Monitoring progression of Mode II delamination during fatigue loading through acoustic emission in laminated glass fiber composite

Roy, Christian; Ghorba, Mohamed El

doi:10.1016/0963-8695(92)90768-c

Cited by 3 publications

(3 citation statements)

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“…The matrix splitting was characterized with other AE event intensities such as amplitude, duration and counts. Roy and Elghorba 17 used acoustic emission to monitor damage development in a glass fibre/epoxy composite during monotonic and cyclic mode‐II loadings of DCB specimens. Acoustic emission was used to investigate the inter‐laminar failure in mode‐II under monotonic and fatigue loading conditions.…”

Section: Introductionmentioning

confidence: 99%

Fatigue and Impact Behaviour of Carbon Fibre Composite Bicycle Forks

Sisneros

Yang

Elhajjar

2012

Fatigue Fract Eng Mat Struct

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A B S T R A C T The use of carbon fibre-based polymeric composites in bicycle components has dramatically increased in the last few decades. This paper presents the results of fatigue and impact testing on bicycle forks that are known to have quality-related manufacturing defects. In the investigation performed, acoustic emission testing is used to monitor crack growth during fatigue loading and impact. The results show three distinct stages in composite fatigue failure related to initiation, propagation and final growth. Implications of the results on design and testing of composite bicycle components are addressed pointing to a greater need in understanding current design procedures.Keywords acoustic emission of manufacturing defects; bicycle components; fatigue and impact response. N O M E N C L A T U R Ea = crack length l = average delamination length m = material parameter C = material constant N = number of cycles ρ = transverse crack density G = difference between maximum and minimum strain energy release rate K = difference between maximum and minimum stress intensity factor I N T R O D U C T I O NThe world's top performing cyclists have been quick to embrace the advantages of carbon fibre composites. During the last decade, the reduction in costs has resulted in this carbon fibre technology being filtered down to the casual consumer. Today, most retail bicycle shops carry several models of carbon fibre bicycle frames and components catering to cyclists willing to pay a premium for the optimum of lightweight bicycle performance. The use of carbon fibre-based composites is expected to grow as trends continue to show a move towards lower costs of production. Manufacturers typically combine carbon fibres with a thermoset or thermoplastic resin to achieve a structural material with a highly superior-specific strength and stiffness in comparison to metallic alternatives. Compared with other material performance criteria, however, carbon fibre composites possess unique design challenges due to the relatively lower strain to failure and linear stress-strain response. As such they require careful design to increase fatigue performance through careful selection of laminate schedules to provide adequate damage tolerance and performance. Laminated carbon fibre components are significantly different in their properties and behaviour from metals, which are homogeneous. These composites can offer several advantages over metals. The direction and number of layers can be varied to achieve greater strength or stiffness in various directions based on the stresses to be experienced by the design. However, the manufacturing process can produce anomalies that are not necessarily accounted for in testing standards that were originally developed for metallic bicycle components (Fig. 1). These anomalies such as porosity or fibre waviness can impact the mechanical behaviour of the composite components. 1,2 Carbon fibre-based composites also vary from metals in that they lack the ductility and toughness that make metals such an ad...

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Section: Introductionmentioning

confidence: 99%

Fatigue and Impact Behaviour of Carbon Fibre Composite Bicycle Forks

Sisneros

Yang

Elhajjar

2012

Fatigue Fract Eng Mat Struct

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“…In particular, there was a sharp rise in the AE ringdown count when damage to the matrix began (without surface cracking), and this was accompanied with a drop in the maximum stress reached during the cycles. Roy and El Ghorba [5] have produced delamination of GFRP during static and fatigue loading, and monitored damage accumulation and cumulative AE events and event rate, concluding that these could be useful indicators of strength degradation.…”

