Putsmier viscoelastic damping material has excellent effect in vibration reduction and noise reduction, and is widely used in aerospace, ship, vehicle and other fields. The constrained damping structure has a strong ability of vibration reduction and noise reduction, especially the constrained damping structure with a new polymer damping material as the damping layer. At present, the main research results and applications are single-layer constrained damping structure. In some special projects, the single-layer constrained damping structure is often difficult to meet the needs, so it is necessary to study the vibration and noise reduction performance of multi-layer constrained damping structure. Based on the subway test section, the viscoelastic damping material and its multi-layer constrained damping structure are studied.
The experimental results are as follows: 1
(1) Firstly, the density, drying time, solid content, mechanical properties, hardness and dynamic mechanical properties of damping materials are studied. The results show that the density of viscoelastic damping material is 0.9652, the gel time is 170.7s, the dry time is 13.3min, the dry time is 32min, the solid content is as high as 94.06%, the tensile property of the material increases gradually with the increase of curing days, and finally stabilized at about 7.62Mpa; the elongation at break decreases gradually with the increase of curing days, and the final stability is about 358%. The hardness gradually increased with the increase of curing days, and basically stabilized at about a57 after 15 days. At a certain frequency, the storage modulus of viscoelastic damping materials decreases with the increase of temperature; at a certain temperature, the storage modulus of materials increases with the increase of frequency, the loss factor of materials increases first and then decreases with the increase of temperature, and under the influence of temperature and frequency, the peak position of the loss factor of materials is different.
(2) Secondly, through the experimental study of multi-layer constrained damping ceramic tile plate, the damping performance of different layers of constrained damping structure is compared and analyzed by using the self spectrum analysis module, double path spectrum analysis module and time domain analysis module of DASP analysis software. The results show that with the increase of the structure from undamped to 1, 3 and 7 layers, the composite loss factor increases gradually, but the increasing range decreases gradually, which is 0.054, 0.052 and 0.037 in turn. After reaching 3 layers, the increasing range of the loss factor decreases obviously. With the increase of the number of damping layers, the total value of vibration acceleration gradually decreases, which is 142.20, 134.49, 131.06 and 128.83, respectively. When it reaches three layers, the increase amplitude obviously decreases. The results show that the three damping layers are ideal.
(3) Through experiments, the performance of multi-layer and single-layer constrained damping structures are compared. The results show that for the same thickness of damping material, the first-order composite loss factor increases by 0.039 and the vibration acceleration level decreases by 1.64db for the three-layer 1mm damping layer structure compared with the one-layer 3mm damping layer structure; the first-order composite loss factor increases by 0.051 and the vibration acceleration level decreases by 4.63db for the seven layer 1mm damping layer structure compared with the one-layer 7mm damping layer structure. Therefore, the damping performance of multi-layer constrained damping structure is better than that of single-layer constrained damping structure.
(4) Finally, through the experimental study of damping wall and concrete wall, and using the time domain analysis module and the time domain analysis module of DASP analysis software, the damping performance of damping wall and concrete wall and damping wall with the number of layers is compared. The results show that the loss factor of damping wall is significantly higher than that of concrete wall.  The average value of the first-order loss factor of each layer of the damping wall is 0.197, and the first-order loss factor of each layer of the concrete wall is 0.143. Compared with the concrete wall, the first-order loss factor of the damping wall increases by 0.054 as a whole. Compared with the concrete wall, the vibration acceleration of the first floor of the damping wall decreased by 2.75db, that of the second floor by 12.38db, that of the third floor by 6.32db and that of the seventh floor by 6.67db. Taking the total level value of vibration acceleration of each floor on the right side as an example, the total level value of vibration acceleration of the first, third, fifth and seventh floors on the right side decreased by 10.02db, 1.5dB and 0.55db in turn. The attenuation time of damping wall is less than that of concrete wall, and the vibration amplitude of each layer is lower than that of concrete wall, and the attenuation time of damping wall decreases with the increase of damping layers. Based on the above experimental research, the performance difference between multi-layer and single-layer constrained damping structures is obtained, and the optimal damping number of multi-layer constrained damping structures is determined, which provides basic data and theoretical support for the practical application of multi-layer constrained damping structures.