens-Johnson综合征2例.骨髓间充质干细胞取自患者,细胞培养14 d后,经细胞检测鉴定为骨髓间充质干细胞,将细胞种植在羊膜表面,细胞扩增融合达90%后使用.手术切除表面结膜化组织达角膜缘外3 mm,将羊膜上培养的自体骨髓间充质干细胞移植到角膜及角膜缘表面,术后予抗生素、激素、人工泪液点眼治疗;病人定期随访,进行裂隙灯显微镜及印迹细胞学检查.结果 6例患眼均覆盖了含有自体骨髓间充质干细胞的羊膜片,术后1周角膜上皮完整.3

  11. Contamination resistant coatings for enhanced laser damage thresholds (United States)

    Weiller, Bruce H.; Fowler, Jesse D.; Villahermosa, Randy M.


    This paper describes a novel approach for the suppression of contamination enhanced laser damage to optical components by the use of fluorinated coatings that repel organic contaminates. In prior work we studied laser damage thresholds induced by ppm levels of toluene under nanosecond 1.064 μm irradiation of fused silica optics. That work showed that moderate vapor-phase concentrations (alcohols dramatically increased the laser damage threshold. The data are consistent with the hypothesis that water and alcohols interact more favorably with the hydroxylated silica surface thereby displacing toluene from the surface. In this work, preliminary results show that fluorinated self assembled monolayer coatings can be used to accomplish the same effect. Optics coated with fluorinated films have much higher survival rates compared with uncoated optics under the same conditions. In addition to enhancing survival of laser optics, these coatings have implications for protecting spacecraft imaging optics from organic contamination.

  12. Mechanism of DNA damage tolerance

    Institute of Scientific and Technical Information of China (English)

    Xin; Bi


    DNA damage may compromise genome integrity and lead to cell death. Cells have evolved a variety of processes to respond to DNA damage including damage repair and tolerance mechanisms, as well as damage checkpoints. The DNA damage tolerance(DDT) pathway promotes the bypass of single-stranded DNA lesions encountered by DNA polymerases during DNA replication. This prevents the stalling of DNA replication. Two mechanistically distinct DDT branches have been characterized. One is translesion synthesis(TLS) in which a replicative DNA polymerase is temporarily replaced by a specialized TLS polymerase that has the ability to replicate across DNA lesions. TLS is mechanistically simple and straightforward, but it is intrinsically error-prone. The other is the error-free template switching(TS) mechanism in which the stalled nascent strand switches from the damaged template to the undamaged newly synthesized sister strand for extension past the lesion. Error-free TS is a complex but preferable process for bypassing DNA lesions. However, our current understanding of this pathway is sketchy. An increasing number of factors are being found to participate or regulate this important mechanism, which is the focus of this editorial.

  13. DNA damage in neurodegenerative diseases. (United States)

    Coppedè, Fabio; Migliore, Lucia


    Following the observation of increased oxidative DNA damage in nuclear and mitochondrial DNA extracted from post-mortem brain regions of patients affected by neurodegenerative diseases, the last years of the previous century and the first decade of the present one have been largely dedicated to the search of markers of DNA damage in neuronal samples and peripheral tissues of patients in early, intermediate or late stages of neurodegeneration. Those studies allowed to demonstrate that oxidative DNA damage is one of the earliest detectable events in neurodegeneration, but also revealed cytogenetic damage in neurodegenerative conditions, such as for example a tendency towards chromosome 21 malsegregation in Alzheimer's disease. As it happens for many neurodegenerative risk factors the question of whether DNA damage is cause or consequence of the neurodegenerative process is still open, and probably both is true. The research interest in markers of oxidative stress was shifted, in recent years, towards the search of epigenetic biomarkers of neurodegenerative disorders, following the accumulating evidence of a substantial contribution of epigenetic mechanisms to learning, memory processes, behavioural disorders and neurodegeneration. Increasing evidence is however linking DNA damage and repair with epigenetic phenomena, thereby opening the way to a very attractive and timely research topic in neurodegenerative diseases. We will address those issues in the context of Alzheimer's disease, Parkinson's disease, and Amyotrophic Lateral Sclerosis, which represent three of the most common neurodegenerative pathologies in humans.

  14. Surface Water & Surface Drainage (United States)

    Earth Data Analysis Center, University of New Mexico — This data set contains boundaries for all surface water and surface drainage for the state of New Mexico. It is in a vector digital data structure digitized from a...

  15. Survey of four damage models for concrete.

    Energy Technology Data Exchange (ETDEWEB)

    Leelavanichkul, Seubpong (University of Utah, Salt Lake City, UT); Brannon, Rebecca Moss (University of Utah, Salt Lake City, UT)


    Four conventional damage plasticity models for concrete, the Karagozian and Case model (K&C), the Riedel-Hiermaier-Thoma model (RHT), the Brannon-Fossum model (BF1), and the Continuous Surface Cap Model (CSCM) are compared. The K&C and RHT models have been used in commercial finite element programs many years, whereas the BF1 and CSCM models are relatively new. All four models are essentially isotropic plasticity models for which 'plasticity' is regarded as any form of inelasticity. All of the models support nonlinear elasticity, but with different formulations. All four models employ three shear strength surfaces. The 'yield surface' bounds an evolving set of elastically obtainable stress states. The 'limit surface' bounds stress states that can be reached by any means (elastic or plastic). To model softening, it is recognized that some stress states might be reached once, but, because of irreversible damage, might not be achievable again. In other words, softening is the process of collapse of the limit surface, ultimately down to a final 'residual surface' for fully failed material. The four models being compared differ in their softening evolution equations, as well as in their equations used to degrade the elastic stiffness. For all four models, the strength surfaces are cast in stress space. For all four models, it is recognized that scale effects are important for softening, but the models differ significantly in their approaches. The K&C documentation, for example, mentions that a particular material parameter affecting the damage evolution rate must be set by the user according to the mesh size to preserve energy to failure. Similarly, the BF1 model presumes that all material parameters are set to values appropriate to the scale of the element, and automated assignment of scale-appropriate values is available only through an enhanced implementation of BF1 (called BFS) that regards scale effects to be coupled to

  16. Effects of Vacuum of Fused Silica UV Damage

    Institute of Scientific and Technical Information of China (English)

    XU Shi-Zhen; LV Hai-Bing; YUAN Xiao-Dong; HUANG Jin; JIANG Xiao-Dong; WANG Hai-Jun; ZU Xiao-Tao; ZHENG Wan-Guo


    Damage points induced by 355 nm laser irradiation increase more quickly on the surface of fused silica in vacuum of about 10-3Pa than in atmospheric air at the same fluence.The larger concentration of point defects in vacuum is confirmed by photoluminescence intensity.X-ray photoelectron spectroscopy and infrared absorption indicate the formation of sub-stoichiometric sillca on the surface.The degradation mechanism of fused silica in vacuum is discussed.

  17. Damage Localization and Quantification of Earthquake Excited RC-Frames

    DEFF Research Database (Denmark)

    Skjærbæk, P.S.; Nielsen, Søren R.K.; Kirkegaard, Poul Henning;

    In the paper a recently proposed method for damage localization and quantification of RC-structures from response measurements is tested on experimental data. The method investigated requires at least one response measurement along the structure and the ground surface acceleration. Further, the t...

  18. Effect of defects on long-pulse laser-induced damage of two kinds of optical thin films. (United States)

    Wang, Bin; Qin, Yuan; Ni, Xiaowu; Shen, Zhonghua; Lu, Jian


    In order to study the effect of defects on the laser-induced damage of different optical thin films, we carried out damage experiments on two kinds of thin films with a 1 ms long-pulse laser. Surface-defect and subsurface-defect damage models were used to explain the damage morphology. The two-dimensional finite element method was applied to calculate the temperature and thermal-stress fields of these two films. The results show that damages of the two films are due to surface and subsurface defects, respectively. Furthermore, the different dominant defects for thin films of different structures are discussed.

  19. Accumulated damage process of thermal sprayed coating under rolling contact by acoustic emission technique (United States)

    Xu, Jia; Zhou, Zhen-yu; Piao, Zhong-yu


    The accumulated damage process of rolling contact fatigue (RCF) of plasma-sprayed coatings was investigated. The influences of surface roughness, loading condition, and stress cycle frequency on the accumulated damage status of the coatings were discussed. A ball-ondisc machine was employed to conduct RCF experiments. Acoustic emission (AE) technique was introduced to monitor the RCF process of the coatings. AE signal characteristics were investigated to reveal the accumulated damage process. Result showed that the polished coating would resist the asperity contact and remit accumulated damage. The RCF lifetime would then extend. Heavy load would aggravate the accumulated damage status and induce surface fracture. Wear became the main failure mode that reduced the RCF lifetime. Frequent stress cycle would aggravate the accumulated damage status and induce interface fracture. Fatigue then became the main failure mode that also reduced the RCF lifetime.

  20. Manual on the Fatigue of Structures. II. Causes and Prevention of Damage. 7. Mechanical Surface Damage, (United States)


    conjuguee du frottement et de la corrosion sur les aciers inoxydables. Corrosion, Vol.19, N°4, pp. 159-170, June July 1971. Archiv. Eisenhüttenwesen, Vol...24, (1/2), p.43. 1953. Contribution ä l’etude de (’Influence de la deformation plastiquc sur la corrosion des aciers dans des solutions sulfurique

  1. Neural networks for damage identification

    Energy Technology Data Exchange (ETDEWEB)

    Paez, T.L.; Klenke, S.E.


    Efforts to optimize the design of mechanical systems for preestablished use environments and to extend the durations of use cycles establish a need for in-service health monitoring. Numerous studies have proposed measures of structural response for the identification of structural damage, but few have suggested systematic techniques to guide the decision as to whether or not damage has occurred based on real data. Such techniques are necessary because in field applications the environments in which systems operate and the measurements that characterize system behavior are random. This paper investigates the use of artificial neural networks (ANNs) to identify damage in mechanical systems. Two probabilistic neural networks (PNNs) are developed and used to judge whether or not damage has occurred in a specific mechanical system, based on experimental measurements. The first PNN is a classical type that casts Bayesian decision analysis into an ANN framework; it uses exemplars measured from the undamaged and damaged system to establish whether system response measurements of unknown origin come from the former class (undamaged) or the latter class (damaged). The second PNN establishes the character of the undamaged system in terms of a kernel density estimator of measures of system response; when presented with system response measures of unknown origin, it makes a probabilistic judgment whether or not the data come from the undamaged population. The physical system used to carry out the experiments is an aerospace system component, and the environment used to excite the system is a stationary random vibration. The results of damage identification experiments are presented along with conclusions rating the effectiveness of the approaches.

  2. A method to estimate wind turbine blade damage and to design damage-resilient blades (United States)

    Fiore, Giovanni

    Wind turbine blades are affected by continuous impacts with airborne particles that deteriorate the blade surface and yield to a drop in output power. Based on the climatic conditions and geographic locations of a given wind farm, multiple types of particles are observed in air. The present study focuses on simulating the impact of four types of particles, namely insects, sand grains, hailstones, and rain drops with the blade surface. A numerical inviscid flowfield code, coupled with a particle position predictor code was used. Upon impact, the damaging effect to the blade surface was evaluated. Each type of particle was associated with a damage mode, which depends on the mass, size, and hardness of the particle. It was found that insects strike and adhere to the blade in a region close to the leading edge. On the other hand, it was seen that sand grains promote erosion just downstream of the leading edge, where local velocity reaches a maximum and the impact angle is shallow. Moreover, particles such as rain drops are associated with fatigue and erosion at the very leading edge and on the upper side of the blade section. Finally, hailstones promote delamination and fatigue in the composite panels of the blade surface. Photographic evidence of damaged blade surfaces was used in the present research as a comparison with the simulations performed for various types of particle and different initial conditions. Based on such observations, a theorization of the damage pattern and evolution was proposed. Finally, given a set of well-established blade section geometries, such as the Delft University and NREL S airfoil families, a comparison of airfoil damage fitness was proposed and possible means of shape optimization were discussed. The investigation of blade geometry features to mitigate damage was performed. Based on previous results, it was argued that a viable blade section optimization may be performed for the lightest and smallest particles considered in the study

  3. Characteristics of damaged layer in micro-machining of copper material

    Institute of Scientific and Technical Information of China (English)

    Dong-Hee KWON; Jeong-Suk KIM; Myung-Chang KANG; Se-Hun KWON; Jong-Hwan LEE


    The study on damaged layer is necessary for improving the machinability in micro-machining because the damaged layer affects the micro mold life and micro machine parts. This study examined the ultra-precision micro-machining characteristics, such as cutting speed, feed rate and cutting depth, of a micro-damaged layer produced by an ultra-high speed air turbine spindle. The micro cutting force, surface roughness and plastic deformation layer were investigated according to the machining conditions. The damaged layer was measured using optical microscope on samples prepared through metallographic techniques. The scale of the damaged layer depends on the cutting process parameters, particularly, the feed per tooth and axial depth of the cut. According to the experimental results, the depth of the damaged layer is increased by increasing the feed per tooth and cutting depth, also the damaged layer occurs less in down-milling compared with up-milling during the micro-machining operation.

  4. Automatic detection and classification of damage zone(s) for incorporating in digital image correlation technique (United States)

    Bhattacharjee, Sudipta; Deb, Debasis


    Digital image correlation (DIC) is a technique developed for monitoring surface deformation/displacement of an object under loading conditions. This method is further refined to make it capable of handling discontinuities on the surface of the sample. A damage zone is referred to a surface area fractured and opened in due course of loading. In this study, an algorithm is presented to automatically detect multiple damage zones in deformed image. The algorithm identifies the pixels located inside these zones and eliminate them from FEM-DIC processes. The proposed algorithm is successfully implemented on several damaged samples to estimate displacement fields of an object under loading conditions. This study shows that displacement fields represent the damage conditions reasonably well as compared to regular FEM-DIC technique without considering the damage zones.

  5. Fatigue damage detection using cyclostationarity (United States)

    Boungou, D.; Guillet, F.; Badaoui, M. El; Lyonnet, P.; Rosario, T.


    In this paper, we present the second-order of cyclostationarity to detect and diagnose the fatigue damage of the stainless steel 316l subjected to low cycle fatigue (LCF). LCF is defined by repetitive cycling in a low stress and a short period. The vibration response of material subjected to LCF provides information linked to the solicitation and to the fatigue damage. Thus, we considered a cantilever beam with breathing cracks and assumed that under the solicitation, breathing cracks generates non-linearity in the stiffness of the material and this one decreases with the damage. We used the second-order of the cyclostationarity to reveal this non-linearity and showed that the fatigue provide a random component in the signal, which increases with the fatigue damage. Thus, in the specific case of a material subjected to LCF, with a non-linear stiffness, we propose a new methodology to detect and diagnose the fatigue damage using a vibration signal. This methodology is based on the second order of the cyclostationarity.

  6. Autophagy in DNA Damage Response

    Directory of Open Access Journals (Sweden)

    Piotr Czarny


    Full Text Available DNA damage response (DDR involves DNA repair, cell cycle regulation and apoptosis, but autophagy is also suggested to play a role in DDR. Autophagy can be activated in response to DNA-damaging agents, but the exact mechanism underlying this activation is not fully understood, although it is suggested that it involves the inhibition of mammalian target of rapamycin complex 1 (mTORC1. mTORC1 represses autophagy via phosphorylation of the ULK1/2–Atg13–FIP200 complex thus preventing maturation of pre-autophagosomal structures. When DNA damage occurs, it is recognized by some proteins or their complexes, such as poly(ADPribose polymerase 1 (PARP-1, Mre11–Rad50–Nbs1 (MRN complex or FOXO3, which activate repressors of mTORC1. SQSTM1/p62 is one of the proteins whose levels are regulated via autophagic degradation. Inhibition of autophagy by knockout of FIP200 results in upregulation of SQSTM1/p62, enhanced DNA damage and less efficient damage repair. Mitophagy, one form of autophagy involved in the selective degradation of mitochondria, may also play role in DDR. It degrades abnormal mitochondria and can either repress or activate apoptosis, but the exact mechanism remains unknown. There is a need to clarify the role of autophagy in DDR, as this process may possess several important biomedical applications, involving also cancer therapy.


