Research on Vibration Isolation and Thermal Insulation of Two Types of Sandwich Panels with Band Gaps
|School||Beijing Jiaotong University|
|Course||Bridge and Tunnel Engineering|
|Keywords||Periodic sandwich panels Stop band(band gap) Vibration isolation Equivalent thermal conductivity Thermal insulation|
Periodic composite structures (PCSs) are made of two or more elastic materials periodically with characteristics of stop bands (band gaps), in which vibrations cannot propagate in the PCSs. As a special type of PCSs, periodic sandwich panels can be designed according to the material parameter and structure parameter to isolate or attenuate the vibrations for some certain frequencies. Besides, foam materials with low thermal conductivity inside the sandwich panels can improve the performance of thermal isolation, so that the periodic sandwich panels can meet the requirements of law carbon and energy saving. This kind of periodic sandwich panels with the performances of both vibration isolation and thermal insulation has an important academic significance and application value.By using the finite element method, vibrations in sandwich panels with cross-shaped periodic ribs and sandwich panels with cylinder-shaped periodic tubes are investigated in detail and the influence of the core’s geometrical parameter on band gaps is discussed. Besides, the equivalent thermal conductivities of these two kinds of sandwich panels have been calculated both numerically and theoretically and the influence of the core’s geometrical parameter on the equivalent thermal conductivities is also discussed. And last, the thermal performance tests of the polystyrene-filled sandwich panels with cylinder-shaped periodic tubes for four cases of different height have been finished. The results show that:1. The sandwich panels with cross-shaped periodic ribs and sandwich panels with cylinder-shaped periodic tubes have the characteristics of stop bands. The size of the ribs or tube has an effect on both the position and the width of band gaps. The longer the ribs are or the larger the tube’s radius is, the higher the frequencies of stop gaps will be. The width of the stop gap first increases and then decreases with the increasing of the length of the ribs or with the enlarging of the tube’s radius.2. The polystyrene-filled sandwich panels with cross-shaped ribs and sandwich panels with cylinder-shaped periodic tubes have a nice ability of thermal insulation. The size of the ribs or tube has an effect on thermal insulation. When the thickness of the top and bottom panels is constant, the equivalent thermal conductivities of the sandwich panels increase with the enlarging of the thickness of ribs or tubes. And the smaller the thickness of the top and bottom panels is, the more obvious the change is. When the total thickness of the sandwich panels is a constant, the equivalent thermal conductivities of the sandwich panels will decrease first and then increase with increasing of the thickness of the top and bottom panels.3. Thermal performance tests of the polystyrene-filled sandwich panels with cylinder-shaped periodic tubes for four cases of different height show that this kind of sandwich panels has a good performance in thermal insulation, and the experimental results agree well with the numerical solutions.