Reduced-order controllers inH ∞-Optimal synthesis methods of the first kind

1989 ◽  
Vol 22 (1) ◽  
pp. 109-148 ◽  
Author(s):  
Madanpal S. Verma ◽  
James C. Romig
Keyword(s):  
Optimal Synthesis ◽  
Synthesis Methods ◽  
Reduced Order

Rotating Mistuned Bladed Disk Assembly Dynamic Response Prediction Using Component Mode Synthesis Methods With Interface Modes

2005 ◽  
Author(s):  
Francois Duvauchelle ◽  
Duc-Minh Tran ◽  
Roger Ohayon
Keyword(s):  
Response Prediction ◽  
Forced Response ◽  
Component Mode Synthesis ◽  
Synthesis Methods ◽  
Cyclic Symmetry ◽  
Reduced Order ◽  
Bladed Disk ◽  
Static Condensation ◽  
Bladed Disk Assembly ◽  
Reduced Order Methods

Finite element-based reduced order methods are presented with application to the prediction of rotating mistuned bladed disk forced response. These methods have already been applied to tuned non-rotating models having cyclic symmetry. The aim is to reduce significantly the number of interface co-ordinates, which can be very important in classical component mode synthesis methods. The approach is based on the use of the interface modes which result from a static condensation of the whole structure on the whole interface. A first implementation of this procedure and numerical results are presented.

Numerical Methods for Calculating Component Modes for Geometric Mistuning Reduced-order Models

2021 ◽  
Author(s):  
Joseph Beck ◽  
Jeffrey Brown ◽  
Alex Kaszynski ◽  
Daniel Gillaugh
Keyword(s):  
Normal Modes ◽  
Solution Time ◽  
Synthesis Methods ◽  
Processing Scheme ◽  
Reduced Order ◽  
Optical Scanner ◽  
Permutation Matrices ◽  
Stiffness Matrices ◽  
Fixed Interface ◽  
Matrix Partitioning

Abstract Geometric mistuning models formulated from a component mode synthesis methods often require the calculation of component modes, particularly constraint and fixed interface normal modes, during substructuring. For Integrally Bladed Rotors, these calculations are required for each sector. This paper proposes methods that reuse information garnered from solving the constraint modes of a single sector on the remaining sectors to reduce memory requirements and solution times. A mesh metamorphosis tool is used to ensure finite element models match geometry obtained from a 3D optical scanner. This tool also produces a common mesh pattern from sector-to-sector. This is exploited to produce common permutation matrices and symbolic factorizations of sector stiffness matrices that are proposed for reuse in solving subsequent constraint modes. Furthermore, a drop tolerance is introduced to remove small values during constraint mode calculation to reduce memory requirements. It is proposed to reuse this dropping pattern produced from a single sector on the remaining sectors. Approaches are then extended to a parallel processing scheme to propose effective matrix partitioning methods. Finally, information gathered during the constraint mode calculations are reused during the solution of the fixed interface normal modes to improve solution time. Results show reusing permutation matrices and symbolic factorizations from sector-to-sector improves solution time and introduces no error. Using a drop tolerance is shown to reduce storage requirements of a constraint mode matrix, while reusing the dropping pattern introduces minimal error. Similarly, reusing constraint mode information in calculating normal modes greatly improves the performance.

Methods of Synthesis and Analysis for Hypoid Gear-Drives of “Formate” and “Helixform”—Part 3. Analysis and Optimal Synthesis Methods For Mismatch Gearing and its Application For Hypoid Gears of “Formate” and “Helixform”

1981 ◽  
Vol 103 (1) ◽  
pp. 102-110 ◽  
Author(s):  
F. L. Litvin ◽  
Y. Gutman
Keyword(s):  
Optimal Synthesis ◽  
Final Part ◽  
Synthesis Methods ◽  
Hypoid Gear ◽  
Hypoid Gears ◽  
Gear Drive ◽  
Analysis And Synthesis ◽  
Methods Of Synthesis ◽  
Gear Drives ◽  
Favorable Conditions

In this third and final part are proposed: (a) methods for analysis and optimal synthesis of mismatch gearing, (b) application of those methods for the analysis and synthesis of hypoid gear-drives generated by “Formate” and “Helixform” methods. In the previous parts, machine settings for the member-gear and the pinion of the Hypoid gear-drive were obtained. Use of these settings guarantee: (a) that the gear surfaces will be in tangency at a previously chosen point M, (b) that the conditions of meshing will be favorable at the point M and in its vicinity. But it is necessary to provide favorable conditions of meshing in the whole area of meshing. Methods proposed in this part permits achievement of those mentioned aims: (a) the analysis of gearing permits collection of the necessary information of meshing conditions in the whole area of meshing, (b) the optimal synthesis permits improvment of the conditions of meshing by variation of some parameters of pinion machine settings.