    Institute of Scientific and Technical Information of China (English)

    X.Bai; D.B.Sun; 等


    The influence of the surface galvanic effects of 1Cr13 SS during cavitation damage has been investigated in NaCl soutions.The results show that the solution concentration and area ratio of bubble unacted surface to the bubble-acted surface greatly influence the cavitation damage of the alloy.The surace galvanic effects can speed up the dissolution rate of the alloy,and the mass loss per area of the alloy increases linearly with the area ratio of bubble unacted surface to the bubble acted surface of the alloy.

  8. Laser induced damage studies in mercury cadmium telluride (United States)

    Garg, Amit; Kapoor, Avinashi; Tripathi, K. N.; Bansal, S. K.


    We have investigated laser induced damage at 1.06 μm laser wavelength in diamond paste polished (mirror finish) and carborundum polished Hg0.8Cd0.2Te (MCT) samples with increasing fluence as well as number of pulses. Evolution of damage morphology in two types of samples is quite different. In case of diamond paste polished samples, evolution of damage morphological features is consistent with Hg evaporation with transport of Cd/Te globules towards the periphery of the molten region. Cd/Te globules get accumulated with successive laser pulses at the periphery indicating an accumulation effect. Real time reflectivity (RTR) measurement has been done to understand melt pool dynamics. RTR measurements along with the thermal profile of the melt pool are in good agreement with thermal melting model of laser irradiated MCT samples. In case of carborundum polished samples, laser damage threshold is significantly reduced. Damage morphological features are significantly influenced by surface microstructural condition. From comparison of the morphological features in the two cases, it can be inferred that laser processing of MCT for device applications depends significantly on surface preparation conditions.

  9. Recent results on bulk laser damage threshold of optical glasses (United States)

    Jedamzik, Ralf; Elsmann, Frank


    Modern pulsed laser applications cover a broad range of wavelength, power and pulse widths. Beam guiding optics in laser systems do not only have specific requirements on the imaging quality but also have to withstand high laser power. The laser damage threshold of an optical component depends on the surface (polishing, coating ...) and also on the bulk material properties. Actual values of bulk laser damage thresholds, particularly at pulse lengths less than 1 nanosecond (1 ns), of optical glasses are rarely found in literature, except for fused silica, which is known as a key optical material for components in high power laser. However, fused silica is rather expensive and limited in optical properties. That is the reason why customers often ask for laser damage threshold data of optical glasses. Therefore, SCHOTT has started a project for the characterization of the bulk laser damage threshold of optical glasses at the wavelengths 532 nm and 1064 nm with pulse lengths in the nano- and pico-second range. Bulk and surface laser damage testing has been performed by the Laser Zentrum Hannover in Germany according to the S-on-1 test of DIN EN ISO 11254-2 / DIN EN ISO 21254.

  10. Rapid and Robust Damage Detection using Radar Remote Sensing (United States)

    Yun, S.; Fielding, E. J.; Simons, M.; Webb, F.; Rosen, P. A.; Owen, S. E.


    Under ARIA (Advanced Rapid Imaging and Analysis) project at JPL and Caltech, we developed a prototype algorithm and data system to rapidly detect surface change caused by natural or man-made damage using a radar remote sensing technique of InSAR coherence. We tested the algorithm with a building demolition site in the City of Pasadena, California. The results show clear signal at the demolition site, with about 150% SNR improvement compared to conventional approach. Out of fourteen strongest detected signals, we confirmed that at least eleven of them were associated with real demolition and construction projects. We applied the algorithm to the February 2011 M6.3 Christchurch earthquake in New Zealand, which killed 185 people and caused financial damage of US $16-24 billion. We produced a damage proxy map (DPM) using radar data from ALOS satellite (Figure A), where red pixels identify regions where there may have been earthquake induced building damage, landslides, and liquefaction. The distribution of the red regions agrees well with the post-earthquake assessment performed on the ground by inspectors from the New Zealand government and summarized in their damage assessment zone map (Figure B). The DPM was derived from radar data acquired 3 days after the earthquake, whereas the ground truth zone map was first published 4 months after the earthquake. In addition to all-weather and day-and-night capability of radar, the sensitivity of radar signal to surface property change is high enough for reliable damage assessment. Current and future satellite and airborne missions should keep the expected composite data acquisition latency within a day. Rapidly produced accurate damage assessment maps will help saving people, assisting effective prioritization of rescue operations at early stage of response, and significantly improve timely situational awareness for emergency management and national / international assessment for response and recovery.

  11. Interacting damage models mapped onto ising and percolation models

    Energy Technology Data Exchange (ETDEWEB)

    Toussaint, Renaud; Pride, Steven R.


    The authors introduce a class of damage models on regular lattices with isotropic interactions between the broken cells of the lattice. Quasistatic fiber bundles are an example. The interactions are assumed to be weak, in the sense that the stress perturbation from a broken cell is much smaller than the mean stress in the system. The system starts intact with a surface-energy threshold required to break any cell sampled from an uncorrelated quenched-disorder distribution. The evolution of this heterogeneous system is ruled by Griffith's principle which states that a cell breaks when the release in potential (elastic) energy in the system exceeds the surface-energy barrier necessary to break the cell. By direct integration over all possible realizations of the quenched disorder, they obtain the probability distribution of each damage configuration at any level of the imposed external deformation. They demonstrate an isomorphism between the distributions so obtained and standard generalized Ising models, in which the coupling constants and effective temperature in the Ising model are functions of the nature of the quenched-disorder distribution and the extent of accumulated damage. In particular, they show that damage models with global load sharing are isomorphic to standard percolation theory, that damage models with local load sharing rule are isomorphic to the standard ising model, and draw consequences thereof for the universality class and behavior of the autocorrelation length of the breakdown transitions corresponding to these models. they also treat damage models having more general power-law interactions, and classify the breakdown process as a function of the power-law interaction exponent. Last, they also show that the probability distribution over configurations is a maximum of Shannon's entropy under some specific constraints related to the energetic balance of the fracture process, which firmly relates this type of quenched-disorder based

  12. System for estimating fatigue damage

    Energy Technology Data Exchange (ETDEWEB)

    LeMonds, Jeffrey; Guzzo, Judith Ann; Liu, Shaopeng; Dani, Uttara Ashwin


    In one aspect, a system for estimating fatigue damage in a riser string is provided. The system includes a plurality of accelerometers which can be deployed along a riser string and a communications link to transmit accelerometer data from the plurality of accelerometers to one or more data processors in real time. With data from a limited number of accelerometers located at sensor locations, the system estimates an optimized current profile along the entire length of the riser including riser locations where no accelerometer is present. The optimized current profile is then used to estimate damage rates to individual riser components and to update a total accumulated damage to individual riser components. The number of sensor locations is small relative to the length of a deepwater riser string, and a riser string several miles long can be reliably monitored along its entire length by fewer than twenty sensor locations.

  13. Remote detection of forest damage (United States)

    Rock, B. N.; Vogelmann, J. E.; Vogelmann, A. F.; Hoshizaki, T.; Williams, D. L.


    The use of remote sensing to discriminate, measure, and map forest damage is evaluated. TM spectal coverage, a helicopter-mounted radiometer, and ground-based surveys were utilized to examine the responses of the spruces and firs of Camels Hump Mountain, Vermont to stresses, such as pollution and trace metals. The basic spectral properties of vegetation are described. Forest damage at the site was estimated as 11.8-76.0 percent for the spruces and 19-43.8 percent for the balsam firs. Shifts in the spectra of the conifers in particular in the near IR region are analyzed, and variations in the mesophyll cell anatomy and pigment content of the spruces and firs are investigated. The relations between canopy moisture and damage is studied. The TM data are compared to aircraft data and found to be well correlated.

  14. The CATDAT damaging earthquakes database

    Directory of Open Access Journals (Sweden)

    J. E. Daniell


    Full Text Available The global CATDAT damaging earthquakes and secondary effects (tsunami, fire, landslides, liquefaction and fault rupture database was developed to validate, remove discrepancies, and expand greatly upon existing global databases; and to better understand the trends in vulnerability, exposure, and possible future impacts of such historic earthquakes.

    Lack of consistency and errors in other earthquake loss databases frequently cited and used in analyses was a major shortcoming in the view of the authors which needed to be improved upon.

    Over 17 000 sources of information have been utilised, primarily in the last few years, to present data from over 12 200 damaging earthquakes historically, with over 7000 earthquakes since 1900 examined and validated before insertion into the database. Each validated earthquake includes seismological information, building damage, ranges of social losses to account for varying sources (deaths, injuries, homeless, and affected, and economic losses (direct, indirect, aid, and insured.

    Globally, a slightly increasing trend in economic damage due to earthquakes is not consistent with the greatly increasing exposure. The 1923 Great Kanto ($214 billion USD damage; 2011 HNDECI-adjusted dollars compared to the 2011 Tohoku (>$300 billion USD at time of writing, 2008 Sichuan and 1995 Kobe earthquakes show the increasing concern for economic loss in urban areas as the trend should be expected to increase. Many economic and social loss values not reported in existing databases have been collected. Historical GDP (Gross Domestic Product, exchange rate, wage information, population, HDI (Human Development Index, and insurance information have been collected globally to form comparisons.

    This catalogue is the largest known cross-checked global historic damaging earthquake database and should have far-reaching consequences for earthquake loss estimation, socio-economic analysis, and the global

  15. Site Effects and Damage Patterns


    Assimaki, Dominic; Ledezma, Christian; Montalva, Gonzalo A.; Tassara,Andrés; Mylonakis, George; Boroschekf, Ruben


    A set of observations on site effects and damage patterns from the M_w 8.8 Maule, Chile, earthquake is presented, focusing on identification of structural damage variability associated with nonuniform soil conditions and subsurface geology. Observations are reported from: (1) the City of Santiago de Chile (Américo Vespucio Norte Ring Highway, Ciudad Empresarial business park), (2) the Municipality of Viña del Mar, and (3) the City of Concepción, extending over 600 km along the Chilean coast. ...

  16. Subsurface damage from oblique impacts into low-impedance layers (United States)

    Stickle, A. M.; Schultz, P. H.


    Layered planetary surfaces occur ubiquitously in the solar system, where sedimentary sequences or icy layers overlay crystalline bedrock. Previous experimental studies investigated how the presence of weak layer overlying a strong basement affects crater morphology, subsurface damage and soft-sediment compression. Numerical studies generally focus on the final morphology as a function of thicknesses and burial depths of weak layers. In field studies of impact craters, the shock state of minerals is a key metric. Here, we evaluate the effect of a surficial low-impedance layer on peak pressure magnitudes and consequent damage extent in the competent substrate. Laboratory experiments coupled with 3D CTH models of oblique (30° from horizontal) hypervelocity impacts at laboratory and planetary scales show that surface layers with a thickness on the order of the projectile diameter shield the underlying surface and absorb/scatter ˜70% of the impact energy. Numerical simulations reveal that surficial layers reduce peak pressure magnitudes within the subsurface by ˜60-70%, while damage in the substrate is due to shear failure. Sedimentary layers are more efficient shields than icy layers, but both reduce the extent of subsurface damage and the resulting shock levels recorded by minerals. These results indicate that a thin surficial low impedance layer mitigates the expression of shocked minerals in the substrate even when a structural response is still observed.

  17. 7 CFR 51.3067 - Serious damage. (United States)


    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Serious damage. 51.3067 Section 51.3067 Agriculture... Standards for Florida Avocados Definitions § 51.3067 Serious damage. Serious damage means any defect which... serious damage: (a) Anthracnose when any spot exceeds the area of a circle one-fourth inch in diameter,...

  18. 7 CFR 51.2960 - Damage. (United States)


    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Damage. 51.2960 Section 51.2960 Agriculture... Standards for Grades of Walnuts in the Shell Definitions § 51.2960 Damage. Damage means any specific defect... considered as damage: (a) Broken shells when the area from which a portion of the shell is missing is...

  19. The Damage Law of HTPB Propellant under Thermomechanical Loading (United States)

    Liu, Cheng-wu; Yang, Jian-hong; Wang, Xian-meng; Ma, Yong-kang


    By way of measuring the acoustic emission (AE) signals of Hydroxyl-terminated polybutadiene (HTPB) propellant in condition of uniform speed, and combined with the scanning electron microscopy (SEM) fracture surface observation, the damage law of HTPB composite solid propellant under thermomechanical loading was studied. The results show that the effects of thermomechanical loading on HTPB propellant are related to the time and can be divided into three different stages. In the first stage, thermal air aging dominates; in the second stage, interface damage is dominant; and in the third stage, thermal air aging is once again dominant.

  20. Understanding Femtosecond-Pulse Laser Damage through Fundamental Physics Simulations (United States)

    Mitchell, Robert A., III

    to those in the simulation. Lastly, this method is applied to the phenomenon known as LIPSS, or Laser-Induced Periodic Surface Structures; a problem of fundamental importance that is also of great interest for industrial applications. While LIPSS have been observed for decades in laser damage experiments, the exact physical mechanisms leading to the periodic corrugation on the surface of a target have been highly debated, with no general consensus. Applying this technique to a situation known to create LIPSS in a single shot, the generation of this periodicity is observed, the wavelength of the damage is consistent with experimental measures and, due to the fundamental nature of the simulation method, the physical mechanisms behind LIPSS are examined. The mechanism behind LIPSS formation in the studied regime is shown to be the formation of and interference with an evanescent surface electromagnetic wave known as a surface plasmon-polariton. This shows that not only can this simulation technique model a basic laser damage situation, but it is also flexible and powerful enough to be applied to complex areas of research, allowing for new physical insight in regimes that are difficult to probe experimentally.

  1. Nonlinear cumulative damage model for multiaxial fatigue

    Institute of Scientific and Technical Information of China (English)

    SHANG De-guang; SUN Guo-qin; DENG Jing; YAN Chu-liang


    On the basis of the continuum fatigue damage theory,a nonlinear uniaxial fatigue cumulative damage model is first proposed.In order to describe multiaxial fatigue damage characteristics,a nonlinear multiaxial fatigue cumulative damage model is developed based on the critical plane approach,The proposed model can consider the multiaxial fatigue limit,mean hydrostatic pressure and the unseparated characteristic for the damage variables and loading parameters.The recurrence formula of fatigue damage model was derived under multilevel loading,which is used to predict multiaxial fatigue life.The results showed that the proposed nonlinear multiaxial fatigue cumulative damage model is better than Miner's rule.

  2. Potential for Fabric Damage by Welding Electron Beam (United States)

    Fragomeni, James M.; Nunes, Arthur C., Jr.


    Welding electron beam effects on Nextel AF-62 ceramic fabric enable a preliminary, tentative interpretation of electron beam fabric damage. Static surface charging does not protect fabric from beam penetration, but penetration occurs only after a delay time. The delay time is thought to be that required for the buildup of outgassing products at the fabric surface to a point where arcing occurs. Extra long delays are noted when the gun is close enough to the surface to be shut off by outgassing emissions. Penetration at long distances is limited by beam attenuation from electronic collisions with the chamber atmosphere.

  3. Damage Propagation Modeling for Aircraft Engine Run-to-Failure Simulation (United States)

    National Aeronautics and Space Administration — This paper describes how damage propagation can be modeled within the modules of aircraft gas turbine engines. To that end, response surfaces of all sensors are...

  4. A review of thermographic techniques for damage investigation in composites

    Directory of Open Access Journals (Sweden)

    Laura Vergani


    Full Text Available The aim of this work is a review of scientific results in the literature, related to the application of thermographic techniques to composite materials. Thermography is the analysis of the surface temperature of a body by infrared rays detection via a thermal-camera. The use of this technique is mainly based on the modification of the surface temperature of a material, when it is stimulated by means of a thermal or mechanical external source. The presence of defects, in fact, induces a localized variation in its temperature distribution and, then, the measured values of the surface temperature can be used to localize and evaluate the dimensions and the evolution of defects. In the past, many applications of thermography were proposed on homogeneous materials, but only recently this technique has also been extended to composites. In this work several applications of thermography to fibres reinforced plastics are presented. Thermographic measurements are performed on the surface of the specimens, while undergoing static and dynamic tensile loading. The joint analysis of thermal and mechanical data allows one to assess the damage evolution and to study the damage phenomenon from both mechanical and energetic viewpoints. In particular, one of the main issues is to obtain information about the fatigue behaviour of composite materials, by following an approach successfully applied to homogenous materials. This approach is based on the application of infrared thermography on specimens subjected to static or stepwise dynamic loadings and on the definition of a damage stress, D, that is correlated to the fatigue strength of the material. A wide series of experimental fatigue tests has been carried out to verify if the value of the damage stress, D, is correlated with the fatigue strength of the material. The agreement between the different values is good, showing the reliability of the presented thermographic techniques, to the study of composite

  5. Engineering Polymer Blends for Impact Damage Mitigation (United States)

    Gordon, Keith L.; Smith, Russell W.; Working, Dennis C.; Siochi, Emilie J.


