Study On Viscoelastic Damping Material And Damping Property Of Rectangular Bosses Constrained Damping Structure

The study in viscoelastic damping material and damping capacity of constrained layer damping structure has been important to the vibration and noise reduction field of railway transport.In this paper,damping performance of Qtech 413 viscoelastic damping material(self-developed and produced by Qingdao university of technology)and traditional plate constraint damping structure which damping layer was made of with that material had been studied.In order to optimize the topology of the traditional plate constrained damping structure,the bending degree of the rectangular boss is changed on the base layer of the traditional plate constrained damping structure,and the damping performance of the rectangular boss constrained damping structure is discussed.Firstly,to illustrate that Qtech 413 viscoelastic damping material is suitable for the constrained layer damping layer,this paper introduces the preparation of viscoelastic damping material,and then describes the basic properties such as curing strength,tensile strength,elongation at break,hardness and damping properties.Secondly,made model analysis on damping capacity of traditional plate constraint damping structure and rectangular bosses constrained damping structure,which influenced by the damping layer thickness of the structural parameter variable,i.e.H,was researched,and the influence of the damping layer thickness and the ratio of the height of the rectangular bosses to the thickness of the base layer,i.e.?,on damping capacity of rectangular bosses constrained damping structure was further analyzed.That also has been provided a basis for the design of the single point hammer test scheme.Finally,the damping performance of the above two constrained layer damping structures was studied through composite loss factor,vibration acceleration level value and the time domain waveform spectrum got by the single point hammer test,and compared the results with the result got by the finite element analysis.The specific conclusions are as follow:(1)It is proved that this material has better mechanical spraying performance through the research that damping performance of Qtech 413 viscoelastic damping material.And its maximum material loss factor is about 0.6 that showed the viscoelasticity of damping material would be better and under dynamic deformation its energy loss should be higher.The viscoelastic damping material has good damping effect,it could be used as the damping layer of constrained layer damping structure.(2)In the scope of this study,according to the analysis of compound loss factor by finite element simulation,the maximum composite loss factor value(0.327)of rectangular bosses constrained damping structure was obtained when the damping layer thickness is 6mm and the ratio of the height of the rectangular bosses to the thickness of the base layer is 1/8.And compered the resulte to the maximum composite loss factor(0.221)of the traditional plate restrained damping structure was increased by 48.0%.The finite element simulation results show that the bending wave number of the overall structure can be changed by rectangular bosses constrained damping structure.And it could obviously improve the damping performance of traditional plate restrained damping structure and improved the damping efficiency of Qtech 413 viscoelastic damping materials.(3)The results obtained from ANSYS15.0 finite element modal analysis of the variation rule of the maximum displacement of traditional plate constraint damping structure and rectangular bosses constrained damping structure in the displacement cloud map were consistent with the results obtained from the composite loss factor?It is further proved that the influence of vibration response on the damping performance of the structures,and the maximum displacement of the two damped structures decreases gradually from mid-span to the constraint end.(4)The analysis of the composite loss factor,vibration acceleration level value and the time domain waveform spectrum obtained by single point hammer test showed that the best value of rectangular bosses constrained damping structure 's damping performance achieved the best results when the damping layer thickness is 6mm and the ratio of the height of the rectangular bosses to the thickness of the base layer is 1/8,which is consistent with the results obtained by using finite element simulation software.In addition,the best compound loss factor of rectangular bosses constrained damping structure obtained by Single point hammer test was 0.329,and that results by finite element simulation analysis was 0.327.And the range between the two approaches was 0.8%,showed a high goodness of fit.Within the scope of this study,it can be considered that the finite element modeling and modal analysis method adopted in this paper has high practical guidance value,and the modeling method adopted in this paper can be used to establish relevant models to conduct modal analysis on the damping performance of large structures to guide the research on the influence of structural vibration and noise reduction in engineering practice.The above conclusions provide a follow-up experimental basis for the application of Qtech 413 viscoelastic damping materials in the constrained layer damping structure,and prove that rectangular bosses constrained damping structure can make better use of the damping properties of this material than traditional plate constraint damping structure.It provides a new research direction for topology optimization of constrained damping structure and parameter variable setting,and provides a research foundation for rectangular bosses constrained damping structure's application in the field of vibration and noise reduction.