Finite Element Analysis C S Krishnamoorthy Free Download In
Book Type: Science Mathematics Book Binding: Paperback Language: English Number of Pages: 710 pages ISBN - 10: 74622102 Finite Element Analysis: Theory and Programming Published On: 15-Jun-01 Resource: Textbooks, Science Mathematics for Students and Professionals Disclaimer: rn rn Finite Element Analysis: Theory and Programming Book is not for reading online or for free download in PDF or eBook format.
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The LSCE is a time-domain algorithm which requires in input the Impulse Response Functions (IRFs), the latter beingobtained via inverse Fourier transform of the experimental FRFs, for all the considered input-outputpairs. 2 ICSV23, Athens (Greece), 10-14 July 2016 The 23rd International Congress of Sound and Vibration 102 103 0 0.25 0.5 0.75 1 Co he ren ce 102 103 80 60 40 20 0 Mo bili ty ( dB ) 102 103 180 90 0 90 180 Ph ase (d eg ) Frequency (Hz) Figure 2: Example of experimental mobility FRFs of the soundboard of the finished violin, for threedifferent input-output location pairs.
See Full Reader prev next out of 7 EXPERIMENTAL MODAL ANALYSIS AND FINITE ELEMENT MODELLING.
Experimental modal analysis was performed on a Download Report View 234.
The attention is focused on the evolution of thesoundboard and the back plate mechanical characteristics during instrument construction.
Exper-imental modal analysis was performed on a contemporary violin at several stages of the musicalinstrument manufacturing process and finite element models, corresponding to the same testedconfigurations, were developed.
A preliminary comparison between experimental results andsimulations is presented.
Introduction During the past decades several researches were performed on musical instruments in order tostudy their mechanical behaviour and enhance the sound quality 1, 2.
The design of the violin, aswell as any other musical instrument, has been modified during the centuries and the modern instru-ment is the result of this natural and empirically driven evolution carried out by luthiers.
Severalstudies have been conducted on the vibroacoustic behaviour of violins 3, 4, 5, nevertheless a com-plete understanding of the influence of the manufacturing details on the acoustical performance hasnot yet been reached.
This paper illustrates the present state of a research project aimed at developing and validatinga vibroacoustic numerical model of a violin that is based on accurate structural modelling.
The at-tention is focused on the evolution of the soundboard and the back plate mechanical characteristicsduring instrument construction.
Experimental modal analysis was performed on a contemporary vio-lin at several stages of the manufacturing process.
In parallel to the experimental tests, finite elementmodels corresponding to the same tested configurations were developed, starting from the geometryobtained from 3D laser scanner measurements.
Some experimental modal analysis results of the soundboard and the back plate are presented.
Apreliminary comparison with finite element simulation, in terms of both natural frequencies and modeshapes, is presented.
The final objective is the validation of the finite element models which will bethe basis for the subsequent sound radiation simulation.
Experimental modal analysis Experimental modal analysis tests were performed on the soundboard and the back plate of acontemporary luthiery instrument at nine steps of its construction.
The main advantage of followinga step-by-step analysis method is the possibility of investigating the influence of the manufacturingprocess on the dynamic behaviour of the sound radiating components of the violin 6, 7.
The 23rd International Congress of Sound and Vibration The instrument was suspended by nylon cables (Fig.
The surfaces of the soundboard and the back plate were excited, on a 67 nodes grid, ac-cording to the roving hammer technique.
At leastfive repetitions were performed for each excitation position to minimize the influence of uncorrelatedinput disturbances.
Figure 1: Experimental modal analysis set up: finished violin (with damped strings) suspended bynylon cables.
The H1 estimator was adopted to derive the Frequency Response Function (FRF): Hoi() Goi() Gii(), (1) where Goi() is the crosspectral density function between the input force i and the output vibra-tion o, whereas Gii() is the autospectral density function of the input force 8.
Carel pj32c0000k manualThe coherencefunction 2oi(), calculated as 2oi() Goi()2 Goo()Gii(), (2) indicates the degree of correlation between input and output and defines the frequency range overwhich the FRF data can be considered reliable.
Fig. 2 shows, as an example, three mobility FRFs ofthe soundboard of the finished violin.
The mobility FRFs (Fig.
Hz the coherence is close to one and themodes are clearly visible, so that it is possible to efficiently apply an identification algorithm.
Theadopted modal parameters identification procedure is based on a two-step approach.
First, the Least Squares Complex Exponential (LSCE) algorithm 9, 10 is applied to estimate thesystem poles and the corresponding natural frequencies and damping ratios.
The LSCE is a time-domain algorithm which requires in input the Impulse Response Functions (IRFs), the latter beingobtained via inverse Fourier transform of the experimental FRFs, for all the considered input-outputpairs.
ICSV23, Athens (Greece), 10-14 July 2016 The 23rd International Congress of Sound and Vibration 102 103 0 0.25 0.5 0.75 1 Co he ren ce 102 103 80 60 40 20 0 Mo bili ty ( dB ) 102 103 180 90 0 90 180 Ph ase (d eg ) Frequency (Hz) Figure 2: Example of experimental mobility FRFs of the soundboard of the finished violin, for threedifferent input-output location pairs.