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Damage assessment in CFRP laminates exposed to impact fatigue loading

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journal contribution
posted on 2011-08-15, 12:53 authored by George Tsigkourakos, Vadim V. Silberschmidt, Ian A. Ashcroft
Demand for advanced engineering composites in the aerospace industry is increasing continuously. Lately, carbon fibre reinforced polymers (CFRPs) became one of the most important structural materials in the industry due to a combination of characteristics such as: excellent stiffness, high strength-to-weight ratio, and ease of manufacture according to application. In service, aerospace composite components and structures are exposed to various transient loads, some of which can propagate in them as cyclic impacts. A typical example is an effect of the wind gusts during flight. This type of loading is known as impact fatigue (IF); it is a repetition of low-energy impacts. Such loads can cause various types of damage in composites: fibre breaking, transverse matrix cracking, de-bonding between fibres and matrix and delamination resulting in reduction of residual stiffness and loss of functionality. Furthermore, this damage is often sub-surface, which reinforces the need for more regular inspection. The effects of IF are of major importance due its detrimental effect on the structural integrity of components that can be generated after relatively few impacts at low force levels compared to those in a standard fatigue regime. This study utilises an innovative testing system with the capability of subjecting specimens to a series of repetitive impacts. The primary subject of this paper is to assess the damaging effect of IF on the behaviour of drilled CFRP specimens, exposed to such loading. A detailed damage analysis is implemented utilising an X-ray micro computed tomography system. The main findings suggested that at early stages of life damage is governed by o degree splits along the length of the specimens resulting in a 20% reduction of stiffness. The final failure damage scenario indicated that transverse crasks in the 90 degree plies are the main reason for complete delamination which can be translated to a 50% stiffness reduction.

History

School

  • Mechanical, Electrical and Manufacturing Engineering

Citation

TSIGKOURAKOS, G., SILBERSCHMIDT, V.V. and ASHCROFT, I.A. , 2011. Damage assessment in CFRP laminates exposed to impact fatigue loading. Journal of Physics: Conference Series, 305 (1), 012047

Publisher

© IOP Publishing Ltd

Version

  • AM (Accepted Manuscript)

Publication date

2011

Notes

This is a journal article. It was published in the serial, Journal of Physics: Conference Series [© IOP Publishing Ltd] and the definitive version is available at: http://iopscience.iop.org/1742-6596/305/1/012047

ISSN

1742-6588

Language

  • en

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