    Structures containing polymers such as DuPont's Surlyn® 8940, demonstrate puncture healing when impacted by a 9 millimeter projectile traveling from speeds near 300 meters per second (1,100 feet per second) to hypervelocity impacts in the micrometeoroid velocity range of 5 kilometers per second (16,000 feet per second). Surlyn® 8940 puncture heals over a temperature range of minus 30 degrees Centigrade to plus 70 degrees Centigrade and shows potential for use in pressurized vessels subject to impact damage. However, such polymers are difficult to process and limited in applicability due to their low thermal stability, poor chemical resistance and overall poor mechanical properties. In this work, several puncture healing engineered melt formulations were developed. Moldings of melt blend formulations were impacted with a 5.56 millimeter projectile with a nominal velocity of 945 meters per second (3,100 feet per second) at about 25 degrees Centigrade, 50 degrees Centigrade and 100 degrees Centigrade, depending upon the specific blend being investigated. Self-healing tendencies were determined using surface vacuum pressure tests and tensile tests after penetration using tensile dog-bone specimens (ASTM D 638-10). For the characterization of tensile properties both pristine and impacted specimens were tested to obtain tensile modulus, yield stress and tensile strength, where possible. Experimental results demonstrate a range of new puncture healing blends which mitigate damage in the ballistic velocity regime.

  6. Compensation for oil pollution damage (United States)

    Matugina, E. G.; Glyzina, T. S.; Kolbysheva, Yu V.; Klyuchnikov, A. S.; Vusovich, O. V.


    The commitment of national industries to traditional energy sources, as well as constantly growing energy demand combined with adverse environmental impact of petroleum production and transportation urge to establish and maintain an appropriate legal and administrative framework for oil pollution damage compensation. The article considers management strategies for petroleum companies that embrace not only production benefits but also environmental issues.

  7. Shanxi Coalmines Face Damage Claims

    Institute of Scientific and Technical Information of China (English)



    In a move designed to improve its environmental reputation, Shanxi Province is to establish a system to compensate against damage made to the environment by coalmines, according to Tian Chengping, the secretary of the Shanxi CPC Provindal Committee, Tian made the point at a conference held in January.

  8. Elastic properties, strength and damage tolerance of pultruded composites (United States)

    Saha, Mrinal Chandra

    parameters were measured in the form of dent depth, back surface crack length, and damage area. The compression tests were performed, using an end-gripped compression test fixture, on both the damaged specimens and open-hole specimens. A relationship between the compressive strength and hole-diameter was established. The compressive strength of damaged specimens was compared to determine the "equivalent-hole-diameter." A correlation between damage parameters and the "equivalent-hole-diameter" was established to find a parameter that could be used as a measure of damage resistance and damage tolerance of pultruded composite structures.

  9. Modeling of Corrosion-induced Concrete Damage

    DEFF Research Database (Denmark)

    Thybo, Anna Emilie A.; Michel, Alexander; Stang, Henrik


    In the present paper a finite element model is introduced to simulate corrosion-induced damage in concrete. The model takes into account the penetration of corrosion products into the concrete as well as non-uniform formation of corrosion products around the reinforcement. To ac-count for the non......-uniform formation of corrosion products at the concrete/reinforcement interface, a deterministic approach is used. The model gives good estimates of both deformations in the con-crete/reinforcement interface and crack width when compared to experimental data. Further, it is shown that non-uniform deposition...... of corrosion products affects both the time-to cover cracking and the crack width at the concrete surface....

  10. Implementation of an anisotropic damage material model using general second order damage tensor

    NARCIS (Netherlands)

    Niazi, Muhammad; Wisselink, Harm; Meinders, Timo; Horn, ten Carel; Mori, K.; Pietrzyk, M.; Kusiak, J.; Majta, J.; Hartley, P.; Lin, J.


    Damage in metals is mainly the process of the initiation and growth of voids. With the growing complexity in materials and forming proc-esses, it becomes inevitable to include anisotropy in damage (tensorial damage variable). Most of the anisotropic damage models define the damage tensor in the prin

  11. Explosive-induced shock damage in copper and recompression of the damaged region (United States)

    Turley, W. D.; Stevens, G. D.; Hixson, R. S.; Cerreta, E. K.; Daykin, E. P.; Graeve, O. A.; La Lone, B. M.; Novitskaya, E.; Perez, C.; Rigg, P. A.; Veeser, L. R.


    We have studied the dynamic spall process for copper samples in contact with detonating low-performance explosives. When a triangular shaped shock wave from detonation moves through a sample and reflects from the free surface, tension develops immediately, one or more damaged layers can form, and a spall scab can separate from the sample and move ahead of the remaining target material. For dynamic experiments, we used time-resolved velocimetry and x-ray radiography. Soft-recovered samples were analyzed using optical imaging and microscopy. Computer simulations were used to guide experiment design. We observe that for some target thicknesses the spall scab continues to run ahead of the rest of the sample, but for thinner samples, the detonation product gases accelerate the sample enough for it to impact the spall scab several microseconds or more after the initial damage formation. Our data also show signatures in the form of a late-time reshock in the time-resolved data, which support this computational prediction. A primary goal of this research was to study the wave interactions and damage processes for explosives-loaded copper and to look for evidence of this postulated recompression event. We found both experimentally and computationally that we could tailor the magnitude of the initial and recompression shocks by varying the explosive drive and the copper sample thickness; thin samples had a large recompression after spall, whereas thick samples did not recompress at all. Samples that did not recompress had spall scabs that completely separated from the sample, whereas samples with recompression remained intact. This suggests that the hypothesized recompression process closes voids in the damage layer or otherwise halts the spall formation process. This is a somewhat surprising and, in some ways controversial, result, and the one that warrants further research in the shock compression community.

  12. Contact damage in artificially aged 3Y-TZP

    Energy Technology Data Exchange (ETDEWEB)

    Armas Sancho, Z de; Jimenez-Pique, E; Mestra, A; Anglada, M, E-mail: [Center for Structural Integrity and Reliability of Materials, CIEFMA Dpt. Materials Science and Metallurgical Engineering Universitat Politecnica de Catalunya, UPC Av. Diagonal 647, 08028 Barcelona (Spain)


    The behaviour of hydrothermal degraded 3% molar yttria stabilised zirconia under monotonic spherical indentation has been studied. The investigation is focused mainly on analysing the response under spherical indentation in terms of the transformed monoclinic surface layer that appears after hydrothermal degradation. The mechanisms of damage are ring and cone cracking, similarly as in as sintered specimens. The permanent damage induced in degraded specimens is always larger than in the as sintered specimens. The 'plastic' damage measured by the value of the indentation strain in degraded specimens is larger than in as sintered specimens at the same indentation pressure. The critical contact load to induce ring cracking is determined and it is found that in degraded specimens its value is lower than in as sintered specimens. The results are discussed in terms of elastic properties and microstructure of the degraded layer.

  13. Anomalous damage in N sup + implanted InAs

    Energy Technology Data Exchange (ETDEWEB)

    Aydinli, A.; Drigo, A.V. (Padua Univ. (Italy). Ist. di Fisica)


    Damage production in (100)InAs by room temperature implantation of N{sup +} at 50 keV in the range of 1E15 to 2E17 N{sup +}/cm{sup 2} has been studied by RBS/Channeling. The {sup 14}N(d,p){sup 15}N nuclear reaction was used to check the implanted doses. A quasi saturation of damage at 2E16 N{sup +}/cm{sup 2} was followed by apparent amorphization of the surface at {approx} 1E17 N{sup +}/cm{sup 2}. Channeling measurements at different probe energies have shown that the damage at the highest dose consists of both point and extended defects with small regions of local order still remaining in the matrix. (author).

  14. Surfactant damages on coastal vegetation in southern Italy

    Directory of Open Access Journals (Sweden)


    Full Text Available Coastal vegetation decline caused by seaspray has been reported to affect a variety of species in several countries: Australia, South of France, along the Italian Tyrrhenian coast, Spain and Tunisia. The most serious injury is due to the interaction between sea salt and surfactants, even if surfactants may cause direct damage on cell membranes. The salt uptake is enhanced by the durfactant-induced erosion of the epicuticular wax, which reduces the water surface tension. The symptoms are non-specific and consist in leaf discoloration and necrosis. In needles, necrosis begins from the apex; in leaves, from the edges. Directionality of crown damage is the main symptom for diagnosing the involvement of polluted seaspray. If an obstacle is placed between trees and sea wind, the trees do not show appreciable damage. In Italy, the tree decline caused by seaspray and surfactants has been investigated with special reference to the pinewoods of the San Rossore (Tuscany, Central Italy, or on the Tyrrhenian coastlands of Central Italy, such as the area around Castelporziano in Lazio. This research is aimed at a preliminary assessment of the extent of surfactant damage to the coastal vegetation in four regions in Southern Italy by: i field surveys and mapping of damage caused by surfactants; ii detecting the presence of surfactants on the tree crowns. The damages have been observed in a lot of zones in Apulia, Basilicata, Campania and Calabria, within 500 m inland from the sea, for a maximum length of 5500 m coastline, near the mouth of a river or stream, near the outlet of sewage canals and in any other coastal areas where the surface currents carry a surfactant load.

  15. Comparative study of approaches to assess damage in thermally fatigued Cusbnd Crsbnd Zr alloy (United States)

    Chatterjee, Arya; Mitra, R.; Chakraborty, A. K.; Rotti, C.; Ray, K. K.


    For the first time the nature of response of thermal fatigue damage (TFD) in Cusbnd Crsbnd Zr alloys, considered for the High Heat Flux components of Tokamak and its subsystems in International Thermonuclear Experimental Reactor application has been studied. Temperature cycling between 290 °C and 30 °C, similar to the service condition, has been carried out on two differently aged Cusbnd Crsbnd Zr alloys. The TFD has been assessed by damage mechanics approach using damage parameters, and by surface characteristics. The damage parameters increase exponentially during initial fatigue cycles and saturates, whilst surface characteristics shows continuous increase with increase in thermal fatigue cycles. Damages are different in the aged alloys depending upon the aging conditions.

  16. Ultrasonic evaluation of creep damage of Cr-Mo-V steel by acoustic microscopy

    Institute of Scientific and Technical Information of China (English)

    WEI Tingcun


    The evaluation of creep damages of Cr-Mo-V steel used in the gas turbine of power plant has been carried out using the line-focus-beam (LFB) acoustic microscopy. The velocity of leaky surface acoustic wave (LSAW) propagated near the specimen surface was used for the quantitative evaluations, which was measured by LFB acoustic microscopy using the v(z) curve analysis method. It has been shown that with the increase of creep damage fraction of metal material the LSAW velocity decreases obviously, which suggests the possibility of nondestructive and quantitative evaluations of creep damages in metal materials by acoustic microscopy.

  17. Prediction of Ductile Fracture Surface Roughness Scaling

    DEFF Research Database (Denmark)

    Needleman, Alan; Tvergaard, Viggo; Bouchaud, Elisabeth


    Experimental observations have shown that the roughness of fracture surfaces exhibit certain characteristic scaling properties. Here, calculations are carried out to explore the extent to which a ductile damage/fracture constitutive relation can be used to model fracture surface roughness scaling....... The scaling properties of the predicted thickness average fracture surfaces are calculated and the results are discussed in light of experimental observations....

  18. A damage model for fracking

    CERN Document Server

    Norris, J Quinn; Rundle, John B


    Injections of large volumes of water into tight shale reservoirs allows the extraction of oil and gas not previously accessible. This large volume "super" fracking induces damage that allows the oil and/or gas to flow to an extraction well. The purpose of this paper is to provide a model for understanding super fracking. We assume that water is injected from a small spherical cavity into a homogeneous elastic medium. The high pressure of the injected water generates hoop stresses that reactivate natural fractures in the tight shales. These fractures migrate outward as water is added creating a spherical shell of damaged rock. The porosity associated with these fractures is equal to the water volume injected. We obtain an analytic expression for this volume. We apply our model to a typical tight shale reservoir and show that the predicted water volumes are in good agreement with the volumes used in super fracking.

  19. Radiation damage in biomolecular systems

    CERN Document Server

    Fuss, Martina Christina


    Since the discovery of X-rays and radioactivity, ionizing radiations have been widely applied in medicine both for diagnostic and therapeutic purposes. The risks associated with radiation exposure and handling led to the parallel development of the field of radiation protection. Pioneering experiments done by Sanche and co-workers in 2000 showed that low-energy secondary electrons, which are abundantly generated along radiation tracks, are primarily responsible for radiation damage through successive interactions with the molecular constituents of the medium. Apart from ionizing processes, which are usually related to radiation damage, below the ionization level low-energy electrons can induce molecular fragmentation via dissociative processes such as internal excitation and electron attachment. This prompted collaborative projects between different research groups from European countries together with other specialists from Canada,  the USA and Australia. This book summarizes the advances achieved by these...

  20. Laser Induced Damage Studies in Borosilicate Glass Using nanosecond and sub nanosecond pulses

    CERN Document Server

    Rastogi, Vinay; Munda, D S


    The damage mechanism induced by laser pulse of different duration in borosilicate glass widely used for making confinement geometry targets which are important for laser driven shock multiplication and elongation of pressure pulse, is studied. We measured the front and rear surface damage threshold of borosilicate glass and their dependency on laser parameters. In this paper, we also study the thermal effects on the damage diameters, generated at the time of plasma formation. These induced damage width, geometries and microstructure changes are measured and analyzed with optical microscope, scanning electron microscope and Raman spectroscopy. The results show that at low energies symmetrical damages are found and these damage width increases nonlinearly with laser intensity. The emitted optical spectrum during the process of breakdown is also investigated and is used for the characterization of emitted plasma such as plasma temperature and free electron density. Optical emission lines from Si I at 500 nm, Si ...

  1. Advanced Mitigation Process (AMP) for Improving Laser Damage Threshold of Fused Silica Optics (United States)

    Ye, Xin; Huang, Jin; Liu, Hongjie; Geng, Feng; Sun, Laixi; Jiang, Xiaodong; Wu, Weidong; Qiao, Liang; Zu, Xiaotao; Zheng, Wanguo


    The laser damage precursors in subsurface of fused silica (e.g. photosensitive impurities, scratches and redeposited silica compounds) were mitigated by mineral acid leaching and HF etching with multi-frequency ultrasonic agitation, respectively. The comparison of scratches morphology after static etching and high-frequency ultrasonic agitation etching was devoted in our case. And comparison of laser induce damage resistance of scratched and non-scratched fused silica surfaces after HF etching with high-frequency ultrasonic agitation were also investigated in this study. The global laser induce damage resistance was increased significantly after the laser damage precursors were mitigated in this case. The redeposition of reaction produce was avoided by involving multi-frequency ultrasonic and chemical leaching process. These methods made the increase of laser damage threshold more stable. In addition, there is no scratch related damage initiations found on the samples which were treated by Advanced Mitigation Process.

  2. Mechanisms and target sites of damage in killing of Candida albicans hyphae by human polymorphonuclear neutrophils. (United States)

    Christin, L; Wysong, D R; Meshulam, T; Wang, S; Diamond, R D


    Target sites of fungal cell damage were studied to define mechanisms of neutrophil-mediated killing of Candida albicans hyphae. Neutrophils induced hyphal cell wall damage, as evidenced by release of cell wall glycoproteins and confocal microscopic changes. Damage occurred in the presence of neutrophil granule extracts and did not require oxidants. However, oxidation of hyphal surface glycoproteins correlated strongly with parallel increments in fungicidal activity, suggesting that oxidants did contribute to maximal cell wall damage. Neutrophil oxidants also induced hyphal DNA fragmentation, primarily single-strand breakage, as shown by increased electrophoretic migration after nuclease-S1 DNA digestion at single-strand break sites. The onset of damage to hyphal cell walls and DNA preceded detectable neutrophil-mediated fungicidal effects. Likewise, hyphal amino acid and nucleotide turnover as well as ATP initially rose, then declined as lethal effects became detectable. Thus, preceding detectable fungal cell death, neutrophil oxidative and oxygen-independent mechanisms damaged defined targets.

