Damage Detection in Glass/Epoxy Laminated Composite Plates Using Modal Curvature for Structural Health Monitoring Applications

Abstract

This paper deals with detection of macro-level crack type damage in rectangular E-Glass fiber/Epoxy resin (LY556) laminated composite plates using modal analysis. Composite plate-like structures are widely found in aerospace and automotive structural applications which are susceptible to damages. The formation of cracks in a structure that undergoes vibration may lead to catastrophic events such as structural failure, thus detection of such occurrences is considered necessary. In this research, a novel technique called as node-releasing technique in Finite Element Analysis (FEA), which was not attempted by the earlier researchers, is used to model the perpendicular cracks (the type of damage mostly considered in all the pioneering research works) and also slant cracks (a new type of damage considered in the present work) of various depths and lengths for Unidirectional Laminate (UDL) ([0]S and [45]S) composite layered configurations using commercial FE code Ansys, thus simulating the actual damage scenario. Another novelty of the present work is that the crack is modeled with partial depth along the thickness of the plate, instead of the through the thickness crack which has been of major focus in the literature so far, in order to include the possibility of existence of the crack up to certain layers in the laminated composite structures. The experimental modal analysis is carried out to validate the numerical model. Using central difference approximation method, the modal curvature is determined from the displacement mode shapes which are obtained via finite element analysis. The damage indicators investigated in this paper are Normalized Curvature Damage Factor (NCDF) and modal strain energy-based methods such as Strain Energy Difference (SED) and Damage Index (DI). It is concluded that, all the three damage detection algorithms detect the transverse crack clearly. In addition, the damage indicator NCDF seems to be more effective than the other two, particularly when the detection is for damage inclined to the longitudinal axis of the plate. The proposed method will provide the base data for implementing online structural health monitoring of structures using technologies such as Machine Learning, Artificial Intelligence, etc.

Structural Health Monitoring in Composite Structures: A Comprehensive Review

“…For more information about using MCM for damage detection in composite structures, the readers are referred to [ 150 ].…”

Experimental Detection and Measurement of Crack-Type Damage Features in Composite Thin-Wall Beams Using Modal Analysis

“…An experimental investigation was carried out using a square steel plate of 560 mm × 560 mm × 3.2 mm; two accelerometers were used to measure vibrations in the structure, and the size of the damaged analyzed was 80 mm × 80 mm. Govinddasamy et al [ 12 ] used the modal curvature (MC) technique for the detection of large crack-type damage features with sizes of 25 mm, 75 mm, and 125 mm in a plate structure with a length of L = 500 mm and a width of W = 250 mm. The experimental work was performed with an accelerometer and an impact hammer.…”

Impact performances and failure modes of glass fiber reinforced polymers in different curvatures and stacking sequences

“…The resin infuses through the porous fabric preform with a pressure gradient which is made by the vacuum. 17–24 The vacuum infusion process, which is a practical and successful method, was used in this study. GFRPs are used as straight or curved shapes practically in industry.…”