Structural health monitoring of an adhesive disbond through electromechanical impedance spectroscopy

Abstract The aerospace industry continues to increase the use of adhesives for structural bonding due to the increased joint efficiency (reduced weight), even distribution of the load path and decrease in stress concentrations. However, the limited techniques for verifying the strength of adhesive bonds has reduced its use on primary structures and requires an intensive inspection schedule. This paper discusses a potential structural health monitoring (SHM) technique for the detection of disbonds through the in situ inspection of adhesive joints. This is achieved through the use of piezoelectric wafer active sensors (PWAS), thin unobtrusive sensors which are permanently bonded to the aircraft structure. The detection method utilized in this study is the electromechanical impedance spectroscopy, a local vibration method. This method detects disbonds from the change in the mechanical impedance of the structure surrounding the disbond. This paper will discuss how predictive modeling can provide valuable insight into the inspection method, and provide better results than purely empirical methods will provide. A method for identifying the appropriate frequency range and sensor locations is presented, and the method was verified experimentally using a large aluminum test article, and included both pristine and disbond coupons.

[1]  Mohammad I. Albakri,et al.  Electromechanical impedance–based damage characterization using spectral element method , 2017 .

[2]  Victor Giurgiutiu,et al.  Electro-Mechanical Impedance Method for Crack Detection in Thin Plates , 2001 .

[3]  Venu Gopal Madhav Annamdas,et al.  Electromechanical impedance of piezoelectric transducers for monitoring metallic and non-metallic structures: A review of wired, wireless and energy-harvesting methods , 2013 .

[4]  Peter Cawley,et al.  The impedance method of non-destructive inspection , 1984 .

[5]  Xinlin Qing,et al.  A real-time active smart patch system for monitoring the integrity of bonded repair on an aircraft structure , 2006 .

[6]  V. Giurgiutiu,et al.  Disbond detection with piezoelectric wafer active sensors in RC structures strengthened with FRP composite overlays , 2003 .

[7]  Fotis Kopsaftopoulos,et al.  Adhesive bond-line degradation detection via a cross-correlation electromechanical impedance–based approach , 2016 .

[8]  Wing Kong Chiu,et al.  Disbond detection in adhesively bonded composite structures using vibration signatures , 2006 .

[9]  Michael A. Sutton,et al.  Predictive modeling of electromechanical impedance spectroscopy for composite materials , 2012 .

[10]  Wei Yan,et al.  Structural Health Monitoring Using High-Frequency Electromechanical Impedance Signatures , 2010 .

[11]  Craig A. Rogers,et al.  Coupled Electro-Mechanical Analysis of Adaptive Material Systems — Determination of the Actuator Power Consumption and System Energy Transfer , 1994 .

[12]  Fotis Kopsaftopoulos,et al.  Bondline Integrity Monitoring of Adhesively Bonded Structures via an Electromechanical Impedance Based Approach , 2015 .

[13]  Suresh Bhalla,et al.  Structural impedance based damage diagnosis by piezo‐transducers , 2003 .

[14]  F. A. Silber,et al.  ULTRASONIC TESTING OF MATERIALS , 1978 .

[15]  Robert D. Adams,et al.  A Vibration Technique for Non-Destructively Assessing the Integrity of Structures: , 1978 .

[16]  Robert D. Adams,et al.  The location of defects in structures from measurements of natural frequencies , 1979 .

[17]  Christian Hochard,et al.  Monitoring of Laminated Composites Delamination Based on Electro-Mechanical Impedance Measurement , 2004 .

[18]  A. Baker,et al.  Towards a practical structural health monitoring technology for patched cracks in aircraft structure , 2009 .

[19]  Victor Giurgiutiu,et al.  Characterization of Piezoelectric Wafer Active Sensors , 2000 .

[20]  Wei Yan,et al.  Monitoring interfacial defects in a composite beam using impedance signatures , 2009 .

[21]  A. A. Khalil,et al.  Non-destructive testing of adhesively bonded joints using vibrational analysis , 1991 .