  3. Induced superficial chondrocyte death reduces catabolic cartilage damage in murine posttraumatic osteoarthritis. (United States)

    Zhang, Minjie; Mani, Sriniwasan B; He, Yao; Hall, Amber M; Xu, Lin; Li, Yefu; Zurakowski, David; Jay, Gregory D; Warman, Matthew L


    Joints that have degenerated as a result of aging or injury contain dead chondrocytes and damaged cartilage. Some studies have suggested that chondrocyte death precedes cartilage damage, but how the loss of chondrocytes affects cartilage integrity is not clear. In this study, we examined whether chondrocyte death undermines cartilage integrity in aging and injury using a rapid 3D confocal cartilage imaging technique coupled with standard histology. We induced autonomous expression of diphtheria toxin to kill articular surface chondrocytes in mice and determined that chondrocyte death did not lead to cartilage damage. Moreover, cartilage damage after surgical destabilization of the medial meniscus of the knee was increased in mice with intact chondrocytes compared with animals whose chondrocytes had been killed, suggesting that chondrocyte death does not drive cartilage damage in response to injury. These data imply that chondrocyte catabolism, not death, contributes to articular cartilage damage following injury. Therefore, therapies targeted at reducing the catabolic phenotype may protect against degenerative joint disease.

  4. Quantification of thermal damage in skin tissue

    Institute of Scientific and Technical Information of China (English)

    Xu Feng; Wen Ting; Lu Tianjian; Seffen Keith


    Skin thermal damage or skin burns are the most commonly encountered type of trauma in civilian and military communities. Besides, advances in laser, microwave and similar technologies have led to recent developments of thermal treatments for disease and damage involving skin tissue, where the objective is to induce thermal damage precisely within targeted tissue structures but without affecting the surrounding, healthy tissue. Further, extended pain sensation induced by thermal damage has also brought great problem for burn patients. Thus, it is of great importance to quantify the thermal damage in skin tissue. In this paper, the available models and experimental methods for quantification of thermal damage in skin tissue are discussed.

  5. Residual force enhancement following eccentric induced muscle damage. (United States)

    Power, Geoffrey A; Rice, Charles L; Vandervoort, Anthony A


    During lengthening of an activated skeletal muscle, the force maintained following the stretch is greater than the isometric force at the same muscle length. This is termed residual force enhancement (RFE), but it is unknown how muscle damage following repeated eccentric contractions affects RFE. Using the dorsiflexors, we hypothesised muscle damage will impair the force generating sarcomeric structures leading to a reduction in RFE. Following reference maximal voluntary isometric contractions (MVC) in 8 young men (26.5±2.8y) a stretch was performed at 30°/s over a 30° ankle excursion ending at the same muscle length as the reference MVCs (30° plantar flexion). Surface electromyography (EMG) of the tibialis anterior and soleus muscles was recorded during all tasks. The damage protocol involved 4 sets of 25 isokinetic (30°/s) lengthening contractions. The same measures were collected at baseline and immediately post lengthening contractions, and for up to 10min recovery. Following the lengthening contraction task, there was a 30.3±6.4% decrease in eccentric torque (Pmuscle damage (Pmuscle function compared to isometric actions succeeding damage. Thus, active force of cross-bridges is decreased because of impaired excitation-contraction coupling but force generated during stretch remains intact because force contribution from stretched sarcomeric structures is less impaired.

  6. Electromagnetomechanical elastodynamic model for Lamb wave damage quantification in composites (United States)

    Borkowski, Luke; Chattopadhyay, Aditi


    Physics-based wave propagation computational models play a key role in structural health monitoring (SHM) and the development of improved damage quantification methodologies. Guided waves (GWs), such as Lamb waves, provide the capability to monitor large plate-like aerospace structures with limited actuators and sensors and are sensitive to small scale damage; however due to the complex nature of GWs, accurate and efficient computation tools are necessary to investigate the mechanisms responsible for dispersion, coupling, and interaction with damage. In this paper, the local interaction simulation approach (LISA) coupled with the sharp interface model (SIM) solution methodology is used to solve the fully coupled electro-magneto-mechanical elastodynamic equations for the piezoelectric and piezomagnetic actuation and sensing of GWs in fiber reinforced composite material systems. The final framework provides the full three-dimensional displacement as well as electrical and magnetic potential fields for arbitrary plate and transducer geometries and excitation waveform and frequency. The model is validated experimentally and proven computationally efficient for a laminated composite plate. Studies are performed with surface bonded piezoelectric and embedded piezomagnetic sensors to gain insight into the physics of experimental techniques used for SHM. The symmetric collocation of piezoelectric actuators is modeled to demonstrate mode suppression in laminated composites for the purpose of damage detection. The effect of delamination and damage (i.e., matrix cracking) on the GW propagation is demonstrated and quantified. The developed model provides a valuable tool for the improvement of SHM techniques due to its proven accuracy and computational efficiency.

  7. Subsurface Damage in Scratch Testing of Potassium Dihydrogen Phosphate Crystal

    Institute of Scientific and Technical Information of China (English)

    WANG Ben; WU Dongjiang; GAO Hang; KANG Renke; GUO Dongming


    Potassium dihydrogen phosphate (KDP) is an important electro-optic crystal, often used for frequency conversion and Pockels cells in large aperture laser systems. To investigate the influence of anisotropy to the depth of subsurface damage and the profiles of cracks in subsurface of KDP crystal, an experimental study was made to obtain the form of subsurface damage produced by scratches on KDP crystal in [100], [120] and [110] crystal directions on (001) crystal plane. The results indicated that there were great differences between depth and crack shape in different directions. For many slip planes in KDP, the plastic deformation and cracks generated under pressure in the subsurfacewerecomplex. Fluctuations of subsurface damage depth at transition point were attributed to the deformation of the surface which consumed more energy when the surface deformation changed from the mixed region of brittle and plastic to the complete brittle region along the scratch. Also, the process of subsurface damage from shallow to deep, from dislocation to big crack in KDP crystal with the increase of radial force and etch pit on different crystal plane were obtained. Because crystallographic orientation and processing orientation was different, etching pits on (100) crystal plane were quadrilateral while on (110) plane and (120) plane were trapezoidal and triangular, respectively.

  8. Investigation of cutting-induced damage in CMC bend bars

    Directory of Open Access Journals (Sweden)

    Neubrand A.


    Full Text Available Ceramic matrix composites (“CMC” with a strong fibre-matrix interface can be made damage-tolerant by introducing a highly porous matrix. Such composites typically have only a low interlaminar shear strength, which can potentially promote damage when preparing specimens or components by cutting. In order to investigate the damage induced by different cutting methods, waterjet cutting with and without abrasives, laser-cutting, wire eroding and cutoff grinding were used to cut plates of two different CMCs with a matrix porosity up to 35 vol.-%. For each combination of cutting method and composite, the flexural and interlaminar shear strength of the resulting specimens was determined. Additionally, the integrity of the regions near the cut surfaces was investigated by high-resolution x-ray computer tomography. It could be shown that the geometrical quality of the cut is strongly affected by the cutting method employed. Laser cut and waterjet cut specimens showed damage and delaminations near the cut surface leading to a reduced interlaminar shear strength of short bend bars in extreme cases.

  9. Economic measurement of environment damages

    Energy Technology Data Exchange (ETDEWEB)

    Krawiec, F.


    The densities, energy consumption, and economic development of the increasing population exacerbate environmental degradation. Air and water pollution is a major environmental problem affecting life and health, outdoor recreation, household soiling, vegetation, materials, and production. The literature review indicated that numerous studies have assessed the physical and monetary damage to populations at risk from excessive concentrations of major air and water pollutants-sulfur dioxide, total suspended particulate matter, oxidants, and carbon monoxide in air; and nutrients, oil, pesticides, and toxic metals and others in water. The measurement of the damages was one of the most controversial issues in pollution abatement. The methods that have been used to estimate the societal value of pollution abatement are: (1) chain of effects, (2) market approaches, and (3) surveys. National gross damages of air pollution of $20.2 billion and of water pollution of $11.1 billion for 1973 are substantial. These best estimates, updated for the economic and demographic conditions, could provide acceptable control totals for estimating and predicting benefits and costs of abating air and water pollution emissions. The major issues to be resolved are: (1) lack of available noneconomic data, (2) theoretical and empirical difficulties of placing a value on human life and health and on benefits such as aesthetics, and (3) lack of available demographic and economic data.

  10. Continuum damage and fracture mechanics

    CERN Document Server

    Öchsner, Andreas


    This textbook offers readers an introduction to damage and fracture mechanics, equipping them to grasp the basic ideas of the presented approaches to modeling in applied mechanics. In the first part, the book reviews and expands on the classical theory of elastic and elasto-plastic material behavior. A solid understanding of these two topics is the essential prerequisite to advancing to damage and fracture mechanics. Thus, the second part of this course provides an introduction to the treatment of damage and fractures in the context of applied mechanics. Wherever possible, the one-dimensional case is first introduced and then generalized in a following step. This departs somewhat from the more classical approach, where first the most general case is derived and then simplified to special cases. In general, the required mathematics background is kept to a minimum.   Tutorials are included at the end of each chapter, presenting the major steps for the solution and offering valuable tips and tricks. The supplem...

  11. A damage diagnostic imaging algorithm based on the quantitative comparison of Lamb wave signals (United States)

    Wang, Dong; Ye, Lin; Lu, Ye; Li, Fucai


    With the objective of improving the temperature stability of the quantitative comparison of Lamb wave signals captured in different states, a damage diagnostic imaging algorithm integrated with Shannon-entropy-based interrogation was proposed. It was evaluated experimentally by identifying surface damage in a stiffener-reinforced CF/EP quasi-isotropic woven laminate. The variations in Shannon entropy of the reference (without damage) and present (with damage) signals from individual sensing paths were calibrated as damage signatures and utilized to estimate the probability of the presence of damage in the monitoring area enclosed by an active sensor network. The effects of temperature change on calibration of the damage signatures and estimation of the probability values for the presence of damage were investigated using a set of desynchronized signals. The results demonstrate that the Shannon-entropy-based damage diagnostic imaging algorithm with improved robustness in the presence of temperature change has the capability of providing accurate identification of damage in actual environments.

  12. 2D-C/[SiC-(B-C)]复合材料在航空发动机燃烧室中的自愈合行为研究%Self-healing Behavior of 2D-C/[SiC-(B-C)] Composite in Aero-engine Combustion Chamber

    Institute of Scientific and Technical Information of China (English)

    刘光海; 成来飞; 栾新刚; 刘永胜


    采用以B-C陶瓷为基体自愈合改性组元的2D-C/[SiC-(B-C)]以及经过硅硼玻璃改性的2D-C/[SiC-(B-C)]制备浮壁瓦片,分别在1000、1200、1350℃下对其进行发动机燃烧室环境考核.对考核后的浮壁瓦片进行取样,并在室温下进行拉伸强度以及三点弯曲强度测试.结果发现:经过环境考核试样的力学性能都有不同程度的提高,拉伸强度和三点弯曲强度随着考核温度的升高而提高,其中三点弯曲强度的升高速率更快.通过SEM观察,B-C自愈合组元氧化生成的玻璃相以及改性硅硼玻璃相在考核过程中有效地封填了试样的孔隙和裂纹.最后通过力学性能测试结合SEM观察,初步分析了两种复合材料在航空发动机燃烧室中的愈合机制.%2D-C/[SiC-(B-C)] samples modified by B-C ceramic as self-healing component and boron-silicon glass phase were assessed by environmental engine experiments at 1000℃, 1200℃, 1350℃. Furthermore, tensile strength and three point bending strength of the samples were tested at room temperature after assessment. The results showed that the tensile strength and three point bending strength increased with the increase of assessment temperature, however, three point bending mechanical properties increased at a higher rate. SEM results showed that the glass phase generated by oxidization of B-C self-healing component and the boron oxide glass phase filled pores and cracks effectively. According to the experiments results, the self-healing mechanisms in aero-engine combustion chamber of such two samples were discussed.

  13. Postoperative gluteal skin damage associated with latent development of gluteal muscle damage. (United States)

    Hattori, Yukari; Ikeuchi, Takashi; Kuroda, Yoshihiro; Matsugi, Kiyotomo; Minami, Shunsuke; Higuchi, Toshihiro; Zaima, Masazumi; Ishitoya, Satoshi; Yamauchi, Chikako; Onishi, Hiroyuki; Kawamura, Junichiro; Kitoh, Koichi; Oshiro, Osamu; Yamamoto, Yosuke; Utani, Atsushi; Hattori, Noboru


    Preceding this study, we observed two cases of concurrent postoperative gluteal skin and muscle damage with extremely high serum creatine kinase (CK) levels, both of which were unrelated to pressure-induced tissue injury. However, postoperative gluteal skin damage accompanied by gluteal muscle damage has not been previously reported and the association between gluteal skin damage, gluteal muscle damage and pressure-induced tissue injury has not previously been investigated. Therefore, we conducted this study to determine the postoperative incidence of gluteal skin damage associated with gluteal muscle damage and assess associations with postoperative serum CK levels and pressure-induced tissue injury. We prospectively evaluated postoperative incidence of gluteal skin damage and measured serum CK levels in 929 consecutive patients who underwent abdominal, urological or gynecological surgery at our hospital. Magnetic resonance imaging (MRI) of the pelvis was performed in 67 patients who consented. As a result, two of 929 patients developed postoperative gluteal skin damage accompanied by gluteal muscle damage. Gluteal muscle damage without gluteal skin damage was observed in 23 of the 67 patients who underwent MRI, and volumes of damaged gluteal muscle and postoperative serum CK levels were positively correlated. Both gluteal skin and muscle damage were distinguishable from pressure-induced tissue injury. Based on the results of this study, we could confirm the occurrence of postoperative gluteal skin damage, distinct from pressure sores, accompanied by gluteal muscle damage. We also revealed latent development of postoperative gluteal muscle damage, distinguishable from compression-induced tissue injury, without accompanying gluteal skin damage.

  14. Case Study of Local Damage Indicators for a 2-Bay, 6-Storey RC-Frame subject to Earthquakes

    DEFF Research Database (Denmark)

    Skjærbæk, P. S.; Nielsen, Søren R. K.; Kirkegaard, Poul Henning

    A simulation study of a 2-bay, 6storey model test RC-frame(scale 1:5) subject to earthquakes is considered in this paper. Based on measured (simulated) storey accelerations and ground surface accelerations several indices for the storey damage, including interstorey drift, flexural damage ratios......, normalized cumulative dissipated energy, Park and Ang's indicator, a low-cycle fatigue damage index and a recently proposed local softening damage index estimated from time-varying eigenfrequencies are used to evaluate the damage state of the structure after the earthquake. Storey displacements are obtained...

  15. Case Study of Local Damage Indicators for a 2-Bay, 6-Storey RC-Frame subject to Earthquakes

    DEFF Research Database (Denmark)

    Skjærbæk, P. S.; Nielsen, Søren R. K.; Kirkegaard, Poul Henning


    A simulation study of a 2-bay, 6storey model test RC-frame(scale 1:5) subject to earthquakes is considered in this paper. Based on measured (simulated) storey accelerations and ground surface accelerations several indices for the storey damage, including interstorey drift, flexural damage ratios......, normalized cumulative dissipated energy, Park and Ang's indicator, a low-cycle fatigue damage index and a recently proposed local softening damage index estimated from time-varying eigenfrequencies are used to evaluate the damage state of the structure after the earthquake. Storey displacements are obtained...

  16. Damage behaviors of fiber Bragg grating sensor in fabrication (United States)

    Tang, Liqun; Sang, Dengfeng; Chen, Jinming; Yang, Bao; Liu, Yiping


    It is has been noted that for fiber Bragg grating sensor (FBGS), the tensile strengths of fiber Bragg grating sensors (FBGSs) were decreased after the gratings were written, which may reduce the sensor's measurement range obviously. In this paper, we focused on the damage behaviours of FBGS after fabrication experimentally. Firstly, the tensile tests were carried to measure the tensile strengths of naked optical fiber, decoated optical fiber and optical fiber with Bragg gratings to learn deduction of the tensile strength of optical fiber in the cases respectively. Further, the microscope photography was used to observe the surfaces of optical fiber with or without exposure of excimer laser. The main conclusion is that the UV pulse is the main contribution to reduce the strength remarkably, and the mechanical decoating method also can induce the surface damage on the optical fiber.

