The measurement of dynamic Young's modulus and the loss factor are two essential parameters for improve the sound insulation of materials.
It is easier to measure the mechanical parameters of materials in static mode. However, dynamic measurement is essential to understand their behavior in acoustic insulation.
Static analysis focuses on a single value. While acoustics requires a study over multiple frequencies. Thus, in addition to mass and thickness, the dynamic Young's modulus and the loss factor directly influence the critical frequency as well as the magnitude of the sound insulation at this frequency.
The critical frequency is an essential parameter in acoustics. It corresponds to the frequency at which a material ceases to provide good sound insulation. This critical frequency is determined by several factors, including the mass of the material, its dynamic Young's modulus and its loss factor. When sound waves reach this frequency, they are coupled to the bending waves of the material, thus reducing the effectiveness of the sound insulation. This is why understanding and controlling the critical frequency is essential in the design of high-performance materials.
To obtain these parameters, materials are excited at different frequencies to evaluate their intrinsic characteristics. ISO 16940 (as well as NF EN 16703 for plasterboards) describes a precise method for obtaining the flexural rigidity modulus, Young's modulus and the loss factor.
The principle is based on vibrating "bars" of the material using a vibrating pot equipped with an impedance head (which measures force and acceleration, and therefore mobility). The bar is subjected to fixed-free boundary conditions, which allows the appearance of bending modes to be observed.
For each resonance frequency of these modes, the stiffness moduli and the loss factor are calculated using the -3dB bandwidth method. This approach allows to obtain an accurate and reliable measurement of the dynamic properties of the materials.
The measurement of dynamic Young's modulus is widely used in research and development to identify the mechanical parameters of materials. In factories, quality controls also use this measurement to ensure the conformity of products in production.
More specifically, several products require this measurement:
In summary, to understand materials and to design them better, the dynamic Young's modulus is essential. This approach makes it possible to optimize their acoustic insulation performance and ensure consistent quality. An essential asset for the innovation and efficiency of insulation materials!
See also: the description of our ImpacTool dynamic stiffness measurement solution
