Numerical Investigation of the Orientability of Single Reinforcement Fibers in Polymer Matrices

Reinforced Polymer Composites III

The development of modern technology requires the development of new materials with improved operational and technological properties [...].

Modelling and Simulation Strategies for Fluid-Structure-Interactions of Highly Viscous Thermoplastic Melt and Single Fibres-A Numerical Study

A virtual test setup for investigating single fibres in a transverse shear flow based on a parallel-plate rheometer is presented. The investigations are carried out to verify a numerical representation of the fluid-structure interaction (FSI), where Arbitrary Lagrangian-Eulerian (ALE) and computational fluid dynamics (CFD) methods are used and evaluated. Both are suitable to simulate flexible solid structures in a transverse shear flow. Comparative investigations with different model setups and increasing complexity are presented. It is shown, that the CFD method with an interface-based coupling approach is not capable of handling small fibre diameters in comparison to large fluid domains due to mesh dependencies at the interface definitions. The ALE method is more suited for this task since fibres are embedded without any mesh restrictions. Element types beam, solid, and discrete are considered for fibre modelling. It is shown that the beam formulation for ALE and 3D solid elements for the CFD method are the preferred options.

Effect of carbon fiber reinforcement on dimensional variations of 3D printed polyamide-6 composites: A simulation study

Due to material design and fabrication flexibility, additive manufacturing (AM) or 3D printing (3DP) processes and polymer composites have paved their way into several industrial sectors. The quality of 3D printed polymer composites is highly dependent on the reinforcement content of polymers and 3DP process parameters. Several experimental studies are performed to optimize the reinforcement contents and process parameters; however, exploring the numerical modeling and simulation techniques is vital to lower the research and development costs. In the study, the numerical simulations for the 3DP process were performed using Digimat® software for carbon fiber-reinforced polyamide-6 (PA6) composites fabricated via the fused filament fabrication (FFF) process to evaluate the effect of reinforcement content on deflections, warpages, and process-induced residual stresses. The FFF process simulations were performed to fabricate tensile testing coupons with pure PA6 and 10%-28% CF-reinforced PA6 composites. A significant impact of CF-reinforcement was observed on the deflections, warpages, and residual stresses. The maximum displacement of 4.518 mm and critical warpage of 3.012 was observed for pure PA6 material. However, with the addition of CF reinforcement, a maximum deflection of 3.369 mm and critical warpage of 2.246 was achieved for PA6 reinforced with 28% CF (PA6-CF28). The improved 3D printed specimen quality was acquired at the cost of increased residual stresses of 14.53 MPa compared to 11.75 MPa in pure PA6 specimen. The CF reinforcement significantly improved the 3DP manufacturing performance of PA6/CF composites, reducing deflections and warpages.

Control of Molecular Orientation and Carrier Transport of Thiophene-Based Semiconducting Polymer via Superparamagnetic Nanoparticles Fe3O4@C-Assisted Magnetic Alignment Method

Realizing the high molecular orientation and structurally ordered microstructure of organic semiconductor polymer thin films is beneficial for enhancing the charge transport of conjugated polymers and achieving high-performance organic electronic devices. In this work, we successfully developed large-area highly aligned films of a thiophene-based polymer, namely poly(2,5-bis(3-alkylthiophen-2-yl) thieno [3,2-b] thiophene) (PBTTT), using the magnetic alignment method at a low magnetic field (0.12 T), which was assisted by superparamagnetic nanoparticles Fe3O4@C. The aligned microstructure of the composite films is confirmed by systematic analysis that includes polarized optical microscopy, polarized UV–visible absorption spectroscopy, and an atomic force microscope. Organic field effect transistors based on magnetic aligned composite film exhibit a 2.8-fold improvement in carrier mobility compared with the unaligned films. We hold a formation mechanism that the rapid magnetically induced self-assembly property of Fe3O4@C and its intermolecular interaction with polymer chains are key to the new method of preparing oriented thin films.