bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Probabilistic Model for Forging Flaw Crack Nucleation Processes for Heavy Duty Gas Turbine Rotor Operations
Authors: Radaelli Francesco , Amann Christian , Aydin Ali , Varfolomeev Igor , Gumbsch Peter , Kadau Kai 
Published: November 2022

Abstract
We present a probabilistic model for quantifying the number of load cycles for nucleation of forging flaws — for a 3.5NiCrMoV high strength low alloy rotor steel — into a crack under gas turbine operating conditions. The model correlates low cycle fatigue data, ultrasonic testing indication data, flaw morphology, and type with the nucleation process. This paper is the third of a series of publications presenting this modeling approach progressively. It focuses on the effect of temperature variation on the nucleation life of forging flaws. We quantified the number of cycles to crack nucleation was for specimens that included forging flaws at elevated temperatures. Flaws of different sizes and shapes are effectively described at respective temperature and stress levels by either an ellipsoidal finite element model or an analytical area-based model. A local probabilistic low-cycle fatigue model analyzes the resulting stress distributions accounting for statistical size effects. Via Maximum Likelihood Estimation of these probabilistic low cycle fatigue results, a probabilistic model for crack nucleation of forging flaws is obtained. This proposed probabilistic model is based on experimental data for realistic heavy duty gas turbine rotor temperature and stress conditions. It can be utilized in the energy sector for component life time quantification. Our suggested approach can support component assessment under flexible gas turbines operation conditions driven by increased availability of intermittent renewable energy sources.
The Impact of Mistuning and Material Damping on Bladed Disks of Similar Geometries
Authors: Nix Jarred A. , Rodriguez Andres M. , Kauffman Jeffrey L. 
Published: November 2022

Abstract
As advances in turbomachinery manufacturing have continued to improve, integrally bladed rotors or blisks have become more prevalent due to the aerodynamic improvements that can be derived from those designs. Despite increases in efficiency, these blisks are prone to significantly higher vibrations due to the removal of friction damping that naturally occurs at the interfaces between each blade and the disk. Mistuning is characterized by a lack of symmetry due to the inevitable imperfections and non-homogeneity that arise across blades from manufacturing inaccuracies and use. Here we report on the frequency response functions of multiple tuned and mistuned academic blisks. The various blisks also exhibit different damping levels based on the material and thickness. These blisks were tested experimentally to determine how the different damping would affect the system response.
Stability Analysis of an Industrial Blade Accounting for a Blade-Tip/Casing Nonlinear Interface
Authors: Colaïtis Yann , Batailly Alain 
Published: November 2022

Abstract
This paper investigates the local stability analysis of periodic solutions corresponding to the nonlinear vibration response of an industrial compressor blade, NASA rotor 37, on which are applied different types of nonlinearities. These solutions are obtained using a harmonic balance method-based approach presented in a previous paper. It accounts for unilateral contact and dry friction of the rotating blade against a rigid casing through a regularized penalty law. A Lanczos filtering technique is also employed to mitigate spurious oscillations related to the Gibbs phenomenon thus enhancing the robustness of the solver. In addition, a component mode synthesis technique is used to reduce the dimension of the numerical model. Stability assessment of the computed solutions relies on Floquet theory. It is performed through the computation of the monodromy matrix as well as Hill’s method. Both methodologies are applied and thoroughly compared as the severity of the nonlinearity is gradually increased from a cubic spring to 3D contact conditions on a deformed casing. While the presented results underline the applicability of both stability assessment methodologies for all types of nonlinearities, they also put forward the much higher computational effort required when computing the monodromy matrix. Indeed, it is shown that Hill’s method yields converged results for significantly lower values of both the number of retained harmonics and the considered number of time steps thus making it a far more efficient method when dealing with industrial models. It is also underlined that the presented results are in excellent agreement with reference solution points obtained with time domain solution methods. Specific implementation tweaks that were found to be of critical importance in order to efficiently assess the stability of computed solutions are also detailed in order to provide a comprehensive view of the challenges inherent to such numerical developments.
Probabilistic Assessment of Gas Turbine Compressor Blade HCF Life
Authors: Meng Zhiqiang , Krishnababu Senthil , Jackson Simon , Sjödin Björn 
Published: November 2022

