An augmented free-interface-based modal substructuring for nonlinear structural dynamics including interface reduction

Mahdiabadi, Morteza Karamooz; Bartl, Andreas; Xu, Duo; Tiso, Paolo; Rixen, Daniel J.

doi:10.1016/j.jsv.2019.114915

Cited by 9 publications

(2 citation statements)

References 29 publications

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“…The formulation was first introduced in [20,21], then the extended Craig-Bampton method was more thoroughly studied in [22], in which SMDs of the constraint modes and fixed interface normal modes for each component were considered and modified as fixed-interface modes for the convenience of interface compatibility during the assembly procedure. The extension of Rubin was also studied in [23] and developed for a 3D flexible multibody system in [24], in which a nonlinear coupling between attachment modes and free-interface modes was considered. These studies concluded that extended CMS techniques can accurately predict the response, while the Rubin substructuring basis enhanced with SMDs provides a better representation of the geometric nonlinearities in the interfaces, since it comprises normal modes and SMDs featuring free motion of the interface.…”

Section: Introductionmentioning

confidence: 99%

Modal Derivatives for Efficient Vibration Prediction of Geometrically Nonlinear Structures with Friction Contact

Mashayekhi,

Zucca

2024

Applied Sciences

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This paper evaluates the performance of the Rubin reduction methods, enhanced with static modal derivatives, for vibration analysis of geometrically nonlinear structures with friction contact. Static modal derivatives are computed numerically based on Rubin reduction, which includes free interface normal modes and residual flexibility attachment modes, by introducing a finite displacement around these modes. Then, the most relevant static modal derivatives are selected using an improved strategy that incorporates weighting factors derived from both a nonlinear static analysis and a geometrically linear transient run. This enhanced Rubin method is also compared with the previously used enhanced Craig–Bampton method, which is based on fixed normal modes, constraint modes, and their static derivatives. The effectiveness of these methods is demonstrated through vibration analysis of a geometrically nonlinear beam in different contact configurations. Both methods proved their robustness, achieving accurate results with a relatively small number of modes in the reduced space, thus ensuring low online computation times. Furthermore, the analyses show the significant impact of using a geometrically nonlinear model on the accurate prediction of a contact state.

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Section: Introductionmentioning

confidence: 99%

Modal Derivatives for Efficient Vibration Prediction of Geometrically Nonlinear Structures with Friction Contact

Mashayekhi,

Zucca

2024

Applied Sciences

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“…One common method is known as frequency-based substructuring, which aims to relate dynamical systems to each other by Power Spectral Densities (PSDs) and has been widely investigated [ 5 , 6 , 7 ]. Another popular model of substructuring was introduced by Craig-Bampton, which utilizes Finite Element Analysis (FEA) to truncate a system of equations through a combination of structure modes and boundary points [ 8 , 9 , 10 ].…”

Section: Introductionmentioning

confidence: 99%

Insights on the Impacts of Accelerometer Location on the Dynamics and Characteristics of Complex Structures

Takeshita,

Madrid,

Granillo

et al. 2023

Sensors

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There exists a high level of difficulty in understanding the physical responses of complex dynamical systems. To this end, researchers have previously used different measurement techniques, such as displacement sensors or accelerometers, in the laboratory to capture a system’s dynamics. A well-known structure in the literature is the Box Assembly with Removable Component (BARC) whose purpose is to gain a deep understanding of testing complex systems. Further breaking down the structure, the Removable Component (RC) portion is often used as a relatively simplified version which retains significant complexity from the original system. However, the placement of accelerometers on the RC have varied greatly throughout the literature which presents a challenge in comparing results and may not accurately represent the system’s dynamics. Finite Element Analysis (FEA) is performed for three common accelerometer locations to determine how their placement affects the frequencies and mode shapes for the RC and results are compared against those without accelerometers. Free vibration experiments are carried out to understand the variation of frequencies and damping for each accelerometer location to obtain the overall response for the first mode of vibration. Next, random vibration experiments are run to gain insight on the interaction between linear and nonlinear responses based on excitation level, while showing the influence of an accelerometer’s location on system dynamics. The results demonstrate that the location of the accelerometer is highly influential on the linear and nonlinear characteristics of the system. It is proved that for the first mode of vibration, nonlinear softening and nonlinear damping behaviors may take place due to the interaction between the location of accelerometers, direction of excitation, and response axis analyzed.

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A highly efficient method for structural model reduction

Yang

Peng

2022

Numerical Meth Engineering

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Model reduction is a commonly used method for quickly computing the lower‐order eigenvalues and eigenvectors of a structure. This article proposed a direct model reduction method without any iterations. Compared with the existing methods, the proposed technique has two main advantages. The first one is that the explicit expression of the transformation matrix can be directly obtained using a recurrence formula. The second one is that the calculation efficiency of the proposed method is very high because there is no need for iterative calculation. Three types of structure are used as examples to verify the proposed method. It is found that the lower‐frequency eigenpairs calculated by the reduced model are very close to the exact ones obtained by the full model. Moreover, the calculation time of the proposed method is much less than that of the existing methods. It has been shown that the proposed method is reliable and effective.

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An augmented free-interface-based modal substructuring for nonlinear structural dynamics including interface reduction

Cited by 9 publications

References 29 publications

Modal Derivatives for Efficient Vibration Prediction of Geometrically Nonlinear Structures with Friction Contact

Modal Derivatives for Efficient Vibration Prediction of Geometrically Nonlinear Structures with Friction Contact

Insights on the Impacts of Accelerometer Location on the Dynamics and Characteristics of Complex Structures

A highly efficient method for structural model reduction

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