A NUMERICAL APPROACH FOR THE INJECTION MOLDING PROCESS OF SHORT-FIBER-REINFORCED COMPOSITES WITH CONSIDERING FIBER ORIENTATION

数値解析手法を用いた短繊維強化複合材料射出成形品の線維配向予測手法に関する研究

2015-03-25

2015-03-25

Being able to measure the fiber orientation distribution in the injection-molded composite parts is of considerable importance, since the distribution locally affects the mechanical and physical properties of the final part such as its strength, impact toughness, internal stress, and fatigue properties. In this study, I experimentally measured the fiber orientations in two injection-molded specimens produced from short-glass-fiber-reinforced plastic using plate-shaped cavities with and without a weld-line. As the results, the following technical findings were obtained. (1) The fiber orientation distributions were observed directly using a high-resolution three-dimensional (3D) X-ray computed tomography (CT) system XVA-160α. A simple method based on a series of X-ray CT images was developed to measure the orientation angles of the individual fibers. Thus, precise 3D calculations of the fiber orientations related to the second-order orientation tensor components were performed to obtain a consistent description of the observed behavior. This thesis explored a novel and powerful technique for observing and measuring fiber orientation, which can be used to test fiber orientation predictions. (2) I proposed a developed fiber interaction model that has been introduced a fiber dynamics simulation in order to obtain a global fiber interaction coefficient. This supposed that the coefficient is a function of the fiber concentration, aspect ratio, and angular velocity. This model has been developed and incorporated into simulations of injection molding with the emphasis on predicting final orientation pattern. The simulation was exercised for a variety of cases and showed a good agreement with experimental results. (3) A study on surface properties of embossed decorative injection-molded parts by experimental methods and numerical analysis was carried out. Herein, the behaviour of fountain flow in cavity filling on surface quality was discussed in detail. Finally, an approach to producing a favorable surface quality by considering the fiber orientation prediction of final part was proposed.

博士（学術）

京都工芸繊維大学

The thesis includes 6 chapters as follows:Chapter 1 "Introduction" introduces about how interesting Fiber reinforced plastic composite is, how important fiber orientation in FRP is,and about motivation, major findings in this thesis. Chapter 2 "Measurement Of Fiber Orientation Distribution In Injection-Molded Short-Glass-Fiber Composites" explains about experimental method to measure the fiber orientation distribution. Chapter 3 "Fundamental Orientation Theory" gives the information of fiber orientation theory and show how to model the fiber-fiber interaction in fiber-reinforced plastic. Chapter 4 "Numerical Approach For Fiber Orientation In Injection-Molded Short-Fiber/Thermoplastic Composites" introduces a numerical approach for fiber orientation in injection-molded short-fiber/thermoplastic composites using proposed model described in chapter 3. Chapter 5 "A Numerical And Experimental Study On Surface Properties Of Embossed Decorative Injection-Molded Parts" investigates the influence of the fiber orientation on the surface properties. Chapter 6 "Summary And Conclusion" provides general summary and conclusion of this thesis.

14303甲第749号

http://hdl.handle.net/10212/2263

en

ETD

Thesis or Dissertation

Thesis