Author(s): Mecking Simon, Schoenwald Stefan, Schanda Ulrich
In multistory buildings the use of Cross Laminated Timber (CLT) is increasing. Therefore, sound insulation requirements have to be met and the prediction of sound insulation for this construction type is necessary. With the exception of low frequencies, Statistical Energy Analysis (SEA) is used in building acoustics for this purpose, which requires material properties as input data.\nThe material characterisation of Cross Laminated Timber is a challenge. On the one hand, the composite material consists of several layers of boards; on the other hand, wood itself is inhomogeneous, anisotropic and has a low shear modulus. Differences in the manufacturing process such as the use of glue and grooves also have an impact on the overall rigidity of the plate.\nA characterisation based on thin plate theory is insufficient for the frequency range of building acoustics.\nOne possibility to address this challenge is the experimental determination of frequency dependent phase velocities of flexural waves in a plate that account for the above-mentioned effects. From the wave velocities the modal density used in SEA can be calculated very efficiently. This contribution focus on the time-of-flight method and phase difference method to determine phase velocities. In a case study, the direction-dependent global stiffness parameters were determined using first shear deformation theory. The measurement conditions and evaluation procedures are discussed.
Name: Mr Simon Mecking