Influence of low-velocity impact-induced delamination on electrical resistance in carbon fiber-reinforced composite laminates

Abstract

In this paper, experiments have been performed and finite element models have been developed for studying the influence of low-velocity impact damage on the four-probe electrical resistance of carbon fiber-reinforced polymer matrix laminates. Sixteen-ply and 32-ply AS4/3501-6 laminates with quasi-isotropic layup were analyzed. Electrical resistance was evaluated using a four-step procedure. First, finite element models were created in Abaqus Finite Element Analysis (FEA) for simulating low-velocity impact using a quasi-static loading approach. Second, matrix rupture in the inside plies was evaluated, and delamination analysis was performed at the corresponding interfaces to determine delamination patterns. Third, four-probe electrical finite element models were developed in Abaqus FEA for specimens before and after impact using the concept of effective conducting thickness and the delamination patterns obtained from the delamination analysis. Effects of the low-velocity impact delamination on four-probe top and oblique electrical resistance were studied. Electrical resistance predictions were compared to the experimental data. Both top and oblique resistance planes were sensitive to presence of delamination with the oblique resistance measurement being more sensitive as compared to the top resistance measurement. In addition, the resistance of the 16-ply specimens was more greatly affected by the delamination compared to the 32-ply specimens. The proposed analysis can be utilized for design of carbon fiber-reinforced polymer matrix composites with optimized damage sensing capabilities.

Damage detection and location in woven fabric CFRP laminate panels

“…2 An alternative way, which may be more natural, to obtain a smart material is to use composite material constituents as a sensor [19,20,21,22]. This is highly possible in carbon fibre reinforced polymers (CFRP) since they consist at least two elements; carbon fibre which is highly conductive (its conductivity 25 is 1500 S /m and matrix that is highly insulating, (for example the electrical conductivity of the epoxy matrix is 10 −11 S /m to 10 −13 S /m.…”

The role of electrical anisotropy and effective conducting thickness in understanding and interpreting static resistance measurements in CFRP composite laminates

“…For example, electrical measurements have been previously used for detecting impact, flexure, fatigue, and other loads. 1–10 The primary focus of the damage detection studies was on investigating the relationship between mechanical damage and the resulting changes to electrical resistance of the CFRP material. It was determined that fiber breakage leads to a reduction in fiber-direction electrical conductivity, whereas fiber–matrix debonding reduces conductivity transverse to fiber direction in-plane and through-thickness.…”

“…The detection and identification of internal damage are further complicated by current spreading. 9 However, in the resistance method, 1,2,10–17 current source and voltage measurement electrodes are placed along a single line, and, thus, resistance of the composite can be calculated using Ohm’s law. The measurement of voltage in line with the current source yields greater sensitivity in identifying damage, compared to the potential method.…”

“…Using this anisotropic resistivity model and 6-probe experimental method, the true electrical resistivity can be determined for any desired coordinate system. The model was successfully applied to CFRP laminates 10,22 in order to experimentally determine the electrical resistivity of a unidirectional CFRP composite in the three principle directions. The experimental study showed that the electrical resistivity perpendicular to the fiber direction was influenced by the volume fraction of fibers and clusters of contact points between adjacent fiber bundles.…”

“…The current study develops a robust method for determining directional resistivities of CFRP composites. This paper expands upon the methods of Hart and Zhupanska, Busch et al and Park et al 10,21,22 in order to determine resistivities for CFRP laminates: in fiber -, transverse -, and through thickness-directions using the 6-probe method. Furthermore, this paper leverages a concept referred to as ''effective conducting thickness'' and presents a novel technique for constructing FE models for electrically anisotropic materials with a significant improvement in accuracy over previous methods.…”