Deformation Modes of Continuous Fibre Reinforcements in Thermoplastic Composites during Thermoforming: A Preliminary Hierarchy and Geometrical Description

摘要

The use of thermoplastic composites in secondary and especially primary structures is still limited by lack of experience with the production of these composite products. More knowledge must be gained about the behavior of the material elements of the composites during thermoforming of laminates into products. The report surveys the possible deformation modes of the continuous fiber reinforcement during thermoforming of a thermoplastic composite sheet. Embedded fabric reinforcements can adjust to a product form in several ways. Movement of the composite layers relative to each other (interply phenomenon) occurs whenever the laminate is deformed. Fabric deformations can take place inside one single layer, depending on the complexity of the product to be formed. The intraply phenomena intraply shear, fiber straightening and elongation, and matrix pressure induced fiber motions will be geometrically described. Furthermore in the report some material and process variables are considered that have important influence on the deformation potential of a composite laminate. Several causes of fiber misalignment in composite products will be pointed out.