Academic literature on the topic 'Component lifing'
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Journal articles on the topic "Component lifing"
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Pickard, A. C. "Component lifing." Materials Science and Technology 3, no. 9 (September 1987): 743–48. http://dx.doi.org/10.1179/mst.1987.3.9.743.
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Whitney-Rawls, Ashley, Paul Copp, Jace Carter, and Tarun Goswami. "Comparison of aero engine component lifing methods." Materials Engineering Research 4, no. 1 (2022): 201–22. http://dx.doi.org/10.25082/mer.2022.01.003.
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Failure of critical engine components such as compressor, fan, and turbine disks during flight can cause the loss of the engine, aircraft, or even life. To reduce the risk of this failure during flight, different methodologies and tools have been developed to determine the safe operating life of these critical disk components. The two most widely used lifing methods, safe-life and damage tolerance, are inherently conservative, retiring all components when a predetermined operating limit is reached. Both methods retire components with theoretical useful life remaining. Additional lifing methods can be used to reduce this conservatism and extend the life of these components. Retirement for cause, developed within the United States Air Force is a lifing method that can extend the life of components by retiring a component only when there is cause to do so. Military and industry standards on lifing methodologies were reviewed. Both deterministic and probabilistic approaches to disk lifing methods are discussed as well as current tools. This paper provides a comparison of the methodologies and tools currently being used today by both the government and industry.
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Pivovarova, M. V., and I. L. Gladkiy. "Life of gas turbine engine components under corrosive exposure." VESTNIK of Samara University. Aerospace and Mechanical Engineering 18, no. 3 (October 31, 2019): 109–17. http://dx.doi.org/10.18287/2541-7533-2019-18-3-109-117.
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Currently, operation of gas turbine engines takes place in the aggressive medium of the atmosphere of some climatic regions. As a consequence, this may cause fast degradation of the strength properties of parts of gas turbine equipment and their subsequent premature failure. The problem of determining the life of gas turbine engine components under corrosive exposure is vital. We present an analysis of the state of the art in the field of assessment of gas turbine engine component life under the influence of corrosive environment in Russia and abroad. UEC-Aviadvigatel, FSUE “VIAM” and NPO “TSKTI” JSC formulated approaches to the development of the lifing process for engine parts operating in corrosive environment.
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Korsunsky, Alexander M., Daniele Dini, and Michael J. Walsh. "Fatigue Crack Growth Rate Analysis in a Titanium Alloy." Key Engineering Materials 385-387 (July 2008): 5–8. http://dx.doi.org/10.4028/www.scientific.net/kem.385-387.5.
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Reliable prediction of fatigue crack growth rates in aerospace materials and components underpins the so-called defect-tolerant approach to lifing. In this methodology the presence or appearance of defects and cracks in components is accepted. However, safe operation is guaranteed by regular inspections and health monitoring, and ensuring (by means of reliable modelling) that no crack may grow far enough to reach the critical size in the interval between inspections. Under such circumstances it is clear that particular attention has to be paid to the development and validation of predictive modelling capabilities for fatigue crack propagation. The situation is complicated by the fact that it is often a challenge to represent correctly the in-service loading experienced by a cracked component. In practice, on top of the major cycles associated with each flight (LCF component), cycles of higher frequency and lower amplitude are also present (HCF component). Sensitivity to dwell at maximum load is also often observed. Furthermore, it is well established that complex load sequences involving overloads and underloads result in fluctuations of fatigue crack growth rates (retardation and acceleration) that must be accounted for in crack growth calculations. In the present study we consider the application of an approach due to Noroozi et al. [1] to the analysis of R-ratio effects in Ti-6Al-4V material, on the basis of the experimental crack growth rate data collected under the auspices of AGARD programme [2]. The approach shows promising results, and has the capacity to capture loading sequence effects.
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Biglari, Farid R., and Kamran M. Nikbin. "Numerical predictions of carburisation and crack evolution using a combined diffusion rate and remaining multi-axial creep ductility damage model." International Journal of Damage Mechanics 26, no. 6 (January 28, 2016): 859–80. http://dx.doi.org/10.1177/1056789516628317.
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A novel numerical damage model has been developed to combine Fick’s second law of diffusivity with microstructure modelling of environmentally assisted creep damage. The environmental acceleration of material degradation has been modelled and compared with experimental observations. The combined multi-site damage and crack growth model for creep and environmentally assisted time-dependent material oxidation/carburisation based on a gas/solid interface diffusion and non-linear time-dependent creep mechanism is proposed. Numerical predictions are presented to develop a methodology for component lifing. The model allows for the development of a hardened layer due to surface oxidation and predicts damage and cracking during subsequent creep under an applied load. The simulated grain mesh structure used can replicate surface healing or diffuse intergranular cracking and material depletion emanating from the gas/solid surface interface by quantifying the strength ratios between grain and grain boundaries. In this article, oxidation/carburisation is estimated both analytically and numerically using Fick’s diffusion laws and carbon/steel diffusion flux properties available in the literature. It is also shown that carbon diffusion distribution can be related to grain hardening due to carburisation as well as grain/grain boundary strength ratios which could vary as much as a factor of 0.5. The model is validated by comparing with actual oxidation/carburisation data for the long-term oxidised 9-12 Cr steels operating at high temperatures. Finally, it is shown that the mode and rate of surface oxidation and hardening, depending on whether the material is homogenous or contains micro-cracks substantially affects the life time of a component under high temperature creep loading.
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Busse, Christian, Frans Palmert, Paul Wawrzynek, Björn Sjödin, David Gustafsson, and Daniel Leidermark. "Crystallographic crack propagation rate in single-crystal nickelbase superalloys." MATEC Web of Conferences 165 (2018): 13012. http://dx.doi.org/10.1051/matecconf/201816513012.
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Single-crystal nickel-base superalloys are often used in the hot sections of gas turbines due to their good mechanical properties at high temperatures such as enhanced creep resistance. However, the anisotropic material properties of these materials bring many difficulties in terms of modelling and crack growth prediction. Cracks tend to switch cracking mode from Mode I cracking to crystallographic cracking. Crystallographic crack growth is often associated with a decrease in crack propagation life compared to Mode I cracking and this must be taken into account for reliable component lifing. In this paper a method to evaluate the crystallographic crack propagation rate related to a crystallographic crack driving force parameter is presented. The crystallographic crack growth rate is determined by an evaluation of heat tints on the fracture surface of a specimen subjected to fatigue loading. The complicated crack geometry including two crystallographic crack fronts is modelled in a three dimensional finite element context. The crack driving force parameter is determined by calculating anisotropic stress intensity factors along the two crystallographic crack fronts by finite-element simulations and post-processing the data in a fracture mechanics tool that resolves the stress intensity factors on the crystallographic slip planes in the slip directions. The evaluated crack propagation rate shows a good correlation for both considered crystallographic cracks fronts.
