| A common practice in injection molding is reinforcing the polymer matrix withshort fibers, the purpose being to improve the mechanical properties of the material.Properties are affected by the presence of the fibers include the elastic modulus, the tensile strength, and the thermal and electrical conductivities. The size of fiber varies.Usually the typical injection molded short-fiber dimension is about ten to twenty microns in radius and ten to fifty in aspect ratio. There are about roughly 10,000 fiber per cubic millimeter oriented in various direction.During the injection molding filling process, the suspended fibers orient in response to the kinematics of the flow. The orientation state of fibers changes with time and position. Consequently, the final microstructure of the solidified composite is complex.And the mechanical properties of the material are anisotropic. Fiber orientation can significantly affect the mechanical properly of parts, which either made parts developing anisotropic property or develop residual stress due to which solidified in the parts cause parts to warp deformation. Fiber orientation is the main properties of the parts' microstructure. Due to the role of the microstructure in determining the mechanical properties of composite product, it is very significant tocatch on and predict the oriented behavior of fibers indeed to control it.For predicting flow induced alignment, we could use two different methods. The fist one is based on using a fiber distribution function, which provides the probability of orienting particle in certain direction and is computationally intensive. A second approach is based on using the moments of the orientation distribution function (orientation tensor). We can get the fiber orientation in the parts by solving the evolution equation of the fiber orientation tensor. This approach requires a closure model since the equation governing the second moment of the orientation distribution function involves an unclosed fourth order tensor.For the short fiber reinforced composites, the motion of a single fiber was studied nalytically in simple shear flow and extensional flow with Jeffery dynamics equation.Besides, Orientation tensor is mainly used in this dissertation to study the fiber orientation. We construct the orientation tensor using the inner product of orientation vector and fiber istribution function by studying the fiber orientation behavior. Based on this, the property of the second and fourth order tensor, and the eigenvalues and invariants of orientation tensor which under different orientation states are discussed.This paper mainly discussed the digital image processing techniques in application of fiber image. Firstly, to process the fiber image so as to enhance the quality of the image, the aim of enhancing the fiber image is to give prominence to the whole and portion feature of the fiber image and improve the effect of vision and the feature of recognition. The method of enhancing the fiber image include gray,—scale transformation,image smoothing and image sharpening etc. gray-scale transformation adjust the gray-scale of the fiber's image and give prominence to the interested area. The method of image smoothing to process the fiber image can eliminate the noises that caused by digital process and transmission and improve the effect of vision. The method of image sharpening give prominence to the edge information of the fiber's image and strengthen the feature of contour so as to the extraction of basic feature, at last by comparison the results that were processed by some kinds of method of image sharpening can get which method is suit for this type of fiber's image.Secondly, there is a survey about image segmentation method including the fiber's image segmentation method, the survey indicate the principle and the characteristic of the segmentation methods. In this paper, the emphasis is the canny application of mathematical morphology to gray-scale fiber's image. Using this meathed to process the fiber image detect. |
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