Study On Vibration Property Of The Viscoelastic Matereials And Slotted Stand-off Structure

Viscoelastic damping materials have been widely used in shipbuilding,aerospace and other aspects for vibration reduction treatment.The slotted stand-off structure had been used in some aerospace fields for vibration and noise reduction.In this paper,the basic properties and related dynamic mechanical properties of viscoelastic damping material called Qtech T501 have been studied.Then through the vibration test experiment,the free damping structure,the unslotted stand-off free damping structure(referred to as the unslotted stand-off structure)and the slotted stand-off free damping structure(referred to as the slotted stand-off structure)have been studied under the conditions of cantilever support and free support constraints.And their change law of damping performance have been studied at the same time.Finally,the influence of the stand-off layer,the width of the slot and the number of the stand-off layer n the damping performance of the free damping structure were analyzed.Firstly,the basic properties and damping properties of Qtech T501 viscoelastic damping materials were studied,including curing time,density,hardness,tensile properties,tear properties,adhesion and dynamic mechanical properties of viscoelastic damping materials.Qtech T501 had a solid content of 98.01%and a density of 0.955g/cm~3.It was a lightweight,high-solid content and environmentally friendly material.The gelation time and curing time of the material were short,and the adhesion also meeted the corresponding requirements and the construction requirements;The tensile strength,elongation at break and tear strength indicated that the material is tacky.The test called DMA of the material showed that the loss factor and storage modulus of the damping material were greatly affected by temperature and frequency,and the influence of temperature is the most important factor.When the temperature was 80°C,The loss factor of the material was up to 0.53.When the frequency was constant,the loss factor and the loss modulus of the material generally increased firstly and then decreased as the temperature increases,while the storage modulus showed an overall decreasing trend.As the frequency increased,the three relationship curves tended to shift to the right.The experimental results of cantilever support conditions showed that the insertion of the stand-off layer can significantly improve the damping performance of the free-damping structure.For the model with different groove widths,when the groove width of the model was increased from 10mm to 30mm,the damping performance of the model structure firstly decreased and then increased,and the overall damping performance appeared as a"concave"shape.The different order composite loss factors of the model and the peak vibration response of different orders all showed this trend.Among them,the optimal groove width is 30mm,followed by 10mm.When the slot width was 10mm,the number of slots increased from 2 to 10,and the damping performance of the model structure was on the rise.Compared with the model of two slots,the damping performance of the model of 10 slots was the largest.When the slot width was30mm,the number of slots increased from 2 to 10,and the damping performance of the model structure tended to decrease.Compared with the model of 10 slots,the damping performance of the model of 2 slots is the largest.As the number of slots increased,the variation of the damping performance of the 10mm model and the 30mm model was exactly the opposite.Therefore,the optimum number of slots is 10 when the groove width is 10 mm,and the number of optimal grooves is 2when the groove width is 30 mm.The results of free support conditions showed that the damping performance of the unslotted stand-off structure model was greatly improved compared with the free damping structure.When the slot width was 10mm,the number of slots increased from2 to 10,and the damping performance of the model structure increased with the number of slots.Compared with the model of 2 slots,the damping performance of the model of10 slots was the largest.Therefore,the optimal number of slots is 10.The results of comparative study of different support conditions showed that the insertion of the stand-off layer will significantly improve the damping performance of the free damping structure.The damping variation of the model with a slot width of 10mm was the same.Due to the different support modes,the composite loss factor,the vibration response peak value and the eigenvalues of the various indicators measured by the total value will be greatly different,but the overall change trend of the damping performance of the model structure was basically the same.The trend was that with the increase of the number of slots,the damping performance of the model structure was continuously improved,and the model had the best damping performance with a number of slots of 10.