Lightning arc channel effects on surface damage development on a PRSEUS composite panel: An experimental study

Boushab, Dounia; Gharghabi, Pedram; Lee, Juhyeong; Lacy, Thomas E.; Pittman, Charles U.; Mazzola, Michael S.; Velicki, Alex

doi:10.1016/j.compositesb.2021.109217

Cited by 16 publications

(10 citation statements)

References 20 publications

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“…This is because the epoxy matrix decomposes and pyrolyzes at much lower temperatures than the fiber sublimation temperature. [ 62–65 ]…”

Section: Resultsmentioning

confidence: 99%

“…This is because the epoxy matrix decomposes and pyrolyzes at much lower temperatures than the fiber sublimation temperature. [62][63][64][65] The primary focus of this study was to examine changes in composite failure surface morphology due to fire exposure, with the goal of post-fire forensic analysis of these surfaces. Determination of the precise composition of char and other fire by-products was not a chief concern; such structures are a consequence of epoxy matrix thermal decomposition, pyrolysis, and combustion rather than fiber thermal degradation.…”

Section: Effects Of Fire Exposure On Mechanically Failed Graphite/epo...mentioning

confidence: 99%

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Fire impact on mechanically failed graphite/epoxy composites

et al. 2023

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Aircraft crashes often initiate or accompany fire incidents. Post‐crash fires, in particular, can mask or destroy critical fractographic failure features necessary for accident reconstruction. As a first step in developing a coherent strategy for composite aircraft post‐crash forensic analysis, a series of vertical flame tests were performed on mechanically failed Cytec T40‐800/Cycom® 5215 graphite/epoxy unnotched compression, short beam strength, and in‐plane shear specimens. Visual inspection and scanning electron microscopy were used to examine the specimens fracture surfaces before and after fire testing. The fire‐induced damage included matrix decomposition, melt dripping, char, soot, delamination, and residual thickness increases. The composite thermal degradation was significantly influenced by the specimen stacking sequence, the fracture surface morphology, and the total available free surface area. In addition, microscopic inspection showed that char layers impeded heat conduction and oxygen transfer to the interior of the specimens resulting in less thermal damage to the underlying plies. Moreover, burned specimens with more available free surface area sustained more thermal degradation and fire combustion damage for a given fire exposure duration. Exposed fiber bundles from the fracture surfaces were susceptible to severe thinning and thermal oxidation, which destroyed critical fractographic failure features necessary for accident reconstruction.

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“…This is because the epoxy matrix decomposes and pyrolyzes at much lower temperatures than the fiber sublimation temperature. [ 62–65 ]…”

Section: Resultsmentioning

confidence: 99%

Section: Effects Of Fire Exposure On Mechanically Failed Graphite/epo...mentioning

confidence: 99%

Fire impact on mechanically failed graphite/epoxy composites

et al. 2023

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“…Waveform A is characterised as the first return stroke; Waveform B is the intermediate current; Waveform C is the long duration, low current; and Waveform D is a subsequent stroke. A sizeable amount of experimental research has been conducted on lightning strike damage in a laboratory environment and has typically focussed on the high peak current Waveforms A or D [3][4][5][6][7][8][9][10][11]. The typical peak natural lightning current amplitude is around 30 kA but can exceed 100 kA.…”

Section: Lightning Strike Experimentsmentioning

confidence: 99%

Developing Test Methods for Compression after Lightning Strikes

Millen

Lee

et al. 2023

Appl Compos Mater

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Research into residual strength after lightning strike is increasing within the literature. However, standard test methods for measuring residual compressive strength after lightning strikes do not exist. For the first time, a systematic experimental study is undertaken to evaluate modifications necessary to standard Compression After Impact (CAI) specimen geometry and test jig design to induce specimen failure at the lightning damage region. Four laboratory generated lightning strike currents with peak amplitudes ranging from 25 to 100 kA have been studied. Test set-up modifications were made considering the scale of the lightning damage and its potential proximity to specimen edges. Specimen geometry and anti-buckling guides were adjusted for each peak current to induce specimen failure at the lightning damage. The Compression After Lightning (CAL) strength was 28% lower than the pristine CAI strength even at a relatively low peak current of 25 kA. This study shows that the standard CAI test setup has the potential for CAL application, however, careful modifications are required depending on the peak amplitude of the applied lightning current waveform.

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“…1,2 Therefore, research into lightning strike damage and protection systems, has been increasing for many years and has followed parallel experimental and simulation pathways. [3][4][5][6][7][8][9][10][11][12] Experimental research has been conducted with the primary focus on idealised standard lightning waveforms with ≥100 kA peak current amplitudes, named Waveforms A or D [13][14][15] since these waveforms produce ample electrical current, which is instantaneously dissipated as heat (i.e., thermal damage). Direct lightning damage in typical carbon fibre-reinforced polymer (CFRP) composites includes a number of significant damage modes including fibre damage (i.e., fray, fracture, or blow-out), matrix damage (i.e., cracking or thermal decomposition), delamination, and through-thickness damage penetration.…”

Section: Introductionmentioning

confidence: 99%

Microscale modelling of lightning damage in fibre-reinforced composites

Millen

Lee

2023

Journal of Composite Materials

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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.

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Lightning arc channel effects on surface damage development on a PRSEUS composite panel: An experimental study

Cited by 16 publications

References 20 publications

Fire impact on mechanically failed graphite/epoxy composites

Fire impact on mechanically failed graphite/epoxy composites

Developing Test Methods for Compression after Lightning Strikes

Microscale modelling of lightning damage in fibre-reinforced composites

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