Damage Detection For Timber Joints Based On Piezoelectric Sensing Technology

As a traditional material that is widely used in ancient and modern buildings,timber is green,renewable,and easy to process.As the key bearing part of timber structures,timber joints are subject to complex forces and suffer from different degrees of damages such as loosening,rotting,cracking,and chipping.This weakens the overall strength,stiffness,and stability of the structure and reduces the service life of timber structures.Therefore,it is necessary to perform health monitoring and damage detection for timber joints to ensure the overall safety and reliability of timber structures.In recent years,the active sensing monitoring technology based on piezoelectric ceramic sensors has been widely used in damage detection and health monitoring within the civil engineering field.However,little research has been conducted on the damage of timber structures,especially the key parts,timber joints.In this paper,the author conducts a research on damage detection of timber joints based on the piezoelectric active sensing technology.The research includes both numerical simulation and relevant experiments.Firstly,the author introduces the current status of domestic and international research on and the basic theory of the piezoelectric active sensing technology.Then,the author uses Abaqus to establish numerical models of typical timber joints and performs numerical simulation of the timber joint damage detection based on the piezoelectric active sensing technology.Typical timber joints include mortise and tenon joints and bolted joints.During the numerical simulation,the author analyzes the relationship between the signal energy collected by piezoelectric ceramic sensors in the receiving end and the damage degree of timber structures,decomposes the signals received by piezoelectric patches by wavelet packets,and then uses the sum of the signal energy of each frequency band as an energy indicator for quantitative evaluation of different damage conditions.This proves the validity and feasibility of the piezoelectric active sensing technology in detecting the damage of timber joints.In addition,based on the finite element analysis,the author carries out an experiment on the damage detection of timber joints by using the piezoelectric active sensing technology,studies five typical methods of timber joints,analyzes the signal energy collected by piezoelectric ceramic sensors in the receiving end,and then uses an energy indicator to analyze the damage degree of timber structures in a quantitative manner.The energy indicator is obtained after the analysis by using the wavelet packet energy method.The experimental results are consistent with the numerical simulation results,which verifies the validity and feasibility of the piezoelectric active sensing technology in detecting the damage of timber joints.The back propagation(BP)neural network is established and trained to detect the damage degree and type of mortise and tenon joints.