Speaker
Description
Fibre-reinforced thermoplastic composites are increasingly employed in structural applications due to their short production cycles, high recyclability, and excellent specific strength and stiffness. The production of three-dimensional shell-like structures involves the thermoforming of fibre-reinforced thermoplastic laminates (FRTPLs). This draping of the fibres within the melted polymer matrix relies on forming mechanisms, including inter- and intralaminar shearing, bending, and stretching, which also significantly affect manufacturing defects such as wrinkling and fibre breakage. However, the stretching behavior of laminates is inherently limited by the brittle tensile characteristics of the reinforcing fibres.
To enhance the formability of FRTPLs, fibre trimming within the laminate can be applied. This approach introduces additional degrees of freedom for laminate forming, enabling improved adaptability during the forming process. However, fibre trimming also weakens the structural properties (stiffness, strength) of the final component. Therefore, the objective is to minimize the number of trimmed fibres and to determine their locations in the initial, undeformed laminate. This ensures enhanced formability only in critical regions.
To identify optimal fibre trimming positions, a thermomechanically coupled simulation of the forming process is conducted. Using a macroscopic homogenized material model, describing the interlaminar shearing, regions with a strong strain localization during forming are identified. Subsequently, a mesoscale material model, accounting for the laminate's anisotropic behaviour during forming, is employed to analyse the forming results of the tailored FRTPL. This tailored laminate features localized fibre trimming in a multilayer configuration of unidirectional FRTP tapes. The numerical model is validated through experimental forming tests, confirming the effectiveness of the proposed approach.