Abstract
This paper uses a novel and practical probabilistic approach to assess the risk of a compressor blade HCF failure in the gas turbine. For a specific design case, the tip timing tests for a newly designed gas turbine compressor blade successfully passed HCF design criteria during engine operation when operated over a wide speed range. However, on a later test high amplitude responses were seen under a VGV configuration which was different from that used during normal operation.
Firstly, the gas turbine operational data and blade bench test data are used by the probabilistic assessment to identify the characteristics of the HCF problem. The resonance counting is carried out by the Monte Carlo simulations. The simulation indicates that the HCF endurance limit for the alternating stress is required to be satisfied for this blade.
Secondly, the material test data, blade tip timing data and finite element (FE) results are used to build a HCF endurance stress probabilistic model, following which the probability of blade HCF failure was estimated. The Monte Carlo simulations are used for the probabilistic model. The simulation results show that the probability of HCF failure per blade and the risk of HCF failure for any blade of the stage are very small and acceptable.
Experimental Modal Analysis of a Full-Scale Rotating Fan
Authors: Jorajuria Corentin , Gibert Claude , Thouverez Fabrice , Esteves Cécile 
Published: November 2022

Abstract
Experimental modal analysis of a full-scale aeronautic fan is performed at design rotating speed and under vacuum conditions. The composite woven fan is excited through embedded piezoelectric actuators and the dynamic response of the system is measured with strain gauges. Presented experiments achieve high quality data measurements of forced responses thanks to a strict control of experimental conditions, an extended instrumentation of the fan and a careful testing method. The study focuses on the two first bending mode families with nodal diameters. The modal testing of the system is performed using frequency stepped sine excitations over a close range around investigated resonances and using travelling wave excitations allowing to investigate specific nodal diameter modes in each family. The forced response measurements are used to estimate the frequency response functions of the rotating fan under different experimental parameters. In particular, the first mode family exhibits a higher modal density which is challenging for modal parameters estimations. Used frequency domain modal identification techniques are presented and adapted to the fitting of frequency response functions. At the end, these techniques are applied to investigate sensitivity of extracted natural frequencies and modal damping ratios with respect to different parameters such as rotational speed, excitation level and nodal diameter content of the excitation pattern.
Research on the Nonlinear Behavior of the Turbine Rotor Assembled by Rabbet Joints
Authors: Han Zhuoluo , Li Yifeng , Wang Yongfeng , Hong Jie 
Published: November 2022

Abstract
Double-stage turbine rotor assembled by rabbet joints is widely used in aero-engine, the mechanical properties of which depends highly on the compression state of the joints’ contact interfaces. The accumulated damages during operation lead to the deterioration of the contact state, which could cause the sliding or partial separation on the interface, and will affect the dynamic characteristics of the rotor system. In this paper, the static mechanical properties, mainly angular stiffness, were studied using the static contact Finite Element Analysis (FEA) method to reveal the nonlinear variation in different conditions. One dynamic model of the rotor with rabbet joints was built based on the Lagrange equations, which was numerically solved by the Runge-Kutta method for the dynamic response of the rotor with nonlinear stiffness. The results show that the rabbet joints stiffness nonlinearity will decrease the critical speed of the flexural mode and cause amplitude sudden jump phenomena during acceleration or deceleration. Moreover, the chaotic motion and impact dynamic response may appear in the vicinity of the flexural mode critical speed. The axial preload is an essential influencing factor affecting the nonlinear response characteristics of the flexural mode, and an adequate preload will minimize or prevent the effects of stiffness nonlinearity during operation.
Efficient Forced Response Analysis for Asymmetric Vane Spacing
Authors: Geihe Benedict , Frey Christian , Ashcroft Graham 
Published: November 2022

