Damage Detection of Textile Composite Structures Using the Piezoelectric Impedance Method

摘要

Structural health monitoring of aerospace structures is becoming vital aslightweight composite materials are increasingly used in aero-structures. Compositeshave various types of failure modes, which make it even more important to identifydamage compared to isotropic materials. Therefore, on-site health monitoring is one ofthe most preferred methodologies for detecting internal crack or damage at its initialstage to enhance operating safety and reduce repair cost. Recently, piezoelectrictransducers are on high demand for on-site health monitoring because of its highbandwidth sensitivity. They simultaneously perform as actuators and sensors andembedded on the structure. The electrical impedance or admittance changes accordingto modification in mass, stiffness or damping properties of the host body. In this study,plain-weave textile composites are utilized to demonstrate capability of piezoelectrictransducer. The elastic properties of composite are determined using the ConcentricCylinder Assemblage micromechanics model. Finite element modeling is done inANSYS APDL to observe electrical admittance variation around natural frequency.Delamination and intra-ply damage cases are studied. Delamination is separation ofadjacent plies and damage is reduction of stiffness in the whole structure. Modalfrequency of the structure decreased with delamination and damage level incrementwithin the body. Pre-preg manufacturing method is carried out to fabricate compositepanel from which samples are cut for testing according to ASTM standards.Piezoelectric test provided voltage drop across the resistor that denoted the couplingeffect of the patch with the host structure. Electrical admittance plot expressedresponse to body deformation actuated by the piezoelectric transducer. Results fromfinite element modeling and experimentation assert that piezoelectric impedancetechnique is efficient in detecting damage or delamination within the compositestructure.