Volume 9B: Structures and Dynamics — Fatigue, Fracture, and Life Prediction; Probabilistic Methods; Rotordynamics; Structural Mechanics and Vibration最新文献

{"title":"Experimental and Numerical Investigation of High-Temperature Multi-Axial Fatigue","authors":"Harish Ramesh Babu, M. Böcker, M. Raddatz, S. Henkel, H. Biermann, U. Gampe","doi":"10.1115/gt2021-58959","DOIUrl":"https://doi.org/10.1115/gt2021-58959","url":null,"abstract":"Gas turbines and aircraft engines are dominated by cyclic operating modes with fatigue-related loads. This may result in the acceleration of damage development on the components. Critical components of turbine blades and discs are exposed to cyclic thermal and mechanical multi-axial fatigue. In the current work, planar-biaxial Low-Cycle-Fatigue (LCF) tests are conducted using cruciform specimens at different test temperatures. The influence on the deformation and lifetime behaviour of the nickel-base disk alloy Inconel 718 is investigated at selected cyclic proportional loading cases, namely shear and equi-biaxial. The calculation of the stress and strain distribution of the cruciform specimens from the experimental data is difficult to obtain due to complex geometry and temperature gradients. Therefore, there is a need for Finite Element (FE) Simulations. A viscoplastic material model is considered to simulate the material behaviour subjected to uniaxial and the selected planar-biaxial loading conditions. At first, uniaxial simulation results are compared with the uniaxial experiment results for both batches of IN718. Then, the same material parameters are used for simulating the biaxial loading cases. The prediction of FE simulation results is in good agreement with the experimental LCF test for both shear and equi-biaxial loadings. The equivalent stress amplitude results of the biaxial simulation are compared with the uniaxial results. Furthermore, the lifetime is calculated based on the stabilized cycle from the simulation and by using Crossland and Sines multi-axial stress-based approaches. The Crossland model predicts fatigue life significantly better than the Sines model. Finally, the simulated lifetime results are compared with the experimental lifetime.","PeriodicalId":143309,"journal":{"name":"Volume 9B: Structures and Dynamics — Fatigue, Fracture, and Life Prediction; Probabilistic Methods; Rotordynamics; Structural Mechanics and Vibration","volume":"2012 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128586785","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Topological Optimization of Piezoelectric Transducers for Vibration Reduction of Bladed Disks","authors":"Yubo Fan, H. Y. Ma, Yaguang Wu, Lin Li, K. Tian, Z. Zhao","doi":"10.1115/gt2021-59461","DOIUrl":"https://doi.org/10.1115/gt2021-59461","url":null,"abstract":"\u0000 In this work, we develop a numerical method to determine the best distribution of piezoelectric materials on a given bladed disk, so as to minimize the added mass of shunted piezoelectric dampers. There is no constrain on the shape of piezoelectric materials, and only the overall mass is limited. The method can be applied to a single mode or several modes from the same or different modal groups. The method is based on the fact that the modal damping is solely determined by the modal electromechanical coupling factor (MEMCF) which is related to the modal stress field and the geometric of the piezoelectric materials only. A linear weighting of stress components is proposed as the criterion to determine the priority of locations for piezoelectric materials. The piezoelectric materials are introduced to the FE model by modifying the type and materials parameters of elements if they are embedded to the bladed disks; or by creating an additional layers of elements if they are bonded to the bladed disks. Details for considering multiple modes, handling polarization direction and electrode connection are also presented. The proposed procedure is applied to an empirical bladed disk with NASA-ROTOR37 profile. Results show that 12% damping ratio can be achieved for multiple modes simultaneously, if we locate piezoelectric materials on the blade with 10% added mass. When locate the piezoelectric materials on the disk and the added mass is only 5%, up to 13% modal damping ratio for the disk dominant modes can be achieved.","PeriodicalId":143309,"journal":{"name":"Volume 9B: Structures and Dynamics — Fatigue, Fracture, and Life Prediction; Probabilistic Methods; Rotordynamics; Structural Mechanics and Vibration","volume":"224 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120942004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effective Evaluation of Rotordynamic Performance Within Rotor-Bearing System Design Bounds","authors":"Zhusan Luo, Carl L. Schwarz","doi":"10.1115/gt2021-60301","DOIUrl":"https://doi.org/10.1115/gt2021-60301","url":null,"abstract":"\u0000 This paper presents a study on the effective evaluation of rotordynamic performance for multiple analysis cases within rotor-bearing system design bounds. The variations in rotordynamic design variables and operating conditions are usually considered in a rotordynamic analysis. This can provide useful information about the current design, potential for modification, and the capability of off-design operation. Typical design bounds of a tilting pad journal bearing are discussed to show the complexity of multiple design cases and a demand for a method to postprocess the analytical results.