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Bache, Martin R., Christopher D. Newton, John Paul Jones, Stephen Pattison, Louise Gale, Pascual Ian Nicholson, and Eleri Weston. "Advances in Damage Monitoring Techniques for the Detection of Failure in SiCf/SiC Ceramic Matrix Composites." Ceramics 2, no. 2 (May 15, 2019): 347–71. http://dx.doi.org/10.3390/ceramics2020028.
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From a disruptive perspective, silicon carbide (SiC)-based ceramic matrix composites (CMCs) provide a considerable temperature and weight advantage over existing material systems and are increasingly finding application in aerospace, power generation and high-end automotive industries. The complex structural architecture and inherent processing artefacts within CMCs combine to induce inhomogeneous deformation and damage prior to ultimate failure. Sophisticated mechanical characterisation is vital in support of a fundamental understanding of deformation in CMCs. On the component scale, “damage tolerant” design and lifing philosophies depend upon laboratory assessments of macro-scale specimens, incorporating typical fibre architectures and matrix under representative stress-strain states. This is important if CMCs are to be utilised to their full potential within industrial applications. Bulk measurements of strain via extensometry or even localised strain gauging would fail to characterise the ensuing inhomogeneity when performing conventional mechanical testing on laboratory scaled coupons. The current research has, therefore, applied digital image correlation (DIC), electrical resistance monitoring and acoustic emission techniques to the room and high-temperature assessment of ceramic matrix composites under axial tensile and fatigue loading, with particular attention afforded to a silicon carbide fibre-reinforced silicon carbide composite (SiCf/SiC) variant. Data from these separate monitoring techniques plus ancillary use of X-ray computed tomography, in-situ scanning electron microscopy and optical inspection were correlated to monitor the onset and progression of damage during mechanical loading. The benefits of employing a concurrent, multi-technique approach to monitoring damage in CMCs are demonstrated.
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Schwagenscheidt, Markus, and Fabian Völz. "Lifting newforms to vector-valued modular forms for the Weil representation." International Journal of Number Theory 11, no. 07 (October 21, 2015): 2199–219. http://dx.doi.org/10.1142/s1793042115500980.
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Given a discriminant form D of level N, there is a natural lifting which maps elliptic modular forms of level N to vector-valued modular forms for the Weil representation associated to D. We show that in some cases the zero component of a lifting of a newform f is just a scalar multiple of f. In order to do so, we split the lifting map into certain partial liftings corresponding to the prime powers exactly dividing N and then proceed to compute the zero components of these partial maps explicitly. As an application, we show that the L-function L𝒜(f, s) of a newform f and an ideal class 𝒜 as defined by Gross and Zagier can be written as a certain L-series of the lifting of f.
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Ponidi, Ponidi, and Ali Makhfud. "Predictive Maintenance Implementation In Reach Stacker Kalmar Type Drd To Reduce Component Failure." R.E.M. (Rekayasa Energi Manufaktur) Jurnal 3, no. 1 (October 11, 2018): 29. http://dx.doi.org/10.21070/r.e.m.v3i1.1538.
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The Reach Stacker lifting tool is the most productive lifting tool for container lifting today. It can move container till 20 container box in every hour, it means that in 3 minutes it can lift and lower 1 box container. In operation the lifting equipment will surely experience a stop operation due to the failure of a component. The purpose of this study was to determine critical and important components of the history of failure data for a year (2016) in PT meratusline, by using tools Fault Tree Analysis, Failure Mode and Effect Analysis and Pareto. From the analysis, it obtained Load Handling component as the most critical component based on the most frequent failure and required a long time to repair. The cause of the failure itself was inconsistent greasing maintenance / Predictive maintenance was not executed and there was no loose handling of Load Handling chain components. From the result of research, it was suggested to make standard rule by adding greasing item in worksheet Predictive maintenance and Standard Operating Procedure Predictive Maintenance for chain replacement on Load Hadling component if already entering 12000 Hour life.
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Schupp, Sibylle. "Lifting a Butterfly – A Component-Based FFT." Scientific Programming 11, no. 4 (2003): 291–307. http://dx.doi.org/10.1155/2003/918501.
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While modern software engineering, with good reason, tries to establish the idea of reusability and the principles of parameterization and loosely coupled components even for the design of performance-critical software, Fast Fourier Transforms (FFTs) tend to be monolithic and of a very low degree of parameterization. The data structures to hold the input and output data, the element type of these data, the algorithm for computing the so-called twiddle factors, the storage model for a given set of twiddle factors, all are unchangeably defined in the so-called butterfly, restricting its reuse almost entirely. This paper shows a way to a component-based FFT by designing a parameterized butterfly. Based on the technique of lifting, this parameterization includes algorithmic and implementation issues without violating the complexity guarantees of an FFT. The paper demonstrates the lifting process for the Gentleman-Sande butterfly, i.e., the butterfly that underlies the large class of decimation-in-frequency (DIF) FFTs, shows the resulting components and summarizes the implementation of a component-based, generic DIF library in C++.
Dissertations / Theses on the topic "Component lifing"
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You, Chao. "Fatigue lifing approaches for shot peened turbine components." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/415882/.
