Advanced Certification Methodology for Composite Structures.

Kan, H. P.; Cordero, R.; Whitehead, R. S.

doi:10.21236/ada326762

Cited by 25 publications

(14 citation statements)

References 5 publications

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“…It is well accepted in the literature [6] that, absorbed energy can be a very useful tool to assess the extent of damage in the laminate, provided that an understanding of the losses in the elastic regime is available. While current Federal Aviation Administration (FAA) damage tolerance certification efforts still rely on impact energy-based rather than force-based criteria [2], the use of an instrumented device, and hence of contact force, undoubtedly presents numerous advantages for gaining more in-depth understanding of the impact response of composite panels. For that reason, a reliable tool is required to predict the value of contact force at failure, but also the value of peak contact force.…”

Section: Super-critical Regimementioning

confidence: 99%

Modified SDOF Models for Improved Representation of the Impact Response of Composite Plates

Feraboli

2006

Journal of Composite Materials

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Previous research has shown that simple single degree of freedom (SDOF) models can be used successfully to reproduce the force-time response of composite plates subjected to low-velocity impacts (LVI). In particular, a simple spring-mass (SM) model yields accurate estimates of the peak contact force as a function of impact energy. The major limitation of this model is that it applies only to elastic impact events, and ceases to be valid after the onset of damage. The effort of this investigation is to modify the SM model, while retaining the simplicity of its formulation, and to extend its range of validity to the super-critical regime. Three models are derived, namely the damaged stiffness, the dissipated energy, and the spring-mass-dashpot models, and their validity is examined through comparisons with experimental data. Impact force-time traces for carbon/epoxy laminates exhibiting various combinations of laminate thickness and support span are collected, and it is found that the additional unknowns introduced for each of the models, although determined empirically, are strongly related to the structural parameters for each configuration investigated.

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Section: Super-critical Regimementioning

confidence: 99%

Modified SDOF Models for Improved Representation of the Impact Response of Composite Plates

Feraboli

2006

Journal of Composite Materials

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“…First, this approach was applied by Cook ( 1 ) for the zoning of a UH-60A Black Hawk helicopter: for each zone of the fuselage, the impact energy exceedance curves were generated and taken as damage tolerance criteria (the considered impact threat scenarios were mostly related to mistakes during standard maintenance procedures). Later this approach was developed by Kan et al ( 2 ) who investigated the relationship between low-velocity impacts energies and damage sizes in wing panels of different thickness. As a result of these studies, the value of 100 ft-lbs (136 J) was adopted for the realistic energy threshold.…”

Section: Methodsmentioning

confidence: 99%

“…The considerable input into a study of metal and composite aircraft structures accidental impact scenarios was made in studies ( 2 , 3 ) performed in the 1990s of the 20th Century. The extensive research program focused on in-service damageability of US Navy fighters (Northrop and MCAir survey) became the basis for statistical analysis made by Kan et al ( 2 ) . This database included 1,644 dents registered on a metal structure of F-4, F-111, A-10 and F-18B aircraft and was used for the development of a probabilistic approach for composite structures certification.…”

Section: Introductionmentioning

confidence: 99%

A study of accidental impact scenarios for composite wing damage tolerance evaluation

et al. 2019

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The field data characterising aircraft accidental in-service damage was collected, sorted and processed. By means of probabilistic analysis, the wing damageability statistical parameters were determined. The scenarios of wing accidental impacts were described and the qualitative distribution of impact intensity over the wing surfaces was obtained. By means of original analytical method, the metal dent depth data were converted into impact energy data and energy probabilistic distributions were established. It was shown that the functional relationships generated on domestic data are generally consistent with similar foreign results obtained on other types of aircraft with serious differences in operating conditions. Along with realistic impact damage scenarios, the high energy impact events were considered. It was noted that in some cases severe damage events should not be addressed as extremely improbable and should be included into design and certification process.

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“…The total number of tests performed at the subcomponent level (305) is much smaller than those performed at the coupon and element levels (8059). Usually, only two full-scale test articles are built and tested to validate the whole analysis process: one for static strength assessment and the other for durability and damage tolerance purposes [1] (Chapter 4), [2] (Chapters 6 and 7), and [5][6][7][8][9][10][11][12].…”

Section: Certification Methodologies and The Building Block Approachmentioning

confidence: 99%

Composite Materials Strength Determination Within the Current Certification Methodology for Aircraft Structures

Feraboli

2009

Journal of Aircraft

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Although several composite failure criteria have been proposed over the years to predict the static strength of polymer composites, including micromechanical and first-ply failure theories, none of them has demonstrated an ability to predict the onset of damage across the wide range of load conditions and structural configurations. For that reason, current aerospace practice uses empirically derived laminate-based allowables to demonstrate compliance with regulatory requirements for static strength. Some examples of certification by analysis supported by test evidence as well as certification by test are given, and the fundamental differences are highlighted in the context of the building block philosophy. The lack of accepted failure criteria and general material-degradation models for the prediction of damage initiation and propagation provides the background for the current methodology, which relies either on testing alone or on analysis supported by extensive test evidence.

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Advanced Certification Methodology for Composite Structures.

Cited by 25 publications

References 5 publications

Modified SDOF Models for Improved Representation of the Impact Response of Composite Plates

Modified SDOF Models for Improved Representation of the Impact Response of Composite Plates

A study of accidental impact scenarios for composite wing damage tolerance evaluation

Composite Materials Strength Determination Within the Current Certification Methodology for Aircraft Structures

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