Delamination at Thick Ply Drops in Carbon and Glass Fiber Laminates Under Fatigue Loading

Samborsky, Daniel D.; Wilson, T.; Agastra, Pancasatya; Mandell, John F.

doi:10.1115/1.2931496

Cited by 23 publications

(30 citation statements)

References 9 publications

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“…The differences in E and G would be expected from Eq. (16) to result in predictable differences in applied strain to produce the same strain energy release rates, and expected fatigue crack growth rates [11]. These differences would translate into about (3.5) 1/2 or 1.9 times higher strain for the same delamination lifetime for glass, or about 1.9 times higher stress for carbon.…”

Section: Approximate Theorymentioning

confidence: 99%

“…The findings of these studies are summarized in recent reports [2][3][4][5][6][7], and in two current public databases [1,10]. Recent publications [11][12][13][14][15] are summarized here, with additional new data in several areas. The databases provide adequate constant amplitude fatigue data for the range of loading conditions necessary to compare materials, define constant life diagrams and predict failure under spectrum loading [2,16].…”

Section: Overviewmentioning

confidence: 99%

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Analysis of SNL/MSU/DOE fatigue database trends for wind turbine blade materials.

Mandell

Ashwill²,

Wilson

et al. 2010

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This report presents an analysis of trends in fatigue results from the Montana State University program on the fatigue of composite materials for wind turbine blades for the period 2005-2009. Test data can be found in the SNL/MSU/DOE Fatigue of Composite Materials Database which is updated annually. This is the fifth report in this series, which summarizes progress of the overall program since its inception in 1989. The primary thrust of this program has been research and testing of a broad range of structural laminate materials of interest to blade structures. The report is focused on current types of infused and prepreg blade materials, either processed in-house or by industry partners. Trends in static and fatigue performance are analyzed for a range of materials, geometries and loading conditions. Materials include: sixteen resins of three general types, five epoxy based paste adhesives, fifteen reinforcing fabrics including three fiber types, three prepregs, many laminate lay-ups and process variations. Significant differences in static and fatigue performance and delamination resistance are quantified for particular materials and process conditions. When blades do fail, the likely cause is fatigue in the structural detail areas or at major flaws. The program is focused strongly on these issues in addition to standard laminates. Structural detail tests allow evaluation of various blade materials options in the context of more realistic representations of blade structure than do the standard test methods. Types of structural details addressed in this report include ply drops used in thickness tapering, and adhesive joints, each tested over a range of fatigue loading conditions. Ply drop studies were in two areas: (1) a combined experimental and finite element study of basic ply drop delamination parameters for glass and carbon prepreg laminates, and (2) the development of a complex structured resininfused coupon including ply drops, for comparison studies of various resins, fabrics and pry drop thicknesses. Adhesive joint tests using typical blade adhesives included both generic testing of materials parameters using a notched-lap-shear test geometry developed in this study, and also a series of simulated blade web joint geometries fabricated by an industry partner.

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Section: Approximate Theorymentioning

confidence: 99%

Section: Overviewmentioning

confidence: 99%

Analysis of SNL/MSU/DOE fatigue database trends for wind turbine blade materials.

Mandell

Ashwill²,

Wilson

et al. 2010

Self Cite

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“…Mandell (2005a, 2005b) studied the effect of both mean stress and an optimized constant-life diagram on the damage of wind turbine blades. Samborsky et al (2008) investigated the fatigue loading effect on delamination at thick ply drops in both carbon and glass fiber laminates. Comparatively, study regarding composites used for hydrokinetic/tidal applications is still much less.…”

Section: Introductionmentioning

confidence: 99%

Reliability-based fatigue life investigation for a medium-scale composite hydrokinetic turbine blade

Chandrashekhara

et al. 2014

Ocean Engineering

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“…Table 21 lists ply mechanical properties for one material of the blade (ELT5500 glass epoxy composite). Properties for other materials can be found in [19][20]. Compared with test results, analytical simulation gives a good prediction as well as the damage progression sequence and structural response characteristics during different degradation stages.…”

Section: De-ee0001359 Advanced Composite Wind Turbine Blade Design Bamentioning

confidence: 99%

Advanced Composite Wind Turbine Blade Design Based on Durability and Damage Tolerance

Abumeri¹,

Abdi²

2012

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The objective of the program was to demonstrate and verify Certification-by-Analysis (CBA) capability for wind turbine blades made from advanced lightweight composite materials. The approach integrated durability and damage tolerance analysis with robust design and virtual testing capabilities to deliver superior, durable, low weight, low cost, long life, and reliable wind blade design. The GENOA durability and life prediction software suite was be used as the primary simulation tool.First, a micromechanics-based computational approach was used to assess the durability of composite laminates with ply drop features commonly used in wind turbine applications. Ply drops occur in composite joints and closures of wind turbine blades to reduce skin thicknesses along the blade span. They increase localized stress concentration, which may cause premature delamination failure in composite and reduced fatigue service life. Durability and damage tolerance (D&DT) were evaluated utilizing a multi-scale micro-macro progressive failure analysis (PFA) technique.PFA is finite element based and is capable of detecting all stages of material damage including initiation and propagation of delamination. It assesses multiple failure criteria and includes the effects of manufacturing anomalies (i.e., void, fiber waviness). Two different approaches have been used within PFA. The first approach is Virtual Crack Closure Technique (VCCT) PFA while the second one is strength-based.Constituent stiffness and strength properties for glass and carbon based material systems were reverse engineered for use in D&DT evaluation of coupons with ply drops under static loading. Lamina and laminate properties calculated using manufacturing and composite architecture details matched closely published test data. Similarly, resin properties were determined for fatigue life calculation. The simulation not only reproduced static strength and fatigue life as observed in the test, it also showed composite damage and fracture modes that resemble those reported in the tests. The results show that computational simulation can be relied on to enhance the design of tapered composite structures such as the ones used in turbine wind blades.A computational simulation for durability, damage tolerance (D&DT) and reliability of composite wind turbine blade structures in presence of uncertainties in material properties was performed. A composite turbine blade was first assessed with finite element based multi-scale progressive failure analysis to determine failure modes and locations as well as the fracture load. D&DT analyses were then validated with static test performed at Sandia National Laboratories.The work was followed by detailed weight analysis to identify contribution of various materials to the overall weight of the blade. The methodology ensured that certain types of failure modes, such as delamination progression, are contained to reduce risk to the structure. Probabilistic analysis indicated that composite shear strength has a great influence on the blade ul...

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Delamination at Thick Ply Drops in Carbon and Glass Fiber Laminates Under Fatigue Loading

Cited by 23 publications

References 9 publications

Analysis of SNL/MSU/DOE fatigue database trends for wind turbine blade materials.

Analysis of SNL/MSU/DOE fatigue database trends for wind turbine blade materials.

Reliability-based fatigue life investigation for a medium-scale composite hydrokinetic turbine blade

Advanced Composite Wind Turbine Blade Design Based on Durability and Damage Tolerance

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