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Life assessment is of great importance to component repair and replacement scheduling of turbine systems which experience cyclic start-up and shut-down operations during their service lives. As vital parts where a severe stress concentration exists, the fir tree blade-disc interfaces are typically shot-peened. Their fatigue resistance is considered to be improved subsequently due to the surface compressive residual stress (CRS) field and strain hardening resulting from shot peening. However, current life assessment models are relatively conservative, merely considering shot peening as an additional safety factor rather than taking account of the benefits derived from the process. The objective of this research is to develop a life assessment method considering the effects of shot peening in the component lifing protocols. Successful development of this approach will achieve a more cost effective scheduling of repair or replacement of the assets while ensuring sufficient safety margins. In this study, a low pressure steam turbine material, FV448, has been selected. The shot peening induced residual stress profiles as well as their evolution during fatigue loading were measured using the X-ray diffraction (XRD) technique. In the modelling work, a 3D finite element (FE) modelling approach has been developed to predict the residual stress relaxation behaviour during fatigue loading. Both the CRS and the strain hardening fields arising from shot peening have been reconstructed in the FE model as pre-defined conditions: The reconstruction of residual stresses was realised by the inverse eigenstrain approach. In this study, the application of this approach has been extended from a flat surface to a notched geometry. The strain hardening field was reconstructed by modifying the material parameters at different depths based on the shot peening induced plastic strain distribution, which was evaluated utilising an approach based on previous measurement of electron backscatter diffraction (EBSD) local misorientations. By allowing for both beneficial effects of shot peening, the simulated quasi-static residual stress relaxation occurring during the first cycle correlated well with corresponding experimental data. The retention of the CRS field in the notched sample during fatigue loading has been highlighted. The application of total life approaches in predicting the low-cycle fatigue (LCF) life of the shot-peened specimens has been investigated. The Smith-Watson-Topper (SWT) and the Fatemi-Socie (FS) critical plane fatigue criteria have been selected in the present study. The developed FE models incorporating shot peening effects have been used to generate the stress and strain data required by the SWT and FS criteria. A good agreement between experiments and predictions was obtained using this FE-based approach. In addition, the FE analysis shows that the degree of the shot peening benefit in improving fatigue life can be reasonably related to the degree of the reduction in the mean stress level within the shot peening affected layer. The application of a critical distance method considering the stress and strain hardening gradients near the shotpeened surface has been found to effectively increase the accuracy of the life prediction. Damage tolerant approaches have also been employed to assess the fatigue life of the shot-peened notched specimens by predicting the short crack growth behaviour through the shot peening affected layer. This analysis was carried out using both 2D and 3D FE models containing a crack emanating from the notch root. The FE models have been upgraded from the models used to study the residual stress relaxation behaviour. The crack driving force has been appropriately characterised using both linear-elastic and elasto-plastic fracture mechanics (LEFM and EPFM), allowing for the effects of shot peening. An accurate quantification of the retardation of the short crack growth behaviour resulting from shot peening has been subsequently realised. Additionally, the associated crack shape evolution has also been predicted using the developed FE model, which explains the experimentally observed significant differences in crack shape evolution between varying surface conditions. The importance of taking the crack shape effects into account when evaluating the short crack growth behaviour has been emphasised. Overall, a FE tool has been developed in this study which has been demonstrated to be effective in analysing the benefits of shot peening in improving fatigue life. It also helps unveil the mechanism behind this life improvement, which contributes to the development of a robust and convenient lifing method that can be applied to shot-peened components and can be used to guide shot peening optimisation.
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Abdallah, Zakaria. "Creep lifing methods for components under high temperature creep." Thesis, Swansea University, 2010. https://cronfa.swan.ac.uk/Record/cronfa43065.
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Morgans, Christopher. "Defect tolerant lifing of airframe components and the influence of corrosion damage." Thesis, Swansea University, 2007. https://cronfa.swan.ac.uk/Record/cronfa42774.
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The present thesis describes a programme of research into corrosion pitting in the airframe aluminium alloy AA 7010-T7651 and its subsequent influence on fatigue performance. The alloy is employed extensively in airframe structures, most commonly as wing spars and skins of the BAE SYSTEMS Hawk Mkl27 lead-in fighter aircraft. The research programme followed from the major international project SICAS (Structural Integrity assessment of pitting Corrosion in Aircraft Structures), which was instigated as an attempt to minimise the costs associated with in-service corrosion damage. Existing corrosion management techniques are time consuming and expensive, typically involving grinding and mechanical blending of corrosion damaged areas. However, by adopting damage tolerant fatigue lifing procedures in partnership with corrosion detection, a reduction in the cost of corrosion management and safe extensions to aircraft operation lives may be achievable. Flat plate specimens were subjected to pitting damage via a laboratory based corrosion protocol. Secondly, a centre hole plate specimen was employed, in this case incorporating end grain corrosion within the root of central hole. Detailed characterisation of the pits demonstrated the critical role of microstructure on pit geometry. Both forms of pre-corroded specimen were subjected to a comprehensive matrix of constant amplitude load controlled fatigue testing under controlled humidity and room temperature. Multiple repeat tests were performed at specific stress levels to produce data sets corresponding to fatigue lives of approximately 1x104, 7x104 and 3x105 cycles. Post testing, LEFM based modelling was performed to describe test specimen performance. This proved successful for the relatively large scale corrosion pitting under consideration.
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Souahi, A. "Structural optimization of aircraft lifting surfaces to satisfy flutter requirements." Thesis, Cranfield University, 1986. http://hdl.handle.net/1826/3657.
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The research reported in this thesis is concerned with
the structural weight optimization of aircraft lifting
surfaces when subjected to the satisfaction of flutter
requirements.
The main text is intended primarily as an expository
account on the work and as such it aims at introducing and
defining the subject of research and presenting the results.
Accordingly, the mathematics have been simplified to the
utmost in the main text and heavy theoretical treatments are
revealed in the appendices.
As the aim of this work is not directed at in-depth
studies of the physical nature of flutter nor for a
comprehensive treatment of structural optimization, the basic
concepts of these two subjects are touched upon in the
beginnings of chapters II and III respectively. We concluded
these two chapters by clarifying the class of flutter,
constraints and design variables for which the program we
developed is designed. We endeavored to keep the problem to
within certain practical boundaries without loosing too much
of either its generality or its applicability to structures
in realistic operational environments.
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Ozaltun, Hakan. "An Energy Based Fatigue Lifing Method for In-Service Components and Numerical Assessment of U10Mo Alloy Based Fuel Mini Plates." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1309210033.
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Sheppard, Phillip S. "Sex-Based Differences In Lifting Technique Under Increasing Load Conditions: A Principal Component Analysis." Thesis, 2012. http://hdl.handle.net/1974/7574.
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The objectives of the present study were: 1) to determine if there is a sex-based difference in lifting technique across increasing load conditions; and, 2) to examine the use of body size-adjusted tasks and back strength-adjusted loads in the analysis of lifting technique. Eleven male and 14 female participants (n=25) with no previous history of low back pain participated in the study. Participants completed freestyle, symmetric lifts of a box with handles from the floor to table height for five trials under three load conditions (10%, 20%, and 30% of their individual maximum isometric back strength). Joint kinematic data for the ankle, knee, hip, and lumbar and thoracic spine were collected using a two-camera Optotrak 3020 system (NDI, Waterloo, ON). Joint angles were calculated using a three-dimensional Euler rotation sequence and PCA was applied to assess differences in lifting technique across the entire waveform. A repeated measures ANOVA with a mixed design revealed no significant effect of sex for any of the PCs. This was contrary to previous research that used discrete points on the lifting curve to analyze sex-based differences but agreed with more recent research using more complex analysis techniques. There was a significant effect of load on lifting technique for six PCs of the lower limb (p<0.005). However, there was no significant difference in lifting technique for the thoracic and lumbar spine. It was concluded that, when load is standardized to individual back strength characteristics, males and females adopted a similar lifting technique. In addition, as load increases participants used more of a semi-squat or squat lifting technique.Thesis (Master, Kinesiology & Health Studies) -- Queen's University, 2012-10-03 21:10:11.889
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SADLER, ERIN. "PRINCIPAL COMPONENT ANALYSES OF JOINT ANGLE CURVES TO EXAMINE LIFTING TECHNIQUE." Thesis, 2010. http://hdl.handle.net/1974/5976.