Abstract
In the context of forced response analysis, we present a computationally efficient method to capture the effect of inflow distortions caused by intentional variation of cyclic vane spacing. Applying such configurations is a typical mitigation strategy when unforeseen critical blade vibrations occur due to synchronous excitation by wakes of an upstream row. Altering the circumferential distance in a section-wise pattern effectively distributes the fluctuations among several engine order frequencies, thereby reducing their amplitudes. The rotationally asymmetric configurations initially call for multi-passage simulations. We show that the circumferential spectrum can be well approximated using single passage results only, without significant additional costs. Our approach is based on an analytically computed Fourier transform of a synthesis functional. For validation, we consider a turbine test case with transonic and subsonic operating points. We determine the reduction in amplitude of dominant inflow modes for an explicitly constructed instance with asymmetric vane spacing and compare our analytical predictions to full-wheel simulations. Furthermore we assess the impact on aerodynamic excitation of downstream rotor blades using both a frequency and a time domain solver.
Measured and Predicted Temperature Differentials Within a Rotor at a Tilting-Pad-Journal Bearing Associated With the Morton Effect
Authors: Kulhanek Chris D. , Cunningham Seth , Delgado Hector A. , Moore Jeff , Hollingsworth Justin R. 
Published: November 2022

Abstract
The current work shows the implementation of a high-speed turbomachinery test rig to measure vibration and internal shaft temperature differentials at a journal bearing for a rotor system designed to induce the Morton effect rotordynamic phenomenon. The vibration and shaft temperature measurements are compared to predictions using an analytical code described by Tong and Palazzolo [6,7]. An existing high-speed test rig was adapted, including a new rotor with six equally-spaced RTDs embedded at the journal bearing centerline. The rotor configuration included an overhung rotor design with a 58 mm (2.3 inch) diameter, 5-pad tilting-pad journal bearing. The in-rotor temperature measurements were conditioned using a custom on-board amplifier and extracted with a high-speed commercial slip ring. Test conditions included various levels of unbalance, bearing oil inlet temperature, and operating speed. Test measurements show that the temperature differential across the shaft is dependent upon operating speed, as well as vibration amplitude. Operating conditions included rotational speeds up to 19.5 krpm and vibration levels approaching the magnitude of the bearing clearance. Testing near the rotor first lateral natural frequency (or critical speed) with a high level of initial unbalance resulted in the highest temperature differentials across the shaft of approximately 11 °C (20 °F) plus. Vibration measurements show hysteresis in the synchronous vibration response in the Bode and polar plots. This measured vibration hysteresis is consistent with the rotor hot spot or temperature differential changing the unbalance level of the rotor. Overall, both the test measurements and predictions show notable temperature differentials and hysteresis behavior in the vibration response that are believed to be associated with the Morton Effect. These conditions are considered precursors to the spiral vibration or fully developed synchronous instability typically associated with the Morton Effect.
Mechanical Behaviour of Variable Nozzle Guide Vane Systems Based on Full-Scale Testing
Authors: Macoretta Giuseppe , Monelli Bernardo Disma , Neri Paolo , Bucciarelli Federico , Giusti Enrico , Checcacci Damaso , Maffulli Gianfranco 
Published: November 2022

Abstract
A full-scale test bench for the analysis of frictional and modal behavior of Nozzle Guide Vanes (NGV) is an advanced tool enabling high design accuracy for these components equipped in an increasing number of turboexpanders. This sub-assembly is a key feature enabling operational flexibility for the expander. Great attention must be paid during the NGV’s design to the natural frequencies of its kinematic chain, which are influenced by internal clearances and by friction. In this paper the results of a testing campaign performed on an NGV assembly employing actual blade geometry are presented together with details concerning the test bench commissioning and set-up procedure. The testing campaign involves three different combinations of blade orientation and pre-load corresponding to typical design conditions of the expander. In addition, two different bushing clearances values corresponding to worn out conditions were investigated. The measurements of the global friction coefficient based on actuator force detection are summarized. After that, the reconstruction of mode shapes based on experimental modal analysis is explained. The results highlight the importance of loading conditions on the actual value of friction force and their influence on blade natural frequencies. The testing campaign was used to properly validate Finite Element Models to be used for further investigations.
Automated Data-Driven Physics Discovery of Turbine Component Damage
Authors: Zhang Sheng , Jacobs Ryan , Ghosh Sayan , Kulkarni Ambarish , Wang Liping 
Published: November 2022

