In Situ Measurement of Fiber Bundle Orientation for Composite Manufacturing Process Via Binocular Vision Technology
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Abstract:
The accurate detection of fiber bundle orientation is vital to ensure the mechanical performance of composite manufacturing. However, the weak texture, high reflectivity and non-contactable properties of fiber bundle surfaces present challenges for existing inspections. In this work, a novel measurement method based on binocular vision reconstruction technology is proposed to measure fiber bundle with high accuracy in a simple way. This approach includes a "coarse-to-fine" target-free stereo matching strategy to reduce the mismatch and enhance the reconstruction accuracy. The strategy is proven to match the homologous points correctly in the numerical simulation. Experiments in the filament winding results show the dimensional accuracy error is less than 0.3% and the winding angle deviation is 1°. As a conclusion, the proposed method is validated for its efficiency and high precision in obtaining fiber bundle trajectories and winding angles.Keywords:
Bundle adjustment
Manufacturing process
Hollow fiber membranes are popular as they have a high specific membrane area. To take advantage of this, it is necessary to pack the fibers into closely packed bundles. The fibers in different positions in the bundle behave differently as they are exposed to different hydrodynamic conditions. In this paper, a ‘model’ bundle of 9 fibers was tested in a setup which provides flow measurement from individual fibers and the same suction pressure in each fiber. The parameters studied were packing density, cross flow velocity, feed concentration and bubbling. It was found that a low cross flow velocities, high pressures and high feed concentrations, the surrounded (center) fiber performed very poorly compared to the fibers at the corner and the sides. Under these conditions, the overall performance of the bundle was much worse that of a single fiber.
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Fiber bundles with statistically distributed thresholds for breakdown of individual fibers are interesting models of the static and dynamics of failures in materials under stress. They can be analyzed to an extent that is not possible for more complex materials. During the rupture process in a fiber bundle avalanches, in which several fibers fail simultaneously, occur. We study by analytic and numerical methods the statistics of such avalanches, and the breakdown process for several models of fiber bundles. The models differ primarily in the way the extra stress caused by a fiber failure is redistributed among the surviving fibers.
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The statistical properties of failure are studied in a fiber bundle model with thermal noise. We show that the macroscopic failure is produced by a thermal activation of microcracks. Most importantly, the effective temperature of the system is amplified by the spatial disorder (heterogeneity) of the fiber bundle. These results give new insight to the study of thermally activated cracks and they can be useful in the study of electrical networks.
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Based on computational modelling the influence of disorder on the rupture process of fibrous materials have been evaluated. This has been done by simulating a bundle of parallel fibers under a constant uniaxial force. The disorder process was introduced by randomly assigning a strength threshold to each fiber of the bundle according to the Weibull distribution. The results indicate that the rupture process is extremely sensitive to the disorder level. In particular, we demonstrated that the load necessary to break a fiber bundle with large disorder is smaller than that necessary to break a fiber bundle with small disorder.
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The precise characterization of the microstructure of bundle is essential for an accurate determination of their properties and behavior. This paper presents a study on the microstructure of continuous fiber bundles by Serial Sectioning Method. Bundle is firstly cured by resin to keep the fiber spatial configuration in the bundle. A series of cross-section images vertical to the bundle direction are captured and polished enough to take digital photographs by the Charge-coupled Device (CCD) microscope. A 3D solid microstructure of the bundle is implemented by linking the correspondent circle for separate fiber in the 3D solid software Pro/E. Reconstructed bundle structure truly represents the spatial configuration of the fibers in the bundle.
Bundle adjustment
Section (typography)
Characterization
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Abstract In this paper we dealt with the problem of wetting and ascending of a liquid along a fiber bundle. Two issues are first addressed including the criterion for complete wetting of the fiber bundle and the ascension liquid profile on a partially dipped vertical fiber bundle. Both topics are studied theoretically by deriving a mathematical theory by which predictions are generated and important parametric analyses are carried out. Further, a 3D Ising model is used for computer modeling to simulate the fiber wetting and liquid ascending processes on a partially dipped single fiber. The significance and potential applications of the study are also summarized.
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A study on the strength of ceramic fiber bundles based on experimental and computational procedures is presented. Tests were performed on single filaments and bundles composed of two fibers with different nominal fiber counts. A method based on fiber rupture signals was developed to estimate the amount of filament rupture during the test. Through this method, the fiber bundle true strength was determined and its variation with the initial fiber count observed. By using different load-sharing models and the single filament data as input parameter, simulations were also developed to verify this behavior. Through different approaches between experiments and simulations, it was noted that the fiber bundle true strength increased with the fiber count. Moreover, a variation of the fibers’ final proportion in the bundles relative to the initial amount was verified in both approaches. Finally, discussions on the influence of different load-sharing models on the results are presented.
Load sharing
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Fiber optic imaging systems are used in many applications, including medical imaging, machinery diagnostics, and remote sensing. Most commonly, coherent bundles of optical fibers are used that maintain the spatial positioning of each fiber throughout the length of the bundle, resulting in a recognizable proximal (camera side) image that is almost identical to the distal image projected into the bundle by the lens. Although coherent fiber bundles provide excellent solutions for many imaging applications, their limited flexibility and thermal stress intolerance may prohibit them from being used in harsh or complex environments. The flexibility and thermal tolerance of a fiber imaging system can be significantly improved by using an incoherent bundle of fibers wherein the spatial positioning of each fiber is not preserved throughout the length of the bundle. Incoherent bundles need to be calibrated to provide the means to reconstruct distal imagery. In reported calibration schemes, the calibration time is strongly dependent on the ratio between the bundle size and the fiber size. The calibration time can thus become prohibitive for highly resolved images using many fibers. A novel calibration scheme is described for incoherent bundles where the calibration time is proportional to the bundle-to-fiber size ratio, resulting in significantly reduced processing time and enabling more highly resolved images. As an added benefit for medical and remote sensing applications, incoherent light guides scramble the scene images, which may provide a desirable level of data privacy.
Bundle adjustment
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Yarns modeling are the key problem for tufted carpet 3D visual simulation. This paper deals with three-dimensional yarns structure modeling for tufted carpet simulation. The yarn is modeled as an assembly of fiber bundles which also include of a lot of fibers. to simulate fiber bundle dividing fiber bundle into many segments along its trajectory, and each fiber paths displayed are generated by NURBS curves. Through control the control points and color of NURBS to get certain cross-section and color effect of fiber bundle outlook. And finally use the fiber bundle to form the final yarn model. Test result shown the modeling method is suitable for carpet simulation.
Section (typography)
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The effect of oxidation on the stress-rupture behavior of fiber bundles was modeled. It is shown that oxidation-induced fiber strength degradation results in the delayed failure of the associated fiber bundle and that the fiber bundle strength decreases with time as t-1/4. It is also shown that the temperature dependence of the bundle loss of strength reflects the thermal dependence of the mechanism controlling the oxidation of the fibers. The effect of gauge length on the fiber bundle strength was also analyzed. Numerical examples are presented for the special case of Nicalon™ fibers.
Degradation
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