HEALTH MONITORING AND DAMAGE IDENTIFICATION OF COMPOSITE STRUCTURES

Thesis (Ph.D.), Department of Civil and Environmental Engineering, Washington State UniversityStructural health monitoring and damage identification method for composite beams and plate-type structures were studied in this dissertation, especially for fiber-reinforced plastic (FRP) sandwich beams and deck panels. A literature review showed that research on 2-D damage identification method for plate-type structure is relatively limited.Two vibration-based methods were presented for damage identification of plate-type of structure. First, the 2-D continuous wavelet transform (CWT)-based method was proposed for damage localization. Then, a strain energy-based Damage Severity Correction Factor (DSCF) method was proposed for damage localization and quantification. In this method, a damage location factor matrix and a damage severity correction factor matrix could be generated from the curvature mode shape of a plate and then be used for damage localization and quantification.A structural health monitoring strategy was proposed for FRP sandwich panels using the combination of experimental modal testing technique and damage identification method. Using this strategy, the two proposed methods were applied to an as-manufactured FRP sandwich deck panel for damage identification. The 2-D CWT-based strategy used an accelerometer and an impact hammer modal testing system, while the DSCF-based strategy adopted a polyvinylidence fluoride (PVDF) sensor network and an impact hammer system. The application of 2-D CWT method on mode shape data from experimental modal analysis showed that it could effectively indicate the location and area of damage in a FRP sandwich plate-type structure. The application of DSCF-based damage identification method on curvature mode shape data from the FE/experimental modal analysis shows that it could not only effectively indicate the location of damage but also approximate the damage severity in a FRP sandwich plate-type structure.The free vibration of cantilevered sinusoidal core sandwich beams was investigated based on a high-order sandwich beam theory. The results were compared with Timoshenko's beam theory, numerical simulation and experimental test results to illustrate the improvement of the high-order approach. The temperature effect on dynamic response of FRP sandwich beams/panels was also studied for condition assessment. A series of FRP sandwich beams and an as-manufactured FRP sandwich panel were investigated for dynamic response change under temperature effect based on the material data obtained from dynamic mechanical analysis.Department of Civil Engineering, Washington State Universit