Section: Introductionmentioning

confidence: 99%

Acoustic emission from the tension fatigue of glass fibre reinforced plastics

Steel

Reuben

Hamlin

et al. 2004

Proc. Instn Mech. Engrs, Part L: J. Mat

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This work investigates acoustic emission (AE) generated during tension fatigue tests carried out on a glass bre reinforced plastic (GFRP) composite specimen. Continuous acquisition of AE events during measurements enables mapping of AE events with fatigue cycle time. The results allow analysis of the event rate obtained during parts of the fatigue cycle so that crack propagation events, at the peak of each load cycle, and crack closure events, on the unloading stage of each cycle, can be identi ed. The event rate in each of these parts of the cycles is also examined with respect to various test parameters, and qualitative results are shown that suggest some distinct correlations between event rate and crack length. The results can be applied as a diagnostic technique for modelling cumulative composite damage in critical composite structures such as pressure vessels and machine structures. The crack closure event rate is strongly correlated to crack length. The results can be used without the need to consider more sophisticated AE parameters in the design of a composite damage monitoring system.

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“…Acoustic emissions (AEs), i.e. the elastic wave released from a localized source in the material, used with mechanical testing, can yield rich information that can help in the characterization of the modes of inter‐facial failure in composite systems ( Kondo et al , 1981, 1985 ; Narisawa & Oba, 1984; Sachse & Kim, 1987; Roy & El Ghorba, 1988; Yuyama, Imanka & Ohtsu, 1988; Kim et al , 1991 ). Many fracture testings and fatigue studies of reinforced composites have used AEs to study failure processes at the microscopic level ( Williams & Lee, 1978; Hamstad, 1985).…”

Section: Introductionmentioning

confidence: 99%

Acoustic emissions generated in aged dental composites using a laser thermoacoustic technique

Lee¹,

Lin²,

Dong

et al. 2000

J of Oral Rehabilitation

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The heating up of dental composites by laser will produce acoustic emissions (AEs) that may be related to fracture mechanisms in the composites. It has been proved that the mechanical properties of dental composites are affected by storage in food simulating liquids, i.e. 75% ethanol, which has a solubility parameter approximating to that of bisphenol glycidyl dimethacrylate (BisGMA) resin. A new method was innovated to evaluate the laser-induced AEs in dental composites aged by 75% ethanol solution. Model systems (50/50 BisGMA/TEGDMA resin filled with 0% and 75 wt.% 5-10 microm silanized BaSiO6) as well as three commercial composites (Marathon One, Z100 and Herculite XRV) were used in this study. Nine samples acting as the control group were tested to establish the correlation of AEs to laser power. The effect of ageing by immersion in 75% ethanol on AEs and diametral tensile strength (DTS) was then evaluated. A quasi-continuous wave CO2 laser was used to heat up the composites. AEs of frequency 100-200 kHz were collected, filtered, recorded and processed using a 4610 Smart Acoustic Monitor. Burst patterns, which formally were assumed to be correlated to fracture mechanisms, were also identified from the data obtained at laser power > or = 5 W for commercial composites and > or = 4 W for model systems. Higher laser powers cause the AE to increase for all composites except unfilled model resin. AEs as a function of power for all aged systems were flat (< 100 events) below 4 W. Emissions then rose sharply to > 1000 events at 7.1 W. Statistically significant differences were found between the AEs obtained at 5 W (commercial composites) and those at 4.3 W (model systems) for material systems and storage times. Marathon One was less affected by the laser and an abrupt change in AE was found between days 0 and 7 of storage for all commercial composites. The AE value from the unfilled model resin was found to be significantly different from that of the model composites. However, they showed an increase in AEs with length of storage time, which was inversely associated with the decreased tendency of their immersed DTS values. Laser-induced AEs may be a valuable adjunct to conventional mechanical testing.

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Monitoring progression of Mode II delamination during fatigue loading through acoustic emission in laminated glass fiber composite

Cited by 3 publications

References 0 publications

Fatigue and Impact Behaviour of Carbon Fibre Composite Bicycle Forks

Fatigue and Impact Behaviour of Carbon Fibre Composite Bicycle Forks

Acoustic emission from the tension fatigue of glass fibre reinforced plastics

Acoustic emissions generated in aged dental composites using a laser thermoacoustic technique

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