scholarly journals Evaluation of Component Mode Synthesis Methods for the Detection of Modal Interaction Through Rotor Stator Contacts

2009 ◽  
Author(s):  
Alain Batailly ◽  
Mathias Legrand ◽  
Patrice Cartraud ◽  
Christophe Pierre ◽  
Jean-Pierre Lombard
Keyword(s):  
Finite Element ◽  
Equations Of Motion ◽  
Time Integration ◽  
Component Mode Synthesis ◽  
Integration Scheme ◽  
Synthesis Methods ◽  
Reduced Order Models ◽  
Reduced Order ◽  
Free Interface ◽  
Fixed Interface

The study of interactions through direct contact between bladetips and outer casings in modern turbomachines may be very time-consuming when the classical finite element method is used. The construction of reduced-order models using component mode synthesis (CMS) methods generally allows for dramatic increase in computational efficiency and may be used in order to improve the knowledge over these interaction phenomena. Among the available approaches, both a fixed-interface method and a free-interface method are considered here in an original manner to reduce the size of a realistic two-dimensional model. The equations of motion are solved using an explicit time integration scheme with the Lagrange multiplier method where friction is accounted for. This method offers energy momentum conserving which is a critical point to ensure the convergence of the algorithm. Moreover, it is shown that even in a non-linear framework the reduced-order models converge to the finite element solution as the number of modes included in the models increases. Considering the fixed-interface method of Craig-Bampton (CB) and the free-interface method of Craig-Chang-Martinez (CCM), it is shown that a method with fast displacement convergence may be less efficient in terms of motion convergence.

A Reduced Order Model for Nonlinear Dynamics of Mistuned Bladed Disks With Shroud Friction Contacts

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
S. Mehrdad Pourkiaee ◽  
Stefano Zucca
Keyword(s):  
Nonlinear Vibration ◽  
Vibration Analysis ◽  
Forced Response ◽  
Reduced Order Model ◽  
Reduced Model ◽  
Synthesis Methods ◽  
Order Model ◽  
Bladed Disks ◽  
Reduced Order ◽  
Bladed Disk

A new reduced order modeling technique for nonlinear vibration analysis of mistuned bladed disks with shrouds is presented. The developed reduction technique employs two component mode synthesis methods, namely, the Craig-Bampton (CB) method followed by a modal synthesis based on loaded interface (LI) modeshapes (Benfield and Hruda). In the new formulation, the fundamental sector is divided into blade and disk components. The CB method is applied to the blade, where nodes lying on shroud contact surfaces and blade–disk interfaces are retained as master nodes, while modal reductions are performed on the disk sector with LIs. The use of LI component modes allows removing the blade–disk interface nodes from the set of master nodes retained in the reduced model. The result is a much more reduced order model (ROM) with no need to apply any secondary reduction. In the paper, it is shown that the ROM of the mistuned bladed disk can be obtained with only single-sector calculation, so that the full finite element model of the entire bladed disk is not necessary. Furthermore, with the described approach, it is possible to introduce the blade frequency mistuning directly into the reduced model. The nonlinear forced response is computed using the harmonic balance method and alternating frequency/time domain approach. Numerical simulations revealed the accuracy, efficiency, and reliability of the new developed technique for nonlinear vibration analysis of mistuned bladed disks with shroud friction contacts.

Hotspots in Psychology – 2020 Edition

2020 ◽  
Vol 228 (1) ◽  
pp. 1-2
Author(s):  
Michael Bošnjak ◽  
Nadine Wedderhoff
Keyword(s):  
Systematic Reviews ◽  
Research Synthesis ◽  
Synthesis Methods ◽  
Common Denominator ◽  
The Common ◽  
Meta Analyses

Abstract. This editorial gives a brief introduction to the six articles included in the fourth “Hotspots in Psychology” of the Zeitschrift für Psychologie. The format is devoted to systematic reviews and meta-analyses in research-active fields that have generated a considerable number of primary studies. The common denominator is the research synthesis nature of the included articles, and not a specific psychological topic or theme that all articles have to address. Moreover, methodological advances in research synthesis methods relevant for any subfield of psychology are being addressed. Comprehensive supplemental material to the articles can be found in PsychArchives ( https://www.psycharchives.org ).

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