A guided-wave system for monitoring the wing skin-to-spar bond in unmanned aerial vehicles

Unmanned Aerial Vehicles (UAVs) are being increasingly used in military as well as civil applications. A critical part of the structure is the adhesive bond between the wing skin and the supporting spar. If not detected early, bond defects originating during manufacturing or in service flight can lead to inefficient flight performance and eventual global failure. This paper will present results from a bond inspection system based on attached piezoelectric disks probing the skin-to-spar bondline with ultrasonic guided waves in the hundreds of kilohertz range. The test components were CFRP composite panels of two different fiber layups bonded to a CFRP composite tube using epoxy adhesive. Three types of bond conditions were simulated, namely regions of poor cohesive strength, regions with localized disbonds and well bonded regions. The root mean square and variance of the received time-domain signals and their discrete wavelet decompositions were computed for the dominant modes propagating through the various bond regions in two different inspection configurations. Semi-analytical finite element analysis of the bonded multilayer joint was also carried out to identify and predict the sensitivity of the predominant carrier modes to the different bond defects. Emphasis of this research is based upon designing a built-in system for monitoring the structural integrity of bonded joints in UAVs and other aerospace structures.

[1]  J. Rose,et al.  Ultrasonic Guided Waves For NDE of Adhesively Bonded Structures , 1995 .

[2]  Victor Giurgiutiu,et al.  Embedded Self-Sensing Piezoelectric Active Sensors for On-Line Structural Identification , 2002 .

[3]  Bruce W. Drinkwater,et al.  Non–destructive testing of adhesively–bonded joints , 1999 .

[4]  Lowe,et al.  The transmission of Lamb waves across adhesively bonded lap joints , 2000, The Journal of the Acoustical Society of America.

[5]  Tribikram Kundu,et al.  Guided Waves in Multilayered Plates for Internal Defect Detection , 1998 .

[6]  Keith Worden,et al.  DAMAGE DETECTION USING OUTLIER ANALYSIS , 2000 .

[7]  Christian Boller,et al.  Health Monitoring of Aerospace Structures , 2003 .

[8]  S. Finnveden.  Evaluation of modal density and group velocity by a finite element method , 2004 .

[9]  Brian Culshaw,et al.  Surface-bonded optical fibre sensors for the inspection of CFRP plates using ultrasonic Lamb waves , 1996 .

[10]  Sébastien Grondel,et al.  The propagation of Lamb waves in multilayered plates: phase-velocity measurement , 1999 .

[11]  Z. Chang,et al.  Scattering of Lamb waves from a rivet hole with edge cracks , 1999 .

[12]  G. Tomlinson,et al.  Wavelet signal processing for enhanced Lamb-wave defect detection in composite plates using optical fiber detection , 1997 .

[13]  M. Lowe,et al.  Guided waves energy velocity in absorbing and non-absorbing plates , 2001 .

[14]  L. Gavric.  Computation of propagative waves in free rail using a finite element technique , 1995 .

[15]  Wei Zhao,et al.  Piezoelectric wafer active sensor embedded ultrasonics in beams and plates , 2003 .

[16]  Laurence J. Jacobs,et al.  Propagation of guided waves in adhesive bonded components , 2002 .

[17]  Hyunjo Jeong,et al.  Analysis of plate wave propagation in anisotropic laminates using a wavelet transform , 2001 .

[18]  Zensheu Chang,et al.  A semi-numerical method for elastic wave scattering calculations , 2000 .

[19]  Hoon Sohn,et al.  Wavelet-based active sensing for delamination detection in composite structures , 2004 .

[20]  F. Chang,et al.  Identifying Delamination in Composite Beams Using Built-In Piezoelectrics , 1995 .

[21]  S. Rokhlin.  Lamb wave interaction with lap-shear adhesive joints : theory and experiment , 1991 .

[22]  Zensheu Chang,et al.  Lap-joint inspection using plate waves , 1996, Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring.

[23]  J. Rose,et al.  Guided wave dispersion curves for a bar with an arbitrary cross-section, a rod and rail example. , 2003, Ultrasonics.

[24]  B. S. Wong,et al.  Experimental evaluation of delaminations in composite plates by the use of Lamb waves , 1995 .

[25]  J.L. Rose,et al.  Guided wave nuances for ultrasonic nondestructive evaluation , 2000, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[26]  Joseph L. Rose,et al.  Rapid Inspection of Composite Skin-Honeycomb Core Structures with Ultrasonic Guided Waves , 2003 .

[27]  G. Neau,et al.  Propagation of Lamb waves in anisotropic and absorbing plates: Theoretical derivation and experiments , 2002 .

[28]  Francesco Lanza di Scalea,et al.  Propagation of ultrasonic guided waves in lap-shear adhesive joints: case of incident a0 Lamb wave. , 2004 .

[29]  R. Badcock,et al.  The use of 0-3 piezocomposite embedded Lamb wave sensors for detection of damage in advanced fibre composites , 2000 .

[30]  Zongqi Sun,et al.  A phased array guided wave approach to adhesive bonding structural integrity analysis , 2003 .

[31]  M. Castaings,et al.  Guided waves propagating in sandwich structures made of anisotropic, viscoelastic, composite materials. , 2003, The Journal of the Acoustical Society of America.