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The objectives of the present body of work were 1) to evaluate the Personal Lift-Assist Device (PLAD) in terms of its effect on lifting technique, interjoint coordination, and whether sex modulates these effects and 2) to explore the use of principal component analysis (PCA) as a method to investigate lifting waveforms. Thirty participants (15M, 15F) completed a freestyle, symmetrical lifting protocol during which three-dimensional kinematics of the ankle, knee, hip, and lumbar and thoracic spine were collected using a two-camera Optotrak 3020 system. There were four testing conditions: a) with and b) without wearing the PLAD; and c) 0% load and d) 10% of maximum back strength load. All data were evaluated using PCA. In the first analysis, the relationship between the PLAD and lifting technique under a loaded condition was explored. Results showed that 8 PCs were significantly different between the PLAD/No PLAD conditions yet there were no significant effects of sex on any of the PCs. It was concluded that wearing the PLAD encourages a lifting technique that is reflective of a squat lift, independent of sex. In the second analysis, the PLAD’s effect on interjoint coordination patterns under both loaded and unloaded conditions was examined using the relative phase angle (RPA). It was found that there were no significant differences between device, sex, or load conditions on any of the PCs retained in the model. A novel approach to enhance interpretability of PCs was developed during this study. Finally, when the PLAD was not worn, male and female differences were further investigated under loaded and unloaded conditions. It was determined that when the load is individualized to personal strength characteristics, sex differences in lifting technique are negligible. This is a contradictory finding from previous research. Overall, the major contributions of this research are: support for the use of the PLAD in industry; the recommendation that load be selected based on individual strength characteristics for lifting research experimental design; the use of PCA as a method to effectively evaluate lifting waveforms; and the development of a novel approach to aid in the interpretation of principal components.Thesis (Master, Kinesiology & Health Studies) -- Queen's University, 2010-08-18 09:35:19.142
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(8741097), Ritwik Bandyopadhyay. "ENSURING FATIGUE PERFORMANCE VIA LOCATION-SPECIFIC LIFING IN AEROSPACE COMPONENTS MADE OF TITANIUM ALLOYS AND NICKEL-BASE SUPERALLOYS." Thesis, 2020.
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In this thesis, the role of location-specific microstructural features in the fatigue performance of the safety-critical aerospace components made of Nickel (Ni)-base superalloys and linear friction welded (LFW) Titanium (Ti) alloys has been studied using crystal plasticity finite element (CPFE) simulations, energy dispersive X-ray diffraction (EDD), backscatter electron (BSE) images and digital image correlation (DIC).
In order to develop a microstructure-sensitive fatigue life prediction framework, first, it is essential to build trust in the quantitative prediction from CPFE analysis by quantifying uncertainties in the mechanical response from CPFE simulations. Second, it is necessary to construct a unified fatigue life prediction metric, applicable to multiple material systems; and a calibration strategy of the unified fatigue life model parameter accounting for uncertainties originating from CPFE simulations and inherent in the experimental calibration dataset. To achieve the first task, a genetic algorithm framework is used to obtain the statistical distributions of the crystal plasticity (CP) parameters. Subsequently, these distributions are used in a first-order, second-moment method to compute the mean and the standard deviation for the stress along the loading direction (σ_load), plastic strain accumulation (PSA), and stored plastic strain energy density (SPSED). The results suggest that an ~10% variability in σ_load and 20%-25% variability in the PSA and SPSED values may exist due to the uncertainty in the CP parameter estimation. Further, the contribution of a specific CP parameter to the overall uncertainty is path-dependent and varies based on the load step under consideration. To accomplish the second goal, in this thesis, it is postulated that a critical value of the SPSED is associated with fatigue failure in metals and independent of the applied load. Unlike the classical approach of estimating the (homogenized) SPSED as the cumulative area enclosed within the macroscopic stress-strain hysteresis loops, CPFE simulations are used to compute the (local) SPSED at each material point within polycrystalline aggregates of 718Plus, an additively manufactured Ni-base superalloy. A Bayesian inference method is utilized to calibrate the critical SPSED, which is subsequently used to predict fatigue lives at nine different strain ranges, including strain ratios of 0.05 and -1, using nine statistically equivalent microstructures. For each strain range, the predicted lives from all simulated microstructures follow a log-normal distribution; for a given strain ratio, the predicted scatter is seen to be increasing with decreasing strain amplitude and are indicative of the scatter observed in the fatigue experiments. Further, the log-normal mean lives at each strain range are in good agreement with the experimental evidence. Since the critical SPSED captures the experimental data with reasonable accuracy across various loading regimes, it is hypothesized to be a material property and sufficient to predict the fatigue life.
Inclusions are unavoidable in Ni-base superalloys, which lead to two competing failure modes, namely inclusion- and matrix-driven failures. Each factor related to the inclusion, which may contribute to crack initiation, is isolated and systematically investigated within RR1000, a powder metallurgy produced Ni-base superalloy, using CPFE simulations. Specifically, the role of the inclusion stiffness, loading regime, loading direction, a debonded region in the inclusion-matrix interface, microstructural variability around the inclusion, inclusion size, dissimilar coefficient of thermal expansion (CTE), temperature, residual stress, and distance of the inclusion from the free surface are studied in the emergence of two failure modes. The CPFE analysis indicates that the emergence of a failure mode is an outcome of the complex interaction between the aforementioned factors. However, the possibility of a higher probability of failure due to inclusions is observed with increasing temperature, if the CTE of the inclusion is higher than the matrix, and vice versa. Any overall correlation between the inclusion size and its propensity for damage is not found, based on inclusion that is of the order of the mean grain size. Further, the CPFE simulations indicate that the surface inclusions are more damaging than the interior inclusions for similar surrounding microstructures. These observations are utilized to instantiate twenty realistic statistically equivalent microstructures of RR1000 – ten containing inclusions and remaining ten without inclusions. Using CPFE simulations with these microstructures at four different temperatures and three strain ranges for each temperature, the critical SPSED is calibrated as a function of temperature for RR1000. The results suggest that critical SPSED decreases almost linearly with increasing temperature and is appropriate to predict the realistic emergence of the competing failure modes as a function of applied strain range and temperature.
LFW process leads to the development of significant residual stress in the components, and the role of residual stress in the fatigue performance of materials cannot be overstated. Hence, to ensure fatigue performance of the LFW Ti alloys, residual strains in LFW of similar (Ti-6Al-4V welded to Ti-6Al-4V or Ti64-Ti64) and dissimilar (Ti-6Al-4V welded to Ti-5Al-5V-5Mo-3Cr or Ti64-Ti5553) Ti alloys have been characterized using EDD. For each type of LFW, one sample is chosen in the as-welded (AW) condition and another sample is selected after a post-weld heat treatment (HT). Residual strains have been separately studied in the alpha and beta phases of the material, and five components (three axial and two shear) have been reported in each case. In-plane axial components of the residual strains show a smooth and symmetric behavior about the weld center for the Ti64-Ti64 LFW samples in the AW condition, whereas these components in the Ti64-Ti5553 LFW sample show a symmetric trend with jump discontinuities. Such jump discontinuities, observed in both the AW and HT conditions of the Ti64-Ti5553 samples, suggest different strain-free lattice parameters in the weld region and the parent material. In contrast, the results from the Ti64-Ti64 LFW samples in both AW and HT conditions suggest nearly uniform strain-free lattice parameters throughout the weld region. The observed trends in the in-plane axial residual strain components have been rationalized by the corresponding microstructural changes and variations across the weld region via BSE images.
