Delamination Identification of Composites using Normalized Modal Curvature and Image Processing

Abstract

Delamination in FRP composites causes a considerable reduction in the transverse load carrying capacity, which is a major apprehension to the aerospace and automotive industries. Because of comparatively low cost and the flexibility of measurement. Modal analysis based damage identification in the composite materials is usefully employed in structural health monitoring. Using normalized modal curvature the delamination location detection is discussed in this paper. For the intact and delaminated composite, numerical modal analysis is performed using ANSYS-ACP. Modal parameters (frequency and mode shape) are extracted from the simulated composite plate. Modal curvature at each node is calculated by double differentiation of mode shape deformation. Damage Index (DI) is formulated using the modal curvature of intact and delaminated composite plates. Analyzing DI at each node of the plate region delamination is identified. Damage Index based delamination identification validated with Image Processing technique. The proposed approaches successfully identify the delamination position and size of the composites.

Effect of Temperature on Damage Identification of Laminated Composite by Means Numerical Methods

“…Mode shapes obtained as a result of Finite Element Analysis (FEA) can be used to determine modal curvatures by central difference approximation. [1] Mathematically, X and Y axis-directed modal curvatures are [6];…”

“…Absolute change in modal curvature is calculated as [6]; (9) It is known that the damage to the composite laminate causes alterations in the mechanical characteristics of the composite lamina. For this reason, in case of damage to the composite…”

“…Due to the presence or extent of damage, the modal curvatures of a damaged composite structure may alter [5]. Between modal curvatures, there is a noticeable variation in plate structure due to intrinsic degradation, particularly delamination [6]. For damage detection, modal curvatures in a predetermined intact reference state are compared with modal curvatures in a damaged structure [6].…”

“…Between modal curvatures, there is a noticeable variation in plate structure due to intrinsic degradation, particularly delamination [6]. For damage detection, modal curvatures in a predetermined intact reference state are compared with modal curvatures in a damaged structure [6]. The modal curvature difference serves as an indicator used to determine the location and extent of damage [7].…”