Intralaminar Shear Behavior of Continuous Fiber Reinforced Thermoplastics and its Quantification
Continuous fiber reinforced thermoplastics offer a great potential for lightweight construction. Due to a variety of forming techniques and the possible combination with other processes such as injection molding, high-performance parts can be manufactured with functional integration in cycle times suitable for large-series production. An obstacle in reaching higher market shares is, besides a partly high material cost, the still insufficient accuracy of processing simulations, which can be traced back to inadequate simulation methods and material characterization methods. For the forming simulation, current trends mainly aim at advancing mesoscopic approaches. The forming properties of continuous fiber reinforced thermoplastics result from a complex interaction of fibers and the polymeric matrix and usually follow a classification based on the corresponding textile forming mechanisms. Besides the bending behavior, the intra-laminar shear properties are the defining factor for the resulting macroscopic forming properties. The currently favored picture frame test for quantification of the intra-laminar shear properties is insufficiently researched, which leads to high deviations and insufficient reproducibility in measured data due to a variety of influences. Hence, this work aims at examining the intra-laminar shear behavior of continuous fiber reinforced thermoplastics to identify the major influencing factors, both on a material level as well as in interaction with the testing setup, in order to derive a widely usable method for reliable quantification of the intra-laminar shear properties. Major influencing factors originating in the picture frame test setup are sought to be identified and suggestions for their compensation are made. An additional aim is to advance the picture frame test to allow for insight into the mesoscopic material properties, which currently is limited to macroscopic evaluations, to bridge the current limitations in material testing and connect the test development to the current developments in simulation methods.