A European standard “EN 29052-1 Acoustics - Determination of dynamic stiffness - Part 1: Materials used under floating floors in residential buildings” describes a test method for determining the dynamic stiffness of flexible materials used under floating floors.
Dynamic stiffness is one of the parameters that determine the sound insulation of such floors in residential buildings. This standard applies to the determination of the dynamic stiffness per unit area of smooth-surfaced flexible materials used as a continuous layer under floating floors in residential buildings. Loads less than 0,4 kPa (e.g. materials in wall cladding) or greater than 4 kPa (e.g. materials under machine foundations) are outside the scope of this standard.
This standard is primarily intended to be used to compare production samples of similar materials of known specified quality. The limitations on the air flow resistance of the flexible material to be tested are described in this standard.
The dependence of dynamic stiffness on prestatic load is generally insignificant in the case of materials applied in wall coverings, for example polystyrene or mineral fibre. According to this standard, the differences between the dynamic stiffness values measured with a static load of 2 kPa and those measured with a very low preload are of the order of 10 to 20 per cent.
The other part of the EN 29052 standard deals with the determination of the dynamic stiffness of materials used in technical floating floors (high static load).
For the purposes of this standard, the following terms and definitions apply:
Determination of the apparent dynamic stiffness per unit area of the test specimen by a resonance method in which the resonance frequency is measured, which is in principle the fundamental vertical vibration of a spring-mass system, where the spring is the test specimen of the flexible material being tested and the mass is a load plate.
The specimen shall be placed between two horizontal surfaces, i.e. between the base (or base plate) and the load plate. The load plate shall be 200 mm plus/minus 3 mm x 200 mm plus/minus 3 mm square and made of steel. The base or base plate and the load plate shall have profile irregularities of less than 0,5 mm and shall be sufficiently rigid to prevent bending waves in the frequency range of interest. The drive shall be applied by one of the methods shown in the figures given in the standard. The total load on the test specimen, including all measuring or driving equipment, shall be 8 kg plus/minus 0,5 kg. The drive and measuring equipment shall be applied in such a way that only vertical oscillations occur.
For the test setup shown in the figure, the inertia of the base should be such that its velocity in vibration is negligible compared to the velocity of the load plate. For the test setups shown in the figures, the mass of the base plate should be at least 100 kg.
Three square samples of at least 200 mm x 200 mm shall be taken as test samples. If the surface irregularities are less than 3 mm, the surfaces of the test samples shall be considered smooth. The test sample shall be covered with a 5 mm thick waterproof plastic foil to which a thin layer of plaster and water paste has been applied to a depth of at least 0,02 mm, so that any irregularities are covered. Before the plaster begins to harden, the load plate shall be placed on it as shown in the figures. In the case of closed-cell materials, the joint between the sample and the base or base plate shall be sealed around its perimeter with a petroleum jelly filling.
The resonant frequency of the fundamental vertical vibration of the test specimen and the load plate can be determined using sinusoidal, white noise or pulse signals. All these methods are equivalent. In case of disagreement, the method using sinusoidal signals is accepted as the reference method.
For sinusoidal signals, the resonance frequency is obtained by changing the frequency excitation while keeping the driving force constant. If the dimensions of the resonance frequency depend on the amplitude of the excitation force, this dependence should be determined to the lowest possible value and the resonance frequency should be found by extrapolation to the zero force amplitude. Depending on the expected hardness value, the measurement range used as the basis for extrapolation should be as described in the standard. Within these measurements, measurements should be taken at least at three points. When testing materials with high internal damping, the vertical vibration maximum is not obvious. In this case, resonance can be detected by observing the phase shift between the excitation and the vibration signal.
Our organization, which has been trying to support businesses from every sector with its testing, measurement, analysis and evaluation studies carried out in a wide range for years, has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. In this context, testing services are also provided to businesses in accordance with the standard “EN 29052-1 Acoustics - Determination of dynamic hardness - Part 1: Materials used under floating floors in residences”.
To get an appointment, to get more detailed information or to request an evaluation, you can ask us to fill in our form and reach you.
