Microscale modelling of lightning damage in fibre-reinforced composites

Abstract

In this work, three-dimensional (3D) finite element simulations were undertaken to study the effects of lightning strikes on the microscale behaviour of continuous fibre-reinforced composite materials and to predict and understand complex lightning damage mechanisms. This approach is different from the conventional mesoscale or macroscale level of analysis, that predicts the overall lightning damage in composite laminates, thus providing better understanding of lightning-induced thermo-mechanical damage at a fundamental level. Micromechanical representative volume element (RVE) models of a UD composite laminate were created with circular carbon fibres randomly distributed in an epoxy matrix. The effects of various grounding conditions (one-, two-, and four-side grounding), fibre volume fractions ( V f = 55, 60%, and 65%), and peak current amplitudes (10, 20, and 40 kA) on microscopic damage in RVE models were characterised to understand fibre, epoxy matrix, and fibre-matrix interfacial damage associated with a lightning strike. Thermal damage, estimated based on epoxy matrix decomposition temperature, was largely constant up to 20 kA before increasing significantly at 40 kA. Severe thermal damage steadily decreased with increasing V f. Thermo-mechanical damage was predicted using a ductile plasticity model with Drucker–Prager yield criterion for epoxy matrix failure, and cohesive surfaces for fibre-matrix interface debonding. Thermal strain had the largest contribution to thermo-mechanical damage, while dynamic pressure loading was negligible in all RVE models. The RVE model proposed in this work, to the best of the authors’ knowledge, is the first model predicting lightning-induced fibre-matrix interfacial damage.

Challenges and Future Recommendations for Lightning Strike Damage Assessments of Composites: Laboratory Testing and Predictive Modeling

“…For instance, most numerical analyses are conducted under the assumption that the electrical conductivities of the composite materials depend only on the temperature or degree of pyrolysis, to simplify the complication of lightning strike which is far away from the actual physical and chemical phenomena. To overcome this, an attempt of representative volume element (RVE) [9] containing fiber, resin, and a fiber-resin interface, was proposed to estimate the effective electrical conduction of CFRP composites.…”

Acoustic Emission during Non-Uniform Progression of Processes in Composite Failure According to the Von Mises Criterion

“…Traditional methods of product condition monitoring, such as visual inspection, color testing, ultrasonic testing, X-ray radiography and tomography, infrared thermography, and others, are aimed at detecting and localizing damages [9][10][11][12] with the possibility of performing a quantitative assessment. At the same time, to increase the reliability of methods for assessing the defects in CM and to follow the developing of underlying processes, as well as predicting the behavior and residual life a broad array of theoretical [13][14][15] and experimental [16][17][18] research is being carried out on the destruction processes of CM. The research focuses on finding criteria for assessing the condition and predicting the state of CM prior to failure.…”