Experimental-Analytical Dynamic Substructuring of Ampair Testbed: A State-Space Approach

Gibanica, Mladen; Johansson, Anders; Liljerehn, Anders; Sjövall, Per; Abrahamsson, Thomas

doi:10.1007/978-3-319-04501-6_1

Cited by 3 publications

(18 citation statements)

References 21 publications

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“…Stability can easily be enforced using MATLAB's System Identification Toolbox, but passivity and Newton's second law can be, and many times are, violated, in that implementation. Synthesis of two non-passive state-space systems can yield an unstable synthesised system [39], shown in Gibanica [9]. A passive system is a system with non-negative energy dissipation, indicating a non-negative real part of the drive point FRF for linear reciprocal systems, see Sjövall and Abrahamsson [39].…”

Section: System Identification Methodologymentioning

confidence: 99%

“…Note that for the (ts) systemB (ts) is negative, see Section "Negative State-Space System". The system in equation (10) is then transformed to coupling form using the transformatioñ…”

Section: Decoupling In the State-space Domainmentioning

confidence: 99%

“…In cases with mounted bolts the density of the bracket FE model is increased to ρ = 5000 kg/m 3 . The FE models of the hub and brackets are further described in Scheel [34] and Gibanica [9]. In Fig.…”

Section: Finite Element Modelsmentioning

confidence: 99%

“…Thereafter all three blades were connected to the hub to acquire a true or reference model to which the substructuring results are compared. The hub was filled with epoxy to remove auxiliary system dynamics from internal parts and the brackets were fixed to the hub, see Gibanica [9] for further details. In the onebladed hub measurements each blade was assembled to its specific bracket to replicate the full system configuration as close as possible.…”

Section: Experimental Set-upmentioning

confidence: 99%

“…The derivation starts from a general state-space system. For a derivation of the state-space synthesis in the general formulation laid out by de Klerk et al [16] see Gibanica [9] and Gibanica et al [10], which also allows for synthesis of multiple substructures simultaneously. Here the states x (s) are no longer directly related to physical coordinates but are arbitrary, linear combinations of the physical coordinates.…”

Section: Appendix A: State-space Synthesismentioning

confidence: 99%

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State-Space Dynamic Substructuring with the Transmission Simulator Method

Gibanica

Nord

2019

Exp Tech

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Dynamic substructuring is a technique to simplify the analysis of complex structures. The vibrational problems of the constituent substructures are analysed and solved individually and their solutions are then assembled to form the global solution. In experimental dynamic substructuring, at least one of the constituent substructures is identified experimentally. The coupling interfaces are commonly simplified in such syntheses, which can result in poor prediction quality in many applications. The transmission simulator was introduced to address this problem. Transmission simulators are well-modelled parts attached to the interface of the substructures to be coupled. This allows for distributed interfaces and a relaxation of the coupling conditions by using the transmission simulator's analytical modes as a basis for the coupling equations, at the cost of adding a decoupling step to the substructuring problem. In this paper, the transmission simulator method is translated to the state-space substructuring domain. The methodology is applied to the Society for Experimental Mechanics' substructuring focus group's Ampair A600 test bed in form of experimental-analytical substructuring. The Ampair wind turbine's hub is used as the transmission simulator and is modelled with finite elements while the three blades, individually attached to the real hub, are experimentally identified. The three experimental blade hub systems are then coupled and two finite element hubs decoupled from the system, using the derived method. Finally, this system is compared to a directly measured hub with three blades by means of frequency response functions and modal properties.

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Section: System Identification Methodologymentioning

confidence: 99%

“…Note that for the (ts) systemB (ts) is negative, see Section "Negative State-Space System". The system in equation (10) is then transformed to coupling form using the transformatioñ…”

Section: Decoupling In the State-space Domainmentioning

confidence: 99%