In the literature, fatigue crack initiation in the LFW Ti-6Al-4V specimens does not usually take place in the seemingly weakest location, i.e., the weld region. From the BSE images, Ti-6Al-4V microstructure, at a distance from the weld-center, which is typically associated with crack initiation in the literature, are identified in both AW and HT samples and found to be identical, specifically, equiaxed alpha grains with beta phases present at the alpha grain boundaries and triple points. Hence, subsequent fatigue performance in LFW Ti-6Al-4V is analyzed considering the equiaxed alpha microstructure.
The LFW components made of Ti-6Al-4V are often designed for high cycle fatigue performance under high mean stress or high R ratios. In engineering practice, mean stress corrections are employed to assess the fatigue performance of a material or structure; albeit this is problematic for Ti-6Al-4V, which experiences anomalous behavior at high R ratios. To address this problem, high cycle fatigue analyses are performed on two Ti-6Al-4V specimens with equiaxed alpha microstructures at a high R ratio. In one specimen, two micro-textured regions (MTRs) having their c-axes near-parallel and perpendicular to the loading direction are identified. High-resolution DIC is performed in the MTRs to study grain-level strain localization. In the other specimen, DIC is performed on a larger area, and crack initiation is observed in a random-textured region. To accompany the experiments, CPFE simulations are performed to investigate the mechanistic aspects of crack initiation, and the relative activity of different families of slip systems as a function of R ratio. A critical soft-hard-soft grain combination is associated with crack initiation indicating possible dwell effect at high R ratios, which could be attributed to the high-applied mean stress and high creep sensitivity of Ti-6Al-4V at room temperature. Further, simulations indicated more heterogeneous deformation, specifically the activation of multiple families of slip systems with fewer grains being plasticized, at higher R ratios. Such behavior is exacerbated within MTRs, especially the MTR composed of grains with their c-axes near parallel to the loading direction. These features of micro-plasticity make the high R ratio regime more vulnerable to fatigue damage accumulation and justify the anomalous mean stress behavior experienced by Ti-6Al-4V at high R ratios.
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Desmoulins, Landry. "Modélisation et analyses cinématiques de l'épaule lors de levers de charges en hauteur." Thèse, 2016. http://hdl.handle.net/1866/18528.
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Thèse de doctorat à mi-chemin entre la recherche fondamentale et appliquée. Les champs disciplinaires sont principalement la biomécanique, l'ergonomie physique ou encore l'anatomie. Réalisé en cotutelle avec le professeur Paul Allard et Mickael Begon.An occupation that requires handling loads combined with large elevation of the arms is associated with the occurrence of shoulders musculoskeletal disorder. The analysis of these joint movements is essential because it helps to quantify the stress applied to the musculoskeletal structures. This thesis provides an innovative model which allows the estimation of the shoulder complex kinematics and used it to analyze the joints kinematics during lifting tasks. It is organized into three sub-objectives. The first aim is the development and validation of a kinematic model the most representative as possible of the shoulder complex anatomy while correcting soft tissue artifacts through the use of global optimization. This model included a scapulothoracic closed loop, which constrains a scapular dot contact to be coincident with thoracic gliding plane modeled by a subject-specific ellipsoid. In the validation process, the reference model used the gold standard for direct measurements of bone movements. In dynamic movements, the closed loop model developed generates barely more kinematic errors that errors obtained for the study of standard movements by existing models. The second aim is to detect and quantify the shoulder articular movements influenced by the combined effects of two risk factors: task height and load weight. The results indicate that many peaks of joint angles are influenced by the interaction of height and weight. According to the different initial and deposits heights when the weight increases, the kinematics changes are substantial, in number and magnitude. The kinematic strategies of participants are more consistent when the weight of load increase for initial height lift at hips level compared to shoulders level, and for a deposit at eye level compared to shoulders. The third aim is to investigate the magnitude and temporality of the maximum peak vertical acceleration of the box. The significant joints movements are characterized with a principal component analysis of joint angle values collected at this instant. In particular, this study highlights that elbow flexion and thoraco-humeral elevation are two correlated invariant joint movements to all lifting tasks whatever the initial and deposit height, and weight of the load. The realism of the developed shoulder model and kinematics analyzes open perspectives in occupational biomechanics and contribute to risk prevention efforts in health and safety.
Une activité professionnelle qui exige de manipuler des charges combinée à de grandes élévations des bras augmente les chances de développer un trouble musculo-squelettique aux épaules. L’analyse de ces mouvements articulaires est essentielle car elle contribue à quantifier les contraintes appliquées aux structures musculo-squelettiques. Cette thèse propose un modèle innovant qui permet l’estimation de la cinématique du complexe de l’épaule, et l’utilise ensuite afin d’analyser la cinématique de levers de charge. Elle s’organise en trois sous-objectifs. Le premier concerne le développement et la validation d’un modèle cinématique le plus représentatif possible de l’anatomie du complexe de l’épaule tout en corrigeant les artéfacts des tissus mous par une optimisation multi-segmentaire. Ce modèle avec une fermeture de boucle scapulo-thoracique, impose à un point de contact scapulaire d’être coïncident au plan de glissement thoracique modélisé par un ellipsoïde mis à l’échelle pour chaque sujet. Le modèle qui a été utilisé comme référence lors des comparaisons du processus de validation bénéficie du « gold standard » de mesures directes des mouvements osseux. Le modèle développé en boucle fermée génère à peine plus d’erreurs cinématiques lors de mouvements dynamiques que les erreurs obtenues par les modèles existants pour l’étude de mouvements standards. Le second identifie et quantifie les mouvements articulaires de l’épaule influencés par la combinaison des effets de deux facteurs de risques : les hauteurs importantes d’agencement de la tâche (hauteurs de saisie et de dépôt) et les masses de charges (6 kg, 12 kg et 18 kg). Les résultats indiquent qu’il existe de nombreux pics d’angles articulaires qui sont influencés par l’interaction des deux effets. Lorsque la masse augmente, les modifications cinématiques sont plus importantes, en nombre et en amplitude, selon les différentes hauteurs de saisies et de dépôts de la charge. Les participants varient peu leur mode opératoire pour une saisie à hauteur des hanches en comparaison des épaules, et pour un dépôt à hauteur des yeux en comparaison aux épaules avec une charge plus lourde. Un troisième s’intéresse au pic maximal d’accélération verticale de la charge dans son intensité et sa temporalité. Basée sur une analyse en composante principale des valeurs d’angles articulaires à cet instant, elle permet de caractériser les mouvements articulaires significatifs. Cette étude met notamment en évidence que la flexion du coude et l’élévation thoraco-humérale sont deux mouvements articulaires corrélés invariants à toutes les tâches de lever en hauteur quelles que soient la hauteur de dépôt et la masse de la charge. Le souci de réalisme du modèle développé et les analyses cinématiques menées ouvrent des perspectives en biomécanique occupationnelle et participent à l’effort de prévention des risques en santé et sécurité.