\u0000 Rotordynamic performance is conventionally assessed by examining undamped critical speed maps, damped modes, stability, and unbalance responses. Evaluating rotordynamic performance for multiple cases is a tedious task for both rotordynamicists and reviewers. A new approach is studied to effectively extract, present and evaluate analytical results. A theoretical study shows the analytical results can be synthesized to determine key performance parameters. It is proposed that the amplification factors at critical speeds can be converted to equivalent logarithmic decrements. Based on the two studies, a new rotordynamic performance diagram is created to present damped modes, critical speeds and relevant acceptance criteria. With this informative diagram, one can quickly and effectively evaluate the acceptability and robustness of multiple design cases. This diagram can also convey the trends of key performance parameters, comparisons between cases, and the sensitivities of key performance parameters to design variables more clearly and concisely. This synthesizing approach and the rotordynamic performance diagram may be useful in modifying an existing design, determining a proper off-design operation range, and investigating rotordynamic issues.","PeriodicalId":143309,"journal":{"name":"Volume 9B: Structures and Dynamics — Fatigue, Fracture, and Life Prediction; Probabilistic Methods; Rotordynamics; Structural Mechanics and Vibration","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116296901","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rubbing Of a Bladed Disk Considering Coriolis Effect: A Reduced Model Based on Complex Modal Analysis","authors":"Da-wei Chen, Jiguo Zhang, Jiaguangyi Xiao, Yong Chen","doi":"10.1115/gt2021-59008","DOIUrl":"https://doi.org/10.1115/gt2021-59008","url":null,"abstract":"\u0000 Due to the high demands of aerodynamic efficiency in modern aero-engines, tip clearances between blades and casings are becoming smaller. This increases the possibility of rubbing between rotating bladed disks and their surrounding casings. Rotational effects exhibit increased significance in the latest generation of fans, which currently have relatively long blade and elongated cantilevered shaft. Previous studies on the rotor dynamics during rub impact have mainly focused on simplified models. However, it is necessary to take both realistic blades and Coriolis effect into account. Based on an open-source bladed disk model, the impact of the Coriolis effect on rub-induced responses is investigated. A two-step model reduction method is adopted by combining the fixed interface reduction and cyclic symmetry reduction. Both centrifugal and gyroscopic effects are incorporated in the numerical model. Complex modal analysis, based on classical Craig-Bampton method, is used to improve the model reduction of the gyroscopic system. The response of a flexible bladed disk to a simplified pulse rubbing force is investigated. With the time and space Fourier transform, a Coriolis-induced frequency split is observed on some nodal diameter lines, which indicates the significance of the Coriolis effect in rub-induced responses. A complex model reduction has been successfully applied to the rub-impact problem of cyclic symmetric bladed disks. Compared with the classical model reduction, the numerical results obtained by complex modal analysis are more reasonable. This lays a solid foundation for further rub-impact research considering rotor dynamics.","PeriodicalId":143309,"journal":{"name":"Volume 9B: Structures and Dynamics — Fatigue, Fracture, and Life Prediction; Probabilistic Methods; Rotordynamics; Structural Mechanics and Vibration","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132291535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"HCF Optimization of a High Speed Variable Geometry Turbine","authors":"A. Simpson, S. Kim, Jong-Yeol Park, Seong-Kon Kwon, Sejong Yoo","doi":"10.1115/gt2021-59626","DOIUrl":"https://doi.org/10.1115/gt2021-59626","url":null,"abstract":"\u0000 This paper describes the structural optimization of a high speed, 35mm tip diameter radial turbine wheel in a Variable Geometry Turbine (VGT) system, subjected to the wide range of aerodynamic loads experienced during the full operating cycle. VGTs exhibit a wide range of unsteady flow features, which vary as the nozzle vanes rotate through different positions during operation, as do the magnitudes and frequencies of the resulting pressure fluctuations experienced by the downstream turbine blades. The turbine wheel typically passes through a number of blade natural frequencies over their operating cycle, and there are a number of potential conditions where these unsteady aerodynamic loads can lead to resonant blade vibration. The focus of this work is on the development of a pragmatic design approach to improve the structural characteristics of a radial turbine blade with respect to High Cycle Fatigue (HCF), informed by detailed time-accurate Computational Fluid Dynamics (CFD) prediction of the unsteady pressure loads, coupled with FE vibration analysis to quantify the resulting blade vibration magnitudes. Unsteady CFD simulations are performed to determine the time-accurate pressure loads on the blades, and the results are used as input to forced response analysis to determine the peak alternating stress amplitudes. The detailed analysis results are then used to guide a subsequent parametric study in order to investigate the influence of key geometric parameters on the structural performance of the blade, with the optimum design identified through the use of a Goodman Diagram. The results quantify the influence of both blade thickness distribution and hub fillet details on the vibration characteristics of