METHOD FOR SELECTING AN INTERLAYER FOR VIBROACOUSTIC DAMPING, INTERLAYER FOR VIBROACOUSTIC DAMPING AND GLAZING UNIT COMPRISING SUCH AN INTERLAYER

The invention relates to a method for selecting a viscoelastic plastic interlayer comprising two outer layers and a central layer and intended to be incorporated between two glass sheets of a glazing unit, the method comprising the following steps: first and second components intended to constitute respectively the central layer and the outer layers are provided; the shear modulus G′ of the first and second components is measured; the material of the second component is selected only if G′ 3×107 Pa at 20° C. and between 100 Hz and 240 Hz; and the thickness h of the first component is set so that h 0.3 mm and so that g=G′/h is between 8×108 Pa/m and 2.67×109 Pa/m at 20° C. and between 100 Hz and 240 Hz. The invention makes it possible to optimize the damping of the second and third natural frequencies of a vehicle windshield without weighing down the windshield.