Numerical Simulation Of Damage Detection For PZT Based Reinforcement Steel Rebar Using The Method Combining Explicit And Implicit Algorithms

The structural health monitoring(SHM) based on smart material piezoelectric ceramics(PZT) and guided stress waves is under wide investigations and interests in recent decades, the piezoelectric ceramics material(PZT) can be used as actuator and sensor at the same time for its piezoelectric effect, and its advantages such as structural stability, low cost,easy machining, high dielectric constant and piezoelectric constant provide a practical technical mean to the inner structural damage detection and time-real health monitoring.The complication of stress wave propagation in the practical concrete structure and the piezoelectric effect of PZT lead to the enormous difficulties of analytical analysis for structural damage detection mechanism, the PZT-reinforced concrete beam component in 2D using the electromechanical coupling analysis function of finite element software was simulated and analyzed in the preliminary study. To discuss the propagation of stress wave in the structure, and then provide theoretical guidance to the engineering practice and the related experimental study, the combination of implicit and explicit methods has been proposed in the complicated 3D numerical simulation for PZT-reinforced concrete beam component usingANSYS/LS-DYNA in this thesis, the major research work includes:(1) The structural health monitoring in civil engineering,the material properties of piezoelectric ceramics(PZT) and the basic principle of guided stress wave are introduced. Then the influence of the different concrete thicknesses and epoxy thicknesses on sensor output are further analyzed to improve the 2D numerical simulation of PZT-reinforced concrete beam component.(2)Introduce two kinds of algorithms for the dynamic numerical analysis(explicit algorithm and implicit algorithm) and compare the advantages and disadvantages of both kinds; To make the 3D numerical simulation closer to the practical engineering of PZT-reinforced concrete beam component, a new kind of finite element method is proposed, which combines both the implicit and explicit algorithms.(3)Based on the preliminary test and 2D numerical simulation, the 3D finite element model of steel rebar with PZT is established, and then the numerical analysis is conducted--using ANSYS/LS-DYNA to verified the feasibility. The 3D numerical simulation method is validated by comparing with the 2D results; The model was optimized by changing the embed modes of PZT to enhance the sensor output and to solve the problem of weak signals.(4)Based on the simulation of PZT-steel rebar, the numerical model for PZT-reinforced concrete component with different debonding sizes are established, and the finite analysis results are compared with the test data.Further discussion is made on the influence of sensor output caused by the asymmetric concrete with different coverage thicknesses on the rebar and the different structural layout.(5)Summarise the main research results and put forward the prospects of future research directions.