Experimental Study On Weld Crack Damage Monitoring Of Steel Pipe Truss Arch Structure Based On Piezoelectric Ceramics

In recent years,steel pipe truss arch structures have been widely used in various modem buildings due to their beautiful shape and reasonable force.With the diversified and complicated style and function of the truss arch structure,the safety of the truss arch structure has become a major problem to be solved.Weld quality is an important criterion for measuring the safety of steel truss arch structures.Due to the large number of structural welds,difficult welding operations,and various welding processes,tihere is great uncertainty in the reliability and safety of welds.Therefore,in order to be able to detect the safety hazard of the weld in time and ensure the health of the truss arch,it is especially important to realize the real-time damage identification and health monitoring of the weld.In this paper,the experimental study on crack damage monitoring of steel truss arch welds based on piezoelectric impedance method and piezoelectric wave method is proposed.The specific research contents are as follows:(1)Summarize the advantages and disadvantages of the existing weld crack damage detection technology,and introduce the application of current piezoelectric ceramic impedance method and wave method in the field of structural health monitoring.Subsequently,the development of piezoelectric ceramics,the basic properties of piezoelectric ceramics,the basic theory of piezoelectric impedance method and the basic theory of piezoelectric wave method are described in detail,which provides the necessary theoretical basis for the experimental development.(2)Aiming at the crack damage of steel truss arch welds,a crack detection metfhod based on piezoelectric impedance method is proposed.Taking the square steel truss triangular arch which is applied to the tunnel support in the actual project as the experimental test piece,two piezoelectric ceramic sensors are arranged at the predetermined position to collect the electromechanical coupling admittance under different damage degrees.The test results show that the conductance nano-curve shifts downward with the increase of weld crack damage;the conductance and susceptance show the same sensitivity to structural loading;the conductance damage of the structure is more than that of susceptance.Sensitive;through the analysis of the admittance curve and the damage index,the damage state of the weld crack can be initially identified by the change of the admittance curve,and the damage index can be used to accurately determine the static loading size and the degree of weld crack damage.judgment.(3)Aiming at the crack damage of steel truss arch welds,a crack detection method based on piezoelectric wave method is proposed.The square steel pipe truss triangular arch used in the tunnel support is used as the experimental test piece,and six piezoelectric ceramic sensors are arranged at predetermined positions,and the sensor response signals under different weld crack damage degrees are recorded,and then based on wavelet The packet theory calculates and analyzes the response signal.The experimental results show that with the increase and deepening of weld cracks,the amplitude and wavelet packet energy of the piezoelectric ceramic sensor show a decreasing trend.With the increase of external load,the amplitude and amplitude of the time domain signal of the piezoelectric ceramic sensor The energy of the wavelet packet shows an increasing trend;the position of the weld crack can be accurately positioned by properly arranging the piezoelectric ceramic sensor.