Full-degrees-of-freedom frequency based substructuring

Drozg, Armin; Čepon, Gregor; Boltežar, Miha

doi:10.1016/j.ymssp.2017.04.051

Cited by 47 publications

(16 citation statements)

References 10 publications

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“…2.6 that the assembled system's hybrid model was computed by the weighted pseudo inverses in Eqs. (21) and (22). This helps in a faster convergence of the joint properties by assigning higher weights to the physical boundary DoF u b and expanding the measured dynamics in a weighted least squares sense.…”

Section: Appendix: Convergence Of the Iterative Methods With Weighted mentioning

confidence: 99%

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Experimental Joint Identification Using System Equivalent Model Mixing in a Bladed Disk

Saeed

Klaassen

Firrone

et al. 2020

Journal of Vibration and Acoustics

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Abstract A joint between two components can be seen as a means to transmit dynamic information from one side to the other. To identify the joint, a reverse process called decoupling can be applied. This is not as straightforward as the coupling, especially when the substructures have three-dimensional characteristics, or sensor mounting effects are significant, or the interface degrees-of-freedom (DoF) are inaccessible for response measurement and excitation. Acquiring frequency response functions (FRFs) at the interface DoF, therefore, becomes challenging. Consequently, one has to consider hybrid or expansion methods that can expand the observed dynamics on accessible DoF to inaccessible DoF. In this work, we attempt to identify the joint dynamics using the system equivalent model mixing (SEMM) decoupling method with a virtual point description of the interface. Measurements are made only at the internal DoF of the uncoupled substructures and also of the coupled structure assuming that the joint dynamics are observable in the assembled state. Expanding them to the interface DoF and performing coupling and decoupling operations iteratively, the joint is identified. The substructures under consideration are a disk and blade—an academic test geometry that has a total of 18 blades but only one blade-to-disk joint is considered in this investigation. The joint is a typical dove-tail assembly. The method is shown to identify the joint without any direct interface DoF measurement.

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Section: Appendix: Convergence Of the Iterative Methods With Weighted mentioning

confidence: 99%

“…In order to accurately capture the interface behavior, rotational information is also very important in experimental DS [12,20]. One possibility is to measure the rotations directly [21][22][23] by rotational accelerometers. However, these sensors are usually heavy and may only be suitable for bulky structures.…”

Section: Introductionmentioning

confidence: 99%

Experimental Joint Identification Using System Equivalent Model Mixing in a Bladed Disk

Saeed

Klaassen

Firrone

et al. 2020

Journal of Vibration and Acoustics

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“…In literature [98], Jetmundsen et al [32] used frequency-domain synthesis method to conduct experimental research on the space steel frame structure, and the difference in frequency-domain synthesis between indirectly obtained rotational degree of freedom information and translational degree of freedom information was compared. Drozg et al [99] proposed a solution method based on frequency response function matrix containing angle freedom degree and extended the response model with modal model. rough the dynamic response test of steel beam (as shown in Figure 10 [99]), it was verified that the solution precision of the angle freedom degree synthesis method was higher than that of the translational freedom degree synthesis method.…”

Section: Testmentioning

confidence: 99%

“…Dynamic response test device of steel beam[99].Beam Experimental device for nonlinear beam structure[101]. KRIGING model modification test device.…”

mentioning

confidence: 99%

Research Progress of Synthesis and Modification Methods Based on Dynamic Substructures

Wang²

2020

Shock and Vibration

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In the process of model modification of large and complex structures, substructure synthesis method and modal reduction method have been widely used, but there are still some difficulties in precision control and engineering application in the process of model updating. In order to better study the dynamic response of the vibration substructure, the synthesis and correction method of the classical dynamic substructure is described in this paper, which provides a new idea for further engineering development. In the aspect of substructure synthesis method, the modal reduction of substructures, two methods of classical substructure synthesis, mechanical impedance method, singular value decomposition method, rigidity-flexibility equivalence, and transformation of degree of freedom are analyzed. The advantages and disadvantages of the above methods are discussed. In terms of substructure modification, the reference datum method, function dynamic modification method, neural network model modification, and frequency response function modification are analyzed, and the shortcomings of the dynamic substructure modification method are summarized. Finally, the development trend of dynamic substructure synthesis and modification algorithm is proposed.

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“…Recently, the rotational accelerometer was introduced by Kristler Instrument which allows the direct measurement of the rotational FRF [21]. However, the force-moment excitation of the experimental substructure still needed to be expanded based on the modal model in order to obtain full DOF at the coupling interface [22].…”

Section: Introductionmentioning

confidence: 99%

Frequency Based Substructuring for Structure with Double Bolted Joints: A Case Study

Mirza

Rani

Yunus

et al. 2019

IJAME

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Adopting dynamic substructuring schemes is a common practice in the field of structural dynamics, where the dynamic behaviour of a structure is predicted by combining the multiple subsystems that are analysed individually. This paper investigated the dynamic behaviour of a structure with doubled bolted joints using the frequency based substructuring (FBS) method. In the attempt, the substructures were combined with the frequency domain that can be numerically derived or experimentally measured. However, the applicability of this method suffered from several issues where most of them were related to the frequency response function (FRF) of the rotational degree of freedom (DOF) at the subsystem’s interface. In some cases, the system’s interface vibrated in the rotary motion of certain modes, for instance, a car side rear view mirror. Therefore, excluding the rotational FRF during the coupling process could lead to a completely different result. This paper presents the use of the FBS method for a structure with double bolted joints by using the equivalent multipoint constraint (EMPC) method through which rotational DOFs can be completely neglected. The actual tested structure for this study was an assembled structure consisting of two substructures: a simple beam and an irregular plate steel structure. The FRFs of both substructures were derived from using the FRF synthesis from finite element models and combined together via the FBS method. This study reveals that the use of the FBS method with the EMPC method for a structure double bolted joints has led to very promising results.

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Full-degrees-of-freedom frequency based substructuring

Cited by 47 publications

References 10 publications

Experimental Joint Identification Using System Equivalent Model Mixing in a Bladed Disk

Experimental Joint Identification Using System Equivalent Model Mixing in a Bladed Disk

Research Progress of Synthesis and Modification Methods Based on Dynamic Substructures

Frequency Based Substructuring for Structure with Double Bolted Joints: A Case Study

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