Research On Damage Identification Of Plate Structure Based On Piezoelectric Impedance Technique

With the rapid development of structural health monitoring in civil engineering,more and more methods are used to monitor structural damage,and the impedance method is one of them.At present,few research is conducted on the structural health monitoring of plate structures,the damage quantification and localization of plate structures is still an important problem to be solved.In this paper,the PZT is pasted on the surface of aluminum plate,reinforced concrete plate and concrete segment.The impedance method is employed for structural damage detection of different damage cases with a new damage indicator.Comprehensive study of theoretical analysis and experiment study of the impedance method are used for damage quantification and localization.Some conclusions are drawn as follows:Firstly,the theory of impedance method in damage detection is summarized.The researchers detect the damage of different structures using the impedance method,and design a lot of experiments to explore the principles and techniques of the impedance measurement techniques,such as testing the signal level,frequency,temperature,voltage,wire length,the bonding layer thickness,PZT size and performance.And the structural damage is quantified and assessed.In the derivation of the formula of piezoelectric impedance theory,the coupling of PZT and the main structure is considered and suitable dynamic stiffness are chosen.This makes the theoretical result closer to the actual performance of the structure,and the structural damage is able to be quantified and localized through analysis of the measured data.Secondly,by pasting PZT on the surface of a structure,the impedance method is studied for the structural damage localization and quantification.By using the damage indices RMSD and CC to determine the damage magnitude,the damage location was determined by plotting the distribution range of the damage indices.And a new damageindex Ry/Rx is proposed,it increases with the increase of the structural damage.In addition,the closer the tested element to the damage,the larger the damage index,which can be used for better damage localization and quantification.Thirdly,the aluminum plate and concrete slab are pasted with enough piezoelectric plates,and various damage conditions are set to identify the damage.The impedance method is conducted to detect the damage of two kinds of material,and it is found that t for concrete slab,compared with the aluminum plate,the change of damage index is small,the test data has a little deviation from the real result,but obvious to the change of damage depth.At the same time,the influence of temperature is taken into consideration,and the influence of temperature on the damage index is obvious,but has certain rules.And the temperature can be reduced by means of temperature compensation.In addition,the damage index distribution map can be used to analyze and determine the damage location.Last,Damage experiments of concrete lining segments are simulated.The damage condition is simulated by loosening the bolts.It is found that with the increase of the angle of bolt looseness,the damage index curve increases significantly,thus indicates the increase of the degree of the damage;Moreover,the PZT damage index near the bolt is large,and the location of the damage can be roughly determined from the damage index profile.The second type of damage is simulated by setting the slot.The damage of three slots is set,and the damage quantification and damage localization are performed by analyzing the measured data.However,there are some errors,so further research should be conducted on the selection of PZT quantity.The experimental data show that the influence of concrete damage on depth is more obvious than that of length,and the location of damage can be roughly determined by the regional distribution of damage index.