Model-Based Analysis of Friction-Induced Subsynchronous Whirl for a Rotor Contacting With Clearance Bearings Under Axial Load

2016 ◽  
Vol 138 (7) ◽  
Author(s):  
Matthew O. T. Cole ◽  
Lawrence Hawkins
Keyword(s):  
Axial Load ◽  
Coulomb Friction ◽  
Friction Forces ◽  
Root Finding ◽  
Model Based ◽  
Simple Physical Interpretation ◽  
Level Of Agreement ◽  
Model Based Analysis

For rotors supported by active magnetic bearings (AMBs), clearance bearings are commonly used to provide backup support under loss of AMB functionality. Test data from real machines shows that vibration during touchdown on backup bearings may involve steady forward whirling of the rotor with a subsynchronous frequency. This excitation is believed to be due to friction forces transmitted between the rotor and a bearing end-face under axial load. This paper proposes a new analytical approach to model and predict such friction-driven forward whirl behaviors. A set of constraint equations are derived that relate a circular whirl motion of arbitrary orbital speed to the frequency response functions for the rotor-housing structure. This model is coupled with an evaluation of Coulomb friction associated with slip between the rotor and the supporting end-face of a thrust bearing. The resulting equations can be used to compute a set of possible whirl motions via a root-finding procedure. A case study is undertaken for a 140 kW energy storage flywheel. Model-based predictions are compared with measured data from spin-down tests and show a good level of agreement. The study confirms the role of friction-related forces in driving forward-whirl response behaviors. It also highlights the key role of housing and machine support characteristics in response behavior. This influence is shown to be complex and not open to simple physical interpretation. Therefore, the proposed analytical method is seen as a useful tool to investigate this influence while avoiding the need for time consuming numerical simulations.

Model-Based Analysis of Friction-Induced Sub-Synchronous Whirl for a Rotor Contacting With Clearance Bearings Under Axial Load

2015 ◽  
Author(s):  
Matthew O. T. Cole ◽  
Lawrence Hawkins
Keyword(s):  
Axial Load ◽  
Coulomb Friction ◽  
Friction Forces ◽  
Root Finding ◽  
Model Based ◽  
Simple Physical Interpretation ◽  
Level Of Agreement ◽  
Model Based Analysis

For rotors supported by active magnetic bearings (AMBs), clearance bearings are commonly used to provide backup support under loss of AMB functionality. Test data from real machines shows that rotor vibration during touchdown on backup bearings may involve steady forward whirling at a sub-synchronous frequency. This excitation is believed to be due to friction forces transmitted between the rotor and a bearing end-face under axial load. This paper proposes a new analytical approach to model and predict such friction-driven forward whirl behaviors. A set of constraint equations are derived that relate a circular whirl motion of arbitrary orbital speed to the frequency response functions of the rotor-housing structure. This model is coupled with an evaluation of Coulomb friction associated with slip between the rotor and the supporting end-face of a thrust bearing. The resulting equations can be used to compute a set of possible whirl motions via a root-finding procedure. A case study is undertaken for a 140 kW energy storage flywheel. Model-based predictions are compared with measured data from spin-down tests and show a good level of agreement. The study confirms the role of friction-related forces in driving forward-whirl response behaviors. It also highlights the key role of housing and machine support characteristics in response behavior. This influence is shown to be complex and not open to simple physical interpretation. Therefore, the proposed analytical method is seen as a useful tool to investigate this influence while avoiding the need for time consuming numerical simulations.

Model based analysis of the EU power system based on RES — A case study for Greece and Germany

2015 ◽  
Author(s):  
Pantelis Capros ◽  
Marilena Zampara ◽  
Nikos Tasios ◽  
Dimitris Papadopoulos ◽  
Christoph Kost ◽  
...  
Keyword(s):  
Power System ◽  
Model Based ◽  
The Eu ◽  
Model Based Analysis

scholarly journals Demonstration, extension, and refinement of the re-proposed notion of design abduction

2020 ◽  
Vol 34 (2) ◽  
pp. 286-297
Author(s):  
Lauri Koskela ◽  
Ehud Kroll
Keyword(s):  
Philosophy Of Science ◽  
Retrospective Case ◽  
Model Based ◽  
Design Reasoning ◽  
Retrospective Case Study ◽  
New Hypothesis

AbstractThe original ideas on design abduction, inspired by treatments in philosophy of science, had a narrow conception on how novelty emerges in design, when looked at in terms of logic. The authors have previously presented a re-proposed notion of abduction in design, taking the differences between science and design into account. Now, in this article, the invention of the airplane by the Wright brothers is analyzed as a retrospective case study. Key parts of the re-proposed notion of design abduction are demonstrated, and two new types of design abduction are identified, namely strategic abduction and dynamic abduction. Perhaps even more importantly, a new hypothesis on the cognitive basis of design abduction is reached. While the importance of model-based abduction (and reasoning) is confirmed, the case also pinpoints the central role of verbalization and discussion in supporting design reasoning in general and especially abduction. All in all, it seems that an improved understanding of design abduction and its cognitive basis would be instrumental in promoting more effective and efficient designing.