radial turbines.","PeriodicalId":143309,"journal":{"name":"Volume 9B: Structures and Dynamics — Fatigue, Fracture, and Life Prediction; Probabilistic Methods; Rotordynamics; Structural Mechanics and Vibration","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124821016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rotordynamic Evaluation of a Large High-Speed Rotor Equipped With Flexure Pivot Journal Bearings and Integral Squeeze Film Damper","authors":"G. Vannini, A. Innocenti, Filippo Cangioli, Kim Jongsoo","doi":"10.1115/gt2021-58800","DOIUrl":"https://doi.org/10.1115/gt2021-58800","url":null,"abstract":"\u0000 The current oil and gas market trends lead the compressor OEMs to increase the rotational speed and maximize the efficiency given a target power output. Especially when applied to large process gas centrifugal compressors, characterized by high-flexibility ratio, the achievement of these targets pushes the rotordynamic design towards its limit in terms of API requirements.\u0000 Tiling pad journal bearings (TPJBs) are commonly adopted in high-speed applications for their inherent stability characteristics that permit to ensure the rotordynamic stability and eliminate self-induced sub-synchronous vibrations.\u0000 The experimental activities subject of this paper aim to assess, for the first time, the rotordynamic behaviour of a large dummy rotor (6 meter long and total weight of 8 tons) equipped with Flexure Pivot tilting-pad journal bearing and Integral squeeze film damper (ISFD). This system level testing program has been performed in the Authors’ high-speed balancing bunker properly equipped with special instrumentation such as: flow meters and pad temperature probes to monitor journal bearing behaviour, displacement probes to measure rotor vibrations relative to the bearings.\u0000 The main objective of the experimental activity is the full assessment of the rotordynamic response and the selection of the best configuration to target the design requirements (e.g. FPJB and “Active ISFD” vs. FPJB and “Inactive ISFD”).","PeriodicalId":143309,"journal":{"name":"Volume 9B: Structures and Dynamics — Fatigue, Fracture, and Life Prediction; Probabilistic Methods; Rotordynamics; Structural Mechanics and Vibration","volume":"87 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125507211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Method for Establishing the Central Crack Stress Intensity Factor Database for Probabilistic Risk Assessment Based on the Universal Weight Function","authors":"Tongge Xu, S. Ding, Hui-li Zhou, Guo Li","doi":"10.1115/gt2021-58727","DOIUrl":"https://doi.org/10.1115/gt2021-58727","url":null,"abstract":"\u0000 Probabilistic failure risk assessment is becoming important in the field of airworthiness. In the fracture mechanics module of probabilistic failure risk assessment, it is important to efficiently and accurately calculate the stress intensity factors (SIFs). At present, the weight function method (WFM), especially the universal weight functions (UWFs) proposed by Glinka and Shen, has been adopted to calculate SIFs with high accuracy and computational efficiency. However, the concrete coefficients in the universal weight functions remain unknown, and the rules of the geometry parameters and these coefficients have not yet been summarized, which hinders their subsequent use. In this article, the specific type of embedded crack-central crack is under discussion, and the derivation of the UWF is introduced. The response surface method (RSM), as a means of database establishment, is used to construct the relations between the geometric parameters including the length and thickness of a three-dimensional finite plate and coefficients in the UWF. The errors of the SIF calculation between the UWF and finite element results are less than 2 MPa m within a certain range. For the evaluation of the boundary effect on central cracks, the difference between finite and infinite plates is discussed. In addition, considering the complexity of the general off-centre crack, an approximation method has been proposed to transform the off-centre crack to the central crack. The results show that the method can be applied with high precision in specific situations and stresses the necessity of follow-up research on general off-centre cracks.","PeriodicalId":143309,"journal":{"name":"Volume 9B: Structures and Dynamics — Fatigue, Fracture, and Life Prediction; Probabilistic Methods; Rotordynamics; Structural Mechanics and Vibration","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128394890","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Searching for the Optimal Arrangement of Mistuned Blades Based on Solving the Traveling Salesman Problem for Simple Mass-Spring Linear System","authors":"N. Serebriakov, A. Selivanov","doi":"10.1115/gt2021-59927","DOIUrl":"https://doi.org/10.1115/gt2021-59927","url":null,"abstract":"\u0000 The article presents an approach to finding the optimal arrangement of blades in a bladed disk based on solving the traveling salesman problem using the ant colony algorithm. The solution to the problem is presented for an equivalent model of the bladed disk. The mistuning parameters are assumed as known — for example, from the data of geometric measurements for each blade from the set used for assembling the bladed disk — considering the influence of the rotation on the investigated resonance mode.\u0000 Approaches have already been published for the construction of equivalent models and the use of combinatorial optimization methods, including solving the traveling salesman problem, to find the optimal arrangement of the blades. Therefore, this article focuses on demonstrating a simple program implementation of this method.