Prediction Of Injection Molded Short Fiber Reinforced Composite Fiber Orientation Distribution

Prediction of fiber orientation distributing in short-fiber-reinforced composites injection moldingDuring injection molding of the fiber reinforced composites, fiber orientation can significantly affect the mechanical property 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.So a prediction of the fiber orientation can analyze mechanical properties with relation to fiber orientation,which satisfy with the need of controling and prediction parts' properties.Therefore,an accurate prediction in producting the parts is very important.Aiming at the progress of injection molding the short fiber reinforced composites, we predict the orientation distributing of the final parts by numerical methods.To analyze fiber orientation and predict the orientation distributing of the final parts, which not only provide the important criterion for the part-designed ,but also building a quantitative relation between the molding technics and the fiber orientation of the final parts.The main result are as follow:1) To study dynamics properties of an elliptical shape mass point(fiber) immersed in Newton fluid .To analyze the motion of the fiber in steady shearing flow and simple stretching flow.The analytic solution showed:shearing flow tend to align fibers in the direction of flow, stretching flows tend to align fibers in the direction of stretching.2) The important purpose is to study the properties of orientation tensor, the relation between orientation tensor and orientation distribution function,the description accuracy of orientation tensor, and the accuracy of the closure approximation of orientation tensor.3) During numerical prediction of fiber orientation induced by injection molding flow, considering the short fiber reinforced composites melt as concentrated suspension, adopting Hele-Shaw model approximate the velocity field in cavity.We believe that the fiber is cylindric rigid body,describing the orientation state of spatial point by ODE,and demonstrating the behavior of the fiberorientation by adopting Folgar-Tucker orientation model.4) A finite-element/finite-difference program is employed to predict the orientation distributing of fiber reinforced injection molding parts.To predict the filling pattern of the melt in the molding progress and the fiber orientation distribution of the final parts by analyzing the flow of the fiber reinforced composites melt and fiber orientation.