Improving accuracy of damage quantification based on two-level consistency control of PZT layers

Structural health monitoring-based quantitative damage diagnosis technique plays a key role in real-time condition monitoring.Among the current research,piezoelectric(PZT)sensor and Guided Wave(GW)based damage quantification methods are promising,which normally establish a calibration model between GW feature and damage degree by experiments on batch specimens,and then conduct the calibration model on the monitored specimen.However,the accuracy of PZT and GW based damage quantification is affected by dispersion introduced by sensor network performance,structural material,and damage propagation among the adopted batch specimens.For improving the accuracy of damage quantification,this paper adopts PZT layer as sensor network and creatively implements theoretical and experimental research on batch PZT layers consistency control.On one hand,a two-level consistency control method based on multidimensional features-Euclidean distance is proposed to ensure the performance consistency of PZT layers placed on different specimens.On the other hand,experimental research on typical aircraft lug structures is also carried out to evaluate the requirement on performance consistency of PZT layers when performing quantitative damage diagnosis,and further verify the proposed two-level consistency control method.Experimental results show that the accuracy of damage quantification raises by 38% when the dispersion of different PZT layers is controlled within 5%.

Robust H_∞ guaranteed cost satisfactory fault-tolerant control for discrete-time systems with quadratic D stabilizability

The problem of robust H∞ guaranteed cost satisfactory fault-tolerant control with quadratic D stabilizability against actuator failures is investigated for a class of discrete-time systems with value-bounded uncertainties existing in both the state and control input matrices.Based on a more practical and general model of actuator continuous gain failures,taking the transient property,robust behaviour on H∞ performance and quadratic cost performance requirements into consideration,sufficient conditions for the existence of satisfactory fault-tolerant controller are given and the effective design steps with constraints of multiple performance indices are provided.Meanwhile,the consistency of the regional pole index,H∞ norm-bound constraint and cost performance indices is set up for fault-tolerant control.A simulation example shows the effectiveness of the proposed method.