Fiber reinforced composite laminates are increasingly replacing traditional metallic materials The manufacturing process and service of the composite laminates frequently lead to delamination Vibration analysis is an integral part of most engineering structures In the present article we provide a relevant survey on the various analytical models and numerical analyses for the free vibration of delaminated composites A basic understanding of the influence of the delamination on the natural frequencies and the mode shapes of composite laminates is presented In addition, other factors affecting the vibration of the delaminated composites are discussed Particular attention is given to composite laminates having piezoelectric sensors and actuators, and ones subjected to axial loadings

Vibration of Delaminated Composite Laminates: A Review

Nonlinear ultrasonic wave modulation for online fatigue crack detection

An overview of layerwise theories for composite laminates and structures: Development, numerical implementation and application

Vibrations of straight and curved composite beams: A review

The paper reviews the recent applications of piezoelectric materials in structural health monitoring and repair conducted by the authors. First, commonly used piezoelectric materials in structural health monitoring and structure repair are introduced. The analysis of plain piezoelectric sensors and actuators and interdigital transducer and their applications in beam, plate and pipe structures for damage detection are reviewed in detail. Second, an overview is presented on the recent advances in the applications of piezoelectric materials in structural repair. In addition, the basic principle and the current development of the technique are examined.

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Applications of piezoelectric materials in structural health monitoring and repair: selected research examples

A novel structural health monitoring (SHM) methodology, based on nonlinear wave modulation spectroscopy, is presented for the detection of delamination cracks in composites. The basic element is a novel active nonlinear acousto-ultrasonic piezoelectric sensor enabling low-cost and wide-frequency operational bandwidth. The active sensor configuration involves two piezoceramic wafer actuators, each one excited with a low- and high-frequency signal respectively, and a piezoceramic sensor, all permanently bonded on the tested structure. Experiments are conducted on two sets of composite strips containing delamination cracks of different sizes. Measured results illustrate first the efficiency of the nonlinear ultrasonics methodology to detect delamination cracks, as well as, the potential and benefits of the new active sensor. The sensitivity of the active sensor response to the crack size and the applied high-frequency carrier signals at the actuators, vary at various frequency and voltage levels indicating t...

Delamination detection in composites using wave modulation spectroscopy with a novel active nonlinear acousto-ultrasonic piezoelectric sensor:

A shear beam finite element for the damping analysis of tubular laminated composite beams

Experimental and analytical studies are presented investigating the effect of delamination cracks on the low-frequency dynamic response of composite beam specimens with surface attached piezoelectric actuators and sensors. Frequency response functions of laminated beams with piezoceramic actuators and piezoelectric sensors having single delamination cracks of various sizes are measured. Comparisons with mechanical actuation–accelerometer sensor configurations illustrate the sufficiency and advantages of piezoelectric actuator–sensor pairs in self-monitoring the effects of delamination on the dynamic response. Modal frequencies and damping values of the beams are also measured and their dependence on delamination size is studied. Comparisons with analytically predicted results are shown. Finally, the sensitivity of damage indices based on changes in modal frequency, modal damping, and modal peak density to the crack size is quantified.

https://iopscience.iop.org/article/10.1088/0964-1726/13/4/011/pdf

Assessing the effects of delamination on the damped dynamic response of composite beams with piezoelectric actuators and sensors

Generalized layerwise mechanics for the static and modal response of delaminated composite beams with active piezoelectric sensors

The paper presents a brief description of composite damping mechanics for blade sections of arbitrary lamination and geometry. A damped 3-D shear beam element is presented enabling the assembly of damped structural dynamic models of blades with hollow multi-cell tubular laminated sections. Emphasis is placed to the inclusion of composite material coupling effects, first in the blade section stiffness and damping matrices and finally into the stiffness and damping matrices of the finite element. Evaluations of the beam element are presented, to quantify the material coupling effect on composite beams of simple box sections. Correlations between predicted and measured modal frequencies and damping values in small model Glass/Epoxy are also shown. Finally, the damped modal characteristics of a 35m realistic wind-turbine blade model design, are predicted.

https://iopscience.iop.org/article/10.1088/1742-6596/75/1/012076/pdf

Nikolaos A. Chrysochoidis

Papers

Delamination detection in composites using wave modulation spectroscopy with a novel active nonlinear acousto-ultrasonic piezoelectric sensor:

A shear beam finite element for the damping analysis of tubular laminated composite beams

Assessing the effects of delamination on the damped dynamic response of composite beams with piezoelectric actuators and sensors

Generalized layerwise mechanics for the static and modal response of delaminated composite beams with active piezoelectric sensors

Damped structural dynamics models of large wind-turbine blades including material and structural damping