  17. Strain localization and damage development in 2060 alloy during bending

    Institute of Scientific and Technical Information of China (English)

    Xiao Jin; Bao-qin Fu; Cheng-lu Zhang; Wei Liu


    The microstructure evolution and damage development of the third-generation Al–Li alloy 2060 (T8) were studied using in situ bending tests. Specimens were loaded with a series of punches of different radii, and the microstructure evolution was studied by scanning electron microscopy, electron backscatter diffraction, and digital image correlation (DIC) methods. The evolution of the microscopic fracture strain distribution and microstructure in 2060 alloy during bending was characterized, where the dispersion distribution of precipitates was recorded by backscattered electron imaging and later inputted into a DIC system for strain calculations. The experimental results showed that strain localization in the free surface of bent specimens induced damage to the microstructure. The region of crack initiation lies on the free surface with maximum strain, and the shear crack propagates along the macro-shear band in the early stages of bending. Crack propagation in the later stages was interpreted on the basis of the conventional mechanism of ductile fracture.

  18. Damage and fatigue crack growth of Eurofer steel first wall mock-up under cyclic heat flux loads. Part 2: Finite element analysis of damage evolution

    Energy Technology Data Exchange (ETDEWEB)

    You, Jeong-Ha, E-mail:


    Highlights: • The surface heat flux load of 3.5 MW/m{sup 2} produced substantial stresses and inelastic strains in the heat-loaded surface region, especially at the notch root. • The notch root exhibited a typical notch effect such as stress concentration and localized inelastic yield leading to a preferred damage development. • The predicted damage evolution feature agrees well with the experimental observation. • The smooth surface also experiences considerable stresses and inelastic strains. However, the stress intensity and the amount of inelastic deformation are not high enough to cause any serious damage. • The level of maximum inelastic strain is higher at the notch root than at the smooth surface. On the other hand, the amplitude of inelastic strain variation is comparable at both positions. • The amount of inelastic deformation is significantly affected by the length of pulse duration time indicating the important role of creep. - Abstract: In the preceding companion article (part 1), the experimental results of the high-heat-flux (3.5 MW/m{sup 2}) fatigue tests of a Eurofer bare steel first wall mock-up was presented. The aim was to investigate the damage evolution and crack initiation feature. The mock-up used there was a simplified model having only basic and generic structural feature of an actively cooled steel FW component for DEMO reactor. In that study, it was found that microscopic damage was formed at the notch root already in the early stage of the fatigue loading. On the contrary, the heat-loaded smooth surface exhibited no damage up to 800 load cycles. In this paper, the high-heat-flux fatigue behavior is investigated with a finite element analysis to provide a theoretical interpretation. The thermal fatigue test was simulated using the coupled damage-viscoplastic constitutive model developed by Aktaa. The stresses, inelastic deformation and damage evolution at the notch groove and at the smooth surface are compared. The different

  19. Galvanic effects on cavitation damage for 1Cr13 stainless steel

    Institute of Scientific and Technical Information of China (English)

    Dongbai Sun; Xia Bai; Hongying Yu; Huimin Meng; Huiqing Li


    Based on the electric-spark principle, a new kind of cavitation damage testing apparatus was designed, which could produce the bubble. Bubbles collapsed and acted on a small surface area of the alloy surface, so an intensive electrochemical inhomoge nous state would be induced and lead to the existence of surface galvanic effect on the alloy. The galvanic effect of 1Cr13 SS during cavitation damage has been quantitatively investigated in NaCl solution. The results show that intensive galvanic effect of 1Crl3 SS during cavitation damage appears the potential of the damaged area shifting negatively with the bubble collapse and simultaneously the galvanic current generates. The mass loss of alloy due to cavitation increases with the bubble quantity, and increases with the in creasing of Cl- content. And both the total mass loss and the mass loss due to galvanic corrosion increase linearly with the area ratio of cavitation damaged to undamaged area. Such surface galvanic effects speed up the dissolution rate of the alloy, which, in turn, accelerates the mechanical damage, and aggravates the mass loss of the alloy. It has been further confirmed that the mass loss due to the surface galvanic effect can be decreased by catholic protection.

  20. Quantification of thermal damage in skin tissue

    Institute of Scientific and Technical Information of China (English)

    徐峰; 文婷; 卢天健; Seffen; Keith


    Skin thermal damage or skin burns are the most commonly encountered type of trauma in civilian and military communities. Besides, advances in laser, microwave and similar technologies have led to recent developments of thermal treatments for disease and damage involving skin tissue, where the objective is to induce thermal damage precisely within targeted tissue structures but without affecting the surrounding, healthy tissue. Further, extended pain sensation induced by thermal damage has also brought great...

  1. Procedural Issues Concerning Environmental Damage In Ecuador

    Directory of Open Access Journals (Sweden)

    René Bedón Garzón


    Full Text Available This paper aims to determine, through a deep analysis of different doctrines, the definition of environmental damage; it also seeks to determine the difference between damage to nature and the civil environmental damage, which is damage to individual interests or collective environmental event occasion. To this purpose, we intend to study certain procedural rules and case law concerning Ecuadorian environmental management, also in comparative law considers how countries like Chile, Spain and Argentina regulate compensation and repair environment.



    Bobyr, M.; Khalimon, O.; Bondarets, O.


    Damage in metals is mainly the process of the initiation and growth of voids. A formulation for anisotropic damage is established in the framework of the principle of strain equivalence, principle of increment complementary energy equivalence and principle of elastic energy equivalence. This paper presents the development of an anisotropic damage theory. This work is focused on the development of evolution anisotropic damage models which is based on a Young’s modulus/Poisson’s ratio change of...

  3. Investigation of mechanisms leading to laser damage morphology (United States)

    Lamaignère, L.; Chambonneau, M.; Diaz, R.; Grua, P.; Courchinoux, R.; Natoli, J.-Y.; Rullier, J. L.


    The original damage ring pattern at the exit surface of fused silica induced by highly modulated nanosecond infrared laser pulses demonstrates the time dependence of damage morphology. Such a damage structure is used to study the dynamics of the plasma issued from open cracks. This pattern originates from electron avalanche in this plasma, which simultaneously leads to an ionization front displacement in air and a silica ablation process. Experiments have shown that the propagation speed of the detonation wave reaches about 20 km/s and scales as the cube root of the laser intensity, in good agreement with theoretical hydrodynamics modeling. During this presentation, we present the different phases and the associated mechanisms leading to this peculiar morphology: • During an incubation phase, a precursor defect provides energy deposit that drives the near surface material into a plasma state. • Next the silica plasma provides free electrons in the surrounding air, under laser irradiation an electron avalanche is initiated and generates a breakdown wave. • Then this breakdown wave leads to an expansion of the air plasma. This latter is able to heat strongly the silica surface as well as generate free electrons in its conduction band. Hence, the silica becomes activated along the breakdown wave. • When the silica has become absorbent, an ablation mechanism of silica occurs, simultaneously with the air plasma expansion, resulting in the formation of the ring patterns in the case of these modulated laser pulses. These mechanisms are supported by experiments realized in vacuum environment. A model describing the expansion of the heated area by thermal conduction due to plasma free electrons is then presented. Next, the paper deals with the two damage formation phases that are distinguished. The first phase corresponds to the incubation of the laser flux by a subsurface defect until the damage occurrence: an incubation fluence corresponds to this phase. The

  4. Collision Risk and Damage after Collision

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup; Hansen, Peter Friis; Nielsen, Lars Peter


    of the damage risk is calculated by a numerical procedure. These directly calculated distributions for hull damages are subsequently approximated by analytical expressions suited for probabilistic damage stability calculations similar to the procedure described in IMO regulation A.265.Numerical results...

  5. Subclinical organ damage and cardiovascular risk prediction

    DEFF Research Database (Denmark)

    Sehestedt, Thomas; Olsen, Michael H


    by measuring subclinical organ damage. We have (i) reviewed recent studies linking markers of subclinical organ damage in the heart, blood vessels and kidney to cardiovascular risk; (ii) discussed the evidence for improvement in cardiovascular risk prediction using markers of subclinical organ damage; (iii...

  6. 7 CFR 51.2966 - Serious damage. (United States)


    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Serious damage. 51.2966 Section 51.2966 Agriculture... Standards for Grades of Walnuts in the Shell Definitions § 51.2966 Serious damage. Serious damage means any... discoloration covering a smaller area if the appearance is equally objectionable; (b) Perforated shells when...

  7. 7 CFR 51.1010 - Damage. (United States)


    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Damage. 51.1010 Section 51.1010 Agriculture... Standards for Persian (Tahiti) Limes Definitions § 51.1010 Damage. Damage means any defect which materially... area of a circle one-fourth inch in diameter; (c) Exanthema (ammoniation) which materially...

  8. 7 CFR 51.2128 - Damage. (United States)


    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Damage. 51.2128 Section 51.2128 Agriculture... Standards for Grades of Shelled Almonds Definitions § 51.2128 Damage. Damage means any defect which... the affected area on an individual kernel aggregates more than the equivalent of a circle...

  9. 7 CFR 51.2655 - Damage. (United States)


    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Damage. 51.2655 Section 51.2655 Agriculture... Standards for Grades for Sweet Cherries 1 Definitions § 51.2655 Damage. Damage means any specific defect... appearance; (c) Hail injury when deep or not well healed, or when the aggregate area exceeds the area of...

  10. The Research of Liquidated Damages in China

    Institute of Scientific and Technical Information of China (English)

    Xu; Ting


    <正>I.Liquidated damages provisions of Anglo-American countries distinguished from that in China Liquidated damages provisions in Anglo-American countries are different from penalty clauses.However,Chinese law does not recognise liquidated damages in the same way as in Anglo-

  11. Effects of Accelerated Aging on Fiber Damage Thresholds

    Energy Technology Data Exchange (ETDEWEB)

    Setchell, R.E.


    Laser-induced damage mechanisms that can occur during high-intensity fiber transmission have been under study for a number of years. Our particular interest in laser initiation of explosives has led us to examine damage processes associated with the transmission of Q-switched, Nd:YAG pulses at 1.06 {micro}m through step-index, multimode, fused silica fiber. Laser breakdown at the fiber entrance face is often the first process to limit fiber transmission but catastrophic damage can also occur at either fiber end face, within the initial entry segment of the fiber, and at other internal sites along the fiber path. Past studies have examined how these various damage mechanisms depend upon fiber end-face preparation, fiber fixturing and routing, laser characteristics, and laser-to-fiber injection optics. In some applications of interest, however, a fiber transmission system may spend years in storage before it is used. Consequently, an important additional issue for these applications is whether or not there are aging processes that can result in lower damage thresholds over time. Fiber end-face contamination would certainly lower breakdown and damage thresholds at these surfaces, but careful design of hermetic seals in connectors and other end-face fixtures can minimize this possibility. A more subtle possibility would be a process for the slow growth of internal defects that could lead to lower thresholds for internal damage. In the current study, two approaches to stimulating the growth of internal defects were used in an attempt to produce observable changes in internal damage thresholds. In the first approach test fibers were subjected to a very high tensile stress for a time sufficient for some fraction to fail from static fatigue. In the second approach, test fibers were subjected to a combination of high tensile stress and large, cyclic temperature variations. Both of these approaches were rather arbitrary due to the lack of an established growth mechanism for

  12. Structural Health Monitoring for Impact Damage in Composite Structures.

    Energy Technology Data Exchange (ETDEWEB)

    Roach, Dennis P.; Raymond Bond (Purdue); Doug Adams (Purdue)


    Composite structures are increasing in prevalence throughout the aerospace, wind, defense, and transportation industries, but the many advantages of these materials come with unique challenges, particularly in inspecting and repairing these structures. Because composites of- ten undergo sub-surface damage mechanisms which compromise the structure without a clear visual indication, inspection of these components is critical to safely deploying composite re- placements to traditionally metallic structures. Impact damage to composites presents one of the most signi fi cant challenges because the area which is vulnerable to impact damage is generally large and sometimes very dif fi cult to access. This work seeks to further evolve iden- ti fi cation technology by developing a system which can detect the impact load location and magnitude in real time, while giving an assessment of the con fi dence in that estimate. Fur- thermore, we identify ways by which impact damage could be more effectively identi fi ed by leveraging impact load identi fi cation information to better characterize damage. The impact load identi fi cation algorithm was applied to a commercial scale wind turbine blade, and results show the capability to detect impact magnitude and location using a single accelerometer, re- gardless of sensor location. A technique for better evaluating the uncertainty of the impact estimates was developed by quantifying how well the impact force estimate meets the assump- tions underlying the force estimation technique. This uncertainty quanti fi cation technique was found to reduce the 95% con fi dence interval by more than a factor of two for impact force estimates showing the least uncertainty, and widening the 95% con fi dence interval by a fac- tor of two for the most uncertain force estimates, avoiding the possibility of understating the uncertainty associated with these estimates. Linear vibration based damage detection tech- niques were investigated in the

  13. Multi-physics modeling of multifunctional composite materials for damage detection (United States)

    Sujidkul, Thanyawalai

    This study presents a modeling of multifunction composite materials for damage detection with its verification and validation to mechanical behavior predictions of Carbon Fibre Reinforced Polymer composites (CFRPs), CFRPs laminated composites, and woven SiC/SiC matrix composites that are subjected to fracture damage. Advantages of those materials are low cost, low density, high strength-to-weight ratio, and comparable specific tensile properties, the special of SiC/SiC is good environmental stability at high temperature. Resulting in, the composite has been used for many important structures such as helicopter rotors, aerojet engines, gas turbines, hot control surfaces, sporting goods, and windmill blades. Damage or material defect detection in a mechanical component can provide vital information for the prediction of remaining useful life, which will result in the prevention of catastrophic failures. Thus the understanding of the mechanical behavior have been challenge to the prevent damage and failure of composites in different scales. The damage detection methods in composites have been investigated widely in recent years. Non-destructive techniques are the traditional methods to detect the damage such as X-ray, acoustic emission and thermography. However, due to the invisible damage in composite can be occurred, to prevent the failure in composites. The developments of damage detection methods have been considered. Due to carbon fibers are conductive materials, in resulting CFRPs can be self-sensing to detect damage. As is well known, the electrical resistance has been shown to be a sensitive measure of internal damage, and also this work study in thermal resistance can detect damage in composites. However, there is a few number of different micromechanical modeling schemes has been proposed in the published literature for various types of composites. This works will provide with a numerical, analytical, and theoretical failure models in different damages to

  14. Radiation damage in multiphase ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Men, Danju [Department of Chemical Engineering and Materials Science, University of California, Irvine, CA 92697-2575 (United States); Patel, Maulik K.; Usov, Igor O. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Toiammou, Moidi; Monnet, Isabelle [CIMAP, CEA/CNRS/ENSICAEN/Universite de Caen-Basse Normandie, Bd Henri Becquerel, BP 5133, F-14070 Caen Cedex 5 (France); Pivin, Jean Claude [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, CNRS-IN2P3-Universite Paris Sud, UMR 8609, Bat. 108, 91405 Orsay (France); Porter, John R. [Materials Department, University of California, Santa Barbara, CA 93106-5050 (United States); Mecartney, Martha L., E-mail: [Department of Chemical Engineering and Materials Science, University of California, Irvine, CA 92697-2575 (United States)


    Graphical abstract: Display Omitted -- Abstract: Four-phase ceramic composites containing 3 mol% Y{sub 2}O{sub 3} stabilized ZrO{sub 2} (3Y-TZP), Al{sub 2}O{sub 3}, MgAl{sub 2}O{sub 4}, and LaPO{sub 4} were synthesized as model materials representing inert matrix fuel with enhanced thermal conductivity and decreased radiation-induced microstructural damage with respect to single-phase UO{sub 2}. This multi-phase concept, if successful, could be applied to design advanced nuclear fuels which could then be irradiated to higher burn-ups. 3Y-TZP in the composite represents a host (fuel) phase with the lowest thermal conductivity and Al{sub 2}O{sub 3} is the high thermal conductivity phase. The role of MgAl{sub 2}O{sub 4} and LaPO{sub 4} was to stabilize the structure under irradiation. The radiation response was evaluated by ion irradiation at 500 °C with 10 MeV Au ions and at 800 °C with 92 MeV Xe ions, to simulate damage due to primary knock-on atoms and fission fragments, respectively. Radiation damage and microstructural changes were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy and computational modeling. Al{sub 2}O{sub 3}, Y{sub 2}O{sub 3} stabilized ZrO{sub 2} and MgAl{sub 2}O{sub 4} phases exhibit high amorphization resistance and remain stable when irradiated with both Au and Xe ions. A monoclinic-to-tetragonal phase transformation, however, is promoted by Xe and Au ion irradiation in 3Y-TZP. The LaPO{sub 4} monazite phase appears to melt, dewet the other phases, and recrystallize under Au irradiation, but does not change under Xe irradiation.