\u0000 This approach allows a quick assessment of the effect of the blade assembly in the bladed disk on the amplitudes of alternating stresses. It even considers several restarts of the algorithm to determine other possible configurations of the system.","PeriodicalId":143309,"journal":{"name":"Volume 9B: Structures and Dynamics — Fatigue, Fracture, and Life Prediction; Probabilistic Methods; Rotordynamics; Structural Mechanics and Vibration","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133015299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Surrogate Models for the Prediction of Damping Ratios in Coupled Acoustoelastic Rotor-Cavity Systems","authors":"Christoph Heinrich, Tina Unglaube, B. Beirow, D. Brillert, Klaus Steff, N. Petry","doi":"10.1115/gt2021-58835","DOIUrl":"https://doi.org/10.1115/gt2021-58835","url":null,"abstract":"\u0000 Centrifugal compressors are versatile machines that many industries employ for a wide range of different applications, including the production of highly compressed gases. During the last decades, comprehensive research was conducted on the impact of high-pressure operating conditions on the vibrational behavior of radial compressors. In various studies, acoustic modes building up in the side cavities were found to be a potential source of high cycle fatigue. Nowadays, it is well-known that an increase in gas pressure levels leads to a more pronounced fluid-structure interaction between the side cavities and the impeller resulting in a frequency shift of the acoustic and structural modes. In a recently published paper, the authors presented a generalized model which can predict this behavior. As it is not always possible to avoid operating close to or accelerating through a resonance, it is crucial to know the damping present within the system. Currently, only a few publications concentrate on the damping of radial impellers. Therefore, the authors present measurement data acquired from a test rig at the University of Duisburg-Essen, which reveals the damping behavior of a disk under varying operating conditions. Two surrogate models are proposed to predict the identified damping behavior. The first one is based solely on a one-dimensional piston model and the second approach uses an enhanced version of the generalized method. Finally, the measurement data is used to validate both surrogate systems.","PeriodicalId":143309,"journal":{"name":"Volume 9B: Structures and Dynamics — Fatigue, Fracture, and Life Prediction; Probabilistic Methods; Rotordynamics; Structural Mechanics and Vibration","volume":"90 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125579181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Method of Coupled Vibration Control for Dual Rotor System With Inter-Shaft Bearing","authors":"Yanhong Ma, Chenglong Shi, Bo Sun, Jie Hong","doi":"10.1115/gt2021-60162","DOIUrl":"https://doi.org/10.1115/gt2021-60162","url":null,"abstract":"\u0000 Structural layout scheme of dual rotor system with inter-shaft bearing plays an important role in reducing the bearing frame and structure weight of areo-engine. This kind of scheme is often used in the design of high thrust-weight ratio turbofan engine. However, the inter-shaft bearing will cause the direct interaction of the force and displacement between the high and low pressure rotor systems, contributing to the coupling of the dynamic characteristics of two rotor systems. The coupling may eventually lead to the failure of the rotor displacement control, loss of the robustness of the connection structure or excessive dynamic load of the bearing. The main purpose of this paper is to, firstly study and quantitatively evaluate the coupling characteristics of the dual rotor system, secondly obtain the correlation between the structural feature parameters such as the position of the inter-shaft bearing and the coupling vibration or interactive excitation characteristics of the system, finally propose the coupling vibration control method of dual rotor system.\u0000 The dynamic model of dual rotor system with inter-shaft bearing is established. The modal frequencies and modes of dual rotor system with or without coupling are analyzed and compared. The results illustrate the complexity of coupled vibration of high pressure and low pressure rotors. Then modal coupling characteristics evaluation parameter of dual rotor system based on energy distribution relationship is proposed. Using the coupling factor defined, the correlation between the inter-shaft bearing support feature and the modal coupling characteristics is discussed. The results show that, placing the inter-shaft bearing near the mass center of low pressure turbine can effectively restrain the mode coupling, meanwhile the proportion of bearing strain energy can also reflect the mode coupling characteristics of dual rotor system to a certain extent. Then a method of controlling the response coupled vibration of dual rotor system with inter-shaft bearing, based on the principle of mode superposition, is proposed. An example verifies the method can control the response coupling vibration of dual rotor system in wide speed range and under complex excitation conditions.","PeriodicalId":143309,"journal":{"name":"Volume 9B: Structures and Dynamics — Fatigue, Fracture, and Life Prediction; Probabilistic Methods; Rotordynamics; Structural Mechanics and Vibration","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123965377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}