Glazing unit with improved vibro-acoustic damping properties, method for making such glazing unit and method for acoustic protection in a vehicle passenger compartment

A method of manufacturing a glazing unit for reducing acoustic and vibratory nuisance in a passenger compartment of a vehicle, or an automobile including such a glazing unit, the method comprising:

• joining at least one vibro-acoustic damping strip to the glazing unit, the strip including at least one element made of damping material having a loss factor of at least 0.4 and a Young's modulus at 20° C. of less than 200 MPa, for frequencies below 5000 Hz, and at least one weighting element having a linear mass of at least 0.05 kg/m fastened onto only a face of the damping element on an opposite side from the glazing unit;
• adapting a cross section of the element made of damping material, the section being defined by a width L being a shorter side of the element made of damping material in contact with the glazing unit and by a thickness e normal to the glazing unit, according to the Young's modulus of the damping material, such that the equivalent linear stiffness K′eq of the damping element satisfies, at a targeted particular frequency fp, the criterion:
• K
• eq
• ′
• ρ
• v
• ⁢
• e
• v
• ⁢
• λ
• p
• ⁢
• ω
• p
• 2
• <
• 1
• 2
• where
• ⁢
• :
• K
• eq
• ′
• =
• E
• ′
• ⁢
• L
• e
• in which:
• E′ is the Young's modulus of the damping material at 20° C. and at the frequency fp;
• L is the width of the damping element in contact with the glazing unit;
• e is the dimension of the damping element normal to the glazing,
• and in which:
• ρv is the density of the material of which the glazing unit is made;
• ev is the thickness of the glazing unit;
• ωp is the target angular frequency at the particular frequency fp defined by ω=2πfp;
• and
• λp is the wavelength in the glazing unit corresponding to the particular frequency fp and defined in a known manner by:
• λ
• p
• =
• 2
• ⁢
• π
• ⁢
• E
• v
• ′
• ⁢
• e
• v
• 2
• 12
• ⁢
• (
• 1
• -
• v
• v
• 2
• )
• ⁢
• ρ
• v
• ⁢
• ω
• p
• 2
• 4
• and in which E′v and νv are the Young's modulus and the Poisson's ratio of the material of which the glazing unit is made, respectively;
• and
• fastening the strip onto the glazing unit via a face of the element made of damping material on an opposite side of a face fixed to the weighting element, no other device being joined to the strip.