  15. Radiation damage of structural materials

    CERN Document Server

    Koutsky, Jaroslav


    Maintaining the integrity of nuclear power plants is critical in the prevention or control of severe accidents. This monograph deals with both basic groups of structural materials used in the design of light-water nuclear reactors, making the primary safety barriers of NPPs. Emphasis is placed on materials used in VVER-type nuclear reactors: Cr-Mo-V and Cr-Ni-Mo-V steel for RPV and Zr-Nb alloys for fuel element cladding. The book is divided into 7 main chapters, with the exception of the opening one and the chapter providing a phenomenological background for the subject of radiation damage. Ch

  16. Effect of focus position of ns pulse laser on damage characteristics of K9 glass (United States)

    Pan, Yunxiang; Zhang, Hongchao; Li, Mengmeng; Shen, Zhonghua; Lu, Jian; Ni, Xiaowu


    Laser-induced damage of optical glasses has been investigated for more than fifty years. Due to the residual scratches, inclusions and other forms of defects at surfaces of optical glasses after the processes of grinding and polishing, it is well known that the sample surface can be damaged more easily than bulk. In order to get the relationship between the damage threshold and the location of the laser spot, we carried out damage experiments on K9 glasses with a 7ns pulse laser. Since ns pulse laser-induced damage of optical glasses always accompanies with the generation of the plasma, a optical microscope connected with a CCD camera was used to observe the plasma flash, which can provide a real time detection of damage sites. The laser pulse was first focused into the bulk, then the spot was moved toward the direction of incident laser beam step by step until the beam was completely focused in ambient air. Damage threshold curves were measured for each focus position, and low thresholds and high thresholds were extracted from those curves. Finally, the relationship between damage thresholds and focus position was analyzed.

  17. Towards a canonical elastoplastic damage model (United States)

    Taher, Salah El-Din F.; Baluch, Mohammed H.; Al-Gadhib, Ali H.


    Fundamental aspects of elastoplastic damage are outlined. Time-independent isotropic damage is considered in order to study material degradation. By splitting the total strain tensor into its components of elastic damage and plastic damage and using recoverable energy equivalence, three distinct modes of behavior are particularized. For each mode of behavior, a suitable damage variable is culled. An in-depth analysis of this formulation reveals a certain incongruity in the assumptions postulated in some of the previously proposed models. The suggested generalized concepts are supported by experimental evidence.

  18. Status of Research on Online Fuel Damage Detection and Core Damage Assessment System

    Institute of Scientific and Technical Information of China (English)

    XU; Xi-an; JI; Song-tao; GAO; Yong-guang; SHI; Xiao-lei


    <正>The technique research on the online fuel element damage detection and reactor core damage assessment is one project in the research program of the technical research for reactor key equipment maintenance and detection. The main research objective is to develop an online fuel damage detection system (FDDS), a core damage assessment system (CDAS) and make the integration of the two systems.

  19. Focused ion beam damage to MOS integrated circuits

    Energy Technology Data Exchange (ETDEWEB)



    Commercial focused ion beam (FIB) systems are commonly used to image integrated circuits (ICS) after device processing, especially in failure analysis applications. FIB systems are also often employed to repair faults in metal lines for otherwise functioning ICS, and are being evaluated for applications in film deposition and nanofabrication. A problem that is often seen in FIB imaging and repair is that ICS can be damaged during the exposure process. This can result in degraded response or out-right circuit failure. Because FIB processes typically require the surface of an IC to be exposed to an intense beam of 30--50 keV Ga{sup +} ions, both charging and secondary radiation damage are potential concerns. In previous studies, both types of effects have been suggested as possible causes of device degradation, depending on the type of device examined and/or the bias conditions. Understanding the causes of this damage is important for ICS that are imaged or repaired by a FIB between manufacture and operation, since the performance and reliability of a given IC is otherwise at risk in subsequent system application. In this summary, the authors discuss the relative roles of radiation damage and charging effects during FIB imaging. Data from exposures of packaged parts under controlled bias indicate the possibility for secondary radiation damage during FIB exposure. On the other hand, FIB exposure of unbiased wafers (a more common application) typically results in damage caused by high-voltage stress or electrostatic discharge. Implications for FIB exposure and subsequent IC use are discussed.

  20. Millennium-long damage to building materials in London. (United States)

    Brimblecombe, Peter; Grossi, Carlota M


    Damage functions from a range of sources are used to estimate deterioration of carbonate stone, iron and copper, in addition to the rate of blackening of stone surfaces in London across the period 1100-2100 CE. Meteorological and pollution input is available for only a relatively short part of this span, so non-instrumental weather records and modelled pollution are utilised for historic values, while future climate is adapted from the HadCM3A2 model output and pollution assessed from likely regulatory trends. The results from the different damage functions compare reasonably well showing comparable changes in damage rates with time. A potential square-root dependence of change in deposition velocity of SO2 to limestone suggests a possible overestimate of damage when pollution is high. Deterioration is especially intense from the 1700s. It is difficult to be certain whether the corrosion of copper accelerated as early as this or it developed in the 20th century. Nevertheless all the functions predict a decline in copper corrosion from the end of the 20th century. A blackening function was developed to relate elemental carbon concentration and the colour of deposited particulate matter to blackening rate, which suggests that soiling was particularly rapid in the late 19th century. The increase and subsequent decrease in damage to building materials is interpreted in terms of a Kuznets curve. The centuries where pollution controlled damage to durable building material seems to be over. Weathering, in a changing climate may have the greatest impact in the future.

  1. Damage Assessment of Composite Structures Using Digital Image Correlation (United States)

    Caminero, M. A.; Lopez-Pedrosa, M.; Pinna, C.; Soutis, C.


    The steady increase of Carbon-Fiber Reinforced Polymer (CFRP) Structures in modern aircraft will reach a new dimension with the entry into service of the Boeing 787 and Airbus 350. Replacement of damaged parts will not be a preferable solution due to the high level of integration and the large size of the components involved. Consequently the need to develop repair techniques and processes for composite components is readily apparent. Bonded patch repair technologies provide an alternative to mechanically fastened repairs with significantly higher performance, especially for relatively thin skins. Carefully designed adhesively bonded patches can lead to cost effective and highly efficient repairs in comparison with conventional riveted patch repairs that cut fibers and introduce highly strained regions. In this work, the assessment of the damage process taking place in notched (open-hole) specimens under uniaxial tensile loading was studied. Two-dimensional (2D) and three-dimensional (3D) Digital Image Correlation (DIC) techniques were employed to obtain full-field surface strain measurements in carbon-fiber/epoxy T700/M21 composite plates with different stacking sequences in the presence of an open circular hole. Penetrant enhanced X-ray radiographs were taken to identify damage location and extent after loading around the hole. DIC strain fields were compared to finite element predictions. In addition, DIC techniques were used to characterise damage and performance of adhesively bonded patch repairs in composite panels under tensile loading. This part of work relates to strength/stiffness restoration of damaged composite aircraft that becomes more important as composites are used more extensively in the construction of modern jet airliners. The behaviour of bonded patches under loading was monitored using DIC full-field strain measurements. Location and extent of damage identified by X-ray radiography correlates well with DIC strain results giving confidence to

  2. Air pollution and brain damage. (United States)

    Calderón-Garcidueñas, Lilian; Azzarelli, Biagio; Acuna, Hilda; Garcia, Raquel; Gambling, Todd M; Osnaya, Norma; Monroy, Sylvia; DEL Tizapantzi, Maria Rosario; Carson, Johnny L; Villarreal-Calderon, Anna; Rewcastle, Barry


    Exposure to complex mixtures of air pollutants produces inflammation in the upper and lower respiratory tract. Because the nasal cavity is a common portal of entry, respiratory and olfactory epithelia are vulnerable targets for toxicological damage. This study has evaluated, by light and electron microscopy and immunohistochemical expression of nuclear factor-kappa beta (NF-kappaB) and inducible nitric oxide synthase (iNOS), the olfactory and respiratory nasal mucosae, olfactory bulb, and cortical and subcortical structures from 32 healthy mongrel canine residents in Southwest Metropolitan Mexico City (SWMMC), a highly polluted urban region. Findings were compared to those in 8 dogs from Tlaxcala, a less polluted, control city. In SWMMC dogs, expression of nuclear neuronal NF-kappaB and iNOS in cortical endothelial cells occurred at ages 2 and 4 weeks; subsequent damage included alterations of the blood-brain barrier (BBB), degenerating cortical neurons, apoptotic glial white matter cells, deposition of apolipoprotein E (apoE)-positive lipid droplets in smooth muscle cells and pericytes, nonneuritic plaques, and neurofibrillary tangles. Persistent pulmonary inflammation and deteriorating olfactory and respiratory barriers may play a role in the neuropathology observed in the brains of these highly exposed canines. Neurodegenerative disorders such as Alzheimer's may begin early in life with air pollutants playing a crucial role.

  3. Excitotoxic damage to white matter (United States)

    Matute, Carlos; Alberdi, Elena; Domercq, María; Sánchez-Gómez, María-Victoria; Pérez-Samartín, Alberto; Rodríguez-Antigüedad, Alfredo; Pérez-Cerdá, Fernando


    Glutamate kills neurons by excitotoxicity, which is caused by sustained activation of glutamate receptors. In recent years, it has been shown that glutamate can also be toxic to white matter oligodendrocytes and to myelin by this mechanism. In particular, glutamate receptor-mediated injury to these cells can be triggered by activation of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid, kainate and N-methyl-d-aspartate glutamate receptor types. Thus, these receptor classes, and the intermediaries of the signal cascades they activate, are potential targets for drug development to treat white matter damage in acute and chronic diseases. In addition, alterations of glutamate homeostasis in white matter can determine glutamate injury to oligodendrocytes and myelin. Astrocytes are responsible for most glutamate uptake in synaptic and non-synaptic areas and consequently are the major regulators of glutamate homeostasis. Activated microglia in turn may secrete cytokines and generate radical oxygen species, which impair glutamate uptake and reduce the expression of glutamate transporters. Finally, oligodendrocytes also contribute to glutamate homeostasis. This review aims at summarizing the current knowledge about the mechanisms leading to oligodendrocyte cell death and demyelination as a consequence of alterations in glutamate signalling, and their clinical relevance to disease. In addition, we show evidence that oligodendrocytes can also be killed by ATP acting at P2X receptors. A thorough understanding of how oligodendrocytes and myelin are damaged by excitotoxicity will generate knowledge that can lead to improved therapeutic strategies to protect white matter. PMID:17504270

  4. [Liver damage caused by drugs]. (United States)

    Strohmeyer, G; Weik, C


    The liver has a central role in the metabolism of many drugs, since this organ is the main site of biotransformation of endo- and xenobiotics. Water-soluble drugs have a small volume of distribution and can be eliminated unchanged in the urine. By contrast, lipid-soluble drugs have a larger volume of distribution and require conversion to water-soluble metabolites for their elimination in urine or bile. The liver with its specific receptors, transporters and enzymes is responsible for the uptake, transformation and excretion of the lipophilic drugs. While most of the drugs are transformed into stable metabolites, other drugs form reactive, potentially toxic, metabolites producing liver cell damage. Liver injury caused by drugs may mimic almost any kind of liver disease. Clinical findings are gastrointestinal symptoms with nausea, vomiting and abdominal pain, cholestatic liver injury with jaundice and pruritus of severe inflammatory and cirrhotic liver damage with signs of liver failure, encephalopathy and cerebral edema. The morphological changes vary from hepatitis, cholestasis, fatty liver, granulomatous hepatitis, peri-/portal inflammation, to fibrosis with cirrhotic alterations and vascular lesions and tumors. The most commonly used drugs causing severe liver injury are discussed in detail. These are anabolics, oral contraceptives, antituberculous and antifungal agents, nonsteroidal anti-inflammatory drugs, ring substituted amphetamins ("designer drugs"), antiarrhythmics and antibiotics.

  5. Flower damage: a case study

    Energy Technology Data Exchange (ETDEWEB)

    James, H.A.


    A review of the recorded losses of Cattleya orchid blooms found in the records of 5 Bay Area growers shows a distinct increasing seasonal loss pattern from ethylene. The losses due to ''dried sepal'' were compared with the total daily and monthly production. Daily orchid bloom losses in excess of 90 percent were found, with a least two growers losing over 60 percent of total month's cut. Highest bloom losses were experienced in San Leandro and South San Francisco with lesser losses in Larkspur, Mt. Eden and San Bruno. Qualitative checks of growers in other sites revealed orchid losses to be wide spread. From the record of these latter growers, only Pacific and Mill Valley had no damage at the time of the visits. The ''dried sepal'' damage is attributed to ethylene since it can be produced by exposure to this gas; ethylene has been found to be present on numerous occasions preceding appearance of symptoms, and no other causative agent has been found in sufficient concentrations in ambient air sampling to cause such an effect.

  6. Malnutrition, liver damage, and cancer. (United States)

    Grasso, P


    There is no clear indication that malnutrition, per se, is a principal cause of cancer in man, but the prevalence of liver cancer in areas where malnutrition exists supports this hypothesis. Liver damage and liver cancer have been induced in laboratory rats by diets consisting of peanut meal and proteins deficient in some essential amino acids. However, liver damage, but not cancer, was produced when the diets contained no peanut meal but consisted of a mixture of amino acids deficient in methionine and cysteine, so that it is possible that aflatoxin, a contaminant of peanut meal, may have been responsible for the malignancies seen in the earlier experiments. Liver cancer developes in a high proportion of mice allowed to feed ad libitum or given a diet containing a high proportion of fat (groundnut oil) or protein (casein). Dietary restriction reduced the incidences of this cancer. This findings lends some support to current thinking that diet may be a factor in the development of cancer in man.

  7. Flood damage modelling: ambition and reality (United States)

    Gerl, Tina; Kreibich, Heidi; Franco, Guillermo; Marechal, David; Schröter, Kai


    Flood damage modelling is of increasing importance for reliable risk assessment and management. Research efforts have improved the understanding of damaging processes and more sophisticated flood damage models have been developed. However, research seems to focus on a limited number of sectors and regions and validation of models still receives too little attention. We present a global inventory of flood damage models which is compiled from a review of scientific papers and research reports on flood damage models. The models are catalogued according to model specifications, geographical characteristics, sectors addressed, input variables used, model validation, transferability and model functions. The inventory is evaluated to position the current state of science and technology in flood damage modelling as well as to derive requirements for benchmarking damage models.

  8. Description of Concrete Durability Damage Process

    Institute of Scientific and Technical Information of China (English)

    CHEN Yueshun; WEI Jun; ZHAO Xiaolong


    Based on the damage mechanics, the concrete damage grade of relative stable environment in measurable spatial is constructed in this paper, and the concrete damage evolving model and corresponding failure rule is constructed based on the damage grade fore-defined. Therefore, the concrete health status and the residual life-span can be assessed according to the measured damage grade. It is propitious to drive the development of concrete durability assessment and life-span forecast. Its feasibility of concrcte damage process description and health assessment is validated with the example in this paper, in which the damage state is described with the ultrasound velocity attenuation, and the freeze-thaw process is regarded as the concrete durability degradation influencing factor to reflect the concrete durability degradation process.

  9. Damage development in the adhesive zone and mortar of porous asphalt concrete

    NARCIS (Netherlands)

    Mo, L.T.


