2018 Volume 67 Issue 4 Pages 453-459
The application of Glass Fiber Reinforced Thermoplastics (GFRTP) using continuous fibers is increasing in automotive industry due to their affordable prices with good mechanical properties. Diaphragm molding, which is one of molding methods of GFRTP, has the advantage in the molding cost because this method requires only a single die instead of the matched dies. In diaphragm molding, GFRTP are placed on the single mold and an upper diaphragm material is pressed against the mold by air pressure to mold. As a disadvantage of this method, since it is difficult to apply a blank holding force, wrinkles are easily formed. While in the laying-up test for FRP and the drape test for NCF, it has been reported that the formability was improved by using in-plane tension to the ± 45° direction of blank material, it is also expected in the diaphragm molding. To reduce the cost of trial molds and shorten a trial manufacture period, it is important to analyze the formability of the diaphragm molding. In this study, the diaphragm molding of GFRTP using in-plane tension by springs to ± 45° direction of blank material was conducted to improve the formability, and the FEM analysis of diaphragm molding was carried out and compared with the experimental result. By applying the in-plane tension to the blank material, the diaphragm molding formability was improved because of the larger shear angle of ± 45° direction of blank materials. The shear angle and wrinkle positions in diaphragm molding can be predicted by FEM analysis.
