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Fig. 3. Experimental values of frequency dependent Young modulus. Values of Young’s modulus, E, as a function of the frequency are depicted in Figure 3 in the frequency range between 100 Hz and 5000 Hz. The curves are obtained from interpolation of the discrete E values obtained from the resonance frequencies with equation 1. In the figure it is possible to observe a strong dependency of E from the frequency.

Figure 3 Experimental values of frequency dependent Young modulus. Values of Young’s modulus, E, as a function of the frequency are depicted in Figure 3 in the frequency range between 100 Hz and 5000 Hz. The curves are obtained from interpolation of the discrete E values obtained from the resonance frequencies with equation 1. In the figure it is possible to observe a strong dependency of E from the frequency.

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Table 1. Tested samples Fig. 1. Sketch of the measurement apparatus: (a) free-free boundary conditions (b) clamped-clamped boundary conditions. Tested materials are summarized in Table | in which two types of PVB have been tested. Measurements of free suspended beams have been carried out on a specimen with a length of 1000 mm and a width of 100 mm by using an accelerometer and an impact hammer as depicted in Figure la. The impulse response has been acquired by using a NI USB 4431 acquisition device and has been post-processed by means of software developed in Labview®. The frequency resolution has been fixed to 0.1 Hz for all the tests. Saas (“SMa | Seane || Care aie Stor asd. ee een emer a Tre earns a! Snes 6 RS Sst ees ss Ses, -iNSatAgQge SHciSneeA = eee 06 Tee SSS Aces Eee SS. SS ae SSRI! ESMGGMRIES ERE ASR oie ferres = nl conditions: free-free and clamped-clamped. A sketch of the measurement set-up is shown in figure la and 1.b. Finally, laboratory tests of sound transmission loss on a 1.48 m x 1.23 m specimen have been carried out according to standards ISO 10140 parts 1, 2, 4 [5] in the EcamRiCert S.r.1. Laboratory. In order to avoid leakages a Perennator TX 2001 S sealant has been used between the wood frame and the plate as indicated in ISO 10140-1 annex D. Sound pressure levels in the source and receiving rooms have been measured by using L&D 824 and the
Table 1. Tested samples Fig. 1. Sketch of the measurement apparatus: (a) free-free boundary conditions (b) clamped-clamped boundary conditions. Tested materials are summarized in Table | in which two types of PVB have been tested. Measurements of free suspended beams have been carried out on a specimen with a length of 1000 mm and a width of 100 mm by using an accelerometer and an impact hammer as depicted in Figure la. The impulse response has been acquired by using a NI USB 4431 acquisition device and has been post-processed by means of software developed in Labview®. The frequency resolution has been fixed to 0.1 Hz for all the tests. Saas (“SMa | Seane || Care aie Stor asd. ee een emer a Tre earns a! Snes 6 RS Sst ees ss Ses, -iNSatAgQge SHciSneeA = eee 06 Tee SSS Aces Eee SS. SS ae SSRI! ESMGGMRIES ERE ASR oie ferres = nl conditions: free-free and clamped-clamped. A sketch of the measurement set-up is shown in figure la and 1.b. Finally, laboratory tests of sound transmission loss on a 1.48 m x 1.23 m specimen have been carried out according to standards ISO 10140 parts 1, 2, 4 [5] in the EcamRiCert S.r.1. Laboratory. In order to avoid leakages a Perennator TX 2001 S sealant has been used between the wood frame and the plate as indicated in ISO 10140-1 annex D. Sound pressure levels in the source and receiving rooms have been measured by using L&D 824 and the
reverberation time by means of the interrupted noise method. During the measurement survey, the structural loss factor of the entire plate was also measured by using the structural reverberation time method using equation 2. A picture of the measurement set-up is depicted in Figure 2. 4. Results and discussions
reverberation time by means of the interrupted noise method. During the measurement survey, the structural loss factor of the entire plate was also measured by using the structural reverberation time method using equation 2. A picture of the measurement set-up is depicted in Figure 2. 4. Results and discussions
Fig. 4. Experimental values of loss factor; a) average values for different boundary conditions; b) frequency dependent values for clamped beams. From the results of the impulse measurements it is possible to observe that the damping is lower than 0.30 for all the tested clamped beams. Figure 6 represents a comparison between the mean loss factors for clamped and free suspended beams and the clamped plate. It is interesting to confirm that, apart from the cases when the acoustic PVB is used, damping from free suspended beams is too low if compared with the beams of the plate. In addition, the loss factors from the clamped beams quite satisfactorily represent the damping of the measured plates.
Fig. 4. Experimental values of loss factor; a) average values for different boundary conditions; b) frequency dependent values for clamped beams. From the results of the impulse measurements it is possible to observe that the damping is lower than 0.30 for all the tested clamped beams. Figure 6 represents a comparison between the mean loss factors for clamped and free suspended beams and the clamped plate. It is interesting to confirm that, apart from the cases when the acoustic PVB is used, damping from free suspended beams is too low if compared with the beams of the plate. In addition, the loss factors from the clamped beams quite satisfactorily represent the damping of the measured plates.
Fig. 5. Comparison between Measured and theoretical Transmission loss: (1) 44.2 glazing plate, (2) 66.4 glazing plate.
Fig. 5. Comparison between Measured and theoretical Transmission loss: (1) 44.2 glazing plate, (2) 66.4 glazing plate.
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Materials EngineeringMechanical EngineeringAcousticsMaterials ScienceClassical PhysicsPackaging EngineeringLaminated GlassElectrical and Electronics EngineeringTransmission Lossloss factor
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