Nonlinear System Identification Technique for a Base-Excited Structure Based on Modal Space Formulation

Doranga, Sushil; Wu, Chenyu

doi:10.1115/1.4034394

Cited by 3 publications

(6 citation statements)

References 19 publications

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“…The force reconstruction procedure for a moving base system is carried out by exciting the system at low base displacement. A reverse explicit formulation is shown in reference [20][21][22] where the system equation is partioned at the measured and the unmeasured degrees of freedom (DOFs). The reconstructed force at the measured DOFs is obtained by the system transfer function and the mode shapes matrix.…”

Section: Force Reconstruction and Nonlinear System Identification Using The Base Excitationmentioning

confidence: 99%

“…The mathematical concept for force reconstruction, base excitation and the nonlinear system identification is described below in brief. For more about this theory readers are suggested to review reference [20][21][22].…”

Section: Force Reconstruction and Nonlinear System Identification Using The Base Excitationmentioning

confidence: 99%

“…(16) in time domain eliminates the strong hypothesis that harmonic excitation to the system produces the response at same harmonic, which is in fact a strong assumption. Similarly, for the nonlinear system, following reference [20][21][22], the nonlinear restoring force at the measure DOFs can be written as:…”

Section: Theoretical Formulation For the Force Reconstruction Base Excitation And Nonlinear System Identificationmentioning

confidence: 99%

“…(18) gives the nonlinear restoring force vector at the measured DOFs. Once such a force vector is obtained, the nonlinear parameters can be extracted by using the harmonic balance approach [20][21]. Using the harmonic balance approach required the location and the functional form of the nonlinearity and this approach work only for the frequency domain data which may limits the use of Eq.…”

Section: Theoretical Formulation For the Force Reconstruction Base Excitation And Nonlinear System Identificationmentioning

confidence: 99%

“…Solving Eq. (20) in the time domain yields the modal restoring force at the nonlinear modal space provided that all the matrices shown in right hand side of Eq. (20) are invertible.…”

Section: Theoretical Formulation For the Force Reconstruction Base Excitation And Nonlinear System Identificationmentioning

confidence: 99%

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Study of nonlinear effects in a bolted joint using the base excitation as an input

Doranga¹,

Wu²

2021

J. vibroeng.

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In this paper, the nonlinearity detection, characterization and identification of a bolted beam assembly is presented. The methodology utilized in this work is based on the force reconstruction using the base excitation as an input and the nonlinear system identification. The force reconstruction procedure was carried out by exciting the bolted beam assembly at very low excitation with fully tightened bolt condition. The nonlinear effect in the bolted beam assembly was induced by reducing the bolt clamping loads. A collection of frequency response functions (FRFs) are shown at different clamping loads to detect and characterize the nonlinearities. Once the nonlinearities are detected and characterized, the restoring force surface method using the reconstructed force was used to identify the nonlinear parameters in the modal space. Four different base excitation (energy) levels with three different tightening torques were considered in the tests in order to study the energy dependence of the damping nonlinearities. In all the cases, the nonlinear system identification methodology employed was successful in identifying the damping and stiffness nonlinearities.

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Section: Force Reconstruction and Nonlinear System Identification Using The Base Excitationmentioning

confidence: 99%

Section: Force Reconstruction and Nonlinear System Identification Using The Base Excitationmentioning

confidence: 99%

Section: Theoretical Formulation For the Force Reconstruction Base Excitation And Nonlinear System Identificationmentioning

confidence: 99%

Section: Theoretical Formulation For the Force Reconstruction Base Excitation And Nonlinear System Identificationmentioning

confidence: 99%

“…Solving Eq. (20) in the time domain yields the modal restoring force at the nonlinear modal space provided that all the matrices shown in right hand side of Eq. (20) are invertible.…”

Section: Theoretical Formulation For the Force Reconstruction Base Excitation And Nonlinear System Identificationmentioning

confidence: 99%

See 3 more Smart Citations

Study of nonlinear effects in a bolted joint using the base excitation as an input

Doranga¹,

Wu²

2021

J. vibroeng.

Self Cite

View full text Add to dashboard Cite

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A Computationally Low-Cost Method for Capturing Airframe Flexibility Effects in Landing Dynamic Simulations

Stachiw

Khouli

Langlois

et al. 2021

Journal of Computational and Nonlinear Dynamics

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Airframe flexibility effects have typically been captured by modal reduction of the airframe. Although efficient, this model may still be prohibitively expensive for preliminary design studies. This paper employs time- and frequency-domain system identification techniques to form a multi-objective optimization problem to identify equivalent transfer functions representing airframe flexibility effects. Pareto-optimal sets are first identified for an equivalent transfer function of a force element between the landing gear attachment point and the centre of gravity of a 150-passenger regional jet, and a second transfer function from the input landing gear force to the cockpit acceleration. The reduced models demonstrate the ability to generally capture flexibility effects with reduced computation times. The combination of time-domain and frequency-domain information ensures the positive time-history matches while the model remains physically realizable as it is rooted to frequency response obtained from the finite element model. It is hypothesized that this physical link allowed the model to be robust to the landing initial conditions.

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A Time Frequency Domain Based Approach for Ball Grid Array Solder Joint Fatigue Analysis Using Global Local Modeling Technique

Doranga

Xie

Lee³

et al. 2023

Journal of Electronic Packaging

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The fatigue life prediction of the electronic packages under dynamic loading conditions is an increasingly important area of research, with direct application in packaging industries. Current life prediction methodologies are, in general, developed through a finite element (FE) model that is correlated using an experimental data measured through sweep sine testing. The frequency response curve (FRF) generated by using a sweep sine testing may suffer from leakage and windowing of the signal may not work correctly, which results in the shift in the amplitude and the resonance frequencies of the package. In consequence, there will be a significant deviation between the actual and the predicted natural frequencies and the amplitude of vibration response in the given excitation range, resulting in the longer time to fail the package during the laboratory based /virtual durability testing. Thus, it is necessary to develop a suitable validation technique in time/frequency domain to address this issue. In this paper, the step sine testing procedure is utilized to validate the FE model of a test vehicle consisting of a board level BGA chip package and the resonance based fatigue testing is performed in the FE based simulation. The global-local modeling approach is utilized to model the test vehicle and the volume average von Mises stress is used to predict the life of the solder joint. Following the numerical simulations, fatigue test is carried out in the test vehicle at the first resonance frequency obtained from the step sine test. Experimental results show that there are full openings of the corner balls in a very short interval of time. The results of the life prediction from the FE model and from experiments are comparable to each other thus validating the proposed methodology.

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Nonlinear System Identification Technique for a Base-Excited Structure Based on Modal Space Formulation

Cited by 3 publications

References 19 publications

Study of nonlinear effects in a bolted joint using the base excitation as an input

Study of nonlinear effects in a bolted joint using the base excitation as an input

A Computationally Low-Cost Method for Capturing Airframe Flexibility Effects in Landing Dynamic Simulations

A Time Frequency Domain Based Approach for Ball Grid Array Solder Joint Fatigue Analysis Using Global Local Modeling Technique

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