Measurement of fiber wrinkles and shear angles of double dome forming parts

This study presents the results of a double dome forming study for fiber reinforced thermoplastics to give an estimation about wrinkles size and fiber angle values. The parts were formed with an industry-oriented process at different forming temperatures and fiber directions (0 °/ 90 ° and ±45 °). They were formed without blank holder to allow wrinkling. The investigated material is a glass fiber –reinforced polyamide 6 with three layers of twill fabric (TEPEX® Dynalite 102-RG600(3)/47 %). The wrinkles are measured with a laser scanner. The shear angles were calculated using image analysis in MATLAB. It determines the fiber directions and calculates the fiber angles at their crossing points. Afterwards, areas with positive and negative shear angle values will be identified and discussed: These areas are in an axially symmetrical formation. At one side there are positive shear angles and on the other side there are negative shear angles. But results show, that absolute values differ. Furthermore, the results show, that shear angles increase with increasing forming temperatures and wrinkles size decrease. The results of this work will be used for the validation of FE forming models of double dome part in further studies.