    This research is focused on damage development in the adhesive zone and the mortar of porous asphalt concrete. The motive of this research is the loss of stone from the pavement surface, the so-called ravelling of noise reducing surface wearing courses. Ravelling is the dominant defect of porous asp

  10. Effect of inclusion matrix model on temperature and thermal stress fields of K9-glass damaged by long-pulse laser (United States)

    Pan, Yunxiang; Wang, Bin; Shen, Zhonghua; Lu, Jian; Ni, Xiaowu


    A model containing an inclusion matrix heated by a millisecond laser is proposed to calculate temperature and thermal stress fields of K9-glass using a finite element method. First, the evolution of temperature and thermal stress fields is analyzed. Results show that both the upper and lower surfaces are damaged. K9-glass is primarily damaged by the combination of radial and axial stresses. Calculated damage morphology is mainly determined by radial stress. Then damage morphology evolution with the increase of the incident laser energy is investigated, which shows that damage area spreads inward from both the front and rear surfaces. Finally, experimental results of long-pulse laser damage of K9-glass are analyzed. The comparison of numerical results with experimental observations shows a good correlation in damage morphology, which indicates that the built inclusion matrix model is applicable to long-pulse laser damage in K9-glass.

  11. Damage Resistant Optical Glasses for High Power Lasers: A Continuing Glass Science and Technology Challenge

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, J H


    A major challenge in the development of optical glasses for high-power lasers is reducing or eliminating laser-induced damage to the interior (bulk) and the polished surface of the glass. Bulk laser damage in glass generally originates from inclusions. With the development of novel glass melting and forming processes it is now possible to make both fused silica and a suit of meta-phosphate laser glasses in large sizes ({approx}>0.5-lm diameter), free of inclusions and with high optical homogeneity ({approx} 10{sup -6}). Considerable attention also has been focused on improving the laser damage resistance to polished optical glass surfaces. Studies have shown that laser-induced damage to surfaces grows exponentially with the number of shots when illuminated with nano-second pulses at 351-nm above a given fluence threshold. A new approach for reducing and eliminating laser-induced surface damage relies on a series of post-polishing treatment steps. This damage improvement method is briefly reviewed.

  12. Evaluation of microstructure and creep damage in high-Cr ferritic steel welds

    Institute of Scientific and Technical Information of China (English)

    Masaaki TABUCHI; Hiromichi HONGO


    11Cr-0.4Mo-2W-CuVNb steel (ASME Gr.122) is used for boiler components in ultrasupercritical (USC) thermal power plants. The creep strength of high-Cr steel welds decreases due to the formation of Type Ⅳ creep damage in the heat-affected zone (HAZ) during long-term use at high temperatures. In the present study, the processes and mechanisms of Type Ⅳ creep damage were elucidated by investigating the long-term creep strength, microstructure and damage behavior of Gr.122 steel welds.Creep tests using thick welded joints were interrupted at several time steps, and the initiation, evolution and distribution of creep damage were measured. It was found that the formation and growth of creep damage was suppressed during the steadystate stage; creep voids formed at 0.5 of life, and coalesced to form a crack after 0.9of life. Type Ⅳ creep damage was mostly observed in the area about 30% below the surface of the plate. Differences in creep damage behavior between Gr.122 and Gr.91 steel welds were examined. Experimental creep damage distribution was compared with computed versions using the finite element method and damage mechanics.

  13. Durable, Low-Surface-Energy Treatments (United States)

    Willis, Paul B.; Mcelroy, Paul M.; Hickey, Gregory S.


    Chemical treatment for creation of durable, low-surface-energy coatings for glass, ceramics and other protonated surfaces easily applied, and creates very thin semipermanent film with extremely low surface tension. Exhibits excellent stability; surfaces retreated if coating becomes damaged or eroded. Uses include water-repellent surfaces, oil-repellent surfaces, antimigration barriers, corrosion barriers, mold-release agents, and self-cleaning surfaces. Film resists wetting by water, alcohols, hydrocarbon solvents, and silicone oil. Has moderate resistance to abrasion, such as rubbing with cloths, and compression molding to polymers and composite materials.

  14. Drilling Damage in Composite Material

    Directory of Open Access Journals (Sweden)

    Luís Miguel P. Durão


    Full Text Available The characteristics of carbon fibre reinforced laminates have widened their use from aerospace to domestic appliances, and new possibilities for their usage emerge almost daily. In many of the possible applications, the laminates need to be drilled for assembly purposes. It is known that a drilling process that reduces the drill thrust force can decrease the risk of delamination. In this work, damage assessment methods based on data extracted from radiographic images are compared and correlated with mechanical test results—bearing test and delamination onset test—and analytical models. The results demonstrate the importance of an adequate selection of drilling tools and machining parameters to extend the life cycle of these laminates as a consequence of enhanced reliability.

  15. Nanofoams Response to Radiation Damage

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Engang [Los Alamos National Laboratory; Serrano De Caro, Magdalena [Los Alamos National Laboratory; Wang, Yongqiang [Los Alamos National Laboratory; Nastasi, Michael [Nebraska Center for Energy Sciences Research, University of Nebraska-Lincoln, NE 68508; Zepeda-Ruiz, Luis [PLS, Lawrence Livermore National Laboratory, Livermore, CA 94551; Bringa, Eduardo M. [CONICET and Inst. Ciencias Basicas, Universidad Nacional de Cuyo, Mendoza, 5500 Argentina; Baldwin, Jon K. [Los Alamos National Laboratory; Caro, Jose A. [Los Alamos National Laboratory


    Conclusions of this presentation are: (1) np-Au foams were successfully synthesized by de-alloying process; (2) np-Au foams remain porous structure after Ne ion irradiation to 1 dpa; (3) SFTs were observed in irradiated np-Au foams with highest and intermediate flux, while no SFTs were observed with lowest flux; (4) SFTs were observed in irradiated np-Au foams at RT, whereas no SFTs were observed at LNT irradiation; (5) The diffusivity of vacancies in Au at RT is high enough so that the vacancies have enough time to agglomerate and thus collapse. As a result, SFTs were formed; (6) The high flux created much more damage/time, vacancies don't have enough time to diffuse or recombine. As a result, SFTs were formed.

  16. Damage detection in composite materials using PZT actuators and sensors for structural health monitoring (United States)

    Spiegel, Michelle DuBose

    Structural Health Monitoring (SHM) of bridges, buildings, aircrafts, and spacecraft using a network of sensors has gained popularity over recent years. In this thesis, the use of piezoelectric actuators and sensors is described for detecting damage in a composite panel. The composite panels are fabricated using the Vacuum Assisted Resin Transfer Molding (VARTM) process. The panels are cut into small coupons (254 mm x 25.4 mm) to test various properties of the composite. A piezoelectric actuator is surface mounted on the composite coupon to generate Lamb waves while a surface mounted piezoelectric sensor measures the response. Data is collected from an undamaged composite coupon, and then the process is repeated for a damaged coupon. The existing damage is quantified by comparing the response of the damaged and undamaged composite coupons.

  17. Chemistry of radiation damage to wire chambers

    Energy Technology Data Exchange (ETDEWEB)

    Wise, J.


    Proportional counters are used to study aspects of radiation damage to wire chambers (wire aging). Principles of low-pressure, rf plasma chemistry are used to predict the plasma chemistry in electron avalanches (1 atm, dc). (1) Aging is studied in CF{sub 4}/iC{sub 4}H{sub 10} gas mixtures. Wire deposits are analyzed by Auger electron spectroscopy. An apparent cathode aging process resulting in loss of gain rather than in a self-sustained current is observed in CF{sub 4}-rich gases. A four-part model considering plasma polymerization of the hydrocarbon, etching of wire deposits by CF{sub 4}, acceleration of deposition processes in strongly etching environments, and reactivity of the wire surface is developed to understand anode wire aging in CF{sub 4}/iC{sub 4}H{sub 10} gases. Practical guidelines suggested by the model are discussed. (2) Data are presented to suggest that trace amounts of Freons do not affect aging rates in either dimethyl ether or Ar/C{sub 2}H{sub 6}. Apparent loss of gain is explained by attachment of primary electrons to a continuously increasing concentration of Freon 11 (CCl{sub 3}F) in the counter gas. An increase in the concentration of Freon 11 in dimethyl ether is caused by a distillation process in the gas supply bottle and is a natural consequence of the unequal volatilities of the two compounds.

  18. DNA Damage Signals and Space Radiation Risk (United States)

    Cucinotta, Francis A.


    Space radiation is comprised of high-energy and charge (HZE) nuclei and protons. The initial DNA damage from HZE nuclei is qualitatively different from X-rays or gamma rays due to the clustering of damage sites which increases their complexity. Clustering of DNA damage occurs on several scales. First there is clustering of single strand breaks (SSB), double strand breaks (DSB), and base damage within a few to several hundred base pairs (bp). A second form of damage clustering occurs on the scale of a few kbp where several DSB?s may be induced by single HZE nuclei. These forms of damage clusters do not occur at low to moderate doses of X-rays or gamma rays thus presenting new challenges to DNA repair systems. We review current knowledge of differences that occur in DNA repair pathways for different types of radiation and possible relationships to mutations, chromosomal aberrations and cancer risks.

  19. Damage Tensor Analysis on Regional Seismic Status

    Institute of Scientific and Technical Information of China (English)

    Zhong Jimao; Cheng Wanzheng


    In this paper, we researched the regional seismic status by using theories of the Damage Mechanics. The macroscopic damage status of the earth crust block, which is caused by earthquake fracture, is described with several concepts-the damage degree, the damage rate and the strain rate. In the earthquake process, the average strain rate of the studied block is equal to the sum of all seismic moment tensors of the earthquakes taking place in unit time and physical volume. To describe the anisotropy of microdamage of the crust block, we use the damage tensor that is expressed in the fissure density. By means of the transformation from the focal coordinate system to the observation system, we obtained the external normal vector of the focal fault plane expressed in its observation system and obtained the macrodamage degree of the researched block, which is calculated in dyadic. This provides a new analysis method for recognizing the underground damage status and the stress status.

  20. Chromatin structure and DNA damage repair

    Directory of Open Access Journals (Sweden)

    Dinant Christoffel


    Full Text Available Abstract The integrity of the genome is continuously challenged by both endogenous and exogenous DNA damaging agents. These damaging agents can induce a wide variety of lesions in the DNA, such as double strand breaks, single strand breaks, oxidative lesions and pyrimidine dimers. The cell has evolved intricate DNA damage response mechanisms to counteract the genotoxic effects of these lesions. The two main features of the DNA damage response mechanisms are cell-cycle checkpoint activation and, at the heart of the response, DNA repair. For both damage signalling and repair, chromatin remodelling is most likely a prerequisite. Here, we discuss current knowledge on chromatin remodelling with respect to the cellular response to DNA damage, with emphasis on the response to lesions resolved by nucleotide excision repair. We will discuss the role of histone modifications as well as their displacement or exchange in nucleotide excision repair and make a comparison with their requirement in transcription and double strand break repair.


    Institute of Scientific and Technical Information of China (English)

    Yang Xinhua; Chen Chuanyao; Hu Yuantai; Wang Cheng


    Mechanical and electrical damages are introduced to study the fracture mechanics of piezoelectric ceramics in this paper. Two kinds of piezoelectric fracture criteria are established using the method of least squares combined with a damage analysis of the well-known piezoelectric fracture experiments of Park and Sun's. One is based on a linear combination of the mechanical and electrical damages and the other on their nonlinear combination. When the combined damage D is up to its critical value Dc, piezoelectric fracture occurs. It is found from the qualitative comparison of the numerical results with the experimental data that the nonlinearly combined damage fracture criterion can give a better prediction of piezoelectric fracture. And it is concluded from the nonlinearly combined damage fracture criterion that a negative electric field impedes fracture whereas the effect of a positive electric field on fracture depends on its magnitude.

  2. Laser-induced damage of 1064-nm narrow-band interference filters under different laser modes

    Institute of Scientific and Technical Information of China (English)

    Weidong Gao(高卫东); Hongbo He(贺洪波); Jianda Shao(邵建达); Zhengxiu Fan(范正修)


    The laser-induced damage behavior of narrow-band interference filters was investigated with a Nd:YAG laser at 1064 nm under single-pulse mode and free-running laser mode.The absorption measurement of such coatings has been performed by surface thermal lensing(STL)technique.The relationship between damage morphology and absorption under the two different laser modes was studied in detail.The explanation was given by the standing-wave distribution theory.


    Institute of Scientific and Technical Information of China (English)

    连传杰; 刘立民; 高闯


    Coal mining under buildings certainly causes surface movement and deformation, therefore, it brings about deformation even fracture for buildings. It is an important task to evaluate correctly the buildings' damage grade caused by coal mining. Fuzzy comprehensive evaluation, considering some factors of buildings' fracture, has been applied to analyze the masonry structure buildings' damage grade after coal mining in this paper. It provides a scientific basis for buildings' reinforcement before mining and maintenance or compensation after mining.

  4. Analysis of damage of superheaters from steel 12Kh1MF in operation (United States)

    Priymak, E. Yu.; Tryakina, N. Yu.; Gryzunov, V. I.; Sokolov, S. O.


    Main cases of damage of superheaters from steel 12Kh1MF due to disturbance of the process of production of the tubes and due to creep, thermal fatigue, and short-term superheating are considered. The methods of metallographic analysis and scanning electron microscopy are used to determine the special features of their microstructure and fracture surfaces. The results obtained are used to develop an algorithm for detecting the causes of damage in superheaters produced from heat-resistant pearlitic steels.

  5. Damage modeling in Small Punch Test specimens

    DEFF Research Database (Denmark)

    Martínez Pañeda, Emilio; Cuesta, I.I.; Peñuelas, I.


    Ductile damage modeling within the Small Punch Test (SPT) is extensively investigated. The capabilities ofthe SPT to reliably estimate fracture and damage properties are thoroughly discussed and emphasis isplaced on the use of notched specimens. First, different notch profiles are analyzed...... and constraint conditionsquantified. The role of the notch shape is comprehensively examined from both triaxiality and notchfabrication perspectives. Afterwards, a methodology is presented to extract the micromechanical-basedductile damage parameters from the load-displacement curve of notched SPT samples...

  6. The political economy of natural disaster damage


    Eric Neumayer; Thomas Plümper; Fabian Barthel


    Economic damage from natural hazards can sometimes be prevented and always mitigated. However, private individuals tend to underinvest in such measures due to problems of collective action, information asymmetry and myopic behavior. Governments, which can in principle correct these market failures, themselves face incentives to underinvest in costly disaster prevention policies and damage mitigation regulations. Yet, disaster damage varies greatly across countries. We argue that rational acto...

  7. Using DNA damage to monitor water environment

    Institute of Scientific and Technical Information of China (English)


    DNA damage of aquatic organisms living in polluted environments can be used as a biomarker of the genotoxicity of toxic agents to organisms. This technique has been playing an important role in ecotoxicological study and environmental risk assessment. In this article, main types of DNA damage caused by pollutants in water environments were reviewed; methods of detecting DNA damage were also documented for water environmental monitoring.

  8. Damage Detection and Verification System (DDVS) for In-Situ Health Monitoring (United States)

    Williams, Martha K.; Lewis, Mark; Szafran, J.; Shelton, C.; Ludwig, L.; Gibson, T.; Lane, J.; Trautwein, T.


    Project presentation for Game Changing Program Smart Book Release. Detection and Verification System (DDVS) expands the Flat Surface Damage Detection System (FSDDS) sensory panels damage detection capabilities and includes an autonomous inspection capability utilizing cameras and dynamic computer vision algorithms to verify system health. Objectives of this formulation task are to establish the concept of operations, formulate the system requirements for a potential ISS flight experiment, and develop a preliminary design of an autonomous inspection capability system that will be demonstrated as a proof-of-concept ground based damage detection and inspection system.

  9. Development of a Near Real-Time Hail Damage Swath Identification Algorithm for Vegetation (United States)

    Bell, Jordan R.; Molthan, Andrew L.; Schultz, Kori A.; McGrath, Kevin M.; Burks, Jason E.