scholarly journals New Model-Based Analysis Method with Multiple Constraints for Integrated Modular Avionics Dynamic Reconfiguration Process

Processes ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 574
Author(s):  
Zeyong Jiang ◽  
Tingdi Zhao ◽  
Shihai Wang ◽  
Hongyan Ju
Keyword(s):  
Petri Net ◽  
Simulation Analysis ◽  
Dynamic Reconfiguration ◽  
Multiple Constraints ◽  
Model Based ◽  
Integrated Modular Avionics ◽  
Configuration Changes ◽  
Model Based Analysis ◽  
Architecture Analysis

With the development of integrated modular avionics (IMA), the dynamic reconfiguration of IMA not only provides great advantages in resource utilization and aircraft configuration, but also acts as a valid means for resource failure management. It is vital to ensure the correction of the IMA dynamic reconfiguration process. The analysis of the dynamic reconfiguration process is a significant task. The Architecture Analysis & Design Language (AADL) is widely used in complicated real-time embedded systems. The language can describe the system configuration and the execution behaviors, such as configuration changes. Petri net is a widely used tool to conduct simulation analysis in many aspects. In this study, a model-based analyzing method with multiple constraints for the IMA dynamic reconfiguration process was proposed. First, several design constraints on the process were investigated. Second, the dynamic reconfiguration process was modeled based on the AADL. Then, a set of rules for the transition of the model from AADL to Petri net was generated, and the multi-constraints proposed were incorporated into Petri net for analysis. Finally, a simulation multi-constraint analysis with Petri net for the process of IMA dynamic reconfiguration was conducted. Finally, a case study was employed to demonstrate this method. This method is advantageous to the validity of IMA dynamic reconfiguration at the beginning of the system design.

scholarly journals Model-based analysis and synthesis of tumor growth under angiogenic inhibition: a case study*

2011 ◽  
Vol 44 (1) ◽  
pp. 3753-3758 ◽  
Author(s):  
Dániel A. Drexler ◽  
Levente Kovács ◽  
Johanna Sápi ◽  
István Harmati ◽  
Zoltán Benyó
Keyword(s):  
Tumor Growth ◽  
Model Based ◽  
Analysis And Synthesis ◽  
Model Based Analysis

A Unifying Model for Mechatronic Systems Specification

2015 ◽  
Vol 789-790 ◽  
pp. 803-811
Author(s):  
Sabah Al-Fedaghi ◽  
Ahmed Abdullah
Keyword(s):  
Coherent System ◽  
System Specification ◽  
Mechatronic Systems ◽  
Model Based ◽  
Development Teams ◽  
Proposed Model ◽  
Baggage Handling ◽  
Specification Analysis

Over the years, mechatronic systems have witnessed an increase in complexity. To address this issue, a model-based approach has been utilized to produce coherent system specification. In model-based engineering, a system is depicted graphically and textually at various levels of granularity and complexity. For this purpose, Systems Modeling Language (SysML) is designed to support development stages in systems, including specification, analysis, design, and validation, and to generate specifications in a single language for use by heterogeneous development teams. Nevertheless, an underlying tool is lacking that would express the totality of a system’s processes and concepts, including mechanical, electrical, and informational aspects. SysML introduces a variety of diagrams and tools that are heterogeneous in notation and terms, e.g., use cases, blocks, activities, components, parameters, sequence, and so forth. This paper proposes a diagrammatic methodology to specify a unified conceptual map for mechatronic systems that can play the role of blueprint for a whole system at different stages of development. The paper focuses on using the proposed methodology as a specification tool, offering a new model that captures the dynamic behaviors of the system. The claim is that this proposed model for specification provides a nontechnical map of the system without a multiplicity of representations as in SysML. To demonstrate the viability of the model, it is applied to a case study of an airport baggage handling system.

scholarly journals Nowcasting Euro Area Economic Activity in Real Time: The Role of Confidence Indicators

2009 ◽  
Vol 210 ◽  
pp. 90-97 ◽  
Author(s):  
Domenico Giannone ◽  
Lucrezia Reichlin ◽  
Saverio Simonelli
Keyword(s):  
Real Time ◽  
Euro Area ◽  
Economic Activity ◽  
Model Based

This paper assesses the role of qualitative surveys for the early estimation of GDP in the Euro Area in a model-based automated procedure which exploits the timeliness of their release. The analysis is conducted using both an historical evaluation and a real-time case study on the current conjuncture.

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