Books on the topic "Component lifing"
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Wanhill, Russell, Simon Barter, and Loris Molent. Fatigue Crack Growth Failure and Lifing Analyses for Metallic Aircraft Structures and Components. Dordrecht: Springer Netherlands, 2019. http://dx.doi.org/10.1007/978-94-024-1675-6.
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Murphy, James R. The Martian dust cycle: Investigation of the surface lifting component : final report, interchange # NCC2-5076 (22 July 1994 - 21 July 1996). [Washington, DC: National Aeronautics and Space Administration, 1996.
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Wanhill, Russell, Simon Barter, and Loris Molent. Fatigue Crack Growth Failure and Lifing Analyses for Metallic Aircraft Structures and Components. Springer, 2019.
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Reaction time components under resisted and unresisted conditions as a function of gains in strength. 1985.
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Adeyanju, Kunle. Reaction time components under resisted and unresisted conditions as a function of gains in strength. 1985.
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Adeyanju, Kunle. Reaction time components under resisted and unresisted conditions as a function of gains in strength. 1985.
Find full textBook chapters on the topic "Component lifing"
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Harrison, G. F., and P. H. Tranter. "Stressing and Lifing Techniques for High Temperature Aeroengine Components." In Mechanical Behaviour of Materials at High Temperature, 327–45. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-009-1714-9_18.
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Longuet, Arnaud, Christian Dumont, and Eric Georges. "Advanced Modeling Tools for Processing and Lifing of Aeroengine Components." In Superalloys 2020, 3–15. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-51834-9_1.
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Akyuz, Burak, and Nicholas Steinhoff. "Failures of Cranes and Lifting Equipment." In Analysis and Prevention of Component and Equipment Failures, 415–34. ASM International, 2021. http://dx.doi.org/10.31399/asm.hb.v11a.a0006830.
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Abstract The types of metal components used in lifting equipment include gears, shafts, drums and sheaves, brakes, brake wheels, couplings, bearings, wheels, electrical switchgear, chains, wire rope, and hooks. This article primarily deals with many of these metal components of lifting equipment in three categories: cranes and bridges, attachments used for direct lifting, and built-in members of lifting equipment. It first reviews the mechanisms, origins, and investigation of failures. Then the article describes the materials used for lifting equipment, followed by a section explaining the failure analysis of wire ropes and the failure of wire ropes due to corrosion, a common cause of wire-rope failure. Further, it reviews the characteristics of shock loading, abrasive wear, and stress-corrosion cracking of a wire rope. Then, the article provides information on the failure analysis of chains, hooks, shafts, and cranes and related members.
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Du, Wenwen, Xiaofei Xu, and Haroon Rashid. "The Analysis of Key Components Structure of Vehicle Thermal Balance Lifting Platform." In Proceedings of the 2022 International Conference on Smart Manufacturing and Material Processing (SMMP2022). IOS Press, 2022. http://dx.doi.org/10.3233/atde220834.
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In this paper, the UG software is used to draw the three dimensional diagram of the key parts of the thermal balance lifting platform of the whole vehicle, and the ANSYS software is also used to simulate the Von-Mises stress on the connecting plate. The structure of the column is optimized, and the stress-strain diagram and the relationship diagram between the time and the strain are obtained. The results show that the structure design is reasonable to meet the needs of production.
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Heuler, P., J. W. Bergmann, and M. Vormwald. "On Lifing Concepts for Cast High Temperature Components Based on LCF and Fracture Mechanics." In Fatigue '96, 1165–70. Elsevier, 1996. http://dx.doi.org/10.1016/b978-008042268-8/50067-8.
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"Method for Semantic Annotation and Lifting of Process Models." In Applications and Developments in Semantic Process Mining, 135–67. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-7998-2668-2.ch005.
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The work done in this chapter demonstrates how the main components of the SPMaAF framework and sets of algorithms described earlier in Chapters 3 and 4, respectively, fit and rely on each other in achieving the semantic enhancement of the discovered process models. This is done by representing the models discovered through the standard process mining techniques as a set of annotated terms that links to or references the concepts defined within ontologies. It permits the process analysts to formally represent and analyse the several information in the underlying knowledge-bases in a more efficient and yet accurate manner. Henceforth, the conceptualisation method or tactics is allied to semantic lifting of the process models.
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Knight, Alan. "4. Counter-revolution and Constitutionalism (1913–1914)." In The Mexican Revolution: A Very Short Introduction, 43–54. Oxford University Press, 2016. http://dx.doi.org/10.1093/actrade/9780198745631.003.0004.
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The coup of February 1913, involving the overthrow and killing of Madero, had decisive effects. ‘Counter-revolution and Constitutionalism’ outlines how Huerta, the interim president, relied on the old Federal Army to support his leadership. In reaction, many of the components of the fragmented Maderista coalition began to reassemble and reorganize. The big northern frontier states—Coahuila, Chihuahua, and Sonora—played a key role under the leadership of Carranza, Obregón, and Villa, alongside the continued Zapatista revolt in Morelos. The rebels made the transition from guerrilla to conventional warfare, aided by the US lifting its arms embargo in early 1914. In August 1914, rebel forces approached Mexico City and Huerta resigned.
Conference papers on the topic "Component lifing"
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Parthasarathy, Girija, and Satyavaraprasad Allumallu. "Reduced Models for Rotating Component Lifing." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53993.
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The most common failure mode for engine rotating components is material fatigue. Low Cycle Fatigue or LCF is caused by stresses and temperatures resulting from start-stop cycles. One current common practice is to assign an LCF life of certain number of start-stop cycles based on a standard flight or mission. This is done during design through detailed calculations of stresses and temperatures for a standard flight, and the use of material property and failure models. The limitation of the design phase stress and temperature calculations is that they cannot take into account actual operating temperatures and stresses. In order to improve significantly the accuracy of the LCF lifing prediction, the component temperatures and stresses need to be computed for the actual operating conditions. However, stress and thermal models are very detailed and complex, and it could take on the order of a few hours to complete a stress and temperature simulation for a flight. The objective of this work is to develop reduced models, that would enable us to compute the stresses and temperatures at critical locations, without the detailed computationally intensive models. This paper describes the development of the reduced model and the results achieved in comparison with the original models for components of Honeywell propulsion engines. Given certain inputs such as engine speed and ambient temperature for the duration of the flight, the reduced models computes the component critical location temperature and thermal stress for the same flight in a very small fraction of time it would take the original finite element model to compute.
