The Prediction of the Dynamic Behaviour of a Structure Using Model Updating and Frequency Based Substructuring

et al. 2022

IJAME

For frequency-based substructuring (FBS) to be accurate, translational and rotational data must be available at the connection points between substructures. However, obtaining rotational FRFs from experimental modal analyses is very difficult in practice. In this paper, an alternative method for estimating rotational FRFs is proposed using an approximated simplified finite element model (ASFE), modal updating, and mode expansion. The proposed approach was demonstrated on an assembled structure consisting of an irregular plate (test model) and a simple beam (FE model). The SEREP method was used to augment the translational and rotational FRFs to the updated ASFE mode shapes. The expanded rotational FRF of the test model was validated with the measured rotational FRF obtained from a piezoelectric direct rotational accelerometer. The results showed that the proposed approach for FBS correctly predicted the experimental FRF of the assembled structure with 90% accuracy. The FBS method is no longer dependent on the experimental rotational FRF, which is very difficult to measure with the methodology presented here.

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…The simplified geometry was then discretised into 12 QUAD4 and 6 TRIA3 elements. The methodology for developing the ASFE model can be found in [16].…”

Section: The Development Of the Approximated And Simplified Finite El...mentioning

confidence: 99%

Section: Ema Of the Irregular Platementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Using Updated and Expanded Data to Estimate the Unmeasured Rotational Data of a Bolted Structure

Mirza

Kyprianou

et al. 2022

IJAME

Assessment of Rotational Accelerometer Mountings for Rotational Frequency Response Function Measurement

IOP Conf. Ser.: Mater. Sci. Eng.

Rosli

et al. 2021

Kistler Kshear 8840 piezoelectric rotational accelerometer is designed with an M5 bolt type of mounting and a 5mm diameter of through or pre-tapped hole is required in a structure under test. However, the mounting is not applicable for some cases, and other types of mounting need to be used. This work investigates the applicability and accuracy of five different configurations of mounting for Kistler Ksher 8840 piezoelectric rotational accelerometer for the measurement of the rotational FRFs of a steel plate. The mounting configurations consist of 3D printed PLA and ABS mounting, bee’s wax, steel, and bolt mounting. The rotational FRF of the steel plate was measured by using impact testing method. The applicability and accuracy of the mountings were evaluated by comparing the measured FRFs with the finite element (FE) FRFs counterparts. The comparisons of the results revealed that using the bee’s wax mounting had produced the most accurate and least noisy FRF. It was also found that using the 3D printed PLA mounting had contributed to the highest contamination of noise and several spurious peaks in the measured FRFs. These findings provide useful information for selecting the appropriate types and designs of mounting for the Kistler 8840 rotational accelerometer.

Estimating Rotational FRFs of a Complex Structure Using FE Model Updating, Mode Expansion and FRF Synthesis Method

Mirza

IOP Conf. Ser.: Mater. Sci. Eng.

Yunus

et al. 2020

Estimating rotational frequency response functions (FRFs) from experimental data is very challenging, and the estimation often leads to poor FRFs due to the presence of spurious resonance peaks. In practice, special equipment is essentially required in the measurement process, unless the rotational FRFs are synthesised using measured modal data. This paper presents an alternative approach for estimating the rotational FRFs of a geometrically complex structure by using finite element modal updating, mode expansion and the FRF synthesis method. The applicability and accuracy of the proposed approach are demonstrated on a car front-end module A simplified finite element (SFE) model of the test structure is introduced and the SFE model is then updated based on the measured modal model obtained from experimental modal analysis. The mode shapes of the updated SFE model are expanded to the test model to obtain the entire translational and rotational modal vector. The rotational FRFs of the expended experimental model is derived via the FRF synthesis method. The derived translational FRF is compared with the measured counterparts for validation purposes. It was found that the derived translational and measured FRF are in a perfect match, and the derived rotational FRF has successfully estimated all the resonance peaks within the frequency of interest. The findings from this work may be useful in improving the accuracy of the experimental rotational FRFs, which are crucial for particular structural dynamics analysis.