Identification of Multiple Cracks in Composite Laminated Beams Using Perturbation to Dynamic Equilibrium.

Aimin Deng,Wei Xu,Qitian Lu,Maosen Cao

doi:10.3390/s21186171

Abstract

Identification of cracks in beam-type components is significant to ensure the safety of structures. Among the approaches relying on mode shapes, the concept of transverse pseudo-force (TPF) has been well proved for single and multiple crack identification in beams made of isotropic materials; however, there is a noticeable gap between the concept of TPF and its applications in composite laminated beams. To fill this gap, an enhanced TPF approach that relies on perturbation to dynamic equilibrium is proposed for the identification of multiple cracks in composite laminated beams. Starting from the transverse equation of motion, this study formulates the TPF in a composite laminated beam for the identification of multiple cracks. The capability of the approach is numerically verified using the FE method. The applicability of the approach is experimentally validated on a carbon fiber-reinforced polymer laminated beam with three cracks, the mode shapes of which are acquired through non-contact vibration measurement using a scanning laser vibrometer. In particular, a statistic manner is utilized to enable the approach to be feasible to real scenarios in the absence of material and structural information; besides, an integrating scheme is utilized to enable the approach to be capable of identifying cracks even in the vicinity of nodes of mode shapes.

Highlights

Initial cracks in beam-type structural components can develop to significant extents subject to long-term transverse loads, jeopardizing local stiffness against bending moments, by which structural failures can be induced [1]
Numerical Results As higher-order mode shapes are more sensitive to local damage [17], the third, fourth, and fifth mode shapes of the carbon fiber-reinforced polymer (CFRP) laminated beam are selected in this study for
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Summary

Introduction

Initial cracks in beam-type structural components can develop to significant extents subject to long-term transverse loads, jeopardizing local stiffness against bending moments, by which structural failures can be induced [1]. The concept of TPF has been widely investigated for single and multiple crack identification in beams made of isotropic materials, its applications in composite laminated beams are hindered owing to the absence of prior knowledge of complex structural and material parameters. To fill this noticeable gap between the concept of TPF and identification of cracks in composite laminated beams, an enhanced approach is proposed in this study, which relies on perturbation to the dynamic equilibrium of a composite laminated beam.

Identification of Multiple Cracks Using Perturbation to Dynamic Equilibrium

Numerical Verification

Experimental Results