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Cathcart, Henry, Christopher Meyer, Mark Joyce, and Richard Green. "Probabilistic Lifing Methods for Digital Assets." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-16187.
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Abstract Modern industrial gas turbines (IGTs) must be capable of operational flexibility to fulfil the requirements of an evolving power industry. Base load applications require turbines to operate for long periods at full load conditions whilst load-following applications require turbines to undergo repeated start-stop cycles. Traditional design and lifing approaches, which are based around an assumed worst case operational scenario and critical damage mechanism, cannot fully represent the durability of components when exposed to flexible operation. Condition based assessments, conversely, consider multiple operating scenarios and damage mechanisms to more accurately predict the durability of components. Condition based assessments are particularly powerful when applied to digital assets, where component lives can be calculated for each individual turbine based on detailed operational data. Despite the additional data available to conduct assessments of a digital asset, the information about the asset’s manufacture, maintenance or environment is unlikely to be complete or perfect. This leads to uncertainty in the current and future condition of the asset, which must be accounted for when deciding upon maintenance, retirement or life extension. The uncertainty can be accounted for using bounding assumptions or safety factors, but these approaches often lead to overly conservative results and do not provide any insight into the underlying causes of the uncertainty. Probabilistic methodologies provide a means to accurately evaluate and interrogate this uncertainty, by explicitly considering the potential variation in calculation inputs and assumptions. The degradation of hot gas path components by creep-fatigue mechanisms often limits turbine life. Probabilistic creep-fatigue assessment methods have been developed and are used to predict and understand the uncertainty in creep-fatigue damage. However, deploying these methods across a large fleet of digital assets, each with multiple components presents several challenges: the assessments rely on Monte Carlo sampling or other discretised calculations and hence are too computationally intensive to be used in real time on a large fleet; assets have often not been digitized for their entire operating lives, hence periods of missing data must be accounted for; finally, predicting the uncertainty of future operation requires information about the likely distribution of future operating regimes. This paper presents a methodology to effectively calculate the uncertainty on hot gas path component creep-fatigue assessments across a large fleet of IGTs. The methodology divides operational periods into two categories. In the first category a full suite of operational data is available. Damage is modelled using an emulator of a full Monte Carlo assessment. The emulator accounts for the fact that different operational profiles may result in different degradation uncertainty, and that the mode of operation of an asset may change throughout its life. In the second category no information is available. This category covers both future operation and historical operation prior to the instrumentation of the asset. These periods are modelled by considering fleet-wide statistics of degradation and the pathdependency of creep-fatigue damage progression. The predictions for both categories of operation are integrated into a system that can predict distributions of the damage accumulated within a turbine component and the future progression of this damage.
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Thomsen, Benjamin, Michael Kokkolaras, Tomas Månsson, and Ola Isaksson. "Component Lifing Decisions and Maintenance Strategies in the Context of Aeroengine Product-Service Systems Design." In ASME 2015 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/detc2015-46967.
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Static structural engine components are typically designed for full lifetime operation. Efforts to reduce weight in order to improve performance result in structural designs associated with higher lifing uncertainty: Maintaining reliability levels may necessitate expensive manufacturing and maintenance solutions. In practice, repair techniques for such structures are available; however, they are not planned for during the design process. The objective of the research presented in this paper is to model and optimize component lifecycle costs with respect to lifing decisions, demonstrated by means of an aeroengine component design example. Both technical (failure) and legislative (certification) implications are considered. The impact of maintenance strategies (repair and/or replace) on lifing design decisions is quantified. It is shown that, under different conditions, it may not be prudent to design for full life but rather accept shorter life and then repair or replace the component. This is especially evident if volumetric effects on low cycle fatigue life are taken into account. It is possible that failure rates based on legacy engines do not translate necessarily to weight-optimized components. Such an analysis can play a significant supporting role in engine component design in a product-service system context.
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Tinga, Tiedo, Wilfried P. J. Visser, Wim B. de Wolf, and Michael J. Broomhead. "Integrated Lifing Analysis Tool for Gas Turbine Components." In ASME Turbo Expo 2000: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/2000-gt-0646.
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A method to predict gas turbine component life based on analysis of engine performance is presented. Engine performance history is obtained from in-flight monitored engine parameters and flight conditions and downloaded for processing by a tool integrating a number of software tools and models. These subsequently include a comprehensive thermodynamical engine system model, heat transfer, thermal and mechanical load models, and finally, a life consumption model. Thermal and mechanical load distributions in the component as well as component life can be predicted. At this stage, the overall life prediction inaccuracy of the tool is dominated by the relatively high inaccuracy of the lifing model, and therefore, component life can only be predicted relative to a reference life. The tool is demonstrated with an analysis of the F100-PW-220 engine 3rd stage turbine rotor blade life consumption during a recorded RNLAF F-16 mission. Using the engine system model with a detailed control system, deterioration effects on engine performance were analyzed and the effect of engine deterioration on blade life consumption rate was determined. The tool has significant potential to enhance on-condition maintenance and optimize aircraft operational use.
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Brooks, J. W., H. C. Basoalto, R. Sahota, and P. Tranter. "Probabilistic Property Prediction of Aero-Engine Components for Fatigue." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22708.
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Service lives for critical rotating parts in aero engine gas turbines are declared using deterministic lifing calculations based on fixed point values of key mechanical properties and factors to allow for the scatter. However, novel probabilistic lifing algorithms have been developed, which are able to take into account the degree of scatter in the material properties throughout the component. Process simulation software has been developed to predict the material flow, residual stresses, microstructure and properties in components during the disc forging operations to ensure robust manufacturing routes. This allows the changes in the materials microstructure, and the mechanical property variation throughout the component, to be predicted as the crack initiation and propagation properties are significantly dependent on the grain structure. These two strains of research have been combined in an attempt to increase the reliability of service life predictions through modelling the scatter in the mechanical properties resulting from manufacturing variation. Results will be presented which indicate that significant life benefits can be obtained by adopting a location specific lifing method based on this approach.
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Peng, Caetano. "Non-Linear Aeromechanical Behaviour of Axial Core Compressor Stator Vanes." In ASME Turbo Expo 2007: Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-27580.
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This paper highlights some engine non-linearities that can affect both performance and robustness of aero engines. It pays particular attention to non-linearities generated at the stator vane contact end joints. These non-linearities resulting from friction contact joints affect the vane modeshapes, damping and forced response. This work proposes upper and lower bound solutions based on vane end restraints non-linearities to predict conservative forced response of stator vanes. Some non-linearities such as those caused by mistuning can be beneficial to the component and system. There are also non-linearities that can be detrimental to engine performance, robustness and reliability. Moreover, it proposes and discusses the concept of temporal HCF or CCF lifing method. Recent developments in FE, CFD, mistuning, forced response and probabilistic codes can help to create more integrated design tools that incorporate time-dependent non-linearities in the lifing of aero engine components. Computations performed here demonstrated some level of component virtual testing. These analyses are important component virtual testing that will be gradually extended to whole aero engine virtual testing.
