Estimation of fatigue curves for design of composite laminates

Ronold, Knut O.; Echtermeyer, Andreas T.

doi:10.1016/1359-835x(95)00068-d

Cited by 27 publications

(19 citation statements)

References 6 publications

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“…3, where, traditionally, the independent parameter, velocity, is plotted on the vertical axis and the dependent parameters, time or amount of rain before the coating is removed, are plotted on the horizontal axis of a semi logarithmic diagram. Such a representation of data is known from fatigue testing of materials (Miner, 1945;Ronold and Echtermeyer, 1996), where the number of load cycles causing failure is shown as a function of the 5 magnitude of each load cycle (for example stress range). The fatigue data are often fitted to a power function as shown in Fig. …”

Section: Analysis Of Rain Erosion Test Datamentioning

confidence: 99%

Extending the life of wind turbine blade leading edges by reducing the tip speed during extreme precipitation events

Bech¹,

Hasager²,

Bak³

2018

Preprint

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Abstract. Impact fatigue caused by collision with rain droplets, hail stones and other airborne particles, also known as rain erosion, is a severe problem for wind turbine blades. Each impact on the leading edge adds an increment to the accumulated damage in the material. After a number of impacts the leading edge material will crack. This paper presents and supports the hypothesis that the vast majority of the damage accumulated in the leading edge is imposed at extreme precipitation condition events, which occur during a very small fraction of the turbines operation life. By reducing the tip speed of the blades during 10 these events, the service life of the leading edges significantly increases from a few years to the full expected lifetime of the wind turbine. In the worst case at the cost of a negligible reduction of annual energy production (AEP) and in the best case with a significant increase in AEP.

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Section: Analysis Of Rain Erosion Test Datamentioning

confidence: 99%

Extending the life of wind turbine blade leading edges by reducing the tip speed during extreme precipitation events

Bech¹,

Hasager²,

Bak³

2018

Preprint

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“…Below these levels, the lower tolerance limits are overestimated, and a more complicated nonlinear evaluation should be used. 24,30 However, because the variance of the fatigue data was constant across the tested load levels for the composite screw (P = .5, F test), we felt confident to extrapolate further in the case of those screws without mathematical modifications. We elected to report the unmodified data and limited our extrapolations to a 200-N load level, close to the extrapolation limit for the metal screw.…”

Section: Discussionmentioning

confidence: 98%

Predicting in vivo Clinical Performance of Anterior Cruciate Ligament Fixation Methods from in Vitro Analysis

et al. 2005

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“…S-N curves for tension-tension and compression-compression testing of glass-epoxy unidirectional laminates for the spar beam for wind turbine blades are shown in Figs 11 and 12 . The data are from the Optidat database [ 40 ]. The measured fatigue data are evaluated according to ASTM E739, and the 50% median line and the lower 95% confi dence limit are shown in these diagrams.…”

Section: Failure Under Cyclic Loadsmentioning

confidence: 99%

“…In addition to buckling and failure due to static overload, perhaps the most important mode of damage that needs to be addressed in design is the cyclic growth Lower 95% confi. Figure 11: S-N curve for tension-tension fatigue of a glass fi ber/epoxy composite [ 40 ]. Figure 13: Schematics of a typical relationship between cyclic crack growth rate (d a /d N ) and maximum applied energy release rate, G max for cyclic crack growth.…”

Section: Failure Under Cyclic Loadsmentioning

confidence: 99%

Blade materials, testing methods and structural design

Sørensen

Holmes

Brøndsted

et al. 2010

WIT Transactions on State of the Art in Science and Engineering

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A major trend in wind energy is the development of larger wind turbines for offshore wind farms. Since access to offshore wind turbines is diffi cult and costly, it is of great importance that they operate safely and reliable. The wind turbine rotor blades, which are the largest rotating component of a wind turbine, are designed for an expected lifetime of 20 years. During this period of time, the blades will be subjected to varying loads. Large wind turbine blades are made of composite materials and can develop a number of interacting failure modes. High structural reliability can be achieved by designing the blades against the development of these failure modes. This chapter provides an overview of experimental and modeling tools for the design of wind turbine blades, with particular emphasis on evolution and interaction of various failure modes. This involves knowledge of materials, testing methods and structural design.The design of the wind turbine blade is a compromise between aerodynamic and structural considerations. Aerodynamic considerations usually dominate the design for the outer two-thirds of the blade, while structural considerations are more important for the design of the inner one third of the blade. Loads on wind turbine rotor bladesThe rotor blade is loaded in a combination of fl apwise and edgewise loads. Basically the blades are exposed to three different load sources. One is the wind load that through the lift and drag on the aerodynamic profi le loads the blade primarily

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Estimation of fatigue curves for design of composite laminates

Cited by 27 publications

References 6 publications

Extending the life of wind turbine blade leading edges by reducing the tip speed during extreme precipitation events

Extending the life of wind turbine blade leading edges by reducing the tip speed during extreme precipitation events

Predicting in vivo Clinical Performance of Anterior Cruciate Ligament Fixation Methods from in Vitro Analysis

Blade materials, testing methods and structural design

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