Abstract
We propose an automated physics discovery algorithm for turbine component damage modeling. Our algorithm utilizes operational data of a mechanical component and discovers an interpretable symbolic formula that describes the physics. We illustrate our algorithm through two numerical examples and demonstrate that the discovered formulas can predict the future damage accurately. Our framework is flexible and easily applicable to all areas of science and engineering. With cutting-edge machine learning tools, researchers can simply input the experimental data and then the physics formulas are printed out automatically. The application of this new algorithm may reduce the time spent on research and development of physics models significantly, while achieving almost the best accuracy in prediction.
Forced Response System Identification of Full Aero-Engine Rotordynamic Systems for Prognostics and Diagnostics
Authors: Hur I. , Spakovszky Z. 
Published: November 2022

Abstract
A first-of-its-kind forced-response system identification approach is introduced to measure rotordynamic damping of shaft modes in a full gas turbine aero-engine. The approach involves forced-response modal analysis in which the rotordynamic system is excited with an external shaker and engine modal characteristics are extracted from rotor shaft response signals. A reduced-order modeling framework capturing full-engine dynamics and coupling between rotor shafts and support static structure was developed and implemented in a Pratt & Whitney Canada PW615 Turbofan engine. The framework was used to guide the design of forced-response system identification experiments. The design study shows that two orthogonal shakers are required to excite both forward- and backward-whirling shaft modes and that excessive forcing amplitudes that produce whirl over 0.4 of journal eccentricity ratio can yield up to 12% lower response magnitudes due to non-linear bearing characteristics. A statistical analysis of virtual experiments under real engine operating conditions demonstrates feasibility and robustness of the approach, measuring rotordynamic damping for key shaft modes with an uncertainty of up to 15%. General applicability of the approach with similar error levels is suggested for multi-spool multi-frame aero-engine architectures. Guidelines for experimental setup, data acquisition and processing are established for full-engine forced-response system identification experiments. The new capability shows promise in supporting aero-engine diagnostics and prognostics to improve the life cycle operation of commercial and military engines.
TRIM35-mediated degradation of nuclear PKM2 destabilizes GATA4/6 and induces P53 in cardiomyocytes to promote heart failure
Authors: Lorenzana-Carrillo Maria Areli , Gopal Keshav , Byrne Nikole J. , Tejay Saymon , Saleme Bruno , Das Subhash K. , Zhang Yongneng , Haromy Alois , Eaton Farah , Mendiola Pla Michelle , Bowles Dawn E. , Dyck Jason R. B. , Ussher John R. , Michelakis Evangelos D. , Sutendra Gopinath 
Published: November 2022

Pyruvate kinase M2 (PKM2) is a glycolytic enzyme that translocates to the nucleus to regulate transcription factors in different tissues or pathologic states. Although studied extensively in cancer, its biological role in the heart remains unresolved. PKM1 is more abundant than the PKM2 isoform in cardiomyocytes, and thus, we speculated that PKM2 is not genetically redundant to PKM1 and may be critical in regulating cardiomyocyte-specific transcription factors important for cardiac survival. Here, we showed that nuclear PKM2 (
S37
P-PKM2) in cardiomyocytes interacts with prosurvival and proapoptotic transcription factors, including GATA4, GATA6, and P53. Cardiomyocyte-specific PKM2-deficient mice (
Pkm2
Mut Cre
+
) developed age-dependent dilated cardiac dysfunction and had decreased amounts of GATA4 and GATA6 (GATA4/6) but increased amounts of P53 compared to Control Cre
+
hearts. Nuclear PKM2 prevented caspase-1–dependent cleavage and degradation of GATA4/6 while also providing a molecular platform for MDM2-mediated reduction of P53. In a preclinical heart failure mouse model, nuclear PKM2 and GATA4/6 were decreased, whereas P53 was increased in cardiomyocytes. Loss of nuclear PKM2 was ubiquitination dependent and associated with the induction of the E3 ubiquitin ligase TRIM35. In mice, cardiomyocyte-specific TRIM35 overexpression resulted in decreased
S37
P-PKM2 and GATA4/6 along with increased P53 in cardiomyocytes compared to littermate controls and similar cardiac dysfunction to
Pkm2
Mut Cre
+
mice. In patients with dilated left ventricles, increase in TRIM35 was associated with decreased
S37
P-PKM2 and GATA4/6 and increased P53. This study supports a previously unrecognized role for PKM2 as a molecular platform that mediates cell signaling events essential for cardiac survival.
A tool to distinguish magmatic from secondarily recrystallized carbonatites—Calcite/apatite rare earth element partitioning
Authors: Sartori Gino , Galli Andrea , Weidendorfer Daniel , Schmidt Max W. 
Published: November 2022

