Vibration Performance And Optimization Design Of Viscoelastic Damping Material And Partial Constrained Damping Structure

Currently,the research on viscoelastic damping materials and their constrained damping structures has been widely carried out.However,due to the fact that the constrained layer and the damping layer cannot be completely covered on the base layer in the actual engineering,the traditional constrained damping structure cannot be widely applied.In this paper,the vibration performance of the partial constrained damping structure was studied and the structure was optimized.Firstly,it was studied that the basic properties and dynamic mechanical properties of two viscoelastic damping materials as damping layers.Then the aluminum plate experiment was conducted to study the factors that affect the vibration of partial constrained damping structure,including the fraction of coverage of constrained layer and damping layer and the thickness of damping layer.Finally,based on its optimal area coverage of 80%,the influence from the larger thickness of damping layer to the vibration performance of the partial constrained damping mortar was studied,and then the damping layer was arranged in sections,and the optimized design of the structure was realized by changing the shear strain field in the damping layer.And the influence of the number and position of the incisions on the vibration performance of the structure was explored.The basic properties of the viscoelastic damping materials showed that the Qtech T501 and Qtech T413 damping materials had densities of 1.136g/cm~3 and 0.995 g/cm~3respectively.Both materials were lightweight materials,therefore,the damping effect of the structure can be increased under the premise of ensuring structural stability;the gel time and dry time of the two materials were short,and the solid content was low,which were all high solid content fast curing materials,so that the thickness can be achieved in one construction;the hardness of the two materials was small,but the toughness was strong,so that it was ensured that brittle fracture does not occur when it and the material having a relatively high rigidity constitute a damping structure.The DMA study results showed that the loss factor was 0.642 in the temperature and frequency range of this experimental study,indicating that the material had good energy dissipation characteristics.At the same frequency,as the temperature increases,the storage modulus of Qtech T413 material decreased and eventually stabilized,while the loss modulus first rised and then droped rapidly after peaking at-25°C.When the temperature was constant,the material storage modulus and loss modulus increased with the increase of frequency.The above can explained that the viscoelastic damping material used in this experiment had the advantages of wide glass transition region,obvious damping effect and wide application range,and can be used as a damping layer of the structure in practical engineering.The vibration performance of the aluminum plate with partial constrained damping structure showed that in the sample with the same constrained layer and damping layer,as the thickness of the damping layer increased from 0.3mm to 0.7mm,the composite loss factor of the sample increased continuously,and both the maximum amplitude of vibration acceleration and the vibration acceleration total value were reduced.The high drop rate was maintained at all times,and the total value was reduced by 1.97dB.It indicated that the damping properties of the sample continued to improve as the thickness of the damping layer increases.In addition,when the thickness of the damping layer was constant,the laying area of the sample constraining layer and the damping layer was increased from 40%to 100%,the maximum amplitude of vibration acceleration of each group of samples was reduced.When the laying area increased from 40%to 80%,the decline rate can reach 21.8%,and from 80%to 100%,the decline rate was only 4.9%,the downward trend was slow.The variation law of composite loss factor and vibration acceleration were basically consistent,and the vibration acceleration total value took the lowest value of 131.54 dB when the laying area was80%.Considering factors such as engineering cost and damping efficiency,0.7mm was selected as the optimum damping layer thickness for the experiment,and 80%was the best area coverage for the experiment.The vibration performance of the mortar with partial constrained damping structure showed that the vibration acceleration,the total vibration acceleration value and the composite loss factor all showed that the damping performance of the sample can be significantly improved when the damping layer thickness was increased from 1mm to2mm.While the thickness of the damping layer was increased to 3 mm,the damping performance improvement of the sample was not obvious.In addition,the shear deformation in the damping layer can be enlarged by opening the incision,so that the vibration can be effectively suppressed,and the optimization effect was most obvious when the incision passes through the center of the structure.In several ways of opening the incision,according to the improvement of vibration acceleration,vibration acceleration total value and composite loss factor,the number of incisions from high to low was 3>1>4>2,and the damping effect of the 3 and 1 incision samples was significantly better than the 4 and 2 incisions and the samples without the incision..Considering the factors such as engineering cost and damping efficiency,the 2mm damping layer was selected as the optimal damping layer thickness of the structure.Among the four schemes for opening the incision,the scheme with three incisions was the best.