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Process monitoring of resin permeation in fiber preform and fabric thickness variation in liquid composite molding (LCM) is important to ensure the quality of the composite parts. However, existing technologies cannot monitor both of them by a single sensor and may disrupt resin flow patterns or fiber deformation inside the part due to their large thickness or rigidity. To achieve accurate monitoring of the signals within the part during the LCM process, a thin and flexible Pt-coated film capacitive sensor was designed to minimize the effect of sensor on flow behaviour. The accuracy of the embedded sensor was verified by the consistent resin flow front and the negligible fiber deformation around the sensor. Moreover, the flow front, thickness variation and curing inside composites preform in LCM can be captured based on the variation of the capacitance curve and its second derivative. These results demonstrated that this multifunctional sensor offers a new solution to obtain signals accurately in the part in LCM. [ABSTRACT FROM AUTHOR]

Abstract: Numerous filler particles are being developed and applied to improve the properties of conventional composite materials or to develop composite materials with additional functionalities. When filler particles are added to the polymer matrix of a fiber-reinforced composite material, the particles dispersed in the polymer resin can be filtered between fiber strands during the manufacturing process, which leads to a nonuniform particle distribution and material defects. Therefore, understanding and controlling such filtration phenomena has become a critical issue. In the present study, a new microscopic methodology for measuring the distribution of filler particles in fully cured composite parts using an electron probe microanalyzer (EPMA) is proposed. The distributions of spherical titanium dioxide particles and carbon nanotubes conjugated with silver nanoparticles as tracers were visualized by elemental mapping analysis. Furthermore, the concentrations were separately measured in the intratow and intertow regions by quantitative analysis. [Copyright &y& Elsevier]

In Liquid Composite Molding (LCM) processes, a fabric reinforcement is placed in a closed cavity and resin is injected into the mold. Almost all reinforcements are dual scale containing fiber tows, which fill at a different rate than the region in between the fiber tows. Simulation of LCM processes can help identify regions that fail to fill. However, the presence of dual scale flow is usually neglected. Here this phenomenon is modeled using Liquid Injection Molding Simulation (LIMS) software in which a complex network of one-dimensional elements is created. This allowed us to simulate transverse and longitudinal flow through the fiber tows taking into consideration the orientation and architecture of the reinforcement and, additionally, adding capillary effects to the model. A sensitivity study has been performed to investigate the effects of properties in non-dimensional form, allowing for comparison with experiments that were conducted to validate the model by visualization of the flow front position and dual scale area dimensions. [Display omitted] • Dual scale flow simulation through complex one-dimensional elements network. • Simulation of anisotropic flow inside fiber tows with low computational effort. • Validation through experiments visualizing flow front and dual scale area. • Parametric study with non-dimensional properties showing model capability. • Study of tow compaction variability using experimental data. [ABSTRACT FROM AUTHOR]