Abstract
Crustal geochemical signatures in carbonatites may arise from carbon recycling through the mantle or from fluid-mediated interaction with the continental crust. To distinguish igneous from fluid-mediated processes, we experimentally determined rare earth element (REE) partitioning between calcite/melt and apatite/melt at subvolcanic emplacement conditions (1–2 kbar, 750–1000 °C). Our data allow modeling of calcite-apatite (Cc/Ap) partition coefficients (D), representing a new tool to bypass the previously required but largely unknown carbonatite melt composition. Experimentally determined magmatic calcite/apatite REE patterns are flat, as is ~0.75, and they show a slight U-shape that becomes more pronounced with temperature decreasing from 1000 to 750 °C. Application to texturally well-equilibrated natural Ca-carbonatites and calcite-bearing nephelinites shows that some calcite-apatite pairs follow this pattern and, hence, confirm the magmatic nature of the carbonates. values of other mineral pairs range from 10−2 to 10−3, which, together with a substantial light REE depletion in the calcite, is interpreted as fluid-mediated light REE removal during secondary calcite recrystallization. Calcite/apatite REE distributions are well suited to evaluate whether a carbonatite mineralogy is primary and magmatic or has been affected by secondary recrystallization. In this sense, our tool provides information about the sample's primary or secondary nature, which is essential when assigning isotopic crustal signatures (in Ca, C, or Sr) or REE patterns to related geologic processes.
Calcitic shells in the aragonite sea of the earliest Cambrian
Authors: Li Luoyang , Topper Timothy P. , Betts Marissa J. , Dorjnamjaa Dorj , Altanshagai Gundsambuu , Enkhbaatar Baktuyag , Li Guoxiang , Skovsted Christian B. 
Published: November 2022

Abstract
The initial acquisition of calcium carbonate polymorphs (aragonite and calcite) at the onset of skeletal biomineralization by disparate metazoans across the Ediacaran-Cambrian transition is thought to be directly influenced by Earth's seawater chemistry. It has been presumed that animal clades that first acquired mineralized skeletons during the so-called “aragonite sea” of the latest Ediacaran and earliest Cambrian (Terreneuvian) possessed aragonite or high-Mg calcite skeletons, while clades that arose in the subsequent “calcite sea” of Cambrian Series 2 acquired low-Mg calcite skeletons. Here, contrary to previous expectations, we document shells of one of the earliest helcionelloid molluscs from the basal Cambrian of southwestern Mongolia that are composed entirely of low-Mg calcite and formed during the Terreneuvian aragonite sea. The extraordinarily well-preserved Postacanthella shells have a simple prismatic microstructure identical to that of their modern low-Mg calcite molluscan relatives. High-resolution scanning electron microscope observations show that calcitic crystallites were originally encased within an intra- and interprismatic organic matrix scaffold preserved by aggregates of apatite during early diagenesis. This indicates that not all molluscan taxa during the early Cambrian produced aragonitic shells, weakening the direct link between carbonate skeletal mineralogy and ambient seawater chemistry during the early evolution of the phylum. Rather, our study suggests that skeletal mineralogy in Postacanthella was biologically controlled, possibly exerted by the associated prismatic organic matrix. The presence of calcite or aragonite mineralogy in different early Cambrian molluscan taxa indicates that the construction of calcium carbonate polymorphs at the time when skeletons first emerged may have been species dependent.