DOE/MSU composite material fatigue database: Test methods, materials, and analysis

Mandell, John F.; Samborsky, Daniel D.

doi:10.2172/578635

Cited by 153 publications

(182 citation statements)

References 9 publications

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“…8,9,11 As described in the previous section, partial material factors were developed based on the values specified by GL. For static calculations, a combined material factor of 2.9 was typically used.…”

Section: Materials Design Strengthmentioning

confidence: 99%

WindPACT Turbine Design Scaling Studies Technical Area 1-Composite Blades for 80- to 120-Meter Rotor

Griffin¹

2001

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. The primary objectives of the Blade-Scaling Study are to assess the scaling of current materials and manufacturing technologies for blades of 40 to 60 meters in length, and to develop scaling curves of estimated cost and mass for rotor blades in that size range. ApproachWe investigated the scaling of current materials and manufacturing technologies for wind turbine blades of 40 to 60 meters in length. Direct design calculations were used to construct a computational blade-scaling model, which was then used to calculate structural properties for a wide range of aerodynamic designs and rotor sizes. Industry manufacturing experience was used to develop cost estimates based on blade mass, surface area, and the duration of the assumed production run. The structural design model was also used to perform a series of parametric analyses. The results quantify the mass and cost savings possible for specific modifications to the baseline blade design, demonstrate the aerodynamic and structural trade-offs involved, and identify the constraints and practical limits to each modification. Conclusions and ResultsThe scaling-model results were compared with mass data for current commercial blades. For a given blade design, the scaling model indicates that blade mass and costs scale as a near-cubic of rotor diameter. In contrast, commercial blade designs have maintained a scaling exponent closer to 2.4 for lengths ranging between 20 and 40 meters. Results from the scaling study indicate that:• To realize this lower scaling exponent on cost and mass has required significant evolution of the aerodynamic and structural designs.• Commercial blades at the upper end of the current size range are already pushing the limits of what can be achieved using conventional manufacturing methods and materials.• For even larger blades, avoiding a near-cubic mass increase will require basic changes in:− Materials, such as carbon or glass/carbon hybrids. − Manufacturing processes that can yield better mean properties and/or reduced property scatter through improvements in fiber alignment, compaction, and void reduction. The extent to which such improvements would result in lower blade masses may be constrained by blade stiffness requirements. − Load-mitigating rotor designs.For the scaling results presented in this report, the basic material and manufacturing process remained unchanged. As such, a reduction in mass will correspond to a reduction of production iii blade costs in the same proportion. However, this will not hold true for mass savings realized through changes in materials, process, and rotor design. In evaluating each such change, the implications on both mass and cost must be considered.As part of the cost analysis, it was shown that the "learning curve" required to achieve a mature production process has a meaningful effect on blade costs for the range of rotor sizes considered. A production rate of 200 megawatts (MW) per year implies 800 blades at 750 kilowatts (kW), but only 120 blades at 5 MW. Therefore, the cost penalty for ini...

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Section: Materials Design Strengthmentioning

confidence: 99%

WindPACT Turbine Design Scaling Studies Technical Area 1-Composite Blades for 80- to 120-Meter Rotor

Griffin¹

2001

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“…A blade in bending will have skin laminates in both tension and compression. S-N curves for compressive failure in laminates tend to have a lower ultimate stress and a higher slope than their tensile counterpart [22]. The ratio of a tensile to a compressive ultimate stress can approach 2.0.…”

Section: Figure 52 Goodman Diagram and Sample Load Case #1mentioning

confidence: 94%

“…At low cycles (typically below 1,000), the transition is somewhere between R = 0.1 and R = -1.0. At higher cycles, the transition is closer to R = -1.0 and may even trend towards R = -2.0 as the cycles increase [22]. This produces a nonlinear Goodman diagram.…”

Section: Figure 52 Goodman Diagram and Sample Load Case #1mentioning

confidence: 94%

NedWind 25 Blade Testing at NREL for the European Standards Measurement and Testing Program

Larwood¹,

Musiał²,

Freebury³

et al. 2001

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“…The end-notched flexure (ENF) test has emerged as the standard test method for measuring Mode II (shearing) type crack growth within the MSU Composites Group. 9 Specimen geometry and loading for an ENF specimen are shown in Figure 14. This specimen produces shear at the mid-plane of a composite loaded in three-point bending and at critical load the crack advances.…”

Section: B Test Methods: Static In-plane and Delaminationmentioning

confidence: 99%

Effects of defects in composite wind turbine blades. Round 1.

Nelson

Riddle

Cairns

2012

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The Wind Turbine Blade Reliability Collaborative (BRC) was formed with the goal of improving wind turbine blade reliability. Led by Sandia National Laboratories (SNL), the BRC is made up of wind farm maintenance companies, turbine manufacturers and third party investigators. Specific tasks have been assigned by SNL to the various parties. The portion of the BRC that will focus on establishing the criticality of manufacturing defects (aka, Effect of Defects) is being researched by the Montana State University Composites Group (MSUCG). The research described herein compiles the second round of a multi-year year plan consisting of three rounds of work performed by Montana State University (MSU) within two areas-Flaw Characterization and Effects of Defects. The first round was published in SAND2012-8110. 1 The purpose of this document is to capture and convey the progress which has been made by the MSUCG team since submission of the Round 1 Report.The work presented has built upon the established framework for quantitative categorization and analysis of flaws. Additional physical testing has been performed utilizing improved manufacturing techniques that have reduced manufacturing time and materials, while providing samples with flaws common to wind turbine blades. This additional physical testing was performed to fill two needs: additional data points to further understand the Effects of Defects; and, to increase in scale away from simple coupons toward larger structures. These data were also analyzed to allow for continued analytical/experimental correlation occurring in this and future portions of this study. Manufactured specimens were evaluated non-destructively to verify flaw parameters and visualize damage utilizing computed tomography and digital image correlation, respectively.A further understanding of the changes in the material properties associated with characterized flaws has been achieved on a coupon level with this additional physical testing. This testing further indicated that fiber misalignment and porosity resulted in decreased material performance . Modeling efforts toward matching these results have been performed utilizing two distinct and fundamentally different approaches. These are modeling damage as a degradation of properties, and modeling the actual damage in the material via finite element analysis with progressive damage. Reasonable agreement has been achieved when compared to the test data, though there is room for improvement.Work will continue with efforts to increase size and scale of tested samples. In addition, research will be continued into reliability methods suitable for wind turbine composites. Finally, analytical/experimental correlation will be improved through the use of improved and more accurate models. This is leading to the goals of establishing the severity and criticality of manufacturing defects, and to provide a cogent approach to accept/reject criteria, and the need for repair and/or maintenance in the field. 4

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DOE/MSU composite material fatigue database: Test methods, materials, and analysis

Cited by 153 publications

References 9 publications

WindPACT Turbine Design Scaling Studies Technical Area 1-Composite Blades for 80- to 120-Meter Rotor

WindPACT Turbine Design Scaling Studies Technical Area 1-Composite Blades for 80- to 120-Meter Rotor

NedWind 25 Blade Testing at NREL for the European Standards Measurement and Testing Program

Effects of defects in composite wind turbine blades. Round 1.

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