    Every year in the Midwest and Great Plains, widespread greenness forms in conjunction with the latter part of the spring-summer growing season. This prevalent greenness forms as a result of the high concentration of agricultural areas having their crops reach their maturity before the fall harvest. This time of year also coincides with an enhanced hail frequency for the Great Plains (Cintineo et al. 2012). These severe thunderstorms can bring damaging winds and large hail that can result in damage to the surface vegetation. The spatial extent of the damage can relatively small concentrated area or be a vast swath of damage that is visible from space. These large areas of damage have been well documented over the years. In the late 1960s aerial photography was used to evaluate crop damage caused by hail. As satellite remote sensing technology has evolved, the identification of these hail damage streaks has increased. Satellites have made it possible to view these streaks in additional spectrums. Parker et al. (2005) documented two streaks using the Moderate Resolution Imaging Spectroradiometer (MODIS) that occurred in South Dakota. He noted the potential impact that these streaks had on the surface temperature and associated surface fluxes that are impacted by a change in temperature. Gallo et al. (2012) examined at the correlation between radar signatures and ground observations from storms that produced a hail damage swath in Central Iowa also using MODIS. Finally, Molthan et al. (2013) identified hail damage streaks through MODIS, Landsat-7, and SPOT observations of different resolutions for the development of a potential near-real time applications. The manual analysis of hail damage streaks in satellite imagery is both tedious and time consuming, and may be inconsistent from event to event. This study focuses on development of an objective and automatic algorithm to detect these areas of damage in a more efficient and timely manner. This study utilizes the

  10. Damage Model of Brittle Coal-Rock and Damage Energy Index of Rock Burst

    Institute of Scientific and Technical Information of China (English)

    尹光志; 张东明; 魏作安; 李东伟


    Based on the mechanical experiment of brittle coal-rock and the damage mechanical theory, a damage model was established. Coal-Rock damage mechanical characteristic was researched. Furthermore, interior energy transformation mechanism of rock was analyzed from the point of view of damage mechanics and damage energy release rate of brittle coal rock was derived. By analyzing the energy transformation of rock burst, a new conception, damage energy index of rock burst, was put forward. The condition of rock burst was also established.

  11. Screening of specific proteins in ultraviolet-induced acute damage of human fibroblasts using proteinchip with surface enhanced laser desorption/ ionization time-of-flight mass spectrometry%采用蛋白芯片结合SELDI-TOF-MS技术筛选紫外线照射后皮肤成纤维细胞损伤的特异性蛋白

    Institute of Scientific and Technical Information of China (English)

    闫言; 徐浩翔; 郑艳华; 刘洁; 张建中; 王宝玺


    目的 探讨应用蛋白芯片结合表面增强激光解吸离子化飞行时间质谱(SELDI-TOF-MS)技术筛选紫外线照射后皮肤成纤维细胞早期损伤的生物标记的可行性.方法 用弱阳离子交换蛋白芯片(CM10)结合SELDI-TOF-MS技术,检测未照射组、2.5 J/cm2长波紫外线(UVA)照射组和100 mJ/cm2中波紫外线(UVB)照射组正常人真皮成纤维细胞差异表达的蛋白.结果 紫外线照射组与未照射组蛋白质指纹图谱比较,发现10种蛋白表达下降,8种蛋白表达增强.将差异蛋白峰在SWISS-PROT和TREMBLE蛋白数据库中搜索,发现相对分子质量为11 320.1的蛋白峰与人半胱氨酸天冬氨酸蛋白酶-7前驱体(caspase-7 precursor)相匹配;相对分子质量为8 574.3的蛋白峰与细胞色素C氧化酶多肽VIc前体(Cytochrome c oxidase polypeptide VIc precursor)相符.结论 蛋白芯片结合SELDI-TOF-MS技术是一种快速、简便的高通量蛋白质组研究方法,为光损伤研究提供了新的研究平台.%Objective To investigate specific proteins in ultraviolet (UV)-induced acute damage of human fibroblasts using proteinchip with surface enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS).Methods CM10 Proteinchip and SELDI-TOF-MS were used for detecting protein samples of non-irradiated group,UVA (2.5 J/cm2)-irradiated group and UVB (100 mJ/cm2)-irradiated group of normal human fibroblasts.Results Ten protein peaks were down-regulated and 8 protein peaks up-regulated in fibroblasts after UV irradiation.By searching in SWISS-PROT and TREMBLE databases,the peaks of 11 320.1 and 8 574.3 accorded with those of caspase-7 precursor and cytochrome C oxidase polypeptide VIc precursor proteins.Conclusion As a quick and convenient high-throughout proteomic analytic method,SELDI-TOF-MS plus proteinchip offers a unique platform for detecting dermal photodamage.

  12. Energy Change due to Off-Fault Damage Evolution associated with Dynamic Fault Tip Growth (United States)

    Suzuki, T.


    We theoretically study off-fault damage evolution effects on dynamic earthquake rupture, especially from a standpoint of energy change in a whole system. The importance of off-fault inelastic energy loss due to damage on dynamic earthquake rupture has attracted interests of many researchers in terms of, for example, rupture velocity reduction and crack tip growth cessation. The damage effect is found to be important on dynamic earthquake slip behavior in terms of porosity increase also in a series of our previous studies, Suzuki and Yamashita (2007; 2008; 2009; 2010). The mathematical formulation of Murakami and Kamiya (1997) is assumed in the present study; the damage tensor D is used to describe damage state in a medium. Damage, which consists of microcracks in a medium, has direction (defined as normal to the crack surface) and the magnitude (crack size), so that a scalar damage variable is insufficient to describe the damage state. We first analytically derive the equation system including the damage tensor and describing energy change in a whole system due to any dynamic elastic and inelastic deformation processes such as macroscopic crack extension and damage evolution. The change in the summation of strain and kinetic energies and damage energy is found to be equal to the summation of energy flowing out of the medium through the boundary and energy turning to heat and irreversibly lost based on the analytical expression; the damage energy is associated with surface energy released by damage evolution. The damage energy is confirmed to be equal to the summation of the loss in strain energy due to change in the elastic moduli and irreversibly lost energy. A mode III crack embedded in a medium causing damage is then assumed to study the off-fault damage effects on dynamic earthquake rupture. Spontaneous crack tip growth with the Coulomb fracture criterion is assumed and in such a case the rupture velocity can be sufficiently smaller than the terminal velocity

  13. Pakistan flood damage mapped by UNOSAT at CERN

    CERN Multimedia

    Katarina Anthony


    As the waters recede, the Pakistan floods are attracting less attention in the world's media. But at the CERN-based headquarters of UNOSAT, the UN Institute for Training and Research Operational Satellite Application Programme, mapping the damage caused by the floods remains the top priority as the “emergency phase” is only now beginning to level off.   Flood analysis in Pakistan from 28 July to 16 September 2010. Credits: © UNOSAT UNOSAT uses impartial, objective data to assess the specifics of a disaster: What surface area has the flood covered? How many bridges and roads have been destroyed? How many areas are impenetrable? Although there are statistical answers to these questions, UNOSAT’s assessment of the damage caused by the Pakistan floods can be simply described in one word: catastrophic. The images used by UNOSAT are taken from a variety of different sources – commercial and scientific. Once a satellite takes an image, the owne...


    Energy Technology Data Exchange (ETDEWEB)

    Hsu, P C


    Thermal damage was applied to LX-17 at 190 C for several hours. The damaged LX-17 samples, after cooled down to room temperature, were characterized for their material properties (density, porosity, permeability, moduli), safety, and performance. Weight losses upon thermal exposure were insignificant (< 0.1% wt.). The damaged LX-17 samples expanded, resulting in a bulk density reduction of 4.3%. Subsequent detonation measurements (cylinder tests) were conducted on the thermally-damaged LX-17 samples. The results showed that the fractions of damaged LX-17 reacted were slightly lower than those of pristine LX-17. The thermally damaged LX-17 had a detonation velocity of 7.315 mm/{micro}s, lower than that (7.638 mm/{micro}s) of pristine LX-17. Detonation energy density for the damaged LX-17 was 5.08 kJ/cm{sup 3}, about 9.0% lower than the detonation energy density of 5.50 kJ/cm{sup 3} for the pristine LX-17. The break-out curves showed reaction zone lengths for pristine LX-17 and damaged LX-17 were similar but the damaged samples had ragged detonation fronts.

  15. An Empirical, Functional approach to Depth Damages

    Directory of Open Access Journals (Sweden)

    Lehman Will


    Full Text Available In order to compute direct damages to structures and contents, the United States Army Corps of Engineers (USACE has traditionally relied on relationships that define damage for a given depth. These relationships are described using paired data relationships of depth and damage. Generally, the curves utilized are based on an Elicitation of Experts (EoE. This paper will present an alternative methodology which takes empirical data of damage and depth, stratified by building classifications, and use Non Linear Least Squares Estimation to fit a parameterized function to compute depth-damage estimates. The general function will be described, and the parameters will be discussed. Parameters include foundation height, ground elevation, percent damages below ground, number of stories, height of stories, maximum damage as a percent, and the beginning elevation for damage. The advantages of this approach include the ability to utilize empirical data, and the ability to change parameters based on building practices across the world. Additionally, the paper will illustrate a bootstrapping approach to the empirical data to assist in describing confidence limits around the parameterized functional depth damage relationship. A Figure (Figure 1 is provided to illustrate the output of the process.

  16. Convolution Sum Discrete Process Neural Network and Its Application in Aeroengine Exhausted Gas Temperature Prediction%卷积和离散过程神经网络及其在航空发动机排气温度预测中的应用

    Institute of Scientific and Technical Information of China (English)

    钟诗胜; 雷达; 丁刚


    The changing process of aeroengine exhausted gas temperature (EGT) is affected by complicated nonlinear time varying factors, which make it difficult to construct its mathematic model. To cope with this issue, a convolution sum discrete process neural network (CSDPNN) model is proposed and used for EGT prediction. This model directly utilizes discrete sampling points as input, and uses the convolution sum to deal with the time accumulation process. Compared with the process neural network(PNN)with continuous function inputs, there is ho need to fit the sampling points to get input functions and then to decompose them by orthogonal basis functions which can lead to precision loss. Therefore, this model can a-chieve higher prediction precision. A learning algorithm for this model is also developed, and the model is explained and validated via Mackey-Glass chaos time series prediction. Then, the model is adopted to predict a real EGT time series. The prediction results are compared with results obtained by the process neural network with function inputs and the traditional artificial neural network(ANN), which proves that CSDPNN model has higher precision than the other two networks, and it exhibits good adaptability to EGT prediction. This model offers an effective method for real EGT prediction.%针对航空发动机排气温度的变化过程受复杂非线性时变因素的影响而难以用精确数学模型描述的问题,提出了卷积和离散过程神经网络(CSDPNN)模型,并将其应用于航空发动机排气温度(EGT)预测.该模型以离散样本作为直接输入,采用卷积和算法实现对时间累积效应的处理.相较于以连续函数作为输入的过程神经网络(PNN),不需要拟合离散样本得到连续函数后进行正交基展开,减少了精度损失,具有更高的预测精度.给出了卷积和离散过程神经网络模型的学习算法,并通过对Mackey-Glass混沌时间序列的预测对提出的方法进行应用说明

  17. Risk and Damage As A Main Factors of Groundwater Vulnerability (United States)

    Zakharova, Julia V.

    It's well known that groundwater is widely used for potable water supply in compar- ison with surface water. However significant urbanization, intensive growth of indus- try, quite limited investments for reconstractision of existed manufactures and also imperfect environmental protective legislation, all these are the cause of ecosystem degradation. Because of these the problem of both preventing of change in groundwa- ter chemical composition and forecasting of negative processes caused by economical activity is the main at present. According to data of Ministry of Economy, the increas- ing of total production in all spheres of industry till 2004 is forecasted. All these lead to increasing of anthropogenic load on ecosystems. So, the problem of environmental risk assessment including groundwater is actual. The methodology of risk assessment includes natural groundwater protection and the damage cost. The first is based on the time calculation of contaminated water in- filtration through the soil and vadoze zone till groundwater level, i.e. assessment of groundwater vulnerability. The second (damage cost) is based on the cost value of measures aimed to the elimination of contamination aftereffects. Damage can be direct and indirect. The first appears as a result of direct destroying of buildings, agricultural areas, natural landscapes, people and animals death or sickness. and amount of direct damage is determined by expendures, necessary for reduction of objects. The second, indirect, damage is determined by product losses or other negative affects connected with supply lines, deterioration of ecological conditions. It is necessary to mark that risk assessment is very important for planning of hy- drotechnical, engineering and civil construction (e.g., construction and location of different buildings depending from hydrogeological and geological conditions; or- ganization of well-fields and etc.), because all these factors correctly estimated can eleminate or

  18. Propagation of Reactions in Thermally-damaged PBX-9501

    Energy Technology Data Exchange (ETDEWEB)

    Tringe, J W; Glascoe, E A; Kercher, J R; Willey, T M; Springer, H K; Greenwood, D W; Molitoris, J D; Smilowitz, L; Henson, B F; Maienschein, J L


    A thermally-initiated explosion in PBX-9501 (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) is observed in situ by flash x-ray imaging, and modeled with the LLNL multi-physics arbitrary-Lagrangian-Eulerian code ALE3D. The containment vessel deformation provides a useful estimate of the reaction pressure at the time of the explosion, which we calculate to be in the range 0.8-1.4 GPa. Closely-coupled ALE3D simulations of these experiments, utilizing the multi-phase convective burn model, provide detailed predictions of the reacted mass fraction and deflagration front acceleration. During the preinitiation heating phase of these experiments, the solid HMX portion of the PBX-9501 undergoes a {beta}-phase to {delta}-phase transition which damages the explosive and induces porosity. The multi-phase convective burn model results demonstrate that damaged particle size and pressure are critical for predicting reaction speed and violence. In the model, energetic parameters are taken from LLNL's thermochemical-kinetics code Cheetah and burn rate parameters from Son et al. (2000). Model predictions of an accelerating deflagration front are in qualitative agreement with the experimental images assuming a mode particle diameter in the range 300-400 {micro}m. There is uncertainty in the initial porosity caused by thermal damage of PBX-9501 and, thus, the effective surface area for burning. To better understand these structures, we employ x-ray computed tomography (XRCT) to examine the microstructure of PBX-9501 before and after thermal damage. Although lack of contrast between grains and binder prevents the determination of full grain size distribution in this material, there are many domains visible in thermally damaged PBX-9501 with diameters in the 300-400 {micro}m range.

  19. Neuroendocrine system response modulates oxidative cellular damage in burn patients. (United States)

    Xie, Xiao-Qi; Shinozawa, Yotaro; Sasaki, Junichi; Takuma, Kiyotsugu; Akaishi, Satoshi; Yamanouchi, Satoshi; Endo, Tomoyuki; Nomura, Ryosuke; Kobayashi, Michio; Kudo, Daisuke; Hojo, Nobuko


    Oxygen-derived free radicals play important roles in pathophysiological processes in critically ill patients, but the data characterizing relationships between radicals and neuroendocrine system response are sparse. To search the cue to reduce the oxidative cellular damage from the point of view of neuroendocrine system response, we studied the indicators of neuroendocrine and inflammatory responses excreted in urine in 14 burn patients (42.3 +/- 31.4 years old, and 32.3 +/- 27.6% burn of total body surface area [%TBSA]) during the first seven days post burn. The daily mean amounts of urinary excretion of 8-hydroxy-2'-deoxy-guanosine (8-OHdG), a marker of oxidative cellular damage, were above the upper limit of the standard value during the studied period. The total amount of urinary excretion of 8-OHdG in the first day post burn correlated with burn severity indices: %TBSA (r = 0.63, p = 0.021) and burn index (r = 0.70, p = 0.008). The daily urinary excretion of 8-OHdG correlated with the daily urinary excretion of norepinephrine and nitrite plus nitrate (NOx) during the studied period except day 2 post burn, and correlated with the daily urinary excretion of 17-hydroxycorticosteriod (17-OHCS) in days 2, 3, and 7 post burn. These data suggest that oxidative cellular damage correlates with burn severity and neuroendocrine system response modulates inflammation and oxidative cellular damage. Modulation of neuroendocrine system response and inflammation in the treatment in the early phase of burn may be useful to reduce the oxidative cellular damage and to prevent multiple organ failures in patients with extensive burn.

  20. Damage to historic brick masonry structures. Masonry damage diagnostic system and damage atlas for evaluation of deterioration

    NARCIS (Netherlands)

    Balen, K. van; Binda, L.; Hees, R.P.J. van; Franke, L.


    The aim of the research on brick masonry degradation supported by the D.G. XII is presented. The project is delivering the following: ► Damage Atlas of ancient brick masonry, a book with a description of the types of damage, and their possible causes, in ancient brick masonry structures; ► Masonry D