Efficient buckling and free vibration analysis of cyclically repeated space truss structures

The vibration of grouped blades on a flexible disk cannot be analyzed using procedures developed for individual, uncoupled groups. The bladed-disk system must be considered either in whole, or as a structure composed ofcyclically symmetric sectors. The latter approach, while being computationally more economical, is more complicated to implement because both the structural system and the applied forces must be transformed to a system based on the geometry of a single sector. However, the sector transformation permits a natural ordering of the modes that cannot be obtained from a complete system model. This paper describes the development of the sector model, and the associated transformation of the applied harmonic forces typically prevalent in turbomachinery. The displacements are expressed in a series of the natural modes of a transformed sector, and expressions are developed for maximum displacements of the complete structure. This approach leads to an easier interpretation of the analytical results and an improved physical understanding of the response. For example, it is shown that a single harmonic, or engine-order excitation, can cause response in only a restricted subset of modes.

Forced Harmonic Response of Grouped Blade Systems: Part I—Discrete Theory

Special kinds of structures exhibit repetitive patterns that can be used in the process of structural analysis in order to decrease the required computational time. This is especially helpful when ...

Optimal design of cyclically symmetric trusses with frequency constraints using cyclical parthenogenesis algorithm

In the present work, a two-dimensional numerical model of heat and mass transfer for the convective drying of ceramic porous system was developed. The governing system of fully coupled non-linear partial differential equations describing the process was derived from a mechanistic approach. A formulation including hygrothermal and moisture transport in soil was adopted as the basis for further development in this work. The calculation results for drying of a ceramic brick showed that the model presented is in good agreement with other studies that have been reported previously in the drying of porous material. Further investigation on the shell drying agrees well with the most drying mechanism of ceramic porous body. The influence of material parameter on the drying profile is taken into consideration by carrying out some investigation on the material sensitivity study.

Combined heat and mass transfer for drying ceramic (shell) body

This paper deals with rotating cyclic symmetric structures, immersed in light fluid flow. Firstly, general and usual cyclic symmetric properties are recovered from the Floquet
theorem for differential equations, having space periodic coefficients in conjunction with a
discrete space Fourier series development. The approach for aeroelastic problem having
cyclic symmetry is then formulated based on the twin mode approach. In addition to modal
one, rotating and stationary wave bases are introduced to derive the equilibrium equations for a non-dissipative system subjected to aerodynamic loading. Rotating wave basis is the natural one, and it also permits consistently to prescribe the aerodynamic pressure on the boundary between the fluid and the structure. The aerodynamic load is then derived from a
harmonic analysis of the fluid flow extending to turbomachinery as in the case of aeroplane
wing. In this way, aerodynamic forces may be obtained as general as required, depending on successive time derivatives of degrees of freedom in addition to themselves. Finally, some special cases are given and stability is studied for a cyclic periodic blade assembly, even when mistuning between sectors can occur.

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Aeroelastic Vibrations and Stability in Cyclic Symmetric Domains

A subspace iteration scheme for the Hermitian eigenvalue problem arising from analysis of cyclic symmetric structures is presented. This operates in the semi-complex domain and its computational efficiency is demonstrated. A modified convergence checking criterion which gives better error estimates, and a new trial vector selection scheme which accelerates convergence for the Hermitian eigenvalue problem based on the Ritz method, are presented.

Free‐vibration analysis of cyclic symmetric structures

Skyline solver for the static analysis of cyclic symmetric structures

On the Use of the Ritz-Wilson Method for the Dynamic Response Analysis of Cyclic Symmetric Structures

Modal methods for the analysis of cyclic symmetric structures

In this study the free vibration of circumferentially periodic structures has been analysed using the block Lanczos method in a semi complex domain for extracting real natural frequencies and complex mode shapes. The influence of the number of vectors in the block and also the effect of renumbering of nodes, depending on whether they are internal, adjacent or boundary nodes, on the CPU time are studied. The efficiency of the present method is compared with the subspace iteration schemes.

H.K. Suhas

Papers

Free‐vibration analysis of cyclic symmetric structures

Skyline solver for the static analysis of cyclic symmetric structures

On the Use of the Ritz-Wilson Method for the Dynamic Response Analysis of Cyclic Symmetric Structures

Modal methods for the analysis of cyclic symmetric structures

Application of block Lanczos method for analysis of cyclic symmetric structures