Study On Preparation And Structure Properties Of PMN/CB/PU Piezoelectric Damping Material

Piezoelectric damping composite which can realize the transformation of mechanical energy,electric energy,thermal energy and the response to the external environment is a kind of damping material with wide application prospect.Due to the elastic modulus of simple viscoelastic damping material is not high,it does not meet the strength requirements of the specific application.We usually use the viscoelastic damping material and the high strength structure to form a composite structure,which greatly expands the application range of the damping material.Using the polyurethane elastomer as matrix,PMN piezoelectric ceramic and conductive carbon black?CB?as the functional filler,prepare the piezoelectric damping composite by casting method.Then we use steel sheet as a grass-roots,aluminum layer as a constraint and PMN/CB/PU piezoelectric damping material as a damping layer to prepare constrained damping structure.When the volume fraction of PMN piezoelectric ceramic is 30%,the tensile strength of the composite reaches the maximum,which shows good mechanical properties.The dielectric constant and dielectric loss of the composite shows a nonlinear increasing with the addition of the piezoelectric ceramic filler.When the volume fraction of PMN increases from 0%to 40%,the dielectric constant of the composite increases from 4.8 to 20.5,and the dielectric loss increases from 0.033 to0.046.The piezoelectric strain constant d₃₃3 of the composite also shows a rising trend.The damping performance of the PMN/PU piezoelectric damping composite is best when the content of PMN is 30%,the maximum loss factor can reach 0.818,and it has a wider damping temperature range.With the addition of conductive carbon black,the mechanical properties and the resistivity of PMN/CB/PU piezoelectric damping material decrease,the dielectric constant and dielectric loss show upward trend.when the content is 7%,it reaches the percolation threshold f_C,the composite has the maximum loss factor and wide damping temperature range,peak of damping factor is 0.902,showing the good damping performance.The 180°peeling strength of the constrained damping structure is 6.49KN/m,which indicates the strong interfacial bonding ability between the damping layer and the structure layer.With the increasing of piezoelectric damping layer thickness of constrained damping structure,structural loss factor increases gradually,structural resonant frequency decreases.When the thickness of the damping layer is 2mm?3.3mm?5mm?8mm,the first-mode and second-mode structural loss factor of composite respectively increases from 0.19559 to 0.3017,from 0.15858 to 0.27529,the first-mode and second-mode structural resonance frequency of composite respectively decreases from 52.5Hz to 41.5Hz,from 290Hz to 220Hz.