Final Report Summary - PAM (the Physics of Acoustic Materials)
See attached file "IEF publishable summary PAM project, Aug 2014.pdf" for the below text including the illustrations.
Light-weight materials are increasingly used by European industry. For example, Airbus has built the largest composite airplane in the world, and BMW has introduced the first car in the world with a composite body (the BMW i3). Also in the built environment, composite and light-weight materials are more often used. Composite materials and light-weight materials in general evidently have both ecological and economic advantages. However, in terms of acoustic comfort and structural dynamic behavior, composite materials pose high design challenges to the manufactures of cars, airplanes, buildings, etc. Often counter measures need to be taken, such as the use of add-on treatments, to keep the acoustics at acceptable comfort levels, with adverse effects in terms of weight, costs, etc. The Physics of Acoustic Materials (PAM) project focusses on the acoustic characterization of poro-elastic materials, composite materials and light-weight structures that are used in aerospace, automotive and building industry. Acoustic characterization of materials is an essential step for the optimal use of these materials when designing cars, airplanes, buildings etc. In addition, knowledge of the physical principles behind the properties of newly developed materials allows the development of materials with even better (acoustic) properties. Clearly, the characterization of materials is of interest to both the industrial sectors that apply materials and the industrial sectors that develop materials.
In the PAM project, the material properties were determined by sending a structural wave through the material and measuring the dynamic response of the material at a large number of points. Combining the measurement data with physical models that describe the wave propagation through materials, the group and phase speeds of the structural waves in the material were determined. The data on the speeds of the structural waves allowed the extraction of material parameters that are useful for the engineer. Furthermore, in the PAM project research was done in the field of acoustic perception, which is highly relevant for the optimization of materials in terms of their acoustic properties, and in the field of the characterization of the crack resistance of composite materials. To illustrate the research outcome of the PAM project, a number of research examples are given.
1) The frequency and temperature dependent material properties, and the shear modulus in particular, of poro-visco-elastic materials were investigated. Results are shown in Figure 1 (see attached "IEF publishable summary PAM project, Aug 2014.pdf").
2) A measurement device to determine the crack resistance of composite materials by means of a newly proposed method is illustrated in Figure 2 (see attached "IEF publishable summary PAM project, Aug 2014.pdf").
3) The determination of the material properties of building materials requires specific attention when it comes down to the measurement of the response of a building material to acoustic fields in a reverberant room. One requirement is that that the record length needs to be larger than the reverberation time of the structural–acoustic system to avoid serious errors in the frequency response function estimate. Results of this research are illustrated in Figure 3. 0 (see attached "IEF publishable summary PAM project, Aug 2014.pdf").
4) Finally, psycho-acoustic listening tests revealed that the cognitive meaning of the acoustic stimuli, in terms of recognition of sound or speech, did not play a significant role in the perceived loudness of sound transmitted through light-weight structures, but that the presence or dynamics of modulations, or the semantics of the sound in terms of their nature (music, rhythm, source, …) do play a role in people’s loudness perception (Figure 4) (see attached "IEF publishable summary PAM project, Aug 2014.pdf").
Contact details:
N.B. (Bert) Roozen, PhD
KU Leuven, Dep. of Physics and Astronomy KU Leuven, Lab. of Acoustics and Thermal Physics, Dep. of Mechanical Engineering, Division Production engineering, Machine design and Automation (PMA)
Celestijnenlaan 200 D 3001 Leuven, Belgium Tel: +32 16 32 7840
Email: bert.roozen@kuleuven.be
Light-weight materials are increasingly used by European industry. For example, Airbus has built the largest composite airplane in the world, and BMW has introduced the first car in the world with a composite body (the BMW i3). Also in the built environment, composite and light-weight materials are more often used. Composite materials and light-weight materials in general evidently have both ecological and economic advantages. However, in terms of acoustic comfort and structural dynamic behavior, composite materials pose high design challenges to the manufactures of cars, airplanes, buildings, etc. Often counter measures need to be taken, such as the use of add-on treatments, to keep the acoustics at acceptable comfort levels, with adverse effects in terms of weight, costs, etc. The Physics of Acoustic Materials (PAM) project focusses on the acoustic characterization of poro-elastic materials, composite materials and light-weight structures that are used in aerospace, automotive and building industry. Acoustic characterization of materials is an essential step for the optimal use of these materials when designing cars, airplanes, buildings etc. In addition, knowledge of the physical principles behind the properties of newly developed materials allows the development of materials with even better (acoustic) properties. Clearly, the characterization of materials is of interest to both the industrial sectors that apply materials and the industrial sectors that develop materials.
In the PAM project, the material properties were determined by sending a structural wave through the material and measuring the dynamic response of the material at a large number of points. Combining the measurement data with physical models that describe the wave propagation through materials, the group and phase speeds of the structural waves in the material were determined. The data on the speeds of the structural waves allowed the extraction of material parameters that are useful for the engineer. Furthermore, in the PAM project research was done in the field of acoustic perception, which is highly relevant for the optimization of materials in terms of their acoustic properties, and in the field of the characterization of the crack resistance of composite materials. To illustrate the research outcome of the PAM project, a number of research examples are given.
1) The frequency and temperature dependent material properties, and the shear modulus in particular, of poro-visco-elastic materials were investigated. Results are shown in Figure 1 (see attached "IEF publishable summary PAM project, Aug 2014.pdf").
2) A measurement device to determine the crack resistance of composite materials by means of a newly proposed method is illustrated in Figure 2 (see attached "IEF publishable summary PAM project, Aug 2014.pdf").
3) The determination of the material properties of building materials requires specific attention when it comes down to the measurement of the response of a building material to acoustic fields in a reverberant room. One requirement is that that the record length needs to be larger than the reverberation time of the structural–acoustic system to avoid serious errors in the frequency response function estimate. Results of this research are illustrated in Figure 3. 0 (see attached "IEF publishable summary PAM project, Aug 2014.pdf").
4) Finally, psycho-acoustic listening tests revealed that the cognitive meaning of the acoustic stimuli, in terms of recognition of sound or speech, did not play a significant role in the perceived loudness of sound transmitted through light-weight structures, but that the presence or dynamics of modulations, or the semantics of the sound in terms of their nature (music, rhythm, source, …) do play a role in people’s loudness perception (Figure 4) (see attached "IEF publishable summary PAM project, Aug 2014.pdf").
Contact details:
N.B. (Bert) Roozen, PhD
KU Leuven, Dep. of Physics and Astronomy KU Leuven, Lab. of Acoustics and Thermal Physics, Dep. of Mechanical Engineering, Division Production engineering, Machine design and Automation (PMA)
Celestijnenlaan 200 D 3001 Leuven, Belgium Tel: +32 16 32 7840
Email: bert.roozen@kuleuven.be