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Gorelik, Michael, Waled T. Hassan, and Harry Kington. "Role of Quantitative NDE Techniques in Life Management of Gas Turbine Components." In ASME Turbo Expo 2006: Power for Land, Sea, and Air. ASMEDC, 2006. http://dx.doi.org/10.1115/gt2006-91337.
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A number of earlier publications discussed the benefits of probabilistic analysis and probabilistic lifing in application to critical rotating engine components. One of the important variables in both probabilistic and deterministic lifing analysis is the level of residual stress in the component. Near surface residual stresses directly influence the fatigue life of critical engine rotating components. Depending on sign and magnitude a near surface residual stress gradient can either inhibit or accelerate fatigue initiation and crack propagation. A major barrier to introducing subsurface residual stress information into the life calculation process is the necessity to make accurate and reliable nondestructive measurements on as produced hardware. The paper reviews several NDE technologies that could be candidates for both production and in-service non-destructive residual stress measurements. The importance of having accurate residual stress information and its use in the probabilistic design and life management process is illustrated on several examples. A linkage with several ongoing industry R&D programs is discussed.
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Gopinathrao, N., C. Mabilat, S. Alizadeh, D. Jackson, and R. Clarkson. "Conjugate Heat Transfer Study of a Spin Pit Rig: Application to the Lifing of HP Turbine Disc Firtrees." In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-51294.
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Structural life and durability of gas turbine engine discs and blade firtree has always been a key design issue for designers and technologists. This is particularly important for gas turbine components which operate at elevated temperatures under high loads. The testing for these components need to be undertaken at operating conditions, particularly when Low Cycle Fatigue (LCF) lives of components are evaluated. The spin pit and biaxial rig tests, the former of which is the concern of this study, are used in the aero gas turbine industry for the lifing analysis of these critical engine parts. In this study a three dimensional conjugate heat transfer analysis of the spin pit rig with the HP turbine disc and blade assembly for a large turbofan engine has been performed. The scope of the Computational Fluid Dynamics (CFD) analysis has allowed a detailed understanding of the flow and thermal field within the domain to be obtained. Flow within the rig was found to be complex, with multiple flow mechanisms simultaneously at play in several distinct areas of the solution domain. All heat transfer processes, radiation, convection and conduction were found to be important in the overall heat. Radiation heat transfer was found to be dominant in terms of temperature levels achieved in components, whilst convection heat transfer majorly influenced temperature gradients in solids. The appropriate capturing of flow leakages in the rig proved to have a significant impact on rig performance and component thermal fields. The component temperatures predicted by the tuned CFD model compared well against thermocouple measurements and predictions of the conjugate CFD analyses were directly used as boundary conditions in follow-on stress analyses for lifing purposes. The methodology adopted has resulted in a very satisfactory outcome on declared disk life. It is understood that this is the first time where a full conjugate heat transfer CFD study of the spin pit rig without any separate thermal analyses, has been applied directly to the lifing of HP disc firtree and the eventual engine certification, in the aero gas turbine industry.
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Mabilat, C., S. Alizadeh, D. Jackson, and R. Clarson. "Conjugate Heat Transfer Study of a Biaxial Rig: Application to the Lifing of HP Turbine Disc Firtrees." In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-51297.
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A full conjugate heat transfer Computational Fluid Dynamics (CFD) study of a Biaxial rig enclosure used for the lifing of the high pressure turbine disc firtrees of a large turbofan engine has been undertaken. Initial rig tests had demonstrated challenges associated with test repeatability and unexpected thermal gradients in some components. The detailed CFD analysis was used to gain an appropriate understanding of the overall heat balance for the assembly, requiring all three modes of heat transfer as well as the fluid dynamics about the disc-blade components. Moreover the detailed modelling methodology presented for the twin short wave infrared emitters allowed the balance of radiation to convection heat transfer from the heaters, essential to the whole study, to be appropriately captured. It was observed that radiation setup the bulk assembly temperature levels (> 900K). Convection heat transfer very much influenced component temperature gradients (10K for disc front-to-back surfaces and >80K for blade front-to-back surfaces). The gap sizes between the assembly and cooling blocks associated with rig setup had a strong influence on the convection currents and flow structures about the assembly and were an important factor in test repeatability. Strong cooler inflows were entrained under the blades, which in the tests had to be compensated by asymmetric top-to-bottom heater power setting of 1.5–2 folds. Once appropriate thermal operating conditions of the assembly were achieved in the tests, the model was tuned to achieve a satisfactory match against the more reliable test thermocouple temperatures, to about -/+10K for the most important locations. Thereafter the model component thermal field was used for follow-on stress analysis, required in critical component lifing and eventual engine certification. This circumvented the need for separate thermal modelling and provided efficient utilization of man-time resource.
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Hasselqvist, Magnus. "TMF Crack Initiation Lifing of Austenitic Carbide Precipitating Alloys." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-54333.
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Recent work within DDIT has shown that Ni base superalloys like HAYNES230, Co base superalloys like HAYNES188, super stainless steels like HAYNES HR-120, and stainless steels like 253MA are similar from a materials modelling point of view. They are austenitic, delivered solutioned, and precipitate secondary carbides and other brittle phases in service and during cyclic tests at elevated temperature. These new phases result in a significantly reduced RT ductility, while the high temperature ductility is at most moderately reduced. Therefore, TMF cycles, which repeatedly go down to low temperatures, see an embrittled alloy whereas LCF tests at Tmax (in the TMF cycle) do not. This suggests that the classical use of LCF data at Tmax might given non-conservative life estimates. Literature studies and materials testing have confirmed that TMF data may be well below LCF data at Tmax verifying the non-conservatism of the classical methodology. Furthermore, the cyclic life tends to decrease with decreasing Tmin in TMF tests, and IP TMF is usually more detrimental than OP TMF due to creep-fatigue interaction. While standard TMF tests are closer to reality than LCF tests, we are still not certain that they capture all detrimental effects under component cycling, and are running additional, carefully planned, TMF tests on aged specimen at low Tmin values to improve the analysis. More tests, especially biaxial IP TMF tests, will eventually be needed to get a comprehensive picture. A new TMF data backed model has, however, already shown a higher precision when compared with service experience than the classical creep-fatigue methodology which is calibrated with LCF data at Tmax. Further testing and analysis will enable us to refine the TMF model and extend it to additional ACP alloys. The main input to the TMF model is the stabilised inelastic strain range, as calculated by the constitutive model described in an earlier ASME Turbo paper, GT2002-30659.