NDE Methodologies for Composite Flywheels Certification

Baaklini, George Y.; Konno, Kevin E.; Martin, Richard E.; Thompson, Richard C.

doi:10.4271/2000-01-3655

Cited by 9 publications

(6 citation statements)

References 1 publication

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“…The same nondestructive evaluation methods were used as those being used by Baaklini and co-workers [24] for flywheel certification. Compaction attributes of flat panel and hoop wound rotors, such as void content and fiber volume fraction, were found to be similar.…”

Section: Flat Coupon Specimen Manufacturingmentioning

confidence: 99%

Time-Temperature Dependent Response of Filament Wound Composites for Flywheel Rotors

Thesken¹,

Bowman

Arnold

et al. 2003

Composite Materials: Testing and Design, Fourteenth Volume

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Flywheel energy storage offers an attractive alternative to the electrochemical battery systems currently used for space applications such as the International Space Station. Rotor designs utilizing the load carrying capacity of carbon fibers wound in the hoop direction are capable of high operational speeds and specific energies. However, the long-term durability of such rotors may be limited by the time-temperature dependent behavior of the epoxy matrix, which controls the uniaxial properties transverse to the fiber and the shear properties. This proposition was investigated for the prototypical rotor material, IM7/8552. Flat filament wound panels were made using the same process as for composite rotors. Coupon specimens, sectioned normal and parallel to the winding axis, were tested in compression and tension, at room temperature (RT), 95 °C and 135 °C for strain rates from 5 × 10-6/s to 5× 10-3/s. Creep and stress relaxation testing ran 72 hrs followed by a 72 hr recovery. Time, temperature and load sign dependent effects were significant transverse to the fiber. Under a fixed deformation of -0.5% strain for 72 hrs, compressive stresses relaxed 16.4% at 135 °C and 13% at 95 °C. Tensile stresses relaxed only 7% in 72 hrs at 135 °C for 0.5% strain. The postulate of a linear hereditary material response and the application of Boltzmann's principle of superposition to describe the behavior observed here are problematic if not intractable. Undoubtedly microstuctural analysis including the influence of residual stresses due to processing will be needed to resolve the observed paradoxes. Within the scope of these experiments, uniaxial compressive stress relaxation data may be used to bound the amount of relaxation with time of radial pre-load stresses in flywheel rotors. A more detailed appraisal of the design implications of these results is made in the analysis by Saleeb and co-workers [1].

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Section: Flat Coupon Specimen Manufacturingmentioning

confidence: 99%

Time-Temperature Dependent Response of Filament Wound Composites for Flywheel Rotors

Thesken¹,

Bowman

Arnold

et al. 2003

Composite Materials: Testing and Design, Fourteenth Volume

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show abstract

“…where _ R R is the reaction rate, N is the atomic density, is the neutron flux, and is a proportionality constant that will vary for different interactions and neutron energies and will be unique for targets of different isotopes. N is typically expressed in atoms per cm 3 , is expressed as neutrons per cm 2 per second, and the proportionality constant, , is expressed in cm 2 . is commonly referred to as the microscopic interaction cross section and can also be expressed in units of barns (b), where 1 b ¼ 10 À24 cm 2 .…”

Section: Cold Neutron Prompt Gamma Activation Analysismentioning

confidence: 99%

“…Both of these approaches are sensitive to density variations within the composite part. Manufactured defects as small as 125Â125 mm have been successfully identified [3].…”

Section: Introductionmentioning

confidence: 99%

Non-Destructive Evaluation of Carbon Fiber Composite Reinforcement Content

Dorsey

Hebner

Charlton

2004

Journal of Composite Materials

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The use of light-weight, high-strength composite materials in motors, generators, and energy storage devices has become common as a means to maximize energy density. To ensure reliability, non-destructive and destructive evaluation techniques have been employed to measure the mechanical properties of fabricated components. In carbon fiber-reinforced, polymer matrix composites, mechanical strength is primarily derived from the fiber volume fraction. Due to the lack of a nondestructive method, common techniques for fiber volume determination are currently destructive. In this investigation, a non-destructive method for the measurement of the fiber volume fraction of carbon fiber-reinforced, polymer matrix composites has been developed using cold neutron prompt gamma activation analysis (PGAA). Fiber volume determination is accomplished in this technique by measuring and comparing the carbon and hydrogen content in a given sample (or samples). PGAA is a nuclear analytical technique performed by exposing a sample to neutron radiation. PGAA measurements are non-destructive and can be performed without chemical preparation of the sample. Fiber volumes of several composite coupons have been determined relative to standard samples of known fiber volume and measurements are in good agreement with values predicted by acid digestion tests. Fiber volume measurement using PGAA can potentially be applied to any composite material where the contents of the matrix and reinforcement differ. The technique can also be spatially sensitive, with resolution limited by the dimensions of the neutron beam that is used.

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“…A competitor to the electrochemical battery is the flywheel, also known as the electromechanical battery [27], [28]. This has been evaluated for electric and hybrid electric vehicles, with considerable developments underway.…”

Section: B Electric Vehiclementioning

confidence: 99%

Trends in transportation sector technology energy use and greenhouse gas emissions

Ortmeyer

Pillay

2001

Proc. IEEE

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Concerns about air pollution, environmental degradation, and petroleum consumption have prompted policy makers in many countries to seek advanced transportation alternatives. In response to such societal needs, automobile manufacturers have developed vehicles which either replace the internal combustion engine with an electric motor or which provide a hybrid configuration with a combination of an IC engine (ICE) and an electric motor. In some concepts, fuel cells replace the IC engine in a hybrid vehicle configuration. Several of these technologies have been brought to market by auto manufacturers, with initial product offerings. In other cases, advanced concept cars are being developed to further these technologies. In response to these same concerns, research and development projects are underway to make the ICE vehicles more efficient. These projects have involved both improvements in engine/drive train efficiency as well as more efficient heating-cooling systems. This paper provides an overview of the transportation sector usage patterns, energy consumption, and emissions, and discusses the societal issues which impact decisions on transportation issues. The article then provides an overview of the electrotechnological advances which are being developed to address transportation energy use and emissions issues, and discusses the potential for emissions reduction through the successful deployment of these and competing technologies. The article concludes that reduction in transportation sector carbon emissions are achievable.

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NDE Methodologies for Composite Flywheels Certification

Cited by 9 publications

References 1 publication

Time-Temperature Dependent Response of Filament Wound Composites for Flywheel Rotors

Time-Temperature Dependent Response of Filament Wound Composites for Flywheel Rotors

Non-Destructive Evaluation of Carbon Fiber Composite Reinforcement Content

Trends in transportation sector technology